JP7764322B2 - Method for manufacturing non-aqueous secondary battery - Google Patents

Description

The present invention relates to a method for manufacturing a non-aqueous secondary battery, and more specifically to a method for manufacturing a non-aqueous secondary battery that can suppress deterioration of the spring constant of the electrode assembly.

Conventional non-aqueous secondary batteries include an electrode assembly having a negative electrode plate, a positive electrode plate, and a separator. Such an electrode assembly is wound in a winding direction with the negative electrode plate, positive electrode plate, and separator stacked in a stacking direction, and is housed in a battery case together with a non-aqueous electrolyte in a state having flat and curved areas.

One method for manufacturing such nonaqueous secondary batteries, as disclosed in Patent Document 1, is to insert spacers with ribs that have different spring constants in the flat and curved regions of the electrode assembly to maintain a constant distance between the plates in each region. This manufacturing method maintains a constant distance between the plates in the flat and curved regions of the electrode assembly even if the flat regions of the electrode assembly expand, thereby suppressing metal deposition in the flat regions of the electrode assembly.

JP 2017-98107 A

However, in the invention described in Patent Document 1, if the distance between the electrode plates in the electrode assembly is shorter than expected, the electrode assembly will be constrained more than necessary. In such cases, there is a risk that the spring constant of the electrode assembly will deteriorate due to the electrode assembly being constrained.

Various aspects of the method for manufacturing a nonaqueous secondary battery that solves the above problems will be described.
[Aspect 1] A method for manufacturing a nonaqueous secondary battery comprising an electrode assembly having a negative electrode plate, a positive electrode plate, and a separator disposed between the negative electrode plate and the positive electrode plate, the method including: an inter-electrode measurement step of measuring the distance between the electrode plates at a predetermined timing during an unconstrained period in which the electrode assembly is not constrained; and an adjustment step of adjusting the constraint force on the electrode assembly in accordance with the distance between the electrode plates measured in the inter-electrode measurement step.

With this configuration, the restraining force on the electrode assembly can be adjusted according to the condition of the electrode assembly, i.e., the distance between the electrode plates actually measured during the non-restraint period. This prevents metal deposition caused by an increase in the distance between the electrode plates, and also prevents deterioration of the spring constant of the electrode assembly.

[Aspect 2] In the method for manufacturing a nonaqueous secondary battery described in [Aspect 1], the adjustment step may include not restraining the electrode assembly when the distance between the electrode plates measured in the electrode-to-electrode measurement step is equal to or less than a first distance, and restraining the electrode assembly when the distance between the electrode plates measured in the electrode-to-electrode measurement step is greater than the first distance.

With the above configuration, when the distance between the electrodes actually measured during the non-restraint period is equal to or less than the first distance, the electrode assembly is not restrained, thereby minimizing the restraint on the electrode assembly and suppressing deterioration of the spring constant of the electrode assembly. On the other hand, when the distance between the electrodes is longer than the first distance, metal deposition can be suppressed by restraining the electrode assembly. Therefore, metal deposition caused by an increase in the distance between the electrodes can be suppressed, and deterioration of the spring constant of the electrode assembly can be suppressed.

[Aspect 3] In the method for manufacturing a nonaqueous secondary battery described in [Aspect 2], the adjustment step may also include restraining the electrode assembly with a stronger restraining force when the distance between the electrode plates measured in the electrode-to-electrode measurement step is longer than the second distance, compared to when the distance between the electrode plates is greater than the first distance and equal to or less than a second distance longer than the first distance.

With the above configuration, when the distance between the electrodes actually measured during the non-restraint period is longer than the second distance, the electrode assembly is restrained with a stronger restraining force than when the distance is longer than the first distance and equal to or less than the second distance, thereby suppressing metal deposition caused by the longer distance between the electrodes. On the other hand, when the distance between the electrodes actually measured during the non-restraint period is longer than the first distance and equal to or less than the second distance, the electrode assembly is restrained with a weaker restraining force than when the distance is longer than the second distance. This suppresses metal deposition caused by the longer distance between the electrodes and also suppresses deterioration of the spring constant of the electrode assembly.

[Aspect 4] In the method for manufacturing a nonaqueous secondary battery described in any one of [Aspects 1] to [Aspect 3], the electrode gap measurement step may measure the distance between the electrode plates at a timing when a predetermined time has elapsed since the electrode plates entered the unconstrained state during the unconstrained period.

With the above configuration, by measuring the distance between the electrodes a predetermined time after the electrode is released, measurement errors due to the timing of measuring the distance between the electrodes can be reduced.

[Aspect 5] In the method for manufacturing a nonaqueous secondary battery described in [Aspect 1], the electrode gap measurement step may measure the distance between the electrode plates at a first timing and a second timing that occurs a specified time after the first timing during the non-constraint period, and the adjustment step may be capable of adjusting the constraint force on the electrode assembly based on the distance between the electrode plates measured at the first timing and the distance between the electrode plates measured at the second timing in the electrode gap measurement step.

With the above configuration, the restraining force on the electrode assembly can be adjusted according to the distance between the electrode plates measured at a first timing and a second timing, which is a specified time after the first timing. This increases the accuracy of adjusting the restraining force on the electrode assembly. This prevents metal deposition caused by an increase in the distance between the electrode plates, and also prevents deterioration of the spring constant of the electrode assembly.

[Aspect 6] The method for manufacturing a nonaqueous secondary battery described in [Aspect 5] may include a gap prediction step of predicting a third time when the distance between the electrode plates will become the first distance, based on the distance between the electrode plates measured at the first timing in the gap measurement step and the distance between the electrode plates measured at the second timing, and the adjustment step may include restraining the electrode assembly at the third time predicted in the gap prediction step.

With the above configuration, by predicting the third timing at which the distance between the electrode plates will be the first distance, the electrode body can be restrained at that third timing. This allows the distance between the electrode plates to be adjusted to the first distance. Therefore, metal deposition caused by an increase in the distance between the electrode plates can be suppressed, and deterioration of the spring constant of the electrode body can be suppressed.

[Aspect 7] A method for manufacturing a non-aqueous secondary battery comprising an electrode assembly having a negative electrode plate, a positive electrode plate, and a separator disposed between the negative electrode plate and the positive electrode plate, a non-aqueous electrolyte, and a battery case containing the electrode assembly and the non-aqueous electrolyte, the method comprising: an inter-electrode measurement step of measuring the distance between the electrode plates at a predetermined timing during an unconstrained period in which the electrode assembly is not constrained; an injection step of injecting the non-aqueous electrolyte into the battery case with the electrode assembly contained therein; and a sealing step of sealing the battery case with the electrode assembly and the non-aqueous electrolyte contained therein, wherein the sealing step shortens the time from when the non-aqueous electrolyte is injected into the battery case in the injection step to when the battery case is sealed, in accordance with the distance between the electrode plates measured in the inter-electrode measurement step.

With the above configuration, the time from when the non-aqueous electrolyte is poured into the battery case to when the battery case is sealed can be shortened depending on the state of the electrode assembly, i.e., the distance between the electrodes actually measured during the unconstrained period. This allows the pressure inside the battery case to be intentionally reduced. This increases the self-constraint force acting on the electrode assembly, preventing the distance between the electrodes in the electrode assembly from increasing. This prevents metal deposition due to an increase in the distance between the electrodes, minimizes constraint on the electrode assembly, and prevents deterioration of the spring constant of the electrode assembly.

[Aspect 8] In the method for manufacturing a nonaqueous secondary battery described in [Aspect 7], the sealing step may shorten the time from when the nonaqueous electrolyte is injected into the battery case in the liquid injection step to when the distance between the electrode plates measured in the liquid interelectrode measurement step is equal to or less than a predetermined distance.

With this configuration, when the distance between the electrodes actually measured during the non-restraint period is equal to or less than a predetermined distance, the pressure inside the battery case can be intentionally reduced. This increases the self-restraint force acting on the electrode assembly, effectively preventing the distance between the electrodes in the electrode assembly from increasing. This effectively prevents metal deposition caused by the increased distance between the electrodes.

[Aspect 9] The method for manufacturing a nonaqueous secondary battery according to [Aspect 7] or [Aspect 8] further includes a charging step of charging the nonaqueous secondary battery after the sealing step is completed, and an aging step of storing the nonaqueous secondary battery after the charging step is completed, and the aging step may store the nonaqueous secondary battery in the unconstrained state if the time from when the nonaqueous electrolyte is injected into the battery case to when the battery case is sealed is shortened.

With this configuration, if the time between injecting the nonaqueous electrolyte into the battery case and sealing the battery case is shortened, the nonaqueous secondary battery is stored in an unconstrained state during the aging process. This minimizes the constraints on the electrode assembly, preventing deterioration of the electrode assembly's spring constant.

This invention makes it possible to suppress deterioration of the spring constant of the electrode body.

1 is a perspective view of a lithium ion secondary battery according to an embodiment of the present invention; FIG. 2 is a schematic diagram showing the configuration of a laminate of an electrode body of a lithium ion secondary battery. 1 is a flowchart showing a manufacturing process of a lithium ion secondary battery. FIG. 2 is a schematic diagram showing a restraint table. FIG. 1 is a schematic diagram showing an embodiment. 1 is a flowchart showing a manufacturing process of a lithium ion secondary battery. FIG. 10 is a schematic diagram showing a prediction result based on a measurement result of the electrode distance. 1 is a flowchart showing a manufacturing process of a lithium ion secondary battery.

[First embodiment]
Hereinafter, one embodiment of a method for manufacturing a nonaqueous secondary battery will be described.
<Lithium-ion secondary battery 10>
As an example of a nonaqueous secondary battery, the structure of a lithium ion secondary battery will be described.

As shown in FIG. 1, the lithium-ion secondary battery 10 is configured as a cell battery. The lithium-ion secondary battery 10 includes a battery case 11. The battery case 11 includes a lid 12. The battery case 11 includes an opening (not shown) on the upper side. The lid 12 seals the opening. The battery case 11 is made of a metal such as an aluminum alloy. The lid 12 includes a negative electrode external terminal 13 and a positive electrode external terminal 14 used for charging and discharging power. The negative electrode external terminal 13 and the positive electrode external terminal 14 may have any shape.

The lithium-ion secondary battery 10 includes an electrode assembly 15. The lithium-ion secondary battery 10 also includes a negative electrode current collector 16 and a positive electrode current collector 17. The negative electrode current collector 16 connects the negative electrode of the electrode assembly 15 to the negative electrode external terminal 13. The positive electrode current collector 17 connects the positive electrode of the electrode assembly 15 to the positive electrode external terminal 14. The electrode assembly 15 is housed inside the battery case 11.

The lithium-ion secondary battery 10 contains a non-aqueous electrolyte 18. The non-aqueous electrolyte 18 is injected into the battery case 11 through a filling hole (not shown). The lithium-ion secondary battery 10 is formed into a sealed battery case by attaching a lid 12 to the opening of the battery case 11. In this way, the battery case 11 contains the electrode assembly 15 and the non-aqueous electrolyte 18.

<Nonaqueous electrolyte 18>
The nonaqueous electrolyte 18 is a composition in which a supporting salt is contained in a nonaqueous solvent. In this embodiment, ethylene carbonate (EC) can be used as the nonaqueous solvent. The nonaqueous solvent may be one or more materials selected from the group consisting of propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), etc.

The supporting salt may be _LiPF6 , _LiBF4 , _LiClO4 , _{LiAsF6 , LiCF3SO3 ,} LiC4F9SO3, LiN( _{CF3SO2 ) 2} , LiC( _{CF3SO2 ) 3} , LiI, or the like. Alternatively, one or more lithium compounds (lithium salts) selected _from these may be used. Thus, the nonaqueous electrolyte ₁₈ contains a lithium compound.

<Electrode body 15>
As shown in Fig. 2, the electrode body 15 includes a negative electrode plate 20, a positive electrode plate 30, and a separator 40. The longitudinal direction of the electrode body 15 is referred to as the "lengthwise direction Z." The thickness direction of the electrode body 15 is referred to as the "thickness direction D." The direction intersecting the lengthwise direction Z and the thickness direction D of the electrode body 15 is referred to as the "widthwise direction W." One direction of the widthwise directions W is referred to as the "first widthwise direction W1," and the other direction of the widthwise directions W is referred to as the "second widthwise direction W2." In other words, the second widthwise direction W2 is the opposite direction to the first widthwise direction W1.

The electrode body 15 is made up of a negative electrode plate 20, a positive electrode plate 30, and a separator 40 stacked in the thickness direction D. The separator 40 is provided between the negative electrode plate 20 and the positive electrode plate 30. More specifically, the electrode body 15 is stacked in the following order: separator 40, positive electrode plate 30, separator 40, and negative electrode plate 20.

The electrode assembly 15 is formed by stacking the negative electrode plate 20, positive electrode plate 30, and separator 40 in the thickness direction D and winding them in the length direction Z. The electrode assembly 15 has a flattened shape in the thickness direction D at the center of the length direction Z.

In this way, the thickness direction D in which the negative electrode plate 20, positive electrode plate 30, and separator 40 are stacked can also be referred to as the stacking direction. Furthermore, the length direction Z in which the negative electrode plate 20, positive electrode plate 30, and separator 40 are wound can also be referred to as the winding direction.

The electrode body 15 has a flat shape in the thickness direction D. The electrode body 15 has a flat region and a curved region in the length direction Z. The flat region is a region that has a flat shape in the thickness direction D. The curved region is a region that has a curved shape in the thickness direction D. The curved regions are located at both ends of the flat region in the length direction Z.

<Negative electrode plate 20>
The negative electrode plate 20 functions as an example of a negative electrode of the lithium-ion secondary battery 10. The negative electrode plate 20 includes a negative electrode substrate 21 and a negative electrode mixture layer 22. The negative electrode mixture layer 22 is provided on both sides of the negative electrode substrate 21.

The negative electrode substrate 21 has a negative electrode connection portion 23. The negative electrode connection portion 23 is an area on both sides of the negative electrode substrate 21 where the negative electrode composite layer 22 is not provided. The negative electrode connection portion 23 is provided at the end of the electrode body 15 in the first width direction W1. The negative electrode connection portion 23 is exposed from the positive electrode plate 30 and the separator 40 in the first width direction W1.

In this embodiment, the negative electrode substrate 21 is made of Cu foil. The negative electrode substrate 21 serves as the base material for the negative electrode composite layer 22. The negative electrode substrate 21 functions as a current collecting member that collects electricity from the negative electrode composite layer 22.

The negative electrode mixture layer 22 contains a negative electrode active material. In this embodiment, the negative electrode active material is a material capable of absorbing and releasing lithium ions, and is a powdered carbon material such as graphite. The negative electrode plate 20 is produced, for example, by kneading the negative electrode active material, a solvent, and a binder, and then applying the kneaded negative electrode mixture paste to the negative electrode substrate 21 and drying it.

<Positive electrode plate 30>
The positive electrode plate 30 functions as an example of a positive electrode of the lithium ion secondary battery 10. The positive electrode plate 30 includes a positive electrode substrate 31 and a positive electrode mixture layer 32. The positive electrode mixture layer 32 is provided on both sides of the positive electrode substrate 31.

The positive electrode substrate 31 has a positive electrode connection portion 33. The positive electrode connection portion 33 is an area on both sides of the positive electrode substrate 31 where the positive electrode composite layer 32 is not provided. The positive electrode connection portion 33 is provided at the end of the electrode body 15 in the second width direction W2. The positive electrode connection portion 33 is exposed from the negative electrode plate 20 and the separator 40 in the second width direction W2.

In this embodiment, the positive electrode substrate 31 is made of Al foil or Al alloy foil. The positive electrode substrate 31 serves as the base material for the positive electrode composite layer 32. The positive electrode substrate 31 functions as a current collecting member that collects electricity from the positive electrode composite layer 32.

The positive electrode mixture layer 32 contains a positive electrode active material. The positive electrode active material is a material capable of absorbing and releasing lithium, such as lithium cobalt oxide (LiCoO ₂ ), lithium manganese oxide (LiMn ₂ O ₄ ), or lithium nickel oxide (LiNiO ₂ ). Alternatively, a material obtained by mixing LiCoO ₂ , LiMn ₂ O ₄ , and LiNiO ₂ in any ratio may be used. The positive electrode mixture layer 32 also contains a conductive material. Examples of the conductive material include carbon black such as acetylene black (AB) or ketjen black, and graphite. The positive electrode plate 30 is fabricated by, for example, mixing a positive electrode active material, a conductive material, a solvent, and a binder, applying the mixed positive electrode mixture paste to the positive electrode substrate 31, and then drying the mixture.

<Separator 40>
The separator 40 is provided between the negative electrode plate 20 and the positive electrode plate 30. The separator 40 holds the non-aqueous electrolyte solution 18. The separator 40 is a non-woven fabric made of a porous resin such as polypropylene. The separator 40 may be a porous polymer membrane such as a porous polyethylene membrane, a porous polyolefin membrane, or a porous polyvinyl chloride membrane, or a lithium ion or ion conductive polymer electrolyte membrane, either singly or in combination. When the electrode assembly 15 is immersed in the non-aqueous electrolyte solution 18, the non-aqueous electrolyte solution 18 permeates the separator 40 from the edges toward the center.

<Manufacturing Process of Lithium-ion Secondary Battery 10>
3, a manufacturing process for the lithium-ion secondary battery 10 of this embodiment will be described. The manufacturing process for the lithium-ion secondary battery 10 of this embodiment includes steps S10 to S22. That is, the manufacturing method for the lithium-ion secondary battery 10 of this embodiment includes steps S10 to S22.

As shown in FIG. 3, in this embodiment, a source process is performed in step S10. The source process is a process for fabricating the battery elements of the lithium-ion secondary battery 10. Specifically, the source process is a process for fabricating the negative electrode plate 20 and the positive electrode plate 30 that constitute the battery elements of the lithium-ion secondary battery 10.

Once the sourcing process is completed, the assembly process is carried out in step S11. This is the process of assembling the lithium-ion secondary battery 10. In detail, the assembly process includes a winding process, a flattening press process, a case insertion process, a liquid injection process, and a sealing process.

The assembly process begins with a winding process in step S12. In this process, the electrode body 15 is wound with the positive electrode plate 30 and the negative electrode plate 20 stacked with the separator 40 in between. Specifically, the electrode body 15 is wound in the longitudinal direction Z while supported around the winding axis, with the negative electrode plate 20 and the positive electrode plate 30 stacked with the separator 40 in between.

Next, in step S13, a flattening press process is performed. In this process, pressure is applied from the thickness direction D, so that the end portion, as viewed from the width direction W, is flattened into a racing track-like shape. The negative electrode connection portion 23 is also pressed into contact with the positive electrode connection portion 33. The electrode body 15 is manufactured through the above procedure.

Next, in step S14, a case insertion process is performed. In this process, the electrode assembly 15 is inserted into the battery case 11. At this time, the positive electrode connection portion 33 is electrically connected to the positive electrode external terminal 14 via the positive electrode current collector 17. The negative electrode connection portion 23 is electrically connected to the negative electrode external terminal 13 via the negative electrode current collector 16. The battery case 11 and the lid 12 are then sealed by laser welding or the like, thereby closing the opening in the battery case 11 with the lid 12. At this stage, the nonaqueous electrolyte 18 has not yet been poured, and the pouring hole in the lid 12 is open.

Next, in step S15, the liquid injection process is performed. The liquid injection process is a process of injecting non-aqueous electrolyte 18 into the battery case 11 through an injection hole (not shown). In other words, the liquid injection process is a process of injecting non-aqueous electrolyte 18 into the battery case 11 with the electrode assembly 15 housed inside. As a result, the electrode assembly 15 and non-aqueous electrolyte 18 are housed inside the battery case 11.

Next, in step S16, a sealing process is performed. In the sealing process, after the injection of the nonaqueous electrolyte 18 into the battery case 11 is completed, the injection hole is sealed to hermetically seal the battery case 11. In other words, the sealing process is a process of sealing the battery case 11 with the electrode assembly 15 and nonaqueous electrolyte 18 housed in the battery case 11. Through the above procedure, the lithium-ion secondary battery 10 is assembled.

Once the assembly process is completed, the activation process is performed in step S17. This activation process activates the lithium-ion secondary battery 10. Specifically, the activation process includes a charging process and an aging process.

The activation process begins with a charging process in step S18. The charging process is a process of charging the lithium-ion secondary battery 10 after the sealing process is completed. In particular, the charging process is a process of initially charging the lithium-ion secondary battery 10 assembled in the assembly process for purposes such as forming an SEI (Solid Electrolyte Interphase) coating. The charging process is performed with the lithium-ion secondary battery 10 in a constrained state. In this way, by placing the lithium-ion secondary battery 10 in a constrained state, the electrode body 15 housed in the lithium-ion secondary battery 10 is also in a constrained state. "Constraining" refers to applying pressure to the electrode body 15 directly or indirectly in the thickness direction D.

Next, in step S19, an aging process is performed. The aging process is a process in which the charged lithium-ion secondary battery 10 is stored after the charging process is completed. The aging process chemically stabilizes and activates the lithium-ion secondary battery 10. One of its purposes is to detect minute short circuits between electrodes caused by minute metal particles present in the electrodes. In this embodiment, the aging process may be performed by keeping the battery at a high temperature of approximately 60°C, but it may also be performed at an ambient temperature of approximately 20°C. In this embodiment, the aging process is performed while the lithium-ion secondary battery 10 is restrained.

When the activation process is complete, the lithium-ion secondary battery 10 is changed from a constrained state to an unconstrained state. By changing the lithium-ion secondary battery 10 to an unconstrained state in this way, the electrode body 15 housed in the lithium-ion secondary battery 10 also becomes unconstrained. The lithium-ion secondary battery 10 is then manufactured as a cell battery, undergoes shipping inspection, and awaits assembly into a stack.

<Lithium deposition resistance and spring constant>
When the lithium ion secondary battery 10 changes from a constrained state to an unconstrained state after the activation process is completed, the electrode body 15 housed in the lithium ion secondary battery 10 may swell over time, increasing the distance between the negative electrode plate 20 and the positive electrode plate 30. Hereinafter, the distance between the negative electrode plate 20 and the positive electrode plate 30 will be referred to as the inter-electrode distance.

One reason the inter-electrode distance increases is that the wound electrode body 15 physically loosens over time. Another reason the inter-electrode distance increases is that gas is generated by a chemical reaction in the wound electrode body 15 over time.

As such, when the inter-electrode distance increases, the non-aqueous electrolyte 18 present between the negative electrode plate 20 and the positive electrode plate 30 becomes less likely to be pushed out of the electrode body 15. As a result, the amount of non-aqueous electrolyte 18 present between the negative electrode plate 20 and the positive electrode plate 30 becomes excessively large. This accelerates metal elution, thereby worsening the metal deposition resistance and thus the lithium deposition resistance.

On the other hand, by keeping the electrode body 15 in a constrained state even after the activation process is complete, it is possible to prevent the inter-electrode distance from becoming longer. This prevents a deterioration in lithium deposition resistance.

However, if the electrode body 15 is constrained more than necessary, the electrode body 15 will be crushed excessively. This could result in a deterioration in the spring constant of the electrode body 15. In particular, if an electrode body 15 with an inter-electrode distance that is not too long is constrained, the spring constant of the electrode body 15 will deteriorate even though the lithium deposition resistance will not deteriorate. However, constraining an electrode body 15 with an excessively long inter-electrode distance does not pose a major problem from the perspective of both lithium deposition resistance and spring constant.

<Measurement process between electrodes>
Therefore, in this embodiment, in step S20, it is determined whether a predetermined time has elapsed since the lithium-ion secondary battery 10 entered an unconstrained state after the activation process was completed. In this embodiment, the predetermined time is, for example, about 480 hours (20 days), but is not limited to this.

The electrode gap measurement process of step S21 is not performed until a predetermined time has elapsed since the electrode assembly 15 entered the unconstrained state. Once the predetermined time has elapsed since the electrode assembly 15 entered the unconstrained state, the electrode gap measurement process is performed in step S21. The electrode gap measurement process is a process of measuring the electrode gap at a predetermined timing after the activation process has ended and a predetermined time has elapsed since the electrode assembly 15 entered the unconstrained state during the unconstrained period. The unconstrained period is the period during which the electrode assembly 15 is in an unconstrained state. In the electrode gap measurement process, the electrode gap distance may be measured from images captured by CT (Computed Tomography).

In the inter-electrode measurement process, the inter-electrode distance may be measured at a predetermined position on the electrode body 15. The predetermined position may be a curved region of the electrode body 15 and may be the end of the negative electrode substrate 21 in the second width direction W2. In particular, because the electrode body 15 is wound, the inter-electrode distance tends to be longer in the curved region than in the flat region. For this reason, measuring the inter-electrode distance in the curved region of the electrode body 15 provides higher measurement accuracy than measuring the inter-electrode distance in the flat region of the electrode body 15. Alternatively, the distance between the negative electrode substrate 21 of the negative electrode plate 20 and the positive electrode substrate 31 of the positive electrode plate 30, which are adjacent in the thickness direction D, may be measured as the inter-electrode distance.

<Restraint process>
Next, in step S22, a restraint process is performed according to the measurement results. The restraint process is a process in which the lithium-ion secondary battery 10 is placed in a restraint state, thereby allowing the electrode assembly 15 housed in the lithium-ion secondary battery 10 to be placed in a restraint state for a restraint period. The restraint period may be a predetermined period, or may be the period until assembly into a stack. In the restraint process, the lithium-ion secondary battery 10 is restrained individually as a cell battery, but multiple lithium-ion secondary batteries 10 may also be restrained together. In the restraint process, the lithium-ion secondary battery 10 can be restrained in a restraint mode based on the restraint table TA shown in FIG. 4.

<Restraint table TA>
4, the constraint table TA is a table in which the inter-electrode distance measured in the inter-electrode measurement process corresponds to the constraint mode. In the drawing, the inter-electrode distance measured in the inter-electrode measurement process will be described using the symbol DP.

The inter-electrode distance thresholds include a first distance D1 and a second distance D2. The first distance D1 is the upper limit of the preferred inter-electrode distance, and is, for example, 150 μm, but is not limited to this. The second distance D2 is an inter-electrode distance that does not require consideration of the spring constant of the electrode body 15, and is, for example, 200 μm, but is not limited to this.

Constraint modes include "no constraint," "medium constraint," and "strong constraint." "No constraint" is a mode in which the lithium-ion secondary battery 10 is not constrained. "Medium constraint" and "strong constraint" are modes in which the lithium-ion secondary battery 10 is constrained. "Strong constraint" is a mode in which the lithium-ion secondary battery 10 is constrained with a stronger constraining force than "medium constraint."

In this embodiment, "medium restraint" refers to a small restraint force that slightly shortens the inter-electrode distance, for example, approximately 3 kN, but is not limited to this. In this embodiment, "strong restraint" refers to a large restraint force that shortens the inter-electrode distance, for example, approximately 8 kN, but is not limited to this.

In the restraint table TA, when the inter-electrode distance measured in the inter-electrode measurement process is equal to or less than the first distance D1, the restraint mode corresponds to "no restraint." As a result, the restraint process does not restrain the electrode body 15 when the inter-electrode distance is equal to or less than the first distance D1.

When the inter-electrode distance measured in the inter-electrode measurement process is greater than the first distance D1 and less than or equal to the second distance D2, the constraint state is "medium constraint." When the inter-electrode distance measured in the inter-electrode measurement process is longer than the second distance D2, the constraint state is "strong constraint."

As a result, the restraint process restrains the electrode body 15 when the inter-electrode distance is longer than the first distance D1. In particular, when the inter-electrode distance is greater than the first distance D1, the restraint process restrains the electrode body 15 with a stronger restraint force when the inter-electrode distance is greater than the second distance D2 than when the inter-electrode distance is equal to or less than the second distance D2.

In this way, the restraint process can restrain the lithium-ion secondary battery 10 according to the inter-electrode distance measured in the inter-electrode measurement process. Furthermore, the restraint process can adjust the restraint force on the electrode body 15 according to the measured inter-electrode distance. This type of restraint process corresponds to an example of an adjustment process.

<Example>
Here, referring to FIG. 5 , an example of the lithium ion secondary battery 10 of this embodiment will be described. In this example, the first distance D1 is 150 μm and the second distance D2 is 200 μm. Also, in this example, the electrode distance is measured under the same conditions as in the electrode distance measurement process. In this example, a predetermined charge/discharge cycle was repeatedly performed, and whether or not lithium deposition resistance deteriorated was evaluated based on whether or not lithium deposition occurred on the negative electrode plate 20. Also, in this example, the lithium ion secondary battery 10 was compressed to measure the spring constant, and whether or not the spring constant deteriorated was evaluated based on whether or not the standard was met. In the figure, lithium deposition resistance is indicated as "Li deposition resistance."

First, a case where the inter-electrode distance measured when a predetermined time has elapsed since the non-constrained state was established is equal to or less than the first distance D1 will be described with reference to the first and second examples.
As shown in FIG. 5 , in the first example, when the inter-electrode distance measured after a predetermined time had elapsed since the non-constrained state was reached was 139 μm, the lithium deposition resistance did not deteriorate and the spring constant did not deteriorate when the magnet was not constrained.

On the other hand, in the second example, when the inter-electrode distance measured a predetermined time after the non-constrained state was reached and the electrode spacing was 142 μm, and the electrode was constrained at a medium constraint, the lithium deposition resistance did not deteriorate, but the spring constant did.

Next, we will explain the case where the inter-electrode distance measured a predetermined time after the non-constrained state is reached is greater than the first distance D1 and less than or equal to the second distance D2, with reference to the third, fourth, and fifth examples.

In the third example, when the inter-electrode distance measured a predetermined time after the electrode was released was 170 μm, the spring constant did not deteriorate when the electrode was not restrained, but the lithium deposition resistance deteriorated.

On the other hand, in the fourth example, when the inter-electrode distance measured a predetermined time after the non-constrained state was reached and the electrode spacing was 172 μm, and the restraint was medium, the lithium deposition resistance did not deteriorate, and the spring constant did not deteriorate either.

In addition, in the fifth example, when the inter-electrode distance measured a predetermined time after the non-constrained state was reached and the electrode distance was 175 μm, when strong constraint was applied, the lithium deposition resistance did not deteriorate, but the spring constant did deteriorate.

Next, a case where the inter-electrode distance measured when a predetermined time has elapsed since the non-constrained state was established is longer than the second distance D2 will be described with reference to a sixth embodiment.
In the sixth example, when the inter-electrode distance measured after a predetermined time had elapsed since the non-constrained state was set to 207 μm, when the strong constraint was applied, the lithium deposition resistance did not deteriorate and the spring constant did not deteriorate either.

From these examples, the constraint table TA determines the first distance D1, the second distance D2, and the constraint mode according to the measured inter-electrode distance so that both the lithium precipitation resistance and the spring constant do not deteriorate.

<Actions and Effects of First Embodiment>
The operation and effects of the first embodiment will be described.
(1-1) The restraining force on the electrode body 15 can be adjusted according to the state of the electrode body 15, that is, the inter-electrode distance actually measured during the non-restraint period. Therefore, lithium deposition due to an increase in the inter-electrode distance can be suppressed, and deterioration of the spring constant of the electrode body 15 can be suppressed.

(1-2) When the inter-electrode distance actually measured during the non-constraint period is equal to or less than the first distance D1, by not constraining the electrode body 15, it is possible to minimize the constraint on the electrode body 15 and suppress deterioration of the spring constant of the electrode body 15. On the other hand, when the inter-electrode distance is longer than the first distance D1, it is possible to suppress lithium deposition by constraining the electrode body 15. Therefore, it is possible to suppress lithium deposition caused by an increase in the inter-electrode distance and suppress deterioration of the spring constant of the electrode body 15.

(1-3) When the inter-electrode distance actually measured during the non-constraint period is longer than the second distance D2, the electrode body 15 is constrained with a stronger constraining force than when it is longer than the first distance D1 and equal to or less than the second distance D2. This makes it possible to suppress lithium deposition due to an increase in the inter-electrode distance. On the other hand, when the inter-electrode distance actually measured during the non-constraint period is longer than the first distance D1 and equal to or less than the second distance D2, the electrode body 15 is constrained with a weaker constraining force than when it is longer than the second distance D2. This makes it possible to suppress lithium deposition due to an increase in the inter-electrode distance while also suppressing deterioration in the spring constant of the electrode body 15.

(1-4) By measuring the inter-electrode distance at a timing when a predetermined time has elapsed since the non-constrained state was established, measurement errors due to the timing of measuring the inter-electrode distance can be suppressed.
Second Embodiment
A second embodiment will now be described. In the following description, the same reference numerals will be used to designate the same configurations and the same control contents as those in the already described embodiments, and redundant description thereof will be omitted or simplified.

In the second embodiment, the inter-electrode distance is measured at both the first and second timings during the period when the lithium-ion secondary battery 10 is in an unconstrained state. The lithium-ion secondary battery 10 can then be constrained based on the inter-electrode distance measured at the first timing and the inter-electrode distance measured at the second timing.

<Measurement process between electrodes>
6 , in this embodiment, a first electrode-to-electrode measurement process is performed in step S30 when the lithium-ion secondary battery 10 is in an unconstrained state after the activation process is completed. The first electrode-to-electrode measurement process is a process for measuring the electrode gap under conditions similar to those of the electrode-to-electrode measurement process of the first embodiment. The timing at which the electrode gap is measured in the first electrode-to-electrode measurement process corresponds to an example of the first timing.

Then, in step S31, it is determined whether a specified time has elapsed since the end of the first inter-electrode measurement process while the lithium-ion secondary battery 10 is in an unconstrained state. In this embodiment, the specified time is shorter than the predetermined time in the first embodiment, for example, approximately 240 hours (10 days), but is not limited to this.

The second electrode gap measurement process in step S32 is not performed until a specified time has elapsed since the end of the first electrode gap measurement process. Once the specified time has elapsed since the end of the first electrode gap measurement process, the second electrode gap measurement process is performed in step S32. The second electrode gap measurement process is performed in step S32. The second electrode gap measurement process is a process of measuring the electrode gap under the same conditions as the first electrode gap measurement process. The timing at which the electrode gap distance is measured in the second electrode gap measurement process corresponds to an example of the second timing. The second timing can also be considered to be the timing at which a specified time has elapsed since the first timing.

As such, in the second embodiment, the electrode gap measurement process includes a first electrode gap measurement process and a second electrode gap measurement process, and the electrode gap distance is measured at a first timing and a second timing during the non-constraint period.

<Gap prediction process>
Next, in step S33, a pole-gap prediction process is performed. In the pole-gap prediction process, since the elapsed time in the non-constraint period and the pole-gap distance are proportional to each other, a correlation line is created based on the pole-gap distance measured in the first pole-gap measurement process and the pole-gap distance measured in the second pole-gap measurement process. The correlation line shows the relationship between the elapsed time in the non-constraint period and the pole-gap distance.

Then, in the electrode gap prediction process, the timing when the electrode gap will become the first distance D1 can be predicted based on the created correlation line. In other words, in the electrode gap prediction process, the timing when the electrode gap will become the first distance D1 can be predicted based on the electrode gap measured at the first timing and the electrode gap measured at the second timing. The timing when the electrode gap will become the first distance D1 corresponds to an example of the third timing.

Furthermore, in the electrode gap prediction process, it is possible to predict, based on the created correlation line, that the electrode gap will not become the first distance D1 until a predetermined time has elapsed since the non-constrained state was entered. In other words, in the electrode gap prediction process, it is possible to predict, based on the electrode gap measured at the first timing and the electrode gap measured at the second timing, that the electrode gap will not become the first distance D1 until a predetermined time has elapsed since the non-constrained state was entered.

<Restraint process>
Next, in step S34, a constraint process is performed according to the prediction result. If the electrode gap prediction process predicts that the electrode gap will become the first distance D1, the constraint process performs a medium constraint at the timing when the electrode gap prediction process predicts that the electrode gap will become the first distance D1. On the other hand, if the electrode gap prediction process predicts that the electrode gap will not become the first distance D1 until a predetermined time has elapsed since the electrode gap prediction process became non-constrained, the constraint process does not perform constraint.

In this way, the restraint process can adjust the restraint force on the electrode body 15 depending on the inter-electrode distance measured at the first timing and the inter-electrode distance measured at the second timing. This type of restraint process corresponds to an example of an adjustment process.

When the inter-electrode distance measured in the first inter-electrode measurement process and the second inter-electrode measurement process is equal to or less than the first distance D1, the process proceeds as described above. On the other hand, when the inter-electrode distance measured in the first inter-electrode measurement process is greater than the first distance D1 and equal to or less than the second distance D2, restraint may be performed with a medium restraint after the first inter-electrode measurement process is completed. When the inter-electrode distance measured in the first inter-electrode measurement process is greater than the second distance D2, restraint may be performed with a strong restraint after the second inter-electrode measurement process is completed.

If the inter-electrode distance measured in the first inter-electrode measurement process is less than or equal to the first distance D1, but the inter-electrode distance measured in the second inter-electrode measurement process is greater than the first distance D1 and less than or equal to the second distance D2, restraint may be performed with a medium restraint after the second inter-electrode measurement process is completed. If the inter-electrode distance measured in the first inter-electrode measurement process is less than or equal to the first distance D1, but the inter-electrode distance measured in the second inter-electrode measurement process is greater than the second distance D2, restraint may be performed with a strong restraint after the second inter-electrode measurement process is completed.

<Example>
An example of the lithium ion secondary battery 10 of this embodiment will now be described with reference to Fig. 7. In this example, the relationship between the elapsed time in the non-constraint period and the inter-electrode distance will be described.

As shown in Figure 7, in graph 50, the vertical axis represents the inter-electrode distance, and the horizontal axis represents the elapsed time. The timing at which the first inter-electrode measurement process is performed is when the elapsed time is 0. The timing at which the second inter-electrode measurement process is performed is when the elapsed time is t1. Time t1 corresponds to the specified time. Furthermore, in the first embodiment, the timing at which a predetermined time has elapsed since the non-constrained state was entered is when the elapsed time is t3.

Graph 50 shows a first correlation line 51. The first correlation line 51 is a straight line that passes through the point where the inter-electrode distance is distance DA in the first inter-electrode measurement process and the point where the inter-electrode distance is distance DB in the second inter-electrode measurement process. In this case, the first correlation line 51 intersects with the first distance D1 at time t2, before the time indicated by time t3. Therefore, in the inter-electrode prediction process, the time indicated by time t2 is predicted as the time when the inter-electrode distance will become first distance D1. Then, in the constraint process, constraint is performed at medium constraint from the time indicated by time t2.

Graph 50 also shows a second correlation line 52. The second correlation line 52 is a straight line that passes through the point where the inter-electrode distance is distance DA in the first inter-electrode measurement process and the point where the inter-electrode distance is distance DA in the second inter-electrode measurement process. In this case, the second correlation line 52 does not intersect with the first distance D1 before time t3. Therefore, in the inter-electrode prediction process, it is predicted that the inter-electrode distance will not become the first distance D1 until a predetermined time has elapsed since the non-constrained state was entered in the inter-electrode prediction process. Then, in the constraint process, constraint is not performed.

<Actions and Effects of Second Embodiment>
The operation and effects of the second embodiment will be described.
(2-1) According to the lithium-ion secondary battery 10 of this embodiment, the restraining force on the electrode assembly 15 can be adjusted according to the inter-electrode distance measured in the first inter-electrode measurement process and the second inter-electrode measurement process. This increases the accuracy of adjusting the restraining force on the electrode assembly 15. Therefore, lithium deposition due to an increase in the inter-electrode distance can be suppressed, and deterioration of the spring constant of the electrode assembly 15 can be suppressed.

(2-2) By predicting the timing when the inter-electrode distance will become the first distance D1, the electrode body 15 can be restrained at that timing. This allows the inter-electrode distance to be adjusted to become the first distance D1. Therefore, lithium deposition caused by an increase in the inter-electrode distance is suppressed, and the electrode body 15 is not restrained more than necessary, thereby suppressing deterioration of the spring constant of the electrode body 15.

[Third embodiment]
A third embodiment will be described.
In the third embodiment, the sealing process is performed before the liquid injection process and in a period in which the lithium ion secondary battery 10 is in an unconstrained state, based on the results of measuring the inter-electrode distance. In addition, in the assembly process, at least the case insertion process, the liquid injection process, and the sealing process are in an unconstrained period in which the lithium ion secondary battery 10 is in an unconstrained state.

<Each process>
8, in this embodiment, after the case insertion step is completed, a gap measurement step is performed in step S40. The gap measurement step is a step of measuring the gap under the same conditions as the gap measurement step in the first embodiment. That is, the gap measurement step measures the gap during the non-constraint period at a predetermined timing, i.e., after the case insertion step is completed.

Next, after the electrode gap measurement process is completed, the liquid injection process is performed in step S15. In this embodiment, the liquid injection process may be a process of creating a vacuum inside the battery case 11 and then injecting the nonaqueous electrolyte 18 into the battery case 11. In this case, creating a vacuum inside the battery case 11 applies negative pressure to the electrode assembly 15 housed in the battery case 11.

After the liquid injection process is completed, in step S41, a sealing process is performed based on the measurement results. In the sealing process, the liquid injection hole is sealed to hermetically seal the battery case 11 based on the inter-electrode distance measured in the inter-electrode measurement process.

Specifically, if the inter-electrode distance measured in the inter-electrode measurement process is equal to or less than the first distance D1, the battery case 11 is sealed by sealing the liquid inlet hole when the shortened sealing time has elapsed. The shortened sealing time is a predetermined time that is shorter than the normal sealing time. The shortened sealing time is a time during which negative pressure is applied to the electrode body 15. The normal sealing time is a time during which negative pressure is not applied to the electrode body 15.

In this way, the sealing process shortens the time from when the non-aqueous electrolyte 18 is poured into the battery case 11 to when the battery case 11 is sealed when the measured inter-electrode distance is equal to or less than the predetermined first distance D1. In other words, the sealing process shortens the time from when the non-aqueous electrolyte 18 is poured into the battery case 11 to when the battery case 11 is sealed, depending on the measured inter-electrode distance.

This allows intentional application of negative pressure to the electrode assembly 15 contained within the battery case 11 when the inter-electrode distance measured in the inter-electrode measurement process is equal to or less than the first distance D1. Therefore, when the inter-electrode distance is equal to or less than the first distance D1, the appropriate negative pressure can be applied to prevent the wound electrode assembly 15 from loosening within the battery case 11. Furthermore, even when the lithium-ion secondary battery 10 changes from a constrained state to an unconstrained state after the activation process is completed, the inter-electrode distance can be prevented from increasing over time.

Therefore, even if the lithium-ion secondary battery 10 changes from a constrained state to an unconstrained state after the activation process is completed, there is no need to constrain the lithium-ion secondary battery 10. Furthermore, there is no need to constrain the lithium-ion secondary battery 10 during the aging process either. In this way, during the aging process, the nonaqueous secondary battery is stored in an unconstrained state when the time until sealing the battery case 11 is shortened. This prevents deterioration of lithium precipitation resistance, prevents the electrode body 15 from being constrained more than necessary, and also prevents deterioration of the spring constant. Furthermore, if a self-discharge process is performed after the aging process to check whether the lithium-ion secondary battery 10 is normal based on the voltage drop value per hour of the lithium-ion secondary battery 10, the self-discharge process may also be performed in an unconstrained state.

<Actions and Effects of Third Embodiment>
The operation and effects of the third embodiment will be described.
(3-1) According to the lithium-ion secondary battery 10 of this embodiment, the time from when the nonaqueous electrolyte solution 18 is poured into the battery case 11 to when the battery case 11 is sealed can be shortened depending on the state of the electrode assembly 15, i.e., the inter-electrode distance actually measured during the unconstrained period. This allows the pressure inside the battery case 11 to be intentionally reduced. This increases the self-constraint force acting on the electrode assembly 15, making it possible to prevent the inter-electrode distance in the electrode assembly 15 from increasing. This therefore prevents lithium deposition due to an increase in the inter-electrode distance, minimizes constraint on the electrode assembly 15, and prevents deterioration of the spring constant of the electrode assembly 15.

(3-2) When the inter-electrode distance actually measured during the non-constraint period is equal to or less than the first distance D1, the pressure inside the battery case 11 can be intentionally reduced. This increases the self-constraint force acting on the electrode body 15, effectively preventing the inter-electrode distance in the electrode body 15 from increasing. This effectively prevents lithium deposition due to an increase in the inter-electrode distance.

(3-3) If the time from when the nonaqueous electrolyte 18 is poured into the battery case 11 until the battery case 11 is sealed is shortened, the lithium-ion secondary battery 10 is stored in an unconstrained state during the aging process. Therefore, the constraint on the electrode body 15 can be kept to a minimum, and deterioration of the spring constant of the electrode body 15 can be suppressed.

[Example of change]
This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

In the second embodiment, for example, if the inter-electrode distance becomes longer than the first distance D1 before a predetermined time has elapsed, the electrode body 15 may not be constrained after the second inter-electrode measurement process is completed, rather than when the inter-electrode distance becomes the first distance D1. Alternatively, for example, the electrode body 15 may be constrained when a predetermined time has elapsed. For example, when the inter-electrode distance is longer than the first distance D1 and equal to or less than the second distance D2 when the predetermined time has elapsed, the electrode body 15 may be constrained with a medium constraint, or when the inter-electrode distance is longer than the second distance D2. In other words, it is sufficient that the constraint force on the electrode body 15 can be adjusted depending on the inter-electrode distance measured at the first timing and the inter-electrode distance measured at the second timing.

In the second embodiment, for example, even if the inter-electrode distance does not become longer than the first distance D1 before the predetermined time has elapsed, the electrode body 15 may be restrained at a timing when it is predicted that the inter-electrode distance will become the first distance D1 after the predetermined time has elapsed. For example, the predetermined time in the second embodiment may be the same as or different from the predetermined time in the first embodiment, and may be any arbitrary time.

In the second embodiment, for example, the first inter-electrode measurement process may be performed some time after the activation process has ended, rather than immediately after the activation process has ended. Specifically, the inspection process may be performed after the activation process has ended, or the first inter-electrode measurement process may be performed after the inspection process has been performed. In other words, the first inter-electrode measurement process may be performed during the non-constrained period. Furthermore, the second inter-electrode measurement process may be performed when a specified time has elapsed since the inter-electrode distance was measured in the first inter-electrode measurement process, regardless of whether the specified time has elapsed since the non-constrained state was entered.

In the third embodiment, for example, if the inter-electrode distance measured in the inter-electrode measurement process of step S40 is longer than the first distance D1, the lithium-ion secondary battery 10 may be manufactured using the same process as in the first embodiment. In the third embodiment, for example, if the inter-electrode distance measured in the inter-electrode measurement process of step S40 is longer than the first distance D1, the lithium-ion secondary battery 10 may be manufactured using the same process as in the second embodiment. In these cases, in step S41, when the normal sealing time has elapsed, the battery case 11 is sealed by sealing the liquid injection hole, so that it is not necessary to apply negative pressure to the electrode body 15.

- In the third embodiment, for example, the time from when the non-aqueous electrolyte 18 is injected into the battery case 11 until the battery case 11 is sealed may be shortened in stages according to the inter-electrode distance. In other words, it is sufficient if the time from when the non-aqueous electrolyte 18 is injected into the battery case 11 until the battery case 11 is sealed can be shortened according to the inter-electrode distance.

In this embodiment, for example, "no constraint" may be replaced with "weak constraint," which has a weaker constraint force than "medium constraint" and "strong constraint." In other words, the constraint process may constrain the electrode body 15 with a weaker constraint force when the inter-electrode distance is equal to or less than the first distance D1, compared to when the inter-electrode distance is greater than the first distance D1. Furthermore, the constraint force on the electrode body 15 includes both intentionally constraining the electrode body 15 and not intentionally constraining the electrode body 15. In other words, the constraint force on the electrode body 15 includes not constraining the electrode body 15.

In this embodiment, for example, the predetermined position of the electrode body 15 measured in the electrode gap measurement process may be a planar region of the electrode body 15. For example, the predetermined position of the electrode body 15 measured in the electrode gap measurement process may be the center of the electrode body 15 in the width direction W, or may be on the second width direction W2 side of the electrode body 15. For example, in the electrode gap measurement process, the electrode gap distance may be measured based on the distance between the negative electrode substrates 21 of adjacent negative electrode plates 20 in the thickness direction D. For example, in the electrode gap measurement process, the electrode gap distance may be measured based on the distance between the positive electrode substrates 31 of adjacent positive electrode plates 30 in the thickness direction D.

In this embodiment, for example, the electrode gap measurement process may be performed after the activation process is completed, as in the first and second embodiments, or may be performed before the activation process is initiated, as in the third embodiment.

In this embodiment, the inter-electrode distance was measured for each lithium-ion secondary battery 10, but this is not limited to this. For example, the inter-electrode distance may be measured for a selected lithium-ion secondary battery 10 from among multiple lithium-ion secondary batteries 10 manufactured in the same lot.

In the present embodiment, the present invention has been described using the lithium ion secondary battery 10 as an example, but it can also be applied to other secondary batteries.
In the present embodiment, a thin-plate lithium-ion secondary battery 10 for vehicle use is illustrated, but the present invention can also be applied to cylindrical batteries, etc. Furthermore, the present invention is not limited to vehicle use, but can also be applied to batteries for ships, aircraft, and even stationary use.

The expression "at least any" as used herein means one or more of the desired options. As an example, when there are two options, the expression "at least any" as used herein means only one option or both options. As another example, when there are three or more options, the expression "at least any" as used herein means only one option or any combination of two or more options.

It goes without saying that those skilled in the art may add, delete, or modify the components of the present invention, and change the order of the components, without departing from the scope of the claims.

D...Thickness direction W...Width direction Z...Length direction 10...Lithium ion secondary battery 11...Battery case 12...Lid 13...Negative electrode external terminal 14...Positive electrode external terminal 15...Electrode body 16...Negative electrode current collector 17...Positive electrode current collector 18...Non-aqueous electrolyte 20...Negative electrode plate 21...Negative electrode substrate 22...Negative electrode composite layer 23...Negative electrode connection part 30...Positive electrode plate 31...Positive electrode substrate 32...Positive electrode composite layer 33...Positive electrode connection part 40...Separator 50...Graph 51...First correlation line 52...Second correlation line

Claims (9)

A method for manufacturing a nonaqueous secondary battery including an electrode assembly having a negative electrode plate, a positive electrode plate, and a separator provided between the negative electrode plate and the positive electrode plate, comprising:
an electrode gap measurement step of measuring the distance between the electrode plates at a predetermined timing during an unconstrained period in which the electrode assembly is not constrained;
an adjusting step of adjusting the restraining force on the electrode assembly in accordance with the distance between the electrode plates measured in the electrode spacing measuring step,
A method for manufacturing a non-aqueous secondary battery. The method for producing a nonaqueous secondary battery according to claim 1,
The adjustment step does not restrain the electrode assembly when the distance between the electrode plates measured in the electrode gap measurement step is equal to or shorter than a first distance, and restrains the electrode assembly when the distance between the electrode plates measured in the electrode gap measurement step is longer than the first distance.
A method for manufacturing a non-aqueous secondary battery. The method for producing a nonaqueous secondary battery according to claim 2,
In the adjustment step, the electrode assembly is constrained with a stronger constraining force when the distance between the electrode plates measured in the electrode gap measurement step is longer than the second distance, compared to when the distance between the electrode plates measured in the electrode gap measurement step is longer than the first distance and is equal to or shorter than a second distance longer than the first distance.
A method for manufacturing a non-aqueous secondary battery. The method for producing a nonaqueous secondary battery according to any one of claims 1 to 3,
the electrode gap measuring step measures the distance between the electrode plates at a timing when a predetermined time has elapsed since the non-constrained state was established during the non-constrained period.
A method for manufacturing a non-aqueous secondary battery. The method for producing a nonaqueous secondary battery according to claim 1,
the electrode gap measuring step measures the distance between the electrode plates at a first timing and at a second timing when a specified time has elapsed since the first timing during the non-constraint period;
the adjusting step can adjust the restraining force on the electrode body according to the distance between the electrode plates measured at the first timing and the distance between the electrode plates measured at the second timing in the electrode gap measuring step.
A method for manufacturing a non-aqueous secondary battery. 6. The method for producing a nonaqueous secondary battery according to claim 5,
a pole-gap prediction step of predicting a third timing at which the distance between the pole plates will become the first distance, based on the distance between the pole plates measured at the first timing in the pole-gap measurement step and the distance between the pole plates measured at the second timing;
The adjusting step restrains the electrode assembly at the third timing predicted in the electrode gap prediction step.
A method for manufacturing a non-aqueous secondary battery. A method for manufacturing a non-aqueous secondary battery comprising: an electrode assembly having a negative electrode plate, a positive electrode plate, and a separator provided between the negative electrode plate and the positive electrode plate; a non-aqueous electrolyte; and a battery case that accommodates the electrode assembly and the non-aqueous electrolyte,
an electrode gap measurement step of measuring the distance between the electrode plates at a predetermined timing during an unconstrained period in which the electrode assembly is not constrained;
a liquid injection step of injecting the nonaqueous electrolyte into the battery case with the electrode assembly housed therein;
a sealing step of sealing the battery case with the electrode assembly and the nonaqueous electrolyte solution accommodated in the battery case,
the sealing step shortens the time from when the nonaqueous electrolyte is poured into the battery case in the pouring step to when the battery case is sealed, in accordance with the distance between the electrode plates measured in the electrode gap measuring step.
A method for manufacturing a non-aqueous secondary battery. The method for producing a nonaqueous secondary battery according to claim 7,
the sealing step shortens the time from when the nonaqueous electrolyte is injected into the battery case in the liquid injection step to when the battery case is sealed when the distance between the electrode plates measured in the electrode gap measurement step is equal to or shorter than a predetermined distance;
A method for manufacturing a non-aqueous secondary battery. The method for producing a nonaqueous secondary battery according to claim 7 or 8,
a charging step of charging the nonaqueous secondary battery after the sealing step is completed;
an aging step of storing the nonaqueous secondary battery after the charging step is completed,
the aging step includes storing the nonaqueous secondary battery in the unconstrained state when the time from when the nonaqueous electrolyte solution is poured into the battery case until when the battery case is sealed is shortened;
A method for manufacturing a non-aqueous secondary battery.