JP6839384B2 - Manufacturing method of sealed battery - Google Patents

Description

The present invention relates to a manufacturing method for manufacturing a sealed battery in which an electrode body and an electrolytic solution are housed in a case.

Secondary batteries such as lithium-ion secondary batteries and nickel-metal hydride batteries are becoming increasingly important as power sources for vehicles and personal computers and mobile terminals. These secondary batteries are constructed as, for example, a sealed battery in which an electrode body and an electrolytic solution are housed in a case and the case is sealed.

If a large amount of water is contained inside the case of such a sealed battery (particularly inside the electrode body), gas is generated during charging, which causes deterioration of battery performance. Therefore, in the manufacturing process of the sealed battery, a drying step is performed in which the electrode body is housed in the case to prepare the case containing the electrode body, and then the inside of the case containing the electrode body is dried.
In this drying step, for example, a method is adopted in which a case containing an electrode body is housed in a decompression furnace and the inside of the decompression furnace is heated to dry the inside of the case. For example, Patent Document 1 describes a battery sandwiching device that sandwiches a plurality of unsealed batteries when the unsealed battery (case containing an electrode body) before injecting the electrolytic solution is housed in a decompression furnace for drying. It is disclosed.

Japanese Unexamined Patent Publication No. 2014-232665

However, the method of drying the case containing the electrode body using the above-mentioned decompression furnace has various problems in terms of equipment cost and manufacturing efficiency. Therefore, in recent years, the case containing the electrode body has been more preferably dried. It has been desired to develop a technology that can achieve this.

Specifically, the above-mentioned decompression furnace requires a structure for surely sealing the inside of the furnace, so that the equipment cost tends to be high. In particular, when drying a case containing a plurality of electrode bodies at the same time, a large decompression furnace is required, and such a large decompression furnace is very expensive because it requires a high-capacity closed structure and a vacuum pump. there were.
Further, there is a problem that an extra dead space is generated inside the decompression furnace and the dead space needs to be decompressed, resulting in poor decompression efficiency. Further, since it is difficult to directly heat the case containing the electrode body housed in the furnace due to the space in the furnace and the equipment configuration, there is still room for improvement in the heating efficiency.

Further, in the prior art using a decompression furnace, it is difficult to confirm in real time whether or not the inside of the case is properly dried while the case containing the electrode body is being dried. Therefore, it is necessary to set the drying time longer than necessary in consideration of the possibility that the case containing the electrode body is not sufficiently dried due to various disturbances. Therefore, improvement has been desired from the viewpoint of manufacturing efficiency. In particular, when drying a plurality of cases containing electrodes at the same time, it is necessary to set a very long drying time so that all the sealed batteries are surely dried, which causes a great decrease in manufacturing efficiency. It was.

The present invention has been created to solve the above-mentioned various problems, and provides a method for manufacturing a sealed battery capable of suitably drying the inside of a case containing an electrode body without using a pressure reducing furnace. The purpose is to do.

In order to realize the above object, the present invention provides a method for manufacturing a sealed battery having the following configuration (hereinafter, also simply referred to as “manufacturing method”).

The method for manufacturing a closed-type battery disclosed here is a method for manufacturing a closed-type battery in which an electrode body and an electrolytic solution are housed in a case and a liquid injection port for injecting the electrolytic solution is provided in the case. Is.
Such a manufacturing method includes a step of housing the electrode body inside the case to prepare a case containing the electrode body, and attaching a pressure reducing nozzle to each liquid injection port of each of the plurality of electrode body containing cases to seal the inside of the electrode body containing case. A step of heating the case containing the electrode body from the outside to evaporate the water content inside the case, and a drying step of depressurizing the inside of the case containing the electrode body via a decompression nozzle to remove the evaporated water content. ing. Then, in the method for manufacturing a sealed battery disclosed here, a pressure measuring means is provided in each of the decompression nozzles attached to each of the cases containing the plurality of electrode bodies, and in the drying step, the electrode body is inserted by the pressure measuring means. The change in the internal pressure of the case is detected, and when the detection result of the change in the internal pressure falls below a predetermined threshold value, the heating of the case containing the electrode body is stopped.

In the method for manufacturing a sealed battery disclosed here, a decompression nozzle is attached to each of the injection ports of a plurality of cases containing electrodes, and the water in the case evaporated by heating is removed by the decompression nozzle. As a result, the cases containing a plurality of electrode bodies can be suitably dried without using a decompression furnace, so that the equipment cost can be significantly reduced as compared with the above-mentioned conventional technique. Further, since only the inside of the case containing the electrode body is depressurized, the dead space in the decompression furnace can also be decompressed, which is higher than the conventional technique. Further, since the case containing the electrode body can be directly heated without considering the structure of the decompression furnace and the like, the heating efficiency can be improved.

In addition, in the manufacturing method disclosed here, each pressure reducing nozzle is provided with a pressure measuring means, and the pressure measuring means detects a change in the internal pressure of the case containing the electrode body. Therefore, it is possible to confirm in real time whether or not the inside of the case is properly dried.
Then, when the detection result of the change in internal pressure falls below a predetermined threshold value, the heating of the case containing the electrode body is stopped, so that the drying step is completed at the timing when each of the plurality of cases containing the electrode body is sufficiently dried. It is possible to improve the manufacturing efficiency as compared with the conventional case.

It is a partial cross-sectional view which shows typically the closed type battery manufactured by the manufacturing method of the closed type battery which concerns on one Embodiment of this invention. It is a side view which shows typically the drying apparatus used in the manufacturing method of the closed type battery which concerns on one Embodiment of this invention. It is a flow chart of the manufacturing method of the closed type battery which concerns on one Embodiment of this invention. It is a graph which shows the relationship between the pressure change in the case containing an electrode body, and the amount of residual water in the case containing an electrode body.

Hereinafter, a method for manufacturing a lithium ion secondary battery will be described as an example of a method for manufacturing a sealed battery according to an embodiment of the present invention. The method for manufacturing a sealed battery disclosed here is not limited to the manufacturing of a lithium ion secondary battery, and can be applied to various sealed batteries such as nickel-metal hydride batteries.

Further, in the drawings referred to in the following description, members / parts having the same action are designated by the same reference numerals. The dimensional relationships (length, width, thickness, etc.) in each figure do not reflect the actual dimensional relationships. In addition, matters other than those specifically mentioned in the present specification and necessary for carrying out the present invention (for example, materials for an electrode body and an electrolytic solution) are those skilled in the art based on the prior art in the art. It can be grasped as a design matter.

1. 1. Structure of Sealed Battery First, a sealed battery which is a manufacturing target of the manufacturing method according to the present embodiment will be described. FIG. 1 is a partial cross-sectional view schematically showing a sealed battery manufactured by the method for manufacturing a closed battery according to the present embodiment.

The sealed battery 100 shown in FIG. 1 is configured by accommodating an electrode body 120 and an electrolytic solution (not shown) inside the case 110. The case 110 of the sealed battery 100 is composed of a flat square case body 112 having an open upper surface and a plate-shaped lid 114 that closes the opening on the upper surface of the case body 112.
The lid 114 forming the upper surface of the case 110 is provided with a liquid injection port 115 for injecting an electrolytic solution into the case 110, and a sealing member 116 is fitted in the liquid injection port 115. There is. Further, in FIG. 1, an electrode terminal 140 for electrically connecting the electrode body 120 in the case 110 and an external device (not shown) is attached to the lid body 114.
The case 110 is preferably made mainly of a lightweight metal material having good thermal conductivity such as aluminum.

Although specific illustration is omitted, the electrode body 120 in the present embodiment includes a long sheet-shaped positive electrode in which a positive electrode mixture layer is provided on the surface of a foil-shaped positive electrode current collector, and a foil-shaped negative electrode current collector. It is provided with a long sheet-shaped negative electrode having a negative electrode mixture layer applied to the surface of the body, and is produced by laminating the sheet-shaped positive electrode and the negative electrode via a separator and then winding the negative electrode.
As the material of each member (for example, positive electrode, negative electrode, separator, etc.) constituting the electrode body 120, the same material as that used for a conventional general lithium ion secondary battery can be used without limitation. Since it does not characterize the invention, detailed description thereof will be omitted.
A winding core portion 120A is formed in the central portion of the electrode body 120 in the width direction (winding axis direction) so that the mixed material layers of the positive electrode and the negative electrode face each other, and the mixed material layers are formed on both side edges. A terminal connection portion 120B is formed in which an unassigned current collector is wound.
One end 140a of the electrode terminal 140 is joined to the terminal connection portion 120B of the electrode body 120. The electrode terminal 140 penetrates the lid 114, and the other end 140b is exposed to the outside of the case 110.

As described above, in the sealed battery 100, the electrolytic solution is housed in the case 110. Such an electrolytic solution is prepared by dissolving a predetermined supporting salt in a solvent. As for the solvent and supporting salt of the electrolytic solution, as with the electrode body 120 described above, general materials can be used without particular limitation, and detailed description thereof will be omitted.

As will be described in detail later, in the sealed battery 100 shown in FIG. 1, the electrode body 120 is housed in the case 110 to prepare a case containing the electrode body, and then the electrolytic solution is injected from the liquid injection port 115 to inject liquid. Manufactured by sealing the mouth 115 with a sealing member 116.

2. 2. Structure of Drying Device In the manufacturing method according to the present embodiment, after the case containing the electrode body is produced, a drying step of drying the inside of the case containing the electrode body is performed before injecting the electrolytic solution from the injection port 115. Next, the drying apparatus used in such a drying step will be described. FIG. 2 is a side view schematically showing a drying device used in the method for manufacturing a sealed battery according to the present embodiment.

As shown in FIG. 2, the drying device 1 includes a decompression means 10 for reducing the pressure inside each of the plurality of electrode body-containing cases A, and a heating means (heating plate 20) for heating the electrode body-containing case A. ing.

(1) Decompression means The decompression means 10 of the drying device 1 shown in FIG. 2 includes a plurality of decompression nozzles 12. A suction cup is provided at the tip of these decompression nozzles 12, and is attached to a liquid injection port 115 (see FIG. 1) provided on the upper surface of the case A containing the electrode body. Further, each pressure reducing nozzle 12 is connected to one intake pipe 13 via a valve 16, and the intake pipe 13 is connected to a vacuum pump 18 via a valve 11. By operating the vacuum pump 18, the decompression means 10 can decompress the inside of the case A containing the electrode body attached to each decompression nozzle 12.
Further, a pressure measuring means (pressure gauge) 14 is attached to each decompression nozzle 12, and by closing the valve 16 provided on each decompression nozzle 12, the pressure measuring means 14 contains the electrode body case A. The pressure inside the can be measured. Although not shown, each pressure measuring means 14 is connected to the control means, and the measurement result by the pressure measuring means 14 is transmitted to the control means.
A valve 17 for opening to the atmosphere is attached to the intake pipe 13, and by opening the valve 17 for opening to the atmosphere, outside air is introduced into the case A containing the electrode body via the intake pipe 13 and the decompression nozzle 12. It can be made to flow in to release the decompression. At this time, a filter 19 is attached to the upstream side of the valve 17 for opening to the atmosphere in order to prevent foreign matter from entering the inside of the case A containing the electrode body.

(2) Heating means The drying device 1 shown in FIG. 2 includes a heating plate 20 as a heating means for heating the case A containing the electrode body. The heating plate 20 is a pedestal-shaped member in which an electric heater is housed, and heats a case A containing an electrode body placed on the upper surface. Although not shown, a control means is attached to the heater inside the heating plate 20 so that the temperature of the heater can be controlled.

(3) Pressurizing Jig Further, the drying device 1 includes a pressurizing jig 30 for holding a plurality of electrode body-containing cases A. The pressurizing jig 30 is configured to sandwich each case A containing an electrode body and restrain it with a predetermined pressure. A positioning guide 24 is provided on the upper surface of the heating plate 20 described above, and by fitting the pressurizing jig 30 into the positioning guide 24, the liquid injection port 115 (see FIG. 1) becomes the pressure nozzle 12. Each case A containing an electrode body can be fixed so as to be arranged below the. The pressurizing jig 30 is preferably made of a metal material having high thermal conductivity such as aluminum.

(4) Control Means As described above, the drying device 1 shown in FIG. 2 includes control means (not shown). Such control means are connected to each device (valves 11, 16, valves 17 for opening to the atmosphere, vacuum pump 18) and heating means (heater of the heating plate 20) constituting the decompression means 10. Such a control means carries out the drying step of the case A containing the electrode body by controlling the operation of each of the above-mentioned devices based on the measurement result of the pressure measuring means 14.

3. 3. Method for Manufacturing a Sealed Battery Next, a method for manufacturing a sealed battery according to the present embodiment for manufacturing the sealed battery 100 shown in FIG. 1 will be described using the drying device 1 shown in FIG. FIG. 3 is a flow chart schematically showing a method for manufacturing a sealed battery according to the present embodiment.

As shown in FIG. 3, the manufacturing method according to the present embodiment includes a step S10 for manufacturing the case A containing the electrode body and a step S20 for attaching the pressure reducing nozzle 12 to each liquid injection port of the plurality of cases A containing the electrode body. A drying step S30 for drying each case A containing an electrode body is provided. Hereinafter, each step will be specifically described.

(1) Preparation of Case with Electrode Body In this step, a case with an electrode body is produced by accommodating the electrode body 120 in the case 110 shown in FIG. Specifically, first, one end 140a of the electrode terminal 140 is connected to the terminal connection portion 120B of the electrode body 120 in which the positive electrode and the negative electrode are wound. Then, after the electrode body 120 is housed inside the case body 112, the lid body 114 is fitted into the opening on the upper surface of the case body 112, and the lid body 114 and the case body 112 are joined by laser welding or the like. As a result, the case A (see FIG. 2) containing the electrode body in which the electrode body 120 is housed in the case 100 is produced.

(2) Attachment of Decompression Nozzle In this step, after the prepared case A containing the electrode body is placed on the heating plate 20, the decompression nozzle 12 is attached to the liquid injection port of each case A containing the electrode body.
Specifically, first, each of the cases A containing the electrode body is restrained by the pressurizing jig 30 and pressurized at a predetermined pressure. Then, the pressurizing jig 30 is fitted into the positioning guide 24 on the upper surface of the heating plate 20. As a result, each case A containing an electrode body is fixed on the heating plate 20 so that the liquid injection port 115 (see FIG. 1) of the case A containing the electrode body is arranged below the pressure reducing nozzle 12 of the decompression means 10. To. Next, the decompression nozzle 12 is lowered, and the tip of the decompression nozzle 12 is attached to the liquid injection port of the case A containing the electrode body. As a result, the inside of each case A containing the electrode body is sealed.

(3) Drying Step Next, a drying step S30 for drying each electrode body-containing case A is carried out. In the manufacturing method according to the present embodiment, in the drying step S30, heating / depressurizing S32 of the case, detection of change in pressure inside the case S34, and determination of continuation of drying S36 are carried out.

(A) Case heating / depressurization First, in the case heating / depressurizing S32, the heater in the heating plate 20 is operated to heat each of the case A containing the electrode body, and the moisture inside the case (particularly the electrode body 120 (particularly the electrode body 120) Evaporate the water inside) (see FIG. 1). The heating temperature at this time is preferably set to a temperature at which water can be appropriately evaporated and the electrode body 120 (see FIG. 1) does not deteriorate due to heat, for example, in the range of 50 ° C. to 160 ° C. Set.
Then, in this step, the inside of the case A containing the electrode body is decompressed by the decompression nozzle 12. Specifically, first, a decompression path is formed from the vacuum pump 18 to the case A containing the electrode body by opening each of the valve 11 on the intake pipe 13 and the valve 16 on the decompression nozzle 12. By operating the vacuum pump 18 in this state, the inside of each electrode body containing case A is depressurized, and the moisture evaporated by heating is removed from the inside of the case.
At this time, from the viewpoint of lowering the evaporation temperature of the water contained in the electrode body to less than 100 ° C. and making it easier to dry the electrode body at a low temperature, the case A containing the electrode body is more than the vapor pressure of the water content contained in the electrode body. It is preferable to set the degree of decompression by the vacuum pump 18 so that the internal pressure becomes low. Further, from the viewpoint of improving the drying efficiency and preventing deterioration of each material contained in the case due to oxidation, it is preferable to set the degree of decompression by the vacuum pump 18 to 500 Pa [abs] or less.

(B) Detection of Change in Case Internal Pressure In the manufacturing method according to the present embodiment, the case internal pressure is detected by the pressure measuring means 14 after the above-mentioned heating / depressurizing S32 of the case is performed for a predetermined time. Change detection S34 is carried out.
In the present embodiment, first, the valve 16 on each decompression nozzle 12 is closed to shut off the decompression path, and the decompression of each electrode body-containing case A is temporarily stopped. Then, the pressure measuring means 14 measures the case internal pressure P1 immediately after the decompression is stopped, and transmits the measurement result to the control means.
Next, after heating by the heating plate 20 is continuously performed for a predetermined time (for example, 10 to 60 seconds) with the depressurization stopped, the internal pressure P2 after the lapse of a predetermined time is measured by the pressure measuring means 14 and measured. Send the result to the control means.
Then, the control means calculates the difference between the internal pressure P1 immediately after the decompression is stopped and the internal pressure P2 after the elapse of a predetermined time, which is transmitted from the pressure measuring means 14, as a case internal pressure change (P2-P1).

(C) Judgment of Continuation of Drying In the manufacturing method according to the present embodiment, it is determined whether or not to continue drying the case A containing the electrode body based on the calculated change in case internal pressure (P2-P1).
Specifically, as shown in FIG. 4, when each case A containing an electrode body is sufficiently dried by the time when the decompression is stopped and the amount of residual water in the case is low, the case A is heated after the decompression is stopped. Since the case internal pressure does not increase significantly even if the above is continued, the case internal pressure change (P2-P1) becomes small. On the other hand, when each case A containing an electrode body is not sufficiently dried and the amount of residual water in the case is large, the water in the case further evaporates after the decompression is stopped, and the case internal pressure P2 rises sharply. Therefore, the change in case internal pressure (P2-P1) becomes large.

In the manufacturing method according to the present embodiment, it is determined whether or not to continue drying the case A containing the electrode body based on the relationship between the amount of residual water in the case and the change in the pressure inside the case (P2-P1). Specifically, in the present embodiment, as shown in the graph of FIG. 4, the threshold value P _A of the case pressure change corresponding to the water standards W which can be regarded as the electrode body containing case A is sufficiently dried Is set as the control means.
Then, the control means, the detected case change in the internal pressure in the detection of S34 vent pressures change (P2-P1), and comparing the threshold value _{P A} described above, case pressure change (P2-P1) is greater than the threshold value _{P A} If so, it is determined that the drying is not sufficient, and “Case heating / depressurization S32” is performed again as shown in No. 3 of FIG. On the other hand, the case pressure change (P2-P1) is when below the threshold P _A, it is judged that the electrode body containing case A is sufficiently dried, and terminates the heating and reduced pressure as shown in Yes of FIG. 3 (S40).
In the manufacturing method according to the present embodiment, the above-mentioned drying step S30 is repeatedly carried out until all of the plurality of electrode body-containing cases A are sufficiently dried. Therefore, it is possible to reliably prevent deterioration of battery performance due to poor drying.

(4) Subsequent Processing In the manufacturing method according to the present embodiment, after the above-mentioned drying step S30 is completed, the air opening valve 17 is opened to release the decompression state of the electrode body-containing case A, and then the decompression nozzle 12 is opened. Remove. Then, after the pressurizing jig 30 is removed from the heating plate 20 and cooled, each electrode body-containing case A is removed from the pressurizing jig 30. At this time, in order to prevent moisture from entering the case A containing the electrode body, it is preferable to perform this step in a dry atmosphere.
Next, after injecting the electrolytic solution into the inside of each case A containing the electrode body from the liquid injection port, the liquid injection port 115 is sealed by the sealing member 116. As a result, a sealed battery in which the moisture in the case is appropriately removed is produced.

As described above, in the manufacturing method according to the present embodiment, since the pressure reducing nozzles 12 are attached to each of the plurality of electrode body-containing cases A to reduce the pressure in each case, a pressure reducing furnace as in the prior art is used. Even without it, the case A containing a plurality of electrode bodies can be dried. Therefore, as compared with the conventional technique using a decompression furnace, the equipment cost can be significantly reduced and the decompression efficiency can be improved. Further, since the decompression furnace is not used, it is possible to provide a heating means capable of directly heating the case A containing the electrode body as in the heating plate 20 in FIG. 2, which can contribute to the improvement of the heating efficiency. it can.

Further, in the manufacturing method according to the present embodiment, the pressure measuring means 14 is provided in each decompression nozzle 12, and the pressure measuring means 14 detects the change in the internal pressure (P2-P1) of the case A containing the electrode body. , It can be confirmed during the drying process whether or not the inside of the case is properly dried. Then, end the drying process in such order case the change in the internal pressure (P2-P1) is to stop the drying process when it falls below a predetermined threshold value P _A, the timing of each electrode body containing case A is sufficiently dried Therefore, the production efficiency can be suitably improved.

4. Other Forms The manufacturing method disclosed here is not limited to the above-described embodiment, and various modifications can be made.

For example, in the manufacturing method according to the above-described embodiment, the drying device 1 shown in FIG. 2 is used. However, the manufacturing method disclosed here is not limited to the method using the drying device 1 shown in FIG. 2, and various drying devices can be used.
Specifically, in the drying device 1 of FIG. 2, a pressurizing jig 30 is used to pressurize each case A containing an electrode body and fix it at an appropriate position. However, when it is not necessary to pressurize each case during the drying process, a fixing means such as a pallet for directly fixing the case containing the electrode body on the heating plate may be used instead of the pressurizing jig 30. ..

Further, in the above-described embodiment, the heating plate 20 for heating the electrode body-containing case A placed on the upper surface is used as the heating means. However, the structure of the heating means is not particularly limited as long as the case containing the electrode body can be appropriately heated. As the heating means, for example, a heating plate in which each electrode body-containing case is sandwiched between plate-shaped heaters and heated from the side surface may be used, or a heating furnace in which the case equipped with the decompression nozzle is housed and heated may be used. You may use it.
Further, although an electric heater is used for the heating plate 20 of the above-described embodiment, a heat exchanger that heats a heating target by circulating a heat medium (hot water, heating oil, etc.) can also be used.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples illustrated above.

1 Drying device 10 Decompression means 11, 16 Valve 12 Decompression nozzle 13 Intake pipe 14 Pressure measuring means 17 Air release valve 18 Vacuum pump 19 Filter 20 Heating plate 24 Positioning guide 30 Pressurizing jig 100 Sealed battery 110 Case 112 Case body 114 Lid 115 Liquid injection port 116 Sealing member 120 Electrode body 120A Winding core part 120B Terminal connection part 140 Electrode terminal 140a One end of electrode terminal 140b The other end of electrode terminal A Case with electrode body S10 Electrode body accommodating S20 termination detection S36 determines S40 heating and reduced pressure heating and reduced pressure S34 case pressure change of the mounting S30 drying step S32 case of vacuum nozzles W moisture standard _{P a} threshold

Claims (1)

It is a method of manufacturing a closed-type battery in which an electrode body and an electrolytic solution are housed in a case, and the case is provided with a liquid injection port for injecting the electrolytic solution.
A step of housing the electrode body inside the case to prepare a case containing the electrode body, and
A step of attaching a decompression nozzle to each of the injection ports of the plurality of cases containing the electrode body and sealing the inside of the case containing the electrode body.
A drying step is provided in which the case containing the electrode body is heated from the outside to evaporate the water content inside the case, and the inside of the case containing the electrode body is depressurized via the decompression nozzle to remove the evaporated water content. ,
A pressure measuring means is provided for each decompression nozzle attached to each of the plurality of cases containing the electrode body.
In the drying step
The heating and depressurizing treatment for heating and depressurizing the case containing the electrode body,
In each of the pressure measuring means, after measuring the internal pressure P1 of the case containing the electrode body when the heating and depressurizing treatment was stopped, the internal pressure P2 when the case containing the electrode body was heated without reducing the pressure was measured. The internal pressure change detection process for detecting the difference between the P2 and the P1 as the internal pressure change (P2-P1) of the case containing the electrode body.
Wherein at least one of the pressure change of the plurality of electrodes body containing case (P2-P1) is re-execute the heating decompression process when it exceeds a predetermined threshold value P _A, all of said plurality of electrodes a body containing case _A determination process for terminating the drying step when the internal pressure change (P2-P1) falls below the predetermined threshold value PA.
A method of manufacturing a sealed battery that at least performs.

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