JP5920157B2 - Electrode plate manufacturing method and battery manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing an electrode plate having an electrode foil and an active material layer formed on the electrode foil, and a method for manufacturing a battery using the electrode plate.

An electrode plate having an active material layer on an electrode foil is generally formed by applying an electrode paste in which an active material, a binder, and the like are dispersed in a solvent to form an electrode paste layer, and then heating the electrode paste layer with hot air. It manufactures by making it dry and forming an active material layer.
However, since the solvent evaporates from the surface of the electrode paste layer during hot air drying, the solvent in the electrode paste layer moves to the surface side, and the binder tends to move to the surface side accordingly. . For this reason, in the active material layer after hot air drying, the binder is unevenly distributed in the thickness direction. Specifically, the binder is less on the electrode foil side of the active material layer, and the binder is increased on the surface side of the active material layer. For this reason, the adhesion strength (peeling strength) between the electrode foil and the active material layer is lowered.

  On the other hand, in Patent Document 1, as a method for producing a gas diffusion electrode for a fuel cell, in forming an electrode catalyst layer on an electrode substrate, the electrode catalyst layer containing a solvent is subjected to vacuum lyophilization to obtain an electrode. A technique for forming a catalyst layer is disclosed. In this document, vacuum freeze-drying is performed without freezing the electrode catalyst layer containing the solvent in advance in order to simplify the manufacturing process and reduce the energy and cost required for production. That is, a method is adopted in which a non-frozen electrode catalyst layer is placed under high vacuum, and the solvent is dried while being frozen by the latent heat of vaporization of the solvent.

JP 2011-108544 A

When this method is applied to the production of an electrode plate having an active material layer on an electrode foil, after forming the electrode paste layer on the electrode foil, the electrode paste layer should be kept under high vacuum without being frozen in advance. Thus, the electrode paste layer is freeze-dried to form an active material layer.
However, even when the electrode plate is formed by such a method, the adhesion strength between the electrode foil and the active material layer is lowered, and the active material layer may be peeled off from the electrode foil.

The reason is that when the electrode paste layer is frozen, depending on the freezing temperature, the difference in thermal shrinkage generated between the electrode foil and the electrode paste layer (active material layer) becomes large, and the stress generated between them causes It is considered that the adhesive strength with the active material layer was lowered and the active material layer was peeled off from the electrode foil. In particular, when the electrode plate is cooled below the glass transition point of the binder, the binder changes its state and the binding action of the binder is greatly reduced. It is considered that the active material layer is easily peeled off from the electrode foil due to the stress caused by the difference in heat shrinkage. In addition, the binder in the electrode paste layer moves in the thickness direction between the formation of the electrode paste layer on the electrode foil and the vacuum freeze-drying, for example, when the electrode plate is transported. This is considered to be caused by the uneven distribution of the binder in the thickness direction.
As described above, in the conventional electrode plate manufacturing method, it is difficult to prevent the binder from being unevenly distributed in the thickness direction in the active material layer and to suppress the decrease in the adhesion strength between the electrode foil and the active material layer. .

  The present invention has been made in view of the current situation, and prevents the binder from being unevenly distributed in the thickness direction in the active material layer and suppresses a decrease in the adhesion strength between the electrode foil and the active material layer. It aims at providing the manufacturing method of an electrode plate, and the manufacturing method of the battery using this electrode plate.

  One embodiment of the present invention for solving the above problems is a method of manufacturing an electrode plate having an electrode foil and an active material layer formed on the electrode foil, wherein the active material and the binder are dispersed in a solvent. A coating step of forming an electrode paste layer by applying the electrode paste on the electrode foil, and the electrode paste layer having a glass transition point lower than the freezing point Tf of the solvent and the binder A freezing step of freezing at a first cooling temperature Tc (Tg <Tc <Tf) higher than Tg (where Tg <Tf), and a second cooling temperature Td satisfying Tg <Td <Tf for the frozen electrode paste layer. And a vacuum freeze-drying step in which the active material layer is formed by vacuum freeze-drying.

  In this electrode plate manufacturing method, after an electrode paste layer is formed on an electrode foil, this electrode paste layer satisfies Tg <Tc <Tf (Tg: glass transition point of binder, Tf: freezing point of solvent). After freezing at the first cooling temperature Tc, the frozen electrode paste layer is vacuum freeze-dried at a second cooling temperature Td that satisfies Tg <Td <Tf to form an active material layer. As described above, after the electrode paste layer is formed, the electrode paste layer is frozen in advance before vacuum freeze-drying. It is possible to prevent the binder from moving in the thickness direction and to prevent the binder from being unevenly distributed in the thickness direction.

  In addition, by setting the first cooling temperature Tc and the second cooling temperature Td to a temperature (Tc, Td> Tg) higher than the glass transition point Tg of the binder, the state of the binder changes and the binding thereof is changed. Since it is possible to prevent the adhesion action from greatly decreasing, it is possible to suppress a decrease in the adhesion strength between the electrode foil and the active material layer due to the stress caused by the difference in thermal shrinkage between the electrode foil and the electrode paste layer (active material layer). . Therefore, according to this method of manufacturing an electrode plate, the binder is prevented from being unevenly distributed in the thickness direction in the active material layer, and the adhesion strength between the electrode foil and the active material layer is increased, so that the active material is formed from the electrode foil. It is possible to prevent or appropriately suppress peeling of the layer.

  The “electrode plate” may be a positive electrode plate in which a positive electrode active material layer containing a positive electrode active material is formed on a positive electrode electrode foil, or a negative electrode plate in which a negative electrode active material layer containing a negative electrode active material is formed on a negative electrode electrode foil. But you can. Alternatively, a bipolar electrode plate (bipolar electrode plate) in which a positive electrode active material layer containing a positive electrode active material is formed on one main surface of the electrode foil and a negative electrode active material layer containing a negative electrode active material is formed on the other main surface. Good.

  Furthermore, in the method for manufacturing the electrode plate, the first cooling temperature Tc and the second cooling temperature Td satisfy (Tg + Tf) / 2 ≦ Tc <Tf and (Tg + Tf) / 2 ≦ Td <Tf. It is good to use the manufacturing method of a board.

  The lower the first cooling temperature Tc and the second cooling temperature Td, the larger the difference in the amount of thermal shrinkage that occurs between the electrode foil and the electrode paste layer (active material layer). The active material layer is easily peeled off. On the other hand, in this electrode plate manufacturing method, the lower limit values of the first cooling temperature Tc and the second cooling temperature Td are limited to (Tg + Tf) / 2, respectively. Therefore, the electrode foil and the electrode paste layer (active material layer) ) To reduce the difference in the amount of heat shrinkage, effectively reducing the decrease in adhesion strength.

  Furthermore, in the method for producing an electrode plate according to any one of the above, the electrode foil is a copper foil, the solvent is water, and the binder is styrene butadiene rubber. A manufacturing method is preferable.

When the electrode foil is a copper foil and the solvent is water, the thermal expansion coefficient (linear expansion coefficient) of copper is 16.8 × 10 ⁻⁶ / K, and the thermal expansion coefficient (linear expansion coefficient) of ice is 50. Since it is 7 × 10 ⁻⁶ / K, the difference in thermal shrinkage generated between the electrode foil and the electrode paste layer (active material layer) tends to be large. On the other hand, when styrene butadiene rubber (SBR) is cooled to below its glass transition point Tg, it becomes vitrified and loses elasticity, and the binding action is greatly reduced. In contrast, by setting the first cooling temperature Tc and the second cooling temperature Td to a temperature (Tc, Td> Tg) higher than the glass transition point Tg of SBR, the adhesion strength between the electrode foil and the active material layer can be increased. Reduction can be effectively suppressed.

  Furthermore, in the method for manufacturing the electrode plate, the glass transition point Tg of the styrene-butadiene rubber is −40 ° C. or less, and the first cooling temperature Tc (° C.) and the second cooling temperature Td (° C. ) Is preferably a method for manufacturing an electrode plate that satisfies −15 ≦ Tc <0 and −15 ≦ Td <0.

  In this method of manufacturing an electrode plate, SBR having a glass transition point Tg of −40 ° C. or lower and having sufficient elasticity even at a low temperature of about −15 ° C. is used as a binder. Moreover, since the first cooling temperature Tc (° C.) is −15 ≦ Tc <0 and the second cooling temperature Td (° C.) is −15 ≦ Td <0, the adhesion strength between the electrode foil and the active material layer is reduced. It can be effectively suppressed.

  Moreover, another aspect is a manufacturing method of a battery provided with the electrode plate which has electrode foil and the active material layer formed on this electrode foil, Comprising: The manufacturing method of the electrode plate in any one of said is included It is a manufacturing method of a battery.

  According to this battery manufacturing method, the binder is prevented from being unevenly distributed in the thickness direction in the active material layer, the adhesion strength between the electrode foil and the active material layer is increased, and the active material layer is peeled off from the electrode foil. A battery including an electrode plate that is prevented or appropriately suppressed can be manufactured.

1 is a perspective view of a lithium ion secondary battery according to an embodiment. 1 is a longitudinal sectional view of a lithium ion secondary battery according to an embodiment. It is an expanded view of an electrode body which concerns on embodiment and shows the state which mutually accumulated the positive electrode plate and the negative electrode plate through the separator. It is sectional drawing of a negative electrode plate concerning embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 show a lithium ion secondary battery 10 (hereinafter also simply referred to as battery 10). 3 shows an electrode body 30, and FIG. 4 shows a negative electrode plate (electrode plate) 41. In the following description, the thickness direction BH, the width direction CH, and the height direction DH of the battery 10 are defined as the directions shown in FIGS. 1 and 2. 1 and 2 will be described as the upper side of the battery 10 and the lower side as the lower side of the battery 10.
The battery 10 is a square sealed battery mounted on a vehicle such as a hybrid vehicle or an electric vehicle. The battery 10 includes a rectangular parallelepiped battery case 20, a flat wound electrode body 30 accommodated in the battery case 20, a positive terminal 60 and a negative terminal 70 supported by the battery case 20, and the like. Has been. Further, a non-aqueous electrolyte solution 27 is held in the battery case 20.

  Among these, the electrode body 30 is accommodated in the battery case 20 in a state of being laid down so that its axis (winding axis) is parallel to the width direction CH of the battery 10 (see FIG. 2). This electrode body 30 has a belt-like positive electrode plate 31 and a belt-like negative electrode plate 41 which are stacked on each other via two belt-like separators 51 and 51 made of a resin porous film (see FIG. 3). It is wound around and compressed into a flat shape. A part of the positive electrode plate 31 in the width direction protrudes from the separators 51, 51 to one side in the axial direction (leftward in FIG. 2, upper in FIG. 3) in a spiral shape and is connected to the positive electrode terminal 60. (Welding). A part of the negative electrode plate 41 in the width direction protrudes from the separators 51, 51 in a spiral shape on the other side in the axial direction (right side in FIG. 2, downward in FIG. 3). Connected (welded).

  The positive electrode plate 31 has a strip-shaped positive electrode foil 32 made of aluminum as a core material. Of the front and back surfaces of the positive electrode foil 32, a part of the width direction (vertical direction in FIG. 3) (downward in FIG. 3) extends in a strip shape in the longitudinal direction (horizontal direction in FIG. 3). Positive electrode active material layers 33 are formed. The positive electrode active material layer 33 is formed of a positive electrode active material, a conductive material, and a binder. In this embodiment, lithium-cobalt-nickel-manganese composite oxide is used as the positive electrode active material, acetylene black (AB) is used as the conductive material, and polyvinylidene fluoride (PVDF) is used as the binder.

  The negative electrode plate (electrode plate) 41 has a strip-shaped negative electrode foil (electrode foil) 42 made of copper as a core material. Of the front and back surfaces of the negative electrode foil 42, a part (width in FIG. 3, upper direction, left in FIG. 4) in the width direction (in FIG. 3, up and down direction, in FIG. Negative electrode active material layers (active material layers) 43 and 43 extending in a strip shape in the longitudinal direction (the left-right direction in FIG. 3 and the direction orthogonal to the paper surface in FIG. 4) are formed. The negative electrode active material layer 43 is formed of a negative electrode active material (active material) 83, a binder 84, and a thickener 85. In this embodiment, natural graphite is used as the negative electrode active material 83, styrene butadiene rubber (SBR) is used as the binder 84, and carboxymethyl cellulose (CMC) is used as the thickener 85.

Next, a method for manufacturing the negative electrode plate 41 and the battery 10 will be described. First, the negative electrode plate 41 is manufactured. That is, a strip-shaped negative electrode foil 42 is prepared. In addition, a negative electrode paste 81 in which a negative electrode active material (natural graphite) 83, a binder (SBR) 84, and a thickener (CMC) 85 are dispersed in a solvent 82 (specifically water) is prepared. The freezing point Tf of this solvent (water) is 0 ° C., and the glass transition point Tg of the binder 84 (SBR) used in the present embodiment is −44 ° C.
And in a coating process, the negative electrode paste 81 is apply | coated on a part of width direction among one main surfaces of the negative electrode electrode foil 42 using a die coater, and the negative electrode paste layer 43p1 (refer FIG. 4) is formed. .

  Next, a freezing process is performed promptly after the coating process. That is, the negative electrode paste layer 43p1 is lower than the freezing point Tf (= 0 ° C.) of the solvent 82, higher than the glass transition point Tg (= −44 ° C.) of the binder 84, and (Tg + Tf). / 2 (= −22 ° C.) or more, that is, freezing at a first cooling temperature Tc (Tc = −2 ° C. in the present embodiment) satisfying (Tg + Tf) / 2 ≦ Tc <Tf (−22 ≦ Tc <0). . Specifically, the negative electrode foil 42 having the negative electrode paste layer 43p1 formed thereon is placed on the cooled metal plate, and cooled at a cooling rate of 6 ° C./sec until the negative electrode paste layer 43p1 reaches −2 ° C. Then, the negative electrode paste layer 43p1 was instantly frozen. This instant freezing is preferably performed at a cooling rate of 3 ° C./sec or more.

Next, in the vacuum freeze-drying process, the frozen negative electrode paste layer 43p2 is subjected to second cooling that satisfies Tg <Td <Tf and further satisfies (Tg + Tf) / 2 ≦ Td <Tf (−22 ≦ Td <0). The anode active material layer 43 is formed by vacuum freeze-drying at a temperature Td (Td = −15 ° C. in the present embodiment). Specifically, the negative electrode foil 42 having the frozen negative electrode paste layer 43p2 is placed in a vacuum freeze dryer, and the temperature is set to −15 ° C. and the pressure is set to 10 ⁻¹ Pa. 82 was sublimated to form a negative electrode active material layer 43.

Next, the coating process is performed again, and the negative electrode paste 81 is applied onto a part of the main surface on the opposite side of the negative electrode electrode foil 42 in the width direction to form the negative electrode paste layer 42p1. Thereafter, a freezing step is performed immediately, and the negative electrode paste layer 43p1 is frozen at the first cooling temperature Tc = −2 ° C. Further, a vacuum freeze-drying step is performed, and the frozen negative electrode paste layer 43p2 is vacuum-freeze-dried at the second cooling temperature Td = −15 ° C. to form the negative electrode active material layer 43.
Thereafter, these negative electrode active material layers 43, 43 are compressed by a pressure roll to increase their density. Thus, the negative electrode plate 41 is formed.

  Separately, the positive electrode plate 31 is manufactured. That is, a strip-shaped positive electrode foil 32 is prepared. Then, using a die coater, a positive electrode paste containing a positive electrode active material, a conductive material, and a binder is applied to a part of one main surface of the positive electrode electrode foil 32 in the width direction, and this is heated with hot air. It is made to dry and the positive electrode active material layer 33 is formed (refer FIG. 3). Similarly, the positive electrode paste is applied to a main surface on the opposite side of the positive electrode foil 32 on a part in the width direction, and dried with hot air to form the positive electrode active material layer 33. Then, these positive electrode active material layers 33 and 33 are compressed with a pressure roll, and the density is raised. Thus, the positive electrode plate 31 is formed.

Next, two strip-shaped separators 51 are prepared, and the above-described positive electrode plate 31 and negative electrode plate 41 are overlapped with each other through the separators 51 and 51 (see FIG. 3), and wound around the axis using a winding core. . Further, the electrode body 30 is formed by compressing it into a flat shape.
Separately, a rectangular plate-like lid member 23 (see FIG. 2) of the battery case 20 is prepared, and a positive electrode terminal 60 and a negative electrode terminal 70 are fixed to the lid member 23, respectively. Thereafter, a bottomed rectangular tube-shaped main body member 21 of the battery case 20 is prepared, and after the electrode body 30 is accommodated in the main body member 21, the main body member 21 and the lid member 23 are laser-welded to form the battery case 20. Form. Thereafter, the electrolytic solution 27 is injected into the battery case 20. Thereafter, the battery is subjected to initial charging and various inspections. Thus, the battery 10 is completed.

(Examples and Comparative Examples)
Subsequently, the result of the test performed in order to verify the effect of the manufacturing method of the negative electrode plate 41 which concerns on embodiment is demonstrated. As Example 1, the negative electrode plate 41 was manufactured by the manufacturing method according to the embodiment. In this manufacturing method, as described above, the first cooling temperature Tc in the freezing step satisfies Tg <Tc <Tf (specifically −44 ≦ Tc <0), and (Tg + Tf) / 2 ≦ Tc. Tc = −2 ° C. satisfying <Tf (specifically −22 ≦ Tc <0).
Further, as Example 2, the first cooling temperature Tc in the freezing step is set to Tc = −31 ° C. that satisfies Tg <Tc <Tf but does not satisfy (Tg + Tf) / 2 ≦ Tc <Tf. A negative electrode plate was produced in the same manner as in Example 1 (embodiment).

On the other hand, as Comparative Example 1, the first cooling temperature Tc in the freezing step was set to Tc = −196 ° C. not satisfying Tg <Tc <Tf, and the negative electrode plate was manufactured in the same manner as in Example 1 except that.
Further, as Comparative Example 2, a negative electrode plate was produced in the same manner as in Example 1 except that a vacuum freeze-drying process was performed after the coating process without performing the freezing process.

  About each negative electrode plate which concerns on these Examples 1 and 2 and Comparative Examples 1 and 2, the peel strength test of the negative electrode active material layer was done, and peel strength (adhesion strength, N / m) was measured, respectively. Specifically, a strip-shaped piece was cut out from each negative electrode plate. Of these strips, one side was fixed to a horizontal base via a double-sided tape, and the other side was lifted vertically by a peel strength measuring machine. And the force (N) applied when the negative electrode active material layer affixed to the double-sided tape peeled from the negative electrode foil was measured by this peel strength measuring device, and the peel strength (N / m) was determined from this. The results are shown in Table 1.

  As can be seen from Table 1, in the negative electrode plate according to Comparative Example 1 in which the first cooling temperature Tc in the freezing step was Tc = −196 ° C. not satisfying Tg <Tc <Tf, the negative electrode active was already performed before the peel strength test was performed. Since the material layer was peeled from the negative electrode foil, the peel strength was zero (0.00 N / m). The reason is that the electrode paste layer was excessively cooled to below the glass transition point Tg of the binder, so that the binder was vitrified and lost its elasticity, and the binding action was greatly reduced. In addition, it is considered that the difference in heat shrinkage generated between the negative electrode foil and the negative electrode active material layer due to excessive cooling is increased, and a large stress is generated between them, resulting in a decrease in the peel strength.

  On the other hand, in each negative electrode plate according to Examples 1 and 2 in which the first cooling temperature Tc in the freezing step is set to a temperature satisfying Tg <Tc <Tf, the peel strength is higher than that of Comparative Example 1, and according to Example 1. The negative electrode plate was 18.73 N / m, and the negative electrode plate according to Example 2 was 10.64 N / m. In particular, the peel strength was high in the negative electrode plate according to Example 1 in which the first cooling temperature Tc was set to a temperature satisfying (Tg + Tf) / 2 ≦ Tc <Tf. The reason is that in Examples 1 and 2, the first cooling temperature Tc was set to a temperature higher than the glass transition point Tg of the binder, so that the binder did not vitrify at the time of cooling, and the binding action was large. The decline was prevented. In addition, the difference in heat shrinkage generated between the negative electrode foil and the negative electrode active material layer during cooling was smaller than that in Comparative Example 1, and the stress generated between them was small. In particular, in Example 1, the difference in heat shrinkage generated between the negative electrode foil and the negative electrode active material layer was small, and the stress generated between them was small. For this reason, it is thought that it was suppressed that the peeling strength of electrode foil and an active material layer fell.

  In addition, in the negative electrode plate which concerns on the comparative example 2 which did not perform the freezing process, peeling strength was lower than Example 1, and was 13.72 N / m. The reason is that the binder in the electrode paste layer moves in the thickness direction between the time when the coating process is performed and the electrode paste layer is dried by vacuum freeze-drying. Occurred. As a result, it is considered that the peel strength between the negative electrode foil and the negative electrode active material layer was lowered.

  As described above, in the manufacturing method of the negative electrode plate 41, after the negative electrode paste layer 42p1 is formed on the negative electrode foil 42, the negative electrode paste layer 42p1 is changed to Tg <Tc <Tf (Tg: binder 84). After freezing at the first cooling temperature Tc satisfying the glass transition point, Tf: the freezing point of the solvent 82), the frozen negative electrode paste layer 42p2 is vacuum lyophilized at the second cooling temperature Td satisfying Tg <Td <Tf. Thus, the negative electrode active material layer 43 is formed. Thus, after the electrode paste layer 42p1 is formed, the electrode paste layer 42p1 is frozen in advance before the vacuum freeze-drying, so that the electrode paste layer 42p1 is formed before the electrode paste layer 42p1 is vacuum-lyophilized. It is possible to prevent the binder 84 in the layer 42p1 from moving in the thickness direction and to prevent the binder 84 from being unevenly distributed in the thickness direction.

  In addition, when the first cooling temperature Tc and the second cooling temperature Td are set to a temperature (Tc, Td> Tg) higher than the glass transition point Tg of the binder 84, the state of the binder 84 changes. Since the binding action can be prevented from greatly decreasing, the negative electrode foil 42 and the negative electrode active material layer 43 are caused by the stress caused by the difference in thermal shrinkage between the negative electrode foil 42 and the negative electrode paste layer 42p1 (negative electrode active material layer 43). It is possible to suppress a decrease in the adhesion strength. Therefore, the binder 84 is prevented from being unevenly distributed in the thickness direction in the negative electrode active material layer 43, and the adhesion strength between the negative electrode electrode foil 42 and the negative electrode active material layer 43 is increased. The layer 43 can be prevented from peeling off.

  Further, in the manufacturing method of the negative electrode plate 41, the lower limit values of the first cooling temperature Tc and the second cooling temperature Td are limited to (Tg + Tf) / 2, respectively, so the negative electrode foil 42 and the negative electrode paste layer 42p2 (negative electrode active The difference in heat shrinkage generated in the material layer 43) can be reduced to effectively suppress the decrease in adhesion strength.

  Moreover, in the manufacturing method of the negative electrode plate 41, since the negative electrode foil 42 is a copper foil and the solvent 82 is water, the difference in thermal shrinkage generated between the negative electrode foil 42 and the negative electrode paste layer 42p2 (negative electrode active material layer 43). Tends to be large. Further, when the SBR 84 is cooled below its glass transition point Tg, it becomes vitrified and loses elasticity, and the binding action is greatly reduced. On the other hand, the first cooling temperature Tc and the second cooling temperature Td are higher than the glass transition point Tg of the SBR 84, thereby reducing the adhesion strength between the negative electrode foil 42 and the negative electrode active material layer 43. Can be suppressed.

  Moreover, in the manufacturing method of the negative electrode plate 41, SBR which has a glass transition point Tg of −40 ° C. or less and has sufficient elasticity even at a low temperature of about −15 ° C. is used as the binder 84. In addition, since the first cooling temperature Tc (° C.) is −15 ≦ Tc <0 and the second cooling temperature Td (° C.) is −15 ≦ Td <0, the adhesion between the negative electrode foil 42 and the negative electrode active material layer 43 is close. A decrease in strength can be effectively suppressed.

In the above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof.
For example, in the embodiment, one main surface of the negative electrode foil 42 is subjected to a coating step, a freezing step, and a vacuum freeze-drying step to form one negative electrode active material layer 43, and then again to the other main surface. The other negative electrode active material layer 43 was formed by performing the coating process, the freezing process, and the vacuum freeze-drying process, but is not limited thereto. The negative electrode active material layers 43 and 43 may be formed on both sides simultaneously. That is, after the coating process is performed on both main surfaces of the negative electrode foil 42 to form the negative electrode paste layers 43p1 and 43p1, a freezing process is performed on them, and a vacuum freeze-drying process is further performed on these layers. The material layers 43 and 43 may be formed simultaneously.

10 Lithium ion secondary battery (battery)
30 Electrode body 31 Positive electrode plate 41 Negative electrode plate (electrode plate)
42 Negative electrode foil (electrode foil)
43 Negative electrode active material layer (active material layer)
43p1 (not frozen) negative electrode paste layer (electrode paste layer)
43p2 (frozen) negative electrode paste layer (electrode paste layer)
51 Separator 81 Negative electrode paste (electrode paste)
82 Solvent 83 Negative electrode active material (active material)
84 Binder 85 Thickener

Claims (5)

A method for producing an electrode plate having an electrode foil and an active material layer formed on the electrode foil,
An electrode paste in which an active material and a binder dispersed in a solvent are applied onto the electrode foil to form an electrode paste layer; and
The electrode paste layer is frozen at a first cooling temperature Tc (Tg <Tc <Tf) lower than the freezing point Tf of the solvent and higher than the glass transition point Tg (where Tg <Tf) of the binder. A freezing step,
A vacuum freeze-drying step of vacuum freeze-drying the frozen electrode paste layer at a second cooling temperature Td satisfying Tg <Td <Tf to form the active material layer. It is a manufacturing method of the electrode plate according to claim 1,
The first cooling temperature Tc and the second cooling temperature Td are:
(Tg + Tf) / 2 ≦ Tc <Tf
(Tg + Tf) / 2 ≦ Td <Tf
The manufacturing method of the electrode plate which satisfy | fills. It is a manufacturing method of the electrode plate according to claim 1 or 2,
The electrode foil is a copper foil,
The solvent is water;
The method for producing an electrode plate, wherein the binder is styrene butadiene rubber. It is a manufacturing method of the electrode plate according to claim 3,
The glass transition point Tg of the styrene butadiene rubber is −40 ° C. or less,
The first cooling temperature Tc (° C.) and the second cooling temperature Td (° C.) are:
−15 ≦ Tc <0
−15 ≦ Td <0
The manufacturing method of the electrode plate which satisfy | fills. A battery manufacturing method comprising an electrode plate having an electrode foil and an active material layer formed on the electrode foil,
The manufacturing method of the battery containing the manufacturing method of the electrode plate as described in any one of Claims 1-4.

Images