JP7213225B2 - ELECTRODE LAMINATE, BATTERY, AND METHOD FOR MANUFACTURING ELECTRODE LAMINATE - Google Patents

Description

The present technology relates to an electrode laminate, a battery, and a method for manufacturing an electrode laminate.

Japanese Patent Application Laid-Open No. 2017-098022 (Patent Document 1) discloses welding separators provided with an electrode therebetween.

JP 2017-098022 A

Batteries including electrode stacks have been developed. For example, an electrode laminate is formed by alternately stacking first electrode plates and second electrode plates with a separator interposed therebetween. An adhesive is placed between the first electrode plate and the separator. An adhesive may also be placed between the second electrode plate and the separator. The first electrode plate, the separator and the second electrode plate are fixed by subjecting the electrode laminate to hot pressing. Hereinafter, in this specification, the first electrode plate and the second electrode plate may be collectively referred to as "electrode plate".

FIG. 1 is a conceptual diagram showing hot pressing of an electrode laminate.
The electrode laminate 50 is sandwiched between the first hot press plate 210 (upper plate) and the second hot press plate 220 (lower plate). First hot press plate 210 and second hot press plate 220 are heated to a predetermined temperature. The first hot press plate 210 presses the electrode laminate 50 along the stacking direction (z-axis direction), thereby softening and solidifying the adhesive. Thereby, the separator and the electrode plate are adhered. After pressing, the first hot press plate 210 is separated from the electrode laminate 50 . At this time, the electrode stack 50 may be separated into two near the middle in the stacking direction. This is because the electrode laminate 50 sticks to the first hot press plate 210 and the second hot press plate 220 . The separated top half then falls due to gravity. The position of the electrode plate may shift due to the impact of the drop. Further, the separator may be deformed (wrinkles, folds, etc.).

The adhesive strength of the adhesive can change depending on the heating temperature. The lower the heating temperature, the lower the adhesive strength of the adhesive tends to be. Also, the adhesive strength of the adhesive can change with pressure. The lower the pressure, the lower the adhesive strength of the adhesive tends to be.

It is considered that heat is likely to escape from the peripheral edge of the electrode plate in a plan view during hot pressing. Furthermore, it is considered that the peripheral edge of the electrode plate has a larger pressure loss than the center of the electrode plate. Therefore, the peripheral edge of the electrode plate tends to have a lower adhesive strength than the center of the electrode plate.

During hot pressing, a temperature distribution may also occur in the stacking direction of the electrode laminate. That is, in the lamination direction of the electrode laminate, the temperature tends to decrease as the distance from the hot press plate increases. Therefore, in the stacking direction, the temperature tends to be the lowest near the middle. It is considered that these influences are combined, and the adhesive strength is particularly low near the middle in the stacking direction and at the periphery in plan view. It is believed that this portion serves as a starting point to lead to the separation of the electrode laminate.

In order to prevent separation of the electrode laminate, it is conceivable to strongly press the entire surface of the electrode laminate during hot pressing. However, in this case, the separator may be in excessive contact with the center of the electrode plate. As a result, permeation of the electrolytic solution may be inhibited.

An object of the present technology is to provide an electrode laminate that is difficult to separate.

The configuration and effects of the present technology will be described below. However, the mechanism of action of this technology includes presumption. Whether the mechanism of action is correct or not does not limit the scope of the present technology.

[1] An electrode laminate includes a plurality of first electrode plates, a plurality of second electrode plates, one or more separators, and an adhesive. The first electrode plate has a different polarity than the second electrode plate. A first electrode plate and a second electrode plate are alternately laminated with a separator interposed therebetween. An adhesive is disposed between the separator and the first electrode plate. The first electrode plate includes a first active material layer. The second electrode plate includes a second active material layer.
In plan view, each of the first active material layer and the second active material layer has a square planar shape. The first active material layer has short sides and long sides that are smaller than those of the second active material layer. The length of the short side of the first active material layer is defined as D, and the length of the long side of the first active material layer is defined as L. The first active material layer includes a first region and a second region. The first region is separated from each vertex of the first active material layer by 0.4D or more and 0.6D or less in the short side direction and 0.4L or more and 0.6L or less in the long side direction. The second region is separated from any vertex of the first active material layer by 0.05D or more and less than 0.4D in the short side direction and by 0.05L or more and less than 0.4L in the long side direction.
The first region is adhered to the separator with a first adhesive force. The second region is adhered to the separator by a second adhesive force. The ratio of the first adhesive force to the second adhesive force is 1 or less.

A first region of the present technology includes the center of the first electrode plate. The second region includes four corners of the first electrode plate. In conventional electrode laminates, the central adhesive strength tends to be higher than the adhesive strength at the four corners (that is, part of the periphery). It is considered that heat escape and pressure loss in plan view have an effect.

In the present technology, the adhesive strength of the four corners (second adhesive strength) is equal to or greater than the central adhesive strength (first adhesive strength). That is, the ratio of the first adhesive force to the second adhesive force is 1 or less. According to the new findings of the present technology, the adhesive force at the four corners is equal to or greater than the adhesive force at the center, so that the electrode laminate tends to be difficult to separate. Furthermore, there is a tendency that a gap is likely to be formed in the center of the electrode laminate. Therefore, it is expected that the permeation of the electrolytic solution is promoted.

Hereinafter, in this specification, the "ratio of the first adhesive strength (F1) to the second adhesive strength (F2)" is also referred to as the "adhesive strength ratio (F1/F2)".

[2] In plan view, the first active material layer may further include a third region and a fourth region. The third region is sandwiched between two adjacent second regions in the short side direction. The fourth region is sandwiched between two adjacent second regions in the long side direction. The third region and the fourth region may also be adhered to the separator by, for example, a second adhesive force.

That is, not only the four corners but also the entire periphery may have adhesive strength equal to or greater than that of the center. This is expected to make it difficult for the electrode laminate to separate.

[3] The ratio of the first adhesive force to the second adhesive force may be, for example, 0.44 to 0.91 in the first electrode plate located in the middle in the stacking direction.

The adhesive force ratio (F1/F2) tends to decrease from the outside to the middle in the lamination direction. This is probably because heat is more likely to be transferred to the entire surface of the first electrode plate as it is closer to the hot press plate during hot pressing. The adhesion force ratio (F1/F2) can take the maximum value in the first electrode plate positioned on the outermost side in the stacking direction (hereinafter also referred to as "outermost electrode plate"). The maximum value can be one. The adhesion force ratio (F1/F2) can take the minimum value in the first electrode plate (hereinafter also referred to as "intermediate electrode plate") positioned in the middle in the stacking direction. The minimum value may be, for example, 0.44 to 0.91. The intermediate electrode plate tends to be easily peeled off. In the intermediate electrode plate, the adhesive force at the four corners is sufficiently greater than the adhesive force at the center, so that the electrode laminate tends to be difficult to separate.

[4] The ratio of the minimum basis weight of the adhesive to the average basis weight of the adhesive may be 0.7 or more. Moreover, the ratio of the maximum basis weight of the adhesive to the average basis weight of the adhesive may be 1.3 or less.

In order to increase the adhesion strength (second adhesion strength) of the four corners, for example, it is conceivable to increase the basis weight of the adhesive at the periphery as compared with the basis weight of the adhesive at the center. However, local variations in the basis weight of the adhesive may complicate the manufacturing process. For example, the manufacturing process can be simplified by applying the adhesive substantially uniformly over the entire surface of the separator.

For example, according to the manufacturing method (described later) of the present technology, even if the basis weight of the adhesive is substantially uniform over the entire area, it is conceivable that the adhesive force at the four corners can be locally increased.

[5] The electrode laminate may include, for example, ten or more first electrode plates.

Hereinafter, the number of first electrode plates included in the electrode laminate is also referred to as "the number of laminates". For example, when the number of first electrode plates is n, the number of second electrode plates may be (n−1), n, or (n+1).

[6] A battery includes the electrode laminate according to any one of [1] to [5] above and an electrolytic solution.

[7] The method for manufacturing the electrode laminate includes the following (A) and (B).
(A) An electrode laminate is formed by alternately laminating a first electrode plate and a second electrode plate with a separator interposed therebetween.
(B) Adhering the first electrode plate and the separator by applying heat press to the electrode laminate along the stacking direction.
An adhesive is placed between the first electrode plate and the separator. A hot press is applied while the electrode laminate is heated from a direction intersecting the lamination direction.

By heating the end surfaces (which can be rephrased as “side surfaces”) of the electrode laminate during hot pressing, the escape of heat from the peripheral edges of the electrode plates can be reduced. As a result, it is expected that the adhesive force at the four corners or the periphery will be enhanced.

Furthermore, it is expected that the temperature distribution in the stacking direction of the electrode stack will be reduced. Due to the synergy of these actions, it is expected that the electrode laminate will be difficult to separate near the middle in the lamination direction.

[8] In the hot press, a hot press plate is pressed against the electrode laminate. In plan view, the hot press plate has a square planar shape. The hot press plate includes a central portion and a peripheral portion. A peripheral portion surrounds the central portion. The perimeter includes protrusions. In the thickness direction of the hot press plate, the projecting portion projects more than the central portion. The protrusions are arranged at least at the four corners of the peripheral edge. In hot pressing, the projection is pressed against the electrode laminate.

The pressure applied to the four corners can be increased by pressing the protrusions of the hot press plate against the four corners of the electrode laminate. As a result, it is expected that the adhesive strength at the four corners will increase.

[9] In the hot press, a hot press plate is pressed against the electrode laminate. In a plan view, the hot press plate has a square planar shape. The hot press plate includes a central portion and a peripheral portion. A peripheral portion surrounds the central portion. The peripheral portion includes an edge heating portion. In the thickness direction of the hot press plate, the end surface heating portion protrudes from the central portion. The end surface heating unit heats the electrode laminate from a direction intersecting the lamination direction during hot pressing.

In the manufacturing method of [7] above, a heater may be used to heat the end face of the electrode laminate. The heater may be integrated with the hot press plate. That is, the hot press plate may include end surface heating portions.

[10] A gas may be supplied around the electrode laminate during hot pressing. A gas may have a high thermal conductivity compared to air.

It is expected that heat transfer to the end surfaces of the electrode laminate is promoted by supplying a gas having a high thermal conductivity to the periphery of the electrode laminate. This is expected to increase the adhesive strength at the four corners or the periphery, for example.

FIG. 1 is a conceptual diagram showing hot pressing of an electrode laminate. FIG. 2 is a schematic flow chart of the manufacturing method of this embodiment. FIG. 3 is a schematic plan view showing an example of the first electrode plate and the second electrode plate. FIG. 4 is a schematic cross-sectional view showing an example of the lamination method. FIG. 5 is a schematic cross-sectional view showing an example of hot press. FIG. 6 is a schematic plan view showing the arrangement of heaters. FIG. 7 is a schematic diagram showing a first example of a hot press plate. FIG. 8 is a schematic diagram showing a second example of the hot press plate. FIG. 9 is a schematic diagram showing a third example of the hot press plate. FIG. 10 is a schematic cross-sectional view showing a fourth example of the hot press plate. FIG. 11 is a schematic cross-sectional view showing a fifth example of the hot press plate. FIG. 12 is a schematic diagram showing an example of the configuration of the battery of this embodiment. FIG. 13 is a schematic plan view showing an example of the first electrode plate. FIG. 14 is a schematic cross-sectional view showing a method for measuring adhesive force.

Hereinafter, embodiments of the present technology (hereinafter also referred to as “present embodiments”) will be described. However, the following description does not limit the scope of this technology.

As used herein, "comprise, include," "have," and variations thereof [e.g., "be composed of," "emcopass, involve," Descriptions of "contain", "carry, support", "hold", etc.] are open-ended. That is, it includes a configuration, but is not limited to including only that configuration. References to "consist of" are closed form. The statement "consisting essentially of" is semi-closed form. That is, the description “consisting essentially of” indicates that additional components may be included in addition to the essential components within a range that does not hinder the purpose of the present technology. For example, components normally assumed in the field to which the present technology belongs (for example, unavoidable impurities, etc.) may be included as additional components.

In this specification, singular forms (“a,” “an,” and “the”) include plural forms unless otherwise stated. For example, "particle" can include not only "one particle" but also "aggregate of particles (powder)".

In this specification, any two or more steps, acts and operations involved in a method are not limited to the order in which they are presented unless specifically stated otherwise.

Geometric terms herein (eg, "orthogonal", etc.) are not to be taken in a strict sense. For example, "perpendicular" may deviate somewhat from "perpendicular" in the strict sense. Geometric terms herein may include, for example, design, work, manufacturing, etc. tolerances, errors, and the like.

In the present specification, numerical ranges such as "0.44 to 0.91" include upper and lower limits unless otherwise specified. For example, "0.44 to 0.91" indicates a numerical range of "0.44 to 0.91". Also, numerical values arbitrarily selected from within the numerical range may be used as the new upper and lower limits. For example, a new numerical range may be set by arbitrarily combining the numerical values within the numerical range and the numerical values described elsewhere in this specification.

The dimensional relationships in each drawing may not match the actual dimensional relationships. Dimensional relationships (length, width, thickness, etc.) in each figure may be changed to facilitate understanding of the present technology. Furthermore, some configurations may be omitted.

In the present specification, "planar view" indicates the case where each configuration or the like is viewed from the "stacking direction" or "the direction that should be the stacking direction" of the electrode laminate. In each figure, the stacking direction or the direction to be the stacking direction is the z-axis direction.

The battery of the present technology can be any battery. In this specification, an application to a "lithium ion battery" is described as an example.

<Manufacturing method>
FIG. 2 is a schematic flow chart of the manufacturing method of this embodiment.
The manufacturing method of the present embodiment includes "(A) formation of electrode laminate" and "(B) hot press". The manufacturing method of the present embodiment may further include "(C) accommodation".

<<(A) Formation of electrode laminate>>
The manufacturing method of the present embodiment includes forming an electrode laminate by alternately laminating first electrode plates and second electrode plates with separators interposed therebetween.

(Preparation of first electrode plate and second electrode plate)
FIG. 3 is a schematic plan view showing an example of the first electrode plate and the second electrode plate.
A plurality of first electrode plates 10 and a plurality of second electrode plates 20 are prepared. The first electrode plate 10 has a different polarity than the second electrode plate 20 . For example, the first electrode plate 10 may be a positive plate and the second electrode plate 20 may be a negative plate. For example, the first electrode plate 10 may be the negative plate and the second electrode plate 20 may be the positive plate. In this specification, as an example, a mode is described in which the first electrode plate 10 is a positive electrode plate and the second electrode plate 20 is a negative electrode plate.

The first electrode plate 10 can be prepared by any method. For example, the first electrode base material 11 is prepared. The first electrode base material 11 may be, for example, a metal foil, a metal plate, or the like. The first electrode base material 11 may be, for example, Al (aluminum) foil or the like. The first electrode substrate 11 may have a thickness of, for example, 10 μm to 30 μm. A first slurry is prepared by mixing an active material, a conductive material, a binder, a dispersion medium, and the like. The active material may contain, for example, a lithium-transition metal composite oxide. The first active material layer 12 can be formed by applying the first slurry to a predetermined area on the surface of the first electrode base material 11 . The first active material layer 12 may be formed only on one side of the first electrode substrate 11 . The first active material layer 12 may be formed on both front and back surfaces of the first electrode base material 11 . For example, the first electrode plate 10 arranged at the end in the stacking direction may have the first active material layer 12 only on one side. The first active material layer 12 may be compressed. The first active material layer 12 after compression may have a thickness of, for example, 10 μm to 100 μm. As described above, the first electrode blank is prepared. A plurality of first electrode plates 10 can be prepared by cutting the first electrode blank into a predetermined shape. A portion of the first electrode plate 10 where the first electrode base material 11 is exposed can be used, for example, for connection with the first electrode terminal 91 (see FIG. 12).

The second electrode plate 20 can also be prepared by any method. For example, the second electrode base material 21 is prepared. The second electrode base material 21 may be, for example, a Cu (copper) foil or the like. The second electrode substrate 21 may have a thickness of, for example, 5 μm to 30 μm. A second slurry is prepared by mixing the active material, the conductive material, the binder, the dispersion medium, and the like. The active material may contain, for example, graphite. The second active material layer 22 can be formed by applying the second slurry to a predetermined area on the surface of the second electrode base material 21 . The second active material layer 22 may be formed only on one side of the second electrode base material 21 . The second active material layer 22 may be formed on both front and back surfaces of the second electrode base material 21 . For example, the second electrode plate 20 arranged at the end in the stacking direction may have the second active material layer 22 only on one side. The second active material layer 22 may be compressed. The second active material layer 22 after compression may have a thickness of, for example, 10 μm to 100 μm. As described above, the second electrode blank is prepared. A plurality of second electrode plates 20 can be prepared by cutting the second electrode material into a predetermined shape. A portion of the second electrode plate 20 where the second electrode base material 21 is exposed can be used, for example, for connection with the second electrode terminal 92 (see FIG. 12).

The first electrode plate 10 includes a first active material layer 12 . The second electrode plate 20 includes a second active material layer 22 . Each of first active material layer 12 and second active material layer 22 has a square planar shape. Each of the first active material layer 12 and the second active material layer 22 may be rectangular or square, for example. The planar shape need not be strictly rectangular or square. For example, each vertex of the rectangle may be rounded.

The first active material layer 12 has short sides and long sides that are smaller than those of the second active material layer 22 . That is, the first active material layer 12 has a smaller area than the second active material layer 22 . For example, the short side of the first active material layer 12 may be 0.90 to 0.99 times the short side of the second active material layer 22 . For example, the long side of the first active material layer 12 may be 0.90 to 0.99 times the long side of the second active material layer 22 . The first electrode plate 10 and the second electrode plate 20 may be stacked such that the entire surface of the first active material layer 12 faces the second active material layer 22 . Separation of the active material layer having a small area (that is, the first active material layer 12 ) and the separator 30 tends to be the starting point of separation of the electrode laminate 50 .

(separator)
One or more separators 30 are prepared. Separator 30 is a porous sheet. Separator 30 is electrically insulating. The separator 30 may be substantially made of polyolefin resin, for example.

For example, the electrode stack 50 may be formed by sequentially stacking the first electrode plate 10 , the separator 30 , the second electrode plate 20 , and the separator 30 . That is, a plurality of separators 30 may be used.

FIG. 4 is a schematic cross-sectional view showing an example of the lamination method.
For example, one sheet of separator 30 may be folded in a zigzag pattern. The electrode laminate 50 may be formed by alternately inserting the first electrode plate 10 and the second electrode plate 20 each time the separator 30 is folded.

The electrode laminate 50 may include, for example, two or more first electrode plates 10, ten or more first electrode plates 10, or thirty or more first electrode plates 10. 10 may be included. The electrode laminate 50 may include, for example, 100 or less first electrode plates 10 or 50 or less first electrode plates 10 . That is, the electrode laminate 50 may have, for example, 2 to 100 layers, 10 to 100 layers, or 30 to 100 layers. may have 30 to 50 laminations.

(glue)
An adhesive (not shown) is prepared. The adhesive can change its adhesive strength depending on the temperature and pressure during hot pressing. The adhesive may include, for example, hot melt adhesives and the like. The adhesive may have a softening point of, for example, 80°C to 120°C. The adhesive may contain, for example, at least one selected from the group consisting of acrylic resins, urethane resins, ethylene vinyl acetate resins, epoxy resins, and fluorine resins.

An adhesive is placed between the first electrode plate 10 and the separator 30 . The adhesive may be applied to the surface of the separator 30, for example. The adhesive may be applied to the surface of the first electrode plate 10, for example. The adhesive may also be placed between the second electrode plate 20 and the separator 30, for example.

The adhesive may be applied, for example, in layers, or may be dispersed in dots. The adhesive may be applied, for example, by screen printing or the like. For example, the adhesive may be applied or scattered in dots so that the basis weight is substantially uniform over the entire surface of the application target. The term “basis weight (g/cm ² )” used herein indicates mass per unit area. Uniformity of basis weight can be evaluated, for example, as follows.

For example, five or more sample pieces are cut out from the separator 30 coated with the adhesive. The sampling points of the sample pieces are randomly selected from the coated surface. A sample piece has a planar size of 1 cm×1 cm. The mass of each sample piece is measured. The mass of the adhesive is calculated by subtracting the mass of the separator per 1 cm ² from the mass of the sample piece. The basis weight of the sample piece is calculated by dividing the mass of the adhesive by the area of the sample piece (1 cm ² ). The average basis weight (arithmetic average value of basis weight), minimum basis weight (minimum basis weight), and maximum basis weight (maximum basis weight) are calculated from the results of five or more sample pieces. For example, when the following conditions are satisfied, it can be evaluated that the basis weight is substantially uniform. That is, the ratio of the minimum basis weight to the average basis weight is 0.7 or more, and the ratio of the maximum basis weight to the average basis weight is 1.3 or less. The ratio of the minimum basis weight to the average basis weight may be, for example, 0.8 or more. The ratio of the maximum basis weight to the average basis weight may be, for example, 1.2 or less.

<<(B) Heat Press>>
The manufacturing method of the present embodiment includes bonding the first electrode plate 10 and the separator 30 by applying heat press to the electrode laminate 50 along the stacking direction. The hot press may be applied substantially parallel to the stacking direction. In the present embodiment, hot pressing is performed while the electrode laminate 50 is heated from the direction intersecting the stacking direction. As a result, the four corners or the periphery of the electrode laminate 50 can be strongly bonded in plan view. That is, an electrode laminate 50 that is difficult to separate after hot pressing can be manufactured.

FIG. 5 is a schematic cross-sectional view showing an example of hot press.
A hot press device is provided. The hot press device includes a first hot press plate 210 and a second hot press plate 220 . The electrode laminate 50 is arranged between the first hot press plate 210 and the second hot press plate 220 . For example, a fluororesin sheet (not shown) or the like may be inserted between the electrode laminate 50 and the first hot press plate 210 so that the electrode laminate 50 can be easily separated from the first hot press plate 210 . A fluororesin sheet or the like may also be inserted between the electrode laminate 50 and the second hot press plate 220 .

The first hot press plate 210 and the second hot press plate 220 are heated. The heating temperature can be appropriately adjusted according to, for example, the types of the separator 30 and the adhesive. The first hot press plate 210 and the second hot press plate 220 may be independently heated to a temperature of 80° C. to 110° C., for example. The temperature of the first hot press plate 210 may be the same as or different from the temperature of the second hot press plate 220 .

The first hot press plate 210 is pressed against the electrode laminate 50 . The pressing pressure can be appropriately adjusted according to the number of layers of the electrode laminate 50 and the like. The pressing pressure may be, for example, 0.5 MPa to 5 MPa or 1 MPa to 3 MPa. Press time may be, for example, 10 to 60 seconds.

The direction intersecting the stacking direction (z-axis direction) may be, for example, the direction (x-axis direction, y-axis direction) orthogonal to the stacking direction. For example, a first heater 231 and a second heater 232 can be arranged in the x-axis direction. The first heater 231 and the second heater 232 heat end surfaces (side surfaces) of the electrode laminate 50 .

FIG. 6 is a schematic plan view showing the arrangement of heaters.
For example, a first heater 231, a second heater 232, a third heater 233, and a fourth heater 234 may be arranged so as to surround the electrode laminate 50 in plan view. The first heater 231 and the second heater 232 heat the end surfaces of the electrode laminate 50 from the x-axis direction. The third heater 233 and the fourth heater 234 heat end surfaces of the electrode laminate 50 in the y-axis direction. In addition, "heating" in this specification indicates applying heat, and does not have to be accompanied by a temperature rise of the object to be heated.

Each heater may be movable. For example, each heater may come close to the electrode laminate 50 after the electrode laminate 50 is transferred onto the second hot press plate 220 . Each heater may be fixed at a position closest to the electrode laminate 50 during hot pressing. After completion of hot pressing, each heater may be separated from the electrode laminate 50 so as not to interfere with the transportation of the electrode laminate 50 .

Each heater may include a heating portion 235 at its tip. The temperature of the heat generating portion 235 can be appropriately adjusted according to, for example, the types of the separator 30 and the adhesive. The temperature of the heat generating part 235 may be, for example, 100°C to 120°C. The temperature of the heat generating portion 235 may be the same as or different from the temperatures of the first hot press plate 210 and the second hot press plate 220 . A clearance may be provided between the heat generating portion 235 and the electrode laminate 50 . The clearance when the heating portion 235 comes closest to the electrode laminate 50 may be, for example, 1 mm to 1.5 mm.

(Heat press plate)
The first hot press plate 210 (upper plate) may have a structure in which the pressing force is concentrated on the four corners or the periphery of the electrode laminate 50 in plan view. It is expected that the pressure at the four corners or the periphery of the electrode laminate 50 is increased during hot pressing, thereby increasing the adhesive force at the four corners or the periphery.

FIG. 7 is a schematic diagram showing a first example of a hot press plate.
In plan view, the first hot press plate 210 may have, for example, a quadrangular planar shape. The first hot press plate 210 includes a central portion 211 and a peripheral edge portion 212 . A peripheral portion 212 surrounds the central portion 211 . Peripheral edge 212 includes protrusions 213 . The projecting portion 213 projects more than the central portion 211 in the thickness direction (z-axis direction) of the first hot press plate 210 . The protrusions 213 are arranged at the four corners. In the hot press, the protrusions 213 are pressed against the four corners of the electrode laminate 50 .

FIG. 8 is a schematic diagram showing a second example of the hot press plate.
The protruding portions 213 may be arranged other than at the four corners. Protrusions 213 may be arranged at any position other than the four corners of peripheral edge 212 .

FIG. 9 is a schematic diagram showing a third example of the hot press plate.
The protruding portion 213 may be formed over the entire peripheral portion. That is, the peripheral edge portion 212 may consist of the projecting portion 213 .

FIG. 10 is a schematic cross-sectional view showing a fourth example of the hot press plate.
For example, peripheral portion 212 may include edge heating portion 214 . In the thickness direction (z-axis direction) of the first hot press plate 210 , the end surface heating portion 214 protrudes from the central portion 211 . The end surface heating unit 214 heats the electrode laminate 50 from a direction intersecting the lamination direction during hot pressing. That is, the heater for heating the end surface of the electrode laminate 50 may be integrated with the first hot press plate 210 . A clearance may be provided between the end surface heating part 214 and the electrode laminate 50 . A clearance may be provided between the end surface heating portion 214 and the second hot press plate 220 at the bottom dead center of the hot press. The temperature of the end surface heating portion 214 may be the same as or different from the temperature of the central portion 211 (the portion in contact with the electrode laminate 50).

FIG. 11 is a schematic cross-sectional view showing a fifth example of the hot press plate.
The first hot press plate 210 may include both the projecting portion 213 and the end surface heating portion 214 . In the thickness direction (z-axis direction) of the first hot press plate 210 , the end surface heating portion 214 protrudes more than the central portion 211 and the projecting portion 213 . The temperature of the end surface heating portion 214 may be the same as or different from the temperature of the protruding portion 213 (the portion in contact with the electrode laminate 50).

The second hot press plate 220 (lower plate) may also have the structure shown in FIGS. For example, the first hot press plate 210 may include the projecting portion 213 and the second hot press plate 220 may include the end surface heating portion 214 . That is, at least one of first hot press plate 210 and second hot press plate 220 may have the structure shown in FIGS. 7 to 11 .

(gas supply)
A gas may be supplied around the electrode laminate 50 during hot pressing. The gas may have a high thermal conductivity (W/m·K) compared to air. It is expected that heat transfer to the end surfaces of the electrode laminate 50 is promoted by supplying a gas having a high thermal conductivity around the electrode laminate 50 . The supplied gas may be a single gas or a mixed gas. The gas includes, for example, at least one selected from the group consisting of argon gas, oxygen gas, hydrogen gas, nitrogen gas, neon gas, helium gas, ammonia gas, carbon monoxide gas, ethane gas, ethylene gas, and methane gas. You can For example, helium gas can have a high thermal conductivity and be relatively easy to handle.

《(C) Storage》
FIG. 12 is a schematic diagram showing an example of the configuration of the battery of this embodiment.
The manufacturing method of the present embodiment may include manufacturing the battery 100 by housing the electrode laminate 50 and an electrolytic solution (not shown) in the exterior body 90 . In the present embodiment, it is expected that the electrode laminate 50 is smoothly impregnated with the electrolytic solution. The electrolyte may contain, for example, an aprotic solvent and a lithium salt.

The exterior body 90 may have any form. The exterior body 90 may be, for example, a metal container or the like. The exterior body 90 may be, for example, a pouch made of Al laminated film. After housing the electrode laminate 50 , an electrolytic solution may be injected into the exterior body 90 . After injection of the electrolytic solution, the exterior body 90 may be sealed.

One electrode laminate 50 may be housed in one exterior body 90 . A plurality of electrode laminates 50 may be housed in one exterior body 90 . For example, two electrode laminates 50 may be housed in one exterior body 90 .

<Battery>
The battery and electrode laminate of this embodiment will be described below.
Battery 100 (see FIG. 12) can be used in any application. Battery 100 may be used, for example, in an electric vehicle as a main power source or power assist power source. A battery module or an assembled battery may be formed by connecting a plurality of batteries 100 .

Battery 100 includes an exterior body 90 . The exterior body 90 is hermetically sealed. The exterior body 90 accommodates the electrode laminate 50 and the electrolytic solution. A first electrode terminal 91 and a second electrode terminal 92 are provided on the exterior body 90 . The first electrode terminal 91 is connected to the plurality of first electrode plates 10 . The second electrode terminal 92 is connected to the plurality of second electrode plates 20 .

The electrode laminate 50 includes a plurality of first electrode plates 10, a plurality of second electrode plates 20, one or more separators 30, and an adhesive (not shown) (see FIG. 4). An adhesive is placed between the separator 30 and the first electrode plate 10 . The adhesive may form an adhesive layer. The adhesive bonds the first electrode plate 10 and the separator 30 together. The adhesive may also be placed between the separator 30 and the second electrode plate 20 . The adhesive strength between the separator 30 and the second electrode plate 20 tends to be higher than the adhesive strength between the separator 30 and the first electrode plate 10 .

FIG. 13 is a schematic plan view showing an example of the first electrode plate.
In this specification, the length of the short side of the first active material layer 12 is defined as "D", and the length of the long side of the first active material layer 12 is defined as "L". The relationship "D≦L" is satisfied. When the relationship "D=L" is satisfied, the first active material layer 12 has a square shape. When the relationship "D<L" is satisfied, the first active material layer 12 has a rectangular shape. "D" may be, for example, 50 mm to 100 mm. "L" may be, for example, 100 mm to 200 mm.

In plan view, the first active material layer 12 includes a first region R1 and a second region R2. The first region R<b>1 is located in the center of the first active material layer 12 . The first region R1 is separated from each vertex of the first active material layer 12 by 0.4D or more and 0.6D or less in the short side direction (y-axis direction) and 0.4L or more in the long side direction (x-axis direction). 0.6 L or less away. The second region R<b>2 includes four corners of the first active material layer 12 . The "four corners" in this specification indicate the vicinity of the vertices of the quadrangle and may not include the vertices. The first active material layer 12 includes four second regions R2. The second region R2 is separated from any vertex of the first active material layer 12 by 0.05D or more and less than 0.4D in the short side direction and by 0.05L or more and less than 0.4L in the long side direction.

(adhesive strength ratio)
The first region R1 is adhered to the separator 30 with a first adhesive force (F1). The second region R2 is adhered to the separator 30 with a second adhesive force (F2). The adhesion force ratio (F1/F2) in this embodiment is 1 or less. In the outermost electrode plate, the adhesion force ratio (F1/F2) can take the maximum value. The maximum value can be one. The adhesion force ratio (F1/F2) can decrease from the outside to the middle in the lamination direction. At the intermediate electrode plate, the adhesion force ratio (F1/F2) can take a minimum value. The minimum value may be, for example, 0.44 to 0.91. The smaller the adhesive force ratio (F1/F2) in the intermediate electrode plate, the more difficult it is for the electrode laminate 50 to separate. The adhesion force ratio (F1/F2) in the intermediate electrode plate may be, for example, 0.83 or less, 0.73 or less, or 0.66 or less. The adhesion force ratio (F1/F2) in the intermediate electrode plate may be, for example, 0.53 or more.

(Method for measuring adhesive force ratio)
In the present embodiment, in the stacking direction, the adhesion force ratio (F1/ F2) is measured. When the adhesion force ratio (F1/F2) is 1 or less in the outermost electrode plate, it is considered that the adhesion force ratio (F1/F2) is 1 or less throughout the electrode stack 50 . When the electrode stack 50 includes an odd number of first electrode plates 10, the first electrode plate 10 located in the middle in the stacking direction is regarded as the intermediate electrode plate. When the electrode stack 50 includes an even number of first electrode plates 10, there are two first electrode plates 10 positioned in the middle in the stacking direction. The adhesion force ratio (F1/F2) is measured with one of the two sheets.

By disassembling the electrode laminate 50, an integrated body of the outermost electrode plate and the separator 30 and an integrated body of the intermediate electrode plate and the separator 30 are recovered. A first sample piece is cut out from within the first region R1 by a predetermined cutting tool (for example, a rotary cutter or the like). A second sample piece is cut out from each of the four second regions R2. The plane size of the first sample piece and the second sample piece may be, for example, about "0.2L×0.2D".

A peel tester is provided. For example, a small desktop testing machine "FGS-TV" (manufactured by Nidec-Shimpo Corporation) may be prepared. The testing machine is equipped with a digital force gauge "FGP-5" (manufactured by Nidec-Shimpo Corporation). A testing machine equivalent to these may be prepared.

FIG. 14 is a schematic cross-sectional view showing a method for measuring adhesive force.
A first sample piece 310 is fixed to the slide stage 320 . In the first sample piece 310 , the grip portion 31 is formed by peeling off one end of the separator 30 . A gripper 31 is fixed to a clip 330 of the digital force gauge. The separator 30 is pulled in a direction (z-axis direction) at 90 degrees to the surface of the first electrode plate 10 . Thereby, the separator 30 is separated from the first active material layer 12 . The slide stage 320 moves as the clip 330 rises. The slide stage 320 does not move in the pulling direction, but moves in a direction perpendicular to the pulling direction (x-axis direction). Slide stage 320 is externally powered such that slide stage 320 and clip 330 move at substantially the same speed. By applying power from the outside, the frictional force associated with the movement of the slide stage 320 can be reduced to a negligible level. The maximum force during peeling of the separator 30 is measured. By dividing the maximum force by the length of the first sample piece 310, the first adhesive force (F1) is calculated. The first adhesive force (F1) may be, for example, 0.5 N/m to 1.1 N/m.

As with the first sample piece 310, the four second sample pieces are also measured for adhesive force. The arithmetic mean of the results of the four second specimens is taken as the second adhesion (F2). The second adhesive force (F2) may be, for example, 1.0 N/m to 1.6 N/m. The second adhesive force (F2) may be, for example, 1.1 N/m or more, 1.2 N/m or more, 1.3 N/m or more, or 1 It may be 0.4 N/m or more, or 1.5 N/m or more.

The adhesion force ratio (F1/F2) is calculated by dividing the first adhesion force (F1) by the second adhesion force (F2). The adhesion ratio (F1/F2) is valid to two decimal places. Numbers after the third decimal place are rounded off.

(Third area, fourth area)
In plan view, the first active material layer 12 may further include a third region R3 and a fourth region R4 (see FIG. 13). The third region R3 is sandwiched between two adjacent second regions R2 in the short side direction (y-axis direction). The fourth region is sandwiched between two adjacent second regions R2 in the long side direction (x-axis direction). The third region R3 and the fourth region R4 may also be adhered to the separator 30 by the second adhesive force (F2). This is expected to make the electrode laminate 50 difficult to separate. Note that the third region R3 does not have to be in contact with the second region R2. That is, there may be a region with low adhesion between the third region R3 and the second region R2. The fourth region R4 does not have to be in contact with the second region R2. That is, there may be a region with low adhesion between the fourth region R4 and the second region R2.

Hereinafter, an embodiment of the present technology (hereinafter also referred to as "this embodiment") will be described. However, the following description does not limit the scope of this technology.

<Experiment 1>
In Experiment 1, No. 1-1 to No. Electrode laminates according to 1-8 were produced (see Table 1 below).

<<(A) Formation of electrode laminate>>
A separator was prepared. Adhesive was applied to both sides of the separator. The adhesive was sprayed in dots so that the basis weight was substantially uniform. The separator was folded in a zigzag pattern. Each time the separator was folded, the first electrode plate and the second electrode plate were alternately inserted. An electrode laminate was thus formed. The electrode stack included 35 first electrode plates (positive plates) and 36 second electrode plates (negative plates).

<<(B) Heat Press>>
A first hot press plate 210, a second hot press plate 220, and four heaters were prepared. In plan view, the first heater 231, the second heater 232, the third heater 233, and the fourth heater 234 are arranged so as to surround the electrode laminate 50 (see FIGS. 5 and 6). The clearance when the heating portion 235 of each heater was closest to the electrode laminate 50 was set to 1 mm to 1.5 mm. Both the first hot-press plate 210 and the second hot-press plate 220 in Experiment 1 were flat plates. As shown in Table 1 below, the temperature of each heater and the temperature of each hot press plate were adjusted. A hot press was applied to the electrode laminate 50 . Press pressure was 2 MPa. Press time was 30 seconds. After hot pressing, it was confirmed whether or not the electrode laminate 50 was separated when the first hot press plate 210 was separated from the electrode laminate 50 . That is, optical sensors were installed outside the first hot press plate 210 and the second hot press plate 220 . The optical sensor constantly measured the thickness of the electrode laminate 50 from the time the hot press was completed until the first hot press plate 210 was completely separated from the electrode laminate 50 . When the amount of change in thickness during measurement was 0.8 mm or more, it was considered that "separation occurred". If the thickness variation during measurement was less than 0.8 mm, it was considered "no separation occurred".

After hot pressing, the intermediate electrode plate was recovered. The intermediate electrode plate was the 18th first electrode plate 10 from the outermost first electrode plate 10 in the stacking direction. The adhesion force ratio (F1/F2) was measured on the intermediate electrode plate.

In this example, the length (L) of the long side of the first electrode plate 10 was 140 mm. The short side length (D) was 75 mm (see FIG. 13).

A first adhesive force (F1) was measured using one first sample piece. The first sample piece was collected from each vertex of the first active material layer at a distance of 0.47D or more and 0.56D or less in the short side direction and 0.43L or more and 0.57L or less in the long side direction. .

Adhesion (F2 ₁ ), Adhesion (F2 ₂ ), Adhesion (F2 ₃ ) and Adhesion (F2 ₄ ) were measured with the four second sample pieces, respectively. The arithmetic mean of the adhesive strength (F2 ₁ ) to the adhesive strength (F2 ₄ ) was taken as the second adhesive strength (F2). The four second sample pieces were separated from each vertex of the first active material layer by 0.07D or more and 0.33D or less in the short side direction and 0.06L or more and 0.2L or less in the long side direction. taken.

<Results of Experiment 1>
As shown in Table 1 above, when the adhesive strength ratio (F1/F2) is 1 or less, the electrode laminate tends to be difficult to separate.

In addition, No. 1, the adhesive force ratio (F1/F2) was also measured for the outermost electrode plate. The adhesion force ratio (F1/F2) was 1. Both the first adhesive strength and the second adhesive strength were 1.6 N/m.

<Experiment 2>
In Experiment 2, No. 2-1 to No. An electrode laminate according to 2-4 was produced (see Table 2 below).

<<(A) Formation of electrode laminate>>
An electrode laminate was prepared in the same manner as in Experiment 1.

<<(B) Heat Press>>
A first hot press plate 210 was prepared. In the first hot press plate 210 of Experiment 2, the peripheral edge portion 212 included end surface heating portions 214 (see FIG. 10). The clearance between the end surface heating portion 214 and the second hot press plate 220 at the bottom dead center was set to 0.5 mm. In Experiment 2, hot pressing was performed while air or helium gas was supplied around the electrode laminate 50 (see Table 2 below). Press pressure was 2 MPa. Press time was 30 seconds. The temperatures of the first hot press plate 210 and the second hot press plate 220 were adjusted as shown in Table 2 below. As in Experiment 1, the presence or absence of separation of the electrode laminate 50 and the adhesive strength ratio (F1/F2) were measured.

<Results of Experiment 2>
As shown in Table 2 above, by supplying helium gas around the electrode laminate during hot pressing, the adhesive strength ratio (F1/F2 ) tends to be smaller. It is believed that helium gas has a high thermal conductivity, thus promoting heat transfer to the end faces of the electrode laminate.

<Experiment 3>
In Experiment 3, No. 3-1, No. An electrode laminate according to 3-2 was manufactured (see Table 3 below).

<<(A) Formation of electrode laminate>>
An electrode laminate was prepared in the same manner as in Experiment 1.

<<(B) Heat Press>>
A first hot press plate 210 was prepared. In the first hot press plate 210 of Experiment 3, the peripheral portion 212 included both the protruding portion 213 and the end surface heating portion 214 (see FIG. 11). The protrusions 213 were arranged at the four corners. The clearance between the end surface heating portion 214 and the second hot press plate 220 at the bottom dead center was set to 0.5 mm. The temperature of each hot press plate was adjusted as shown in Table 3 below. Press pressure was 2 MPa. Press time was 30 seconds. In Experiment 3, hot pressing was performed so that the protrusions 213 of the first hot pressing plate 210 pressed the four corners of the electrode laminate 50 . At the bottom dead center, the clearance between the electrode laminate 50 and the central portion 211 of the first hot press plate 210 was set to 0.2 mm. As in Experiment 1, the presence or absence of separation of the electrode laminate 50 and the adhesive force ratio (F1/F2) were measured.

<Results of Experiment 3>
As shown in Table 3 above, when the peripheral edge portion 212 of the first hot press plate 210 includes the projecting portion 213, the adhesion force ratio (F1/F2) tends to decrease. This is probably because the pressure applied to the four corners increases during hot pressing.

Note that in Experiment 3, the center (first region R1) of the electrode laminate 50 did not come into contact with the first hot press plate 210 in terms of design. However, the first region R1 and the separator 30 were adhered. It is considered that the center of the electrode laminate 50 is also in contact with the first hot press plate 210 due to the bending of the electrode laminate 50 during hot pressing.

This embodiment and this example are illustrative in all respects. This embodiment and this example are not restrictive. The scope of the present technology includes all changes within the meaning and range of equivalence to the description of the claims. For example, it is planned from the beginning that arbitrary configurations are extracted from this embodiment and this example and they are arbitrarily combined. When a plurality of actions and effects are described in this embodiment and this example, the scope of the present technology is not limited to the range in which all the actions and effects are exhibited.

10 first electrode plate, 11 first electrode base material, 12 first active material layer, 20 second electrode plate, 21 second electrode base material, 22 second active material layer, 30 separator, 31 grip portion, 50 electrode laminate Body 90 Exterior body 91 First electrode terminal 92 Second electrode terminal 100 Battery 210 First hot press plate 211 Central part 212 Peripheral part 213 Protruding part 214 End face heating part 220 Second hot press plate, 231 first heater, 232 second heater, 233 third heater, 234 fourth heater, 235 heating part, 310 first sample piece, 320 slide stage, 330 clip, R1 first region, R2 second region, R3 3rd region, R4 4th region.

Claims (10)

including a plurality of first electrode plates, a plurality of second electrode plates, one or more separators, and an adhesive;
the first electrode plate has a different polarity than the second electrode plate;
The first electrode plate and the second electrode plate are alternately laminated with the separator interposed therebetween,
The adhesive is disposed between the separator and the first electrode plate,
The first electrode plate includes a first active material layer,
the second electrode plate includes a second active material layer,
In plan view,
each of the first active material layer and the second active material layer has a square planar shape,
The first active material layer has a short side and a long side that are smaller than those of the second active material layer,
When the length of the short side of the first active material layer is defined as D and the length of the long side of the first active material layer is defined as L,
The first active material layer includes a first region and a second region,
The first region is separated from each vertex of the first active material layer by 0.4D or more and 0.6D or less in the short side direction and 0.4L or more and 0.6L or less in the long side direction,
The second region is separated from any vertex of the first active material layer by 0.05D or more and less than 0.4D in the short side direction and 0.05L or more and less than 0.4L in the long side direction. cage,
The first region is adhered to the separator by a first adhesive force,
The second region is adhered to the separator by a second adhesive force,
A ratio of the first adhesive force to the second adhesive force is 1 or less,
The ratio of the minimum basis weight of the adhesive to the average basis weight of the adhesive is 0.7 or more, and
The ratio of the maximum basis weight of the adhesive to the average basis weight of the adhesive is 1.3 or less.
electrode laminate. In the plan view, the first active material layer further includes a third region and a fourth region,
The third region is sandwiched between two adjacent second regions in the short side direction,
The fourth region is sandwiched between two adjacent second regions in the long side direction,
The third region and the fourth region are also adhered to the separator by the second adhesive force,
The electrode laminate according to claim 1. In the first electrode plate positioned in the middle in the stacking direction,
wherein the ratio of said first adhesion to said second adhesion is from 0.44 to 0.91;
The electrode laminate according to claim 1 or 2. A ratio of the minimum basis weight of the adhesive to the average basis weight of the adhesive is 0.5. 8 or more, and the ratio of the maximum basis weight of the adhesive to the average basis weight of the adhesive is 1. is less than or equal to 2 ;
The electrode laminate according to any one of claims 1 to 3. including 10 or more first electrode plates,
The electrode laminate according to any one of claims 1 to 4. Containing the electrode laminate according to any one of claims 1 to 5 and an electrolytic solution,
battery. forming an electrode laminate by alternately laminating a first electrode plate and a second electrode plate with a separator sandwiched therebetween;
and,
Adhering the first electrode plate and the separator by applying a hot press to the electrode laminate along the stacking direction;
including
an adhesive is disposed between the first electrode plate and the separator;
The ratio of the minimum basis weight of the adhesive to the average basis weight of the adhesive is 0.7 or more, and
The ratio of the maximum basis weight of the adhesive to the average basis weight of the adhesive is 1.3 or less,
The hot press is applied while the electrode laminate is heated from a direction intersecting the lamination direction ,
In the hot press, a hot press plate is pressed against the electrode laminate,
In plan view,
The hot press plate has a square planar shape,
The hot press plate includes a central portion and a peripheral portion,
The peripheral portion surrounds the central portion,
The peripheral portion includes a protrusion,
In the thickness direction of the hot press plate, the protruding portion protrudes from the central portion,
The protrusions are arranged at least at four corners of the peripheral edge,
In the hot press, the protrusion is pressed against the electrode laminate,
A method for manufacturing an electrode laminate. The first electrode plate includes a first active material layer,
the second electrode plate includes a second active material layer,
In the planar view,
each of the first active material layer and the second active material layer has a square planar shape,
The first active material layer has a short side and a long side that are smaller than those of the second active material layer,
When the length of the short side of the first active material layer is defined as D and the length of the long side of the first active material layer is defined as L,
The first active material layer includes a first region and a second region,
The first region is separated from each vertex of the first active material layer by 0.4D or more and 0.6D or less in the short side direction and 0.4L or more and 0.6L or less in the long side direction,
The second region is separated from any vertex of the first active material layer by 0.05D or more and less than 0.4D in the short side direction and 0.05L or more and less than 0.4L in the long side direction. cage,
the first region is adhered to the separator with a first adhesive force, and
The heat press is applied so that the second region is adhered to the separator by a second adhesive force,
The ratio of the first adhesive force to the second adhesive force is 1 or less,
The method for manufacturing the electrode laminate according to claim 7. In the hot press, the hot press plate is pressed against the electrode laminate,
In the planar view ,
The peripheral part includes an end face heating part,
In the thickness direction of the hot press plate, the end surface heating portion protrudes from the central portion,
The end face heating unit heats the electrode laminate from a direction intersecting the lamination direction during the hot press.
The method for manufacturing the electrode laminate according to claim 7. Gas is supplied around the electrode laminate during the hot pressing,
the gas has a high thermal conductivity compared to air;
The method for manufacturing an electrode laminate according to any one of claims 7 to 9.

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