JP6066254B2 - Electric storage element and method for manufacturing electric storage element - Google Patents

Description

The present invention relates to a power storage element including a power generation element and a method for manufacturing the power storage element . In particular, the present invention relates to a power storage element including a power generation element having a separator, and a positive electrode plate and a negative electrode plate sandwiched between the separators , and a method for manufacturing the power storage element .

  In recent years, chargeable / dischargeable power storage elements have been adopted as power sources for various devices. In the present specification, the “storage element” is a concept including both a battery (such as a lithium ion battery and a nickel metal hydride battery) and a capacitor (such as an electric double layer capacitor).

  Generally, a power storage element includes a power generation element, a pair of current collectors electrically connected to the power generation element, a case containing the power generation element and the pair of current collectors, and a pair disposed outside the case. External terminals.

  The power generation element includes a positive electrode plate, a negative electrode plate, and a separator. Each of the positive electrode plate and the negative electrode plate includes a base layer having conductivity and an active material layer formed on the base layer. On the other hand, the separator includes a microporous resin film layer having electrical insulation (see, for example, Patent Document 1).

  The positive electrode plate and the negative electrode plate are overlaid with the active material layers facing each other. The separator is set to a size larger than a region where the positive electrode plate and the negative electrode plate overlap. And the separator is arrange | positioned between the positive electrode plate and the negative electrode plate so that it may exist in the whole region of the area | region with which a positive electrode plate and a negative electrode plate overlap.

  One current collector of the pair of current collectors is electrically connected to the positive electrode plate of the power generation element and is electrically connected to one external terminal of the pair of external terminals. On the other hand, the other current collector of the pair of current collectors is electrically connected to the negative electrode plate of the power generation element and electrically connected to the other external terminal of the pair of external terminals. ing.

  Accordingly, the power storage element having the above configuration can supply the power generated by the power generation element to the pair of external terminals, and can charge the power generation element with the power input to the pair of external terminals.

Japanese Patent Laid-Open No. 2003-31265

  By the way, the separator (microporous resin film layer) is generally composed of a heat-shrinkable resin (for example, polyolefin resin). Therefore, in the battery having the above configuration, when the temperature in the case becomes high, the separator contracts between the positive electrode plate and the negative electrode plate. As a result, the separator exists except for a part of the region where the positive electrode plate and the negative electrode plate overlap (for example, near the edge of the region where the positive electrode plate and the negative electrode plate overlap), and a part of the positive electrode plate and a part of the negative electrode plate May face each other directly. For this reason, when the inside of the case becomes hot, the battery having the above configuration may not be able to reliably insulate the positive electrode plate and the negative electrode plate, and the power generation elements (positive electrode plate and negative electrode plate) may be short-circuited.

Then, this invention makes it a subject to provide the electrical storage element which can prevent that an electric power generation element short-circuits under the influence of heat , and the manufacturing method of an electrical storage element in view of such a situation.

The electricity storage device of the present invention,
A positive electrode plate including a positive electrode base layer having conductivity and a positive electrode active material layer formed on the positive electrode base layer;
A negative electrode plate comprising a negative electrode base layer having conductivity and a negative electrode active material layer formed on the negative electrode base layer, wherein the negative electrode active material layer is superimposed on the positive electrode plate in a state of facing the positive electrode active material layer Negative electrode plate,
A separator having electrical insulation properties and heat shrinkability, the separator disposed between the positive electrode plate and the negative electrode plate so as to exist in the entire region where the positive electrode plate and the negative electrode plate overlap; A power generation element having
The size of the separator is set larger than the size of the positive electrode active material layer and the size of the negative electrode active material layer,
The separator is
Including a base layer composed of a microporous film and a heat-resistant layer formed on the base layer;
Arranged so as to protrude on both sides of the positive electrode active material layer and the negative electrode active material layer,
At least a part of each of the portions protruding on both sides of the positive electrode active material layer and the negative electrode active material layer includes a thick portion thicker than the thickness of the portion facing the positive electrode active material layer and the negative electrode active material layer,
The heat-resistant layer is formed on at least one of both surfaces of the base material layer,
Each of the thick-walled portions has a protruding amount that is locked to at least one of the positive electrode active material layer and the negative electrode active material layer facing the heat resistant layer when the separator attempts to thermally shrink. The heat-resistant layer is formed so as to protrude and thereby protrude toward at least one of the positive electrode plate side and the negative electrode plate side, whereby the positive electrode active material layer and the negative electrode active material layer are projected. It exists on both sides of the active material layer of at least one of the material layers.

Further, in the power storage element,
The interval between the thick portions present on both sides of the active material layer may be set to be equal to or larger than the size of the active material layer in the direction in which the separator protrudes from the active material layer.

In any of the electricity storage elements having the above-described configuration, when the separator of the power generation element tries to shrink due to the influence of heat, the thick part of the separator is activated by at least one of the positive electrode active material layer and the negative electrode active material layer. It is caught (locked) on the material layer. This restricts the separator from shrinking due to heat shrinkage. Accordingly, the separator is maintained in a state where it exists in the entire region where the positive electrode plate and the negative electrode plate overlap. Therefore, a part of the positive electrode plate and a part of the negative electrode plate do not directly face each other, and the positive electrode plate and the negative electrode plate can be maintained in an insulated state.
In any of the power storage elements having the above structure, the heat-resistant layer suppresses shrinkage of the base material layer. Moreover, the heat resistant layer increases the heat resistance of the entire separator. Therefore, even if the temperature in the case rises, the separator is hardly damaged. Thereby, a separator ensures insulation with a positive electrode plate and a negative electrode plate.
In any of the power storage elements having the above structure, the heat-resistant layer has a characteristic that it is difficult to melt or soften even when the temperature becomes high. Therefore, even if the temperature in the case increases, the portion (heat resistant layer) protruding toward at least one of the positive electrode side and the negative electrode side in the thick part is maintained in a fixed form. Therefore, when the separator is about to contract due to the influence of heat, the thick portion is reliably caught (locked) on at least one of the positive electrode active material layer and the negative electrode active material layer. Thereby, shrinkage | contraction of a separator is controlled reliably.

  As one aspect of the present invention, the size of the separator in the shrinkage characteristic direction to be shrunk by the heat shrinkability is the size of the positive electrode active material layer and the size of the negative electrode active material layer in a direction corresponding to the shrinkage characteristic direction. The separator is disposed so as to protrude from both sides of the positive electrode active material layer and the negative electrode active material layer in the direction corresponding to the shrinkage characteristic direction, and in the direction corresponding to the shrinkage characteristic direction. At least a part of each of the portions protruding on both sides of the positive electrode active material layer and the negative electrode active material layer is provided with the thick portion, and each of the thick portions is formed of the positive electrode active material layer and the negative electrode active material layer. It is preferable that it exists on both sides of the direction corresponding to the shrinkage characteristic direction in at least one of the active material layers. If it does in this way, the thick part in the both ends of a separator will be arrange | positioned at intervals in the shrinkage | contraction characteristic direction of this separator. In addition, at least one of the positive electrode active material layer and the negative electrode active material layer is interposed between the thick portions at both ends. As a result, when the separator attempts to shrink due to the influence of heat, the thick part of the separator is caught by at least one of the positive electrode active material layer and the negative electrode active material layer, and the shrinkage of the separator is restricted. The Accordingly, the separator is maintained in a state where it exists in the entire region where the positive electrode plate and the negative electrode plate overlap. Therefore, a part of the positive electrode plate and a part of the negative electrode plate do not directly face each other, and the positive electrode plate and the negative electrode plate can be maintained in an insulated state.

  The heat-resistant layer is preferably provided on the surface on the positive electrode plate side of both surfaces of the base material layer. In this way, the heat-resistant layer is interposed between the positive electrode plate and the base material layer. Thereby, damage to a separator (base material layer) when a fine short circuit etc. occur can be controlled.

A gap may be formed between at least one of the positive electrode active material layer and the negative electrode active material layer and each of the thick portions present on both sides of the active material layer. . In this way, the electrolytic solution can easily enter between the separator and the electrode plate. Thereby, the performance of a battery becomes favorable.
The heat resistant layer may include an inorganic filler.
In addition, at least one of the positive electrode base layer and the negative electrode base layer is formed in the direction in which the separator protrudes from the positive electrode active material layer and the negative electrode active material layer, and the positive electrode active material layer and the negative electrode active material layer. May be larger than the corresponding active material layer.
The method for producing the electricity storage device of the present invention comprises:
A positive electrode plate including a positive electrode base layer having conductivity and a positive electrode active material layer formed on the positive electrode base layer;
A negative electrode plate comprising a negative electrode base layer having conductivity and a negative electrode active material layer formed on the negative electrode base layer, wherein the negative electrode active material layer is superimposed on the positive electrode plate in a state of facing the positive electrode active material layer Negative electrode plate,
Possess electrical insulating properties, and a separator comprising a microporous substrate layer composed of a film and the substrate layer a heat-resistant layer formed on the overlap of the positive electrode plate and the negative electrode plate area And a separator disposed between the positive electrode plate and the negative electrode plate so as to protrude from both sides of the positive electrode active material layer and the negative electrode active material layer. A method,
In the separator, at least a part of each of the positive electrode active material layer and the negative electrode active material layer protruding on both sides by pressing a portion facing the positive electrode active material layer and the negative electrode active material layer, the A thick portion thicker than the thickness of the portion facing the positive electrode active material layer and the negative electrode active material layer, wherein the separator is disposed between the positive electrode plate and the negative electrode plate; Thickness existing on both sides of at least one of the positive electrode active material layer and the negative electrode active material layer by projecting toward at least one of the negative electrode plate sides A meat part is formed,
Each of the thick-walled portions has a protruding amount that is locked to at least one of the positive electrode active material layer and the negative electrode active material layer facing the heat resistant layer when the separator attempts to thermally shrink. The heat-resistant layer is formed so as to protrude and thereby protrude toward at least one of the positive electrode plate side and the negative electrode plate side, whereby the positive electrode active material layer and the negative electrode active material layer are projected. It exists on both sides of the active material layer of at least one of the material layers.

As described above, the power storage element and the method for manufacturing the power storage element of the present invention can provide an excellent effect that the power generation element can be prevented from being short-circuited due to heat.

FIG. 1 is an overall perspective view of a power storage element (battery) according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the energy storage device (battery) according to the embodiment. FIG. 3 is a partial schematic cross-sectional view of a power generation element of the energy storage device (battery) according to the embodiment. FIG. 4 is a partial schematic cross-sectional view of a power generation element of a power storage element (battery) according to another embodiment of the present invention.

  Hereinafter, a power storage device according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the present embodiment, a battery (lithium ion battery) will be described as an example of a power storage element.

  As shown in FIGS. 1 and 2, the battery includes a power generation element 2, a pair of current collectors 3 and 3 electrically connected to the power generation element 2, and the power generation element 2 and a pair of current collectors 3 and 3. And a pair of external terminals 5 and 5 disposed outside the case 4.

  As illustrated in FIG. 2, the power generation element 2 includes a positive electrode plate 20, a negative electrode plate 21, and a separator 22.

  As shown in FIG. 3, the positive electrode plate 20 includes a positive electrode base layer 200 having conductivity, and a positive electrode active material layer 201 formed on the positive electrode base layer 200.

  The positive electrode base layer 200 is made of a conductive material (in this embodiment, aluminum (aluminum foil)). The positive electrode active material layer 201 is formed of a material capable of inserting and extracting metal ions. The battery 1 according to this embodiment is a lithium ion battery as described above. Therefore, the positive electrode active material layer 201 is made of a material that can occlude / release lithium ions. The expansion / contraction rate of this type of positive electrode active material layer 201 is about 1% to several percent.

  The positive electrode active material layer 201 is formed on at least one of both surfaces of the positive electrode base layer 200. In the present embodiment, the positive electrode active material layer 201 is formed on both surfaces of the positive electrode base layer 200. The positive electrode active material layer 201 is formed on the entire surface of the region excluding at least one end of the positive electrode base layer 200 in the first direction. The positive electrode active material layer 201 is formed with a uniform or substantially uniform thickness over the entire length in the first direction. In general, each of the positive electrode active material layers 201 formed on both surfaces of the positive electrode base layer 200 is formed with a thickness of 20 μm to 200 μm.

  In the present embodiment, the positive electrode plate 20 (positive electrode base layer 200) is formed in a strip shape. Accordingly, the positive electrode active material layer 201 is formed on the entire region excluding one end portion in the short direction (direction corresponding to the first direction) orthogonal to the longitudinal direction of the positive electrode base layer 200. That is, a base layer exposed portion 202 without the positive electrode active material layer 201 is formed at one end portion in the short direction perpendicular to the longitudinal direction of the positive electrode plate 20.

  The negative electrode plate 21 includes a negative electrode base layer 210 having conductivity and a negative electrode active material layer 211 formed on the negative electrode base layer 210. The negative electrode base layer 210 is made of a conductive material (copper (copper foil) in the present embodiment). The negative electrode active material layer 211 is formed of a material that can electrochemically occlude and release metal ions. The battery 1 according to this embodiment is a lithium ion battery as described above. Therefore, the negative electrode active material layer 211 is made of a material that can occlude and release lithium ions. The expansion / contraction rate of the negative electrode active material layer 211 of this type is about 1% to 10% when the negative electrode active material layer 211 is a carbon material, and the carbon material when the negative electrode active material layer 211 is an alloy material. The expansion / contraction rate may be higher than that. Specifically, when the negative electrode active material layer 211 is amorphous carbon, the expansion / contraction rate of the negative electrode active material layer 211 is about 1%, and when the negative electrode active material layer 211 is graphite, the negative electrode The expansion / contraction rate of the active material layer 211 is about 10%. When the negative electrode active material layer 211 is an alloy material such as Si, the expansion / contraction rate of the negative electrode active material layer 211 may be 20% to 30%.

  The negative electrode active material layer 211 is formed on at least one of both surfaces of the negative electrode base layer 210. In the present embodiment, the negative electrode active material layer 211 is formed on both surfaces of the negative electrode base layer 210. The negative electrode active material layer 211 is formed on the entire surface of the region excluding at least one end of the negative electrode base layer 210 in the first direction. The negative electrode active material layer 211 is formed with a uniform or substantially uniform thickness over the entire length in the first direction. In general, each of the negative electrode active material layers 211 formed on both surfaces of the negative electrode base layer 210 is formed with a thickness of 20 μm to 200 μm.

  In the present embodiment, the negative electrode plate 21 (negative electrode base layer 210) is formed in a strip shape. Accordingly, the negative electrode active material layer 211 is formed on the entire region excluding one end in the short direction (direction corresponding to the first direction) orthogonal to the longitudinal direction of the negative electrode base layer 210. That is, the base layer exposed portion 212 without the negative electrode active material layer 211 is formed at one end portion in the short direction perpendicular to the longitudinal direction of the negative electrode plate 21.

  The negative electrode plate 21 is overlaid on the positive electrode plate 20 with the negative electrode active material layer 211 facing the positive electrode active material layer 201. The size of the negative electrode active material layer 211 in the first direction is set to be larger than the size of the positive electrode active material layer 201 in the first direction. Accordingly, the negative electrode active material layer 211 protrudes on both sides of the positive electrode active material layer 201 in the first direction.

  The positive electrode plate 20 and the negative electrode plate 21 are disposed in a relatively displaced state. In the present embodiment, each of the positive electrode plate 20 and the negative electrode plate 21 is formed in a strip shape. Therefore, the positive electrode plate 20 and the negative electrode plate 21 are disposed so as to be relatively displaced in the short direction (first direction).

  In the present embodiment, the positive electrode plate 20 is arranged such that one end portion in the short direction of the positive electrode plate 20 is on the other end side in the short direction of the negative electrode plate 21 (inverted with respect to the center line extending in the longitudinal direction). And the negative electrode plate 21 are overlapped. As described above, the positive electrode plate 20 and the negative electrode plate 21 are disposed so as to be relatively displaced in the lateral direction. Accordingly, the base layer exposed portion 202 of the positive electrode plate 20 protrudes from the negative electrode plate 21, and the base layer exposed portion 212 of the negative electrode plate 21 protrudes from the positive electrode plate 20.

  The separator 22 has electrical insulation and heat shrinkability. The size of the separator 22 in the shrinkage characteristic direction to be shrunk by heat shrinkage is set larger than the size of the positive electrode active material layer 201 and the size of the negative electrode active material layer 211 in the direction corresponding to the shrinkage characteristic direction. Yes. The separator 22 according to the present embodiment is formed in a band shape and has heat shrinkability in the first direction (short direction). Accordingly, the size of the separator 22 in the first direction is set larger than the size of the positive electrode active material layer 201 and the size of the negative electrode active material layer 211 in the first direction. In the present embodiment, the size in the second direction (longitudinal direction) orthogonal to the first direction of the separator 22 is also larger than the size of the positive electrode active material layer 201 and the size of the negative electrode active material layer 211 in the second direction. Is also set larger.

  The separator 22 is disposed so as to protrude from both sides of the positive electrode active material layer 201 and the negative electrode active material layer 211 in a direction corresponding to the shrinkage characteristic direction. In the present embodiment, the separator 22 is disposed so as to protrude from both sides of the positive electrode active material layer 201 and the negative electrode active material layer 211 in the first direction.

  The separator 22 has the positive electrode active material layer 201 and the negative electrode active material layer on at least a part of each of the portions protruding on both sides of the positive electrode active material layer 201 and the negative electrode active material layer 211 in a direction corresponding to the shrinkage characteristic direction. Thick portions (a pair of thick portions) 221 and 221 that are thicker than the thickness of a portion (hereinafter referred to as a thin portion) 220 facing 211. In the present embodiment, the separator 22 includes thick portions 221 and 221 over the entire areas of the portions protruding on both sides of the positive electrode active material layer 201 and the negative electrode active material layer 211 in the first direction.

  Each of the pair of thick portions 221 and 221 protrudes toward at least one of the positive electrode plate 20 side and the negative electrode plate 21 side, and the first active material layer 201 and the negative electrode active material layer 211 have a first one. Present on both sides in one direction. In the present embodiment, the pair of thick portions 221 and 221 protrude toward the positive electrode plate 20 side and exist on both sides of the positive electrode active material layer 201 in the first direction. The difference between the thin-walled portion 220 and the thick-walled portions 221 and 221 in the separator 22 (the protruding amount of the thick-walled portion 221 with respect to the surface in contact with the active material layer 201) is the difference between the positive electrode active material layer 201 or the negative electrode active material layer 211. It is set to be equal to or greater than the value obtained by multiplying the expansion / contraction rate by the thickness of the positive electrode active material layer 201 or the negative electrode active material layer 211 (product of the expansion / contraction rate and the thickness of the active material layers 201 and 211). In the present embodiment, as described above, the thick portions 221 and 221 protrude toward the positive electrode plate 20 side. Therefore, the protruding amount of the thick portion 221 with respect to the surface in contact with the active material layer 201 is set to a value equal to or greater than the value obtained by multiplying the expansion / contraction rate of the positive electrode active material layer 201 by the thickness of the positive electrode active material layer 201. . Thereby, the thermal contraction of the separator 22 is suppressed in any case.

  In the present embodiment, the protruding amount of each of the pair of thick portions 221 and 221 is set to be equal to or less than the thickness of the positive electrode active material layer 201. Specifically, in the present embodiment, each of the pair of thick portions 221 and 221 is in a discharge state with reference to the surface of the thin portion 220 on the positive electrode plate 20 side (surface in contact with the positive electrode active material layer 201). 1% or more of the thickness of the positive electrode active material layer 201 or the negative electrode active material layer 210 protrudes. Thereby, the smoothness of the supply of the electrolyte solution between the positive electrode plate 20 and the separator 22 is improved. The protruding amount of the thick portions 211 and 221 preferably satisfies the above conditions, but can be appropriately changed as long as the separator 22 can be wound together with the positive electrode plate 20 and the negative electrode plate 21.

  In the present embodiment, the pair of thick portions 221 and 221 are formed at both ends of the separator 22 in the first direction. Therefore, the surface of the separator 22 on the negative electrode plate 21 side is a flat surface over the entire length in the first direction. On the other hand, the surface of the separator 22 on the side of the positive electrode plate 20 is raised and recessed at both ends in the first direction.

  The separator 22 according to the present embodiment includes a base material layer 222 formed of a microporous film and a heat resistant layer 223 formed on the base material layer 222.

  The base material layer 222 is made of a polyolefin-based resin. In the present embodiment, the thickness of the base material layer 222 is set to be constant over the entire surface. The heat-resistant layer 223 is formed by hardening an inorganic filler with a resin binder. The heat resistant layer 223 is provided on at least one of both surfaces of the base material layer 222. In the present embodiment, the heat-resistant layer 223 is provided on the surface on the positive electrode plate 20 side of both surfaces of the base material layer 222. Accordingly, both end portions in the first direction of the heat-resistant layer 223 are thicker than other portions (the heat-resistant layer 223 of the thin-walled portion 220 facing the positive electrode active material layer 201).

  In the present embodiment, the thin portion 220 is formed by compression-molding (pressing) the heat-resistant layer 223 formed to have a uniform thickness over the entire surface of the base material layer 222 within a range corresponding to the size of the positive electrode active material layer 201. At the same time, the heat-resistant layers 223 at both ends are thickened. That is, in the separator 22, a thin portion 220 composed of the base material layer 222 and the compressed heat-resistant layer 223 is formed in a region facing the positive electrode active material layer 201, and the separator not facing the positive electrode active material layer 201. Thick portions 221 and 221 composed of the base material layer 222 and the uncompressed heat-resistant layer 223 are formed at both ends of 22. Thereby, the thickness of the part facing the positive electrode active material layer 201 and the negative electrode active material layer 211 in the separator 22 is uniform or substantially uniform. By doing so, the distance between the positive electrode plate 20 (the positive electrode active material layer 201) and the negative electrode plate 21 (the negative electrode active material layer 211) sandwiching the separator 22 (thin wall portion 220) is any place. The charge / discharge reaction occurs uniformly. For this reason, capacity reduction and output reduction are suppressed.

  The maximum value of the distance between the thick portions 221 and 221 formed at both ends of the separator 22 is two times the size (width dimension) of the separator 22 in the first direction and the size of the thick portions 221 and 221 in the first direction. This is a value obtained by subtracting double (the sum of the width dimensions of the two thick portions 221 and 221). Considering this, the size of the separator 22 in the first direction is appropriately determined in a common sense range according to the structure of the battery 1.

  In the case of the present embodiment (when the wound power generation element 2 is employed), the size of the separator 22 in the first direction is determined by welding the current collector 3 and the base layer exposed portion 202 of the positive electrode plate 20 and the other. The positive electrode plate 20 and the negative electrode plate are not obstructed from welding of the current collector and the base layer exposed portion 212 of the negative electrode plate 21, and the positive electrode plate 20, the negative electrode plate 21, and the separator 22 are taken into account even when winding deviation is taken into account. It is preferable to set the size so that 21 can be surely isolated.

  In addition, the size of the separator 22 in the first direction is preferably set in a range in which the positive electrode plate 20 and the negative electrode plate 21 are not short-circuited even by heat shrinkage. Furthermore, in order to suppress the shrinkage of the separator 22, the size in the first direction of each of the thick portions 221 is preferably equal to or greater than the thickness of the thick portion 221. And the space | interval of the thick parts 221 and 221 formed in the both ends of the separator 22 in a 1st direction is the space | interval of the both ends of the active material layers 201 and 211 in a 1st direction (active material layer 201 in the 1st direction, More preferably, the size is 211 or more).

  Based on such conditions, the interval between the thick portions 221 and 221 formed at both ends of the separator 22 is set to be equal to or larger than the size of the positive electrode active material layer 201 in the first direction. More specifically, the interval between the thick portions 221 and 221 formed at both ends of the separator 22 is set to be the same as or substantially the same as the size of the positive electrode active material layer 201 in the first direction. Thereby, the part which protruded (projected) to the positive electrode plate 20 side of the thick parts 221 and 221 is in a state of being in close or close contact with the side end face of the positive electrode active material layer 201 in the first direction.

  In the present embodiment, the positive electrode plate 20, the separator 22, and the negative electrode plate 21 are overlaid with their respective longitudinal directions being matched. The positive electrode plate 20, the separator 22, and the negative electrode plate 21 are wound in a flat shape. Thereby, the electric power generation element 2 is formed in the external appearance flat spiral shape. Each of the pair of thick portions 221 and 221 is disposed over the entire length of the separator 22 in the winding circumferential direction. That is, the thick portions 221 and 221 are disposed at both ends in the shrinkage characteristic direction of the separator 22 in the arc portion of the power generation element 2.

  A positive electrode lead portion 23 in which only the positive electrode plate 20 (base layer exposed portion 202) is laminated is formed at one end portion of the power generation element 2 in the first direction. On the other hand, a negative electrode lead portion 24 in which only the negative electrode plate 21 (base layer exposed portion 212) is laminated is formed at the other end portion of the power generation element 2 in the first direction.

  In addition to the above conditions, the power generation element 2 according to the present embodiment satisfies the following conditions. Specifically, the shrinkage rate in a state where no tension is applied in the separator 22 (a state where no tension or compression is applied), and the shrinkage rate measured after heating at 150 ° C. for at least 1 hour is G (%) And the size of the active material layer 201 (the positive electrode active material layer in this embodiment) facing the thick portions 221 and 221 of the positive electrode active material layer 201 and the negative electrode active material layer 211, The size in the direction (first direction) in which the separator 22 protrudes from the active material layer 201 is A, and the size of the separator 22 before being heated to 150 ° C., which is from the active material layer (positive electrode active material layer) 201 to the separator 22. The size of the separator 22 is the size of the separator 22 when heated to 150 ° C., where B is the size in the direction of protrusion (first direction), from the active material layer (positive electrode active material layer) 201 to the separator 22. Protrude size direction (first direction) and C, G (%) = 100- (C / B × 100) and the case, satisfy the following expression (1). B−A <B × G (1)

  When this conditional expression (1) is satisfied, the effect obtained by the thick portions 221 and 221 becomes remarkable. The reason why the physical property (size) at 150 ° C. is used as the standard is that the stability of the material used for the lithium ion battery tends to decrease near 150 ° C., and the separator 22 (base material layer 222) This is because the polyolefin resin employed has a softening temperature of 120 ° C to 150 ° C.

  Returning to FIG. 2, one of the pair of current collectors 3, 3 (referred to as a positive electrode current collector) 3 is formed by bending a metal plate. The positive electrode current collector 3 includes a fixing piece 30 disposed along the inner surface of the case 4, and a power generation element connection portion 31 extending from the fixing piece 30.

  The fixing piece 30 is formed in a rectangular shape in plan view. Further, the fixing piece 30 is provided with a through hole 300. The power generation element connection portion 31 is perpendicular to or substantially perpendicular to the fixing piece 30. The power generation element connection portion 31 is disposed along the power generation element 2 (positive electrode lead portion 23) in a direction orthogonal to the winding center direction of the power generation element 2.

  The power generation element connection portion 31 of the positive electrode current collector 3 is electrically and mechanically connected to the positive electrode lead portion 23. In the present embodiment, the power generation element connection portion 31 of the positive electrode current collector 3 is sandwiched together with the positive electrode lead portion 23 by a clip member 32 in which a thin plate is folded in half. And the electric power generation element connection part 31, the positive electrode lead part 23, and the clip member 32 are integrally connected by ultrasonic welding etc. Thereby, the positive electrode lead part 23 and the positive electrode current collector 3 can be energized.

  The other of the pair of current collectors 3 and 3 (referred to as a current collector for negative electrode) 3 is formed in the same form as the current collector for positive electrode (one current collector) 3. Therefore, the above description regarding the positive electrode current collector 3 is a description of the negative electrode current collector 3 by replacing “positive electrode” in the text with “negative electrode”. Accordingly, the description of the positive electrode current collector 3 is substituted for the individual description of the negative electrode current collector 3.

  The case 4 includes a case main body 40 having an opening 400 formed on one surface, and a lid 41 that closes the opening 400 of the case main body 40.

  The case main body 40 is formed so as to be able to accommodate the positive electrode current collector 3 and the negative electrode current collector 3 connected to the power generation element 2 together with the power generation element 2. The lid 41 is formed corresponding to the planar shape of the opening 400 of the case body 40. The lid body 41 is provided with two through holes 410 and 410 (hereinafter, one through hole 410 is referred to as a positive electrode through hole and the other through hole 410 is referred to as a negative electrode through hole) at an interval. It has been. The outer periphery of the lid body 41 is welded to the upper end portion of the case body 40. Thereby, the cover body 41 has sealed the opening part 400 of the case main body 40 (refer FIG. 1).

  Each of the pair of external terminals 5 and 5 is a portion connected to an electrical load or another battery. One of the pair of external terminals 5 and 5 (hereinafter, referred to as a positive electrode external terminal) 5 is formed in a shaft shape. More specifically, the positive electrode external terminal 5 includes a shaft-like terminal portion 50 and a rotation stop portion 51 that is continuous with the terminal portion 50. The external terminal for positive electrode 5 is provided with a screw groove on the outer periphery of the terminal portion 50 in which a female screw member (for example, a nut) (not shown) can be screwed. That is, in the present embodiment, a bolt terminal is employed for the positive electrode external terminal 5.

  The stop part 51 is formed in a size larger than the terminal part 50. And the flat part is formed in the outer periphery of the rotation stop part 51. FIG. In this embodiment, the rotation stop part 51 is formed in the planar view polygonal shape (substantially square shape).

  The other external terminal (hereinafter referred to as negative electrode external terminal) 5 of the pair of external terminals 5 and 5 is formed in the same form as the positive electrode external terminal 5 (one external terminal 5). Therefore, the above description regarding the positive electrode external terminal 5 is a description of the negative electrode external terminal 5 by replacing “positive electrode” in the text with “negative electrode”. Accordingly, the description of the positive electrode external terminal 5 is substituted for the individual description of the negative electrode external terminal 5.

  In addition to the above-described configuration, the battery 1 according to the present embodiment includes a pair of internal gaskets 6 and 6 disposed along the inner surface of the case 4 corresponding to the arrangement of the pair of current collectors 3 and 3, and the pair of A pair of external gaskets 7 and 7 are provided along the outer surface of the case 4 corresponding to the arrangement of the internal gaskets 6 and 6. In the present embodiment, each of the pair of external terminals 5 and 5 is indirectly connected to the current collector 3 having the corresponding polarity of the pair of current collectors 3 and 3. Specifically, in addition to the above-described configuration, the battery 1 according to the present embodiment includes a pair of connection rods 8 and 8 each connected to the corresponding external terminal 5 of the pair of external terminals 5 and 5. The pair of shaft-like members 9 and 9 inserted through the case 4 includes a pair of shaft-like members 9 and 9 that electrically connect the corresponding current collector 3 and the connecting rod 8 respectively. Yes.

  One of the pair of internal gaskets 6 and 6 (hereinafter, referred to as positive electrode internal gasket) 6 is a synthetic resin molded product having electrical insulation and sealing properties. In the present embodiment, the positive electrode internal gasket 6 is formed in a plate shape. A through hole 60 is formed in the positive electrode internal gasket 6. Also, a cylindrical portion 61 communicating with the through hole 60 is formed on one surface of the positive electrode internal gasket 6. The internal gasket for positive electrode 6 is arranged along the inner surface of the lid body 41 in a state where the cylindrical portion 61 is inserted into the through hole for positive electrode 410 of the case 4. Then, the positive electrode current collector 3 is disposed on the other surface of the positive electrode internal gasket 6 so that the through hole 300 of the fixing piece 30 of the positive electrode current collector 3 and the through hole 60 of the positive electrode internal gasket 6 are concentric. A fixing piece 30 of the electric body 3 is arranged.

  The other internal gasket (hereinafter referred to as negative electrode internal gasket) 6 of the pair of internal gaskets 6 and 6 is formed in the same form as the positive electrode internal gasket 6. Therefore, the above description regarding the internal gasket 6 for the positive electrode is a description of the internal gasket 6 for the negative electrode by replacing “positive electrode” in the sentence with “negative electrode”. Accordingly, the description of the positive internal gasket 6 is substituted for the individual description of the negative internal gasket 6 here.

  One of the pair of external gaskets 7, 7 (hereinafter, referred to as a positive external gasket) 7 is a synthetic resin molded product having electrical insulation and sealing properties, similar to the positive internal gasket 6. . The positive external gasket 7 is formed in a plate shape. A through hole 70 is formed in the positive external gasket 7.

  The positive electrode external gasket 7 has a concave portion 71 capable of accommodating the rotation stop portion 51 of the positive electrode external terminal 5 on one surface (surface facing outward). The recess 71 is formed at a position shifted from the through hole 70. The planar shape and the planar size of the recess 71 are set to be the same as or substantially the same as the planar shape and the planar size of the rotation stopping portion 51 of the positive electrode external terminal 5. As a result, the flat surface portion on the outer periphery of the rotation stop portion 51 of the positive electrode external terminal 5 comes into surface contact with the flat surface portion on the inner peripheral surface of the recess 71, and the rotation of the positive electrode external terminal 5 is regulated. ing. The positive external gasket 7 is disposed on the outer surface of the case 4 (lid 41) so that the through hole 70 of the positive external gasket 7 and the positive through hole 410 of the case 4 are concentric. Yes.

  The other external gasket (hereinafter referred to as negative electrode external gasket) 7 of the pair of external gaskets 7 and 7 is formed in the same form as the positive electrode external gasket 7. Therefore, the above description regarding the positive electrode external gasket 7 is a description of the negative electrode external gasket 7 by replacing “positive electrode” in the text with “negative electrode”. Accordingly, the description of the external gasket 7 for the positive electrode is substituted for the individual description of the external gasket 7 for the negative electrode.

  One of the pair of connection rods 8 and 8 (hereinafter referred to as a positive electrode connection rod) 8 is formed of a rectangular metal plate. The positive electrode connecting rod 8 is formed with two through-holes (hereinafter, one through-hole is referred to as a first hole 80 and the other through-hole is referred to as a second hole 81) with an interval in the longitudinal direction. .

  The terminal portion 50 of the positive electrode external terminal 5 is inserted into the first hole 80 of the positive electrode connecting rod 8. Then, a female screw member (not shown) is screwed into the terminal portion 50 of the positive electrode external terminal 5 and is tightened, so that the rotation stop portion 51 of the positive electrode external terminal 5 and the positive electrode connecting rod 8 come into contact with each other. Thereby, the positive electrode external terminal 5 and the positive electrode connecting rod 8 are electrically connected.

  The other connection rod (hereinafter referred to as a negative electrode connection rod) 8 of the pair of connection rods 8, 8 is formed in the same form as the positive electrode connection rod 8. Therefore, the above description regarding the positive electrode connection rod 8 is a description of the negative electrode connection rod 8 by replacing “positive electrode” in the text with “negative electrode”. In connection with this, the description regarding the positive electrode connection rod 8 is substituted for the individual description of the negative electrode connection rod 8 here.

  One shaft-like member (hereinafter, referred to as a positive electrode shaft-like member) 9 of the pair of shaft-like members 9 and 9 is made of a conductive metal material. The positive shaft member 9 includes a second hole 81 of the positive connection rod 8, a through hole 70 of the positive external gasket 7, a positive through hole 410 of the case 4 (the cylindrical portion 61 of the positive internal gasket 6), The through hole 60 of the positive electrode internal gasket 6 and the through hole 300 of the fixing piece 30 of the positive electrode current collector 3 are inserted.

  One end of the positive electrode shaft-like member 9 is caulked inside the case 4 so as to be in close contact with the fixing piece 30 of the positive electrode current collector 3. On the other hand, the other end portion of the positive electrode shaft member 9 is caulked outside the case 4 so as to be in close contact with the positive electrode connecting rod 8. Thus, the positive shaft member 9 electrically connects the fixing piece 30 of the positive current collector 3 inside and outside the case 4 and the positive connection rod 8. At the same time, the positive shaft member 9 sandwiches the case 4 and the positive electrode current collector 3 (fixing piece 30) at both ends (both ends that are crimped) inside and outside the case 4. The positive electrode current collector 3 is fixed to the case 4.

  The other of the pair of shaft-like members 9, 9 (hereinafter referred to as a negative electrode shaft-like member) 9 is formed in the same form as the positive electrode shaft-like member 9. Moreover, the attachment aspect of the negative electrode shaft-like member 9 is the same as the attachment aspect of the positive electrode shaft-like member 9. Therefore, the above description regarding the positive electrode shaft-shaped member 9 is a description of the negative electrode shaft-shaped member 9 by replacing “positive electrode” in the text with “negative electrode”. In connection with this, the description regarding the positive electrode shaft-shaped member 9 is substituted for description of the negative electrode shaft-shaped member 9 and the attachment aspect of the negative electrode shaft-shaped member 9 here.

  The configuration of the battery 1 according to the present embodiment is as described above. In the battery 1 configured as described above, when a slight short circuit occurs in the power generation element 2 and the temperature in the case 4 increases, the separator 22 of the power generation element 2 tends to contract in the first direction due to heat shrinkage. Then, as shown in FIG. 3, the thick portions 221 and 221 formed at both ends of the separator 22 are hooked (locked) on both side ends of the positive electrode active material layer 201 in the first direction. That is, each of the pair of thick portions 221 and 221 formed at the portions of the separator 22 that protrude from both sides of the positive electrode active material layer 201 protrudes (protrudes) toward the positive electrode plate 20 and is positive electrode active material layer in the first direction. It is in a state facing the side surface of 201.

  Therefore, when the separator 22 is about to shrink in the first direction, each of the pair of thick portions 221 and 221 formed at both ends of the separator 22 in the first direction is the side surface of the positive electrode active material layer 201 facing each other. Interfere with. Thereby, it is controlled that the separator 22 shrinks due to heat shrinkability. Accordingly, the separator 22 is maintained in a state where it exists in the entire region where the positive electrode plate 20 and the negative electrode plate 21 overlap. Therefore, even if the inside of the case 4 becomes high temperature, a part of the positive electrode plate 20 and a part of the negative electrode plate 21 do not directly face each other, and the positive electrode plate 20 and the negative electrode plate 21 are maintained in an insulated state. Can do.

  In particular, the thick portions 221 and 221 of the separator 22 having the above-described configuration can be maintained in a state of protruding toward the positive electrode plate 20 side even when the inside of the case 4 reaches a high temperature. It will be caught on the side. That is, the heat-resistant layer 223 of the thick portions 221 and 221 has characteristics that are difficult to melt and soften even at high temperatures. Therefore, each of the pair of thick portions 221 and 221 is maintained in a state of protruding toward the positive electrode plate 20 side even when the temperature in the case 4 increases. Therefore, each of the pair of thick portions 221 and 221 is reliably caught by the positive electrode active material layer 201, and the contraction in the contraction characteristic direction of the separator 22 is reliably regulated.

  Therefore, the battery 1 having the above-described configuration can exhibit an excellent effect that the power generation element 2 can be prevented from being short-circuited due to the film breakage of the separator 22 at a high temperature.

  Further, in the battery 1 having the above configuration, the heat-resistant layer 223 is formed on one surface of the base material layer 22, and the heat-resistant layer 223 is raised to form the thick portions 221 and 221. Even if the height increases, the thick portions 221 and 221 are maintained in a fixed shape. Therefore, when the separator 22 is about to shrink due to heat, the thick portions 221 and 221 are reliably caught on the positive electrode active material layer 201, and the shrinkage of the separator 22 is reliably regulated.

  In the battery 1 having the above configuration, the heat-resistant layer 223 is interposed between the positive electrode plate 20 and the base material layer 222. Thereby, the damage of the separator 22 (base material layer 222) when a fine short circuit etc. generate | occur | produce can be suppressed.

  In addition, the thick wall portions 221 and 221 are formed at both ends in the winding center direction of the power generation element 2 and over the entire circumference including the arc portion of the power generation element 2, so that the thermal contraction of the separator 22 Can be reliably suppressed. Specifically, the arc portion of the power generation element 2 has a high density of the positive electrode plate 20 and the negative electrode plate 21 due to the difference in curvature radius between the inside and the outside, and easily generates heat. Therefore, the separator 22 in the arc portion of the power generation element 2 is highly likely to contract in the winding center direction due to the influence of heat. Therefore, when the thick portions 221 and 221 are formed at both ends in the winding center direction in the arc portion of the power generation element 2, the thermal contraction of the separator 22 can be reliably suppressed.

  In addition, this invention is not limited to the said embodiment, Of course, it can change suitably in the range which does not deviate from the summary of this invention.

  In the said embodiment, although the lithium ion battery was demonstrated as an example of an electrical storage element, it is not limited to this. For example, the storage element may be another battery such as a sodium ion battery or a capacitor (such as an electric double layer capacitor).

  In the said embodiment, although each of the thick parts 221 and 221 of the separator 22 protruded and formed in the positive electrode plate 20 side, it is not limited to this. For example, each of the thick portions 221 and 221 of the separator 22 may protrude toward the negative electrode plate 21 and be present on both sides of the negative electrode active material layer 211 in the first direction. Further, the thick portions 221 and 221 of the separator 22 protrude toward the positive electrode plate 20 side and the negative electrode plate 21 side, respectively, on both sides in the first direction of the positive electrode active material layer 201 and on both sides in the first direction of the negative electrode active material layer 211. It may be present.

  In the above-described embodiment, each of the thick portions 221 and 221 is disposed so as to be in close contact with the side end of the positive electrode active material layer 201, but is not limited thereto. For example, as shown in FIG. 4, assuming that each of the thick portions 221 and 221 is locked to the side end of the positive electrode active material layer 201, each of the thick portions 221 and 221 has a shrinkage characteristic direction (first In the direction) with respect to the positive electrode active material layer 201.

  When the thick portions 221 and 221 of the separator 22 are formed so as to exist on both sides of the negative electrode active material layer 211, the thick portions 221 and 221 of the separator 22 are formed on both sides of the positive electrode active material layer 201 and the negative electrode active material layer 201, respectively. The same applies to the case where the material layer 211 is formed so as to exist on both sides. As described above, the thick portions 221 and 221 are arranged with a gap with respect to at least one of the positive electrode active material layer 201 and the negative electrode active material layer 211, so that the electrolytic solution is separated from the separator 22 and the electrode. It becomes easy to enter between the plates 20 and 21. Thereby, the performance of the battery 1 becomes favorable.

  In the said embodiment, although the separator 22 was provided with the base material layer 222 and the heat-resistant layer 223, it is not limited to this. For example, the separator 22 may be composed of only the base material layer 222 (only the porous film). However, the separator 22 in this case is formed with thick portions 221 and 221 at the time of molding.

  In the above embodiment, the thick portions 221 and 221 are 1% or more of the thickness of the positive electrode active material layer 201 in the discharge state on both sides of the positive electrode active material layer 201 in the first direction with reference to the thin wall portion 220 in the separator 22. Although protruded, it is not limited to this. For example, the thick portions 221 and 221 are on both sides of the positive electrode active material layer 201 or the negative electrode active material layer 211, on the positive electrode active material layer 201 or the negative electrode active material layer 211 in the discharge state with reference to the thin portion 220 in the separator 22. You may protrude by the protrusion amount of less than 1% of thickness. That is, the thick portions 221 and 221 may be formed with a protruding amount that can be locked with at least one of the positive electrode active material layer 201 and the negative electrode active material layer 211.

  Moreover, in the said embodiment, although the physical property of 150 degreeC was applied as a value substituted to conditional expression (1), it is not limited to this. The value substituted into the conditional expression (1) is a temperature corresponding to the temperature at which the stability of the material used for the battery 1 is lowered and the softening temperature of the resin used for the separator 22 (base material layer 222). The physical properties should be adopted.

  In the above embodiment, the battery 1 (power storage element) including the power generating element 2 having the configuration in which the positive electrode plate 20, the separator 22, and the negative electrode plate 21 each having a belt shape are wound has been described. It is not limited. For example, the battery 1 (electric storage element) including the power generation element 2 in which the positive electrode plate 20, the separator 22, and the negative electrode plate 21 each having a single sheet shape are overlaid may be used. Moreover, the battery 1 (cylindrical battery: electrical storage element) provided with the electric power generation element 2 of the structure by which the positive electrode plate 20, the separator 22, and the negative electrode plate 21 were wound by the column shape may be sufficient. In the case of a cylindrical battery, the width of the separator (the size in the direction corresponding to the first direction in the present embodiment) is set to a width that is larger than the width of the positive electrode plate in the same direction and does not decrease the internal volume of the battery. It is preferable.

  In the power generation element 2 of the above embodiment, the separator 22 (base material layer 222) whose shrinkage characteristic direction to be shrunk due to heat shrinkage is only the first direction is employed, but is not limited thereto. For example, in the power generation element 2, a separator 22 having a plurality of shrinkage characteristics directions (for example, a separator 22 having heat shrinkability that shrinks in a second direction orthogonal to the first direction in addition to the first direction) is employed. May be.

  In this case, the size of the separator 22 in the shrinkage characteristic direction (a plurality of directions) is larger than the size of the positive electrode active material layer 201 and the size of the negative electrode active material layer 211 in the direction (a plurality of directions) corresponding to the shrinkage characteristic direction. It is set large. The separator 22 is disposed so as to protrude from both sides of the positive electrode active material layer 201 and the negative electrode active material layer 211 in a direction (a plurality of directions) corresponding to the shrinkage characteristics. The separator 22 is thick portions 221 and 221 that are thicker than the thickness of the thin portion 220 at portions protruding on both sides of the positive electrode active material layer 201 and the negative electrode active material layer 211 in the corresponding direction (a plurality of directions), Thick portions 221 that protrude toward at least one of the positive electrode plate 20 and the negative electrode plate 21 and exist on both sides of at least one of the positive electrode active material layer 201 and the negative electrode active material layer 211 in the corresponding direction (a plurality of directions). , 221 may be provided.

  In the said embodiment, the thick part 221,221 is formed in the both ends of the transversal direction of the strip | belt-shaped separator 22, and the positive electrode plate 20 and the negative electrode plate 21 are wound with this separator 22 in a 1st direction. Although the thick portions 221 and 221 are disposed over the entire circumference of both ends of the power generation element 2, the present invention is not limited to this. Thus, when the positive electrode plate 20 and the negative electrode plate 21 are wound flat together with the separator 22, the thick portions 221 and 221 may be provided on the separator 22 in the arc portion of the power generation element 2. That is, the separator 22 having the thick portions 221 and 221 may be employed in a region that is an arc portion during winding (a region that is intermittently arranged in the longitudinal direction). The arc portion in the power generation element 2 is a portion where the positive electrode plate 20 and the negative electrode plate 21 are high in density and easily generate heat. Therefore, the separator 22 in the arc portion of the power generation element 2 is highly likely to contract in the contraction characteristic direction (winding center direction) due to the influence of heat. Therefore, by forming the thick portions 221 and 221 at both ends in the shrinkage characteristic direction of the separator 22 in the arc portion of the power generating element 2, the thermal contraction of the separator 22 can be reliably suppressed.

  In the above embodiment, the thickness of the base material layer 222 of the separator 22 is made uniform, while the thickness of the portion of the heat-resistant layer 223 of the separator 22 that protrudes from the positive electrode plate 20 and the negative electrode plate 21 is the positive electrode active material layer 201 and the negative electrode active material. The thick portions 221 and 221 are formed by setting the thickness to be thicker than the thickness of the portion facing the layer 211 (the protruding heat-resistant layer 223 is raised), but is not limited thereto. For example, the portion of the base material layer 22 that protrudes from the positive electrode active material layer 201 and the negative electrode active material layer 211 of the separator 22 has a thickness that faces the positive electrode active material layer 201 and the negative electrode active material layer 211 of the separator 22. The heat-resistant layer 223 having a thickness that is set to be greater than the thickness of the layer 22 and that is uniform or substantially uniform may be formed on the base material layer 222. By doing in this way, the thick parts 221 and 221 are formed in the part which protruded from the positive electrode active material layer 201 and the negative electrode active material layer 211 in the separator 22 like the said embodiment.

  In the above embodiment, as a method of forming the thin portion 220 and the thick portions 221 and 221 on the separator 22, the heat resistant layer 223 formed to have a uniform thickness on the entire surface of the base material layer 222 is formed to the size of the positive electrode active material layer 201. Although compression-molding (pressing) is performed in a range corresponding thereto, the present invention is not limited to this. For example, when the positive electrode plate 20, the negative electrode plate 21, and the separator 22 are wound in a stacked state, the separator 22 is wound with either the positive electrode plate 20 or the negative electrode plate 21 while being tensioned. You may make it press (press either the positive electrode plate 20 or the negative electrode plate 21 against the separator 22). In this way, the region pressed by either the positive electrode plate 20 or the negative electrode night 21 in the separator 22 becomes the thin portion 220, and the unpressed region becomes the thick portions 221, 221.

  In this case, the tension on the positive electrode plate 20, the negative electrode plate 21, and the separator 22 can be arbitrarily set when the difference in thickness (step) between the thin portion 220 and the thick portions 221 and 221 is set to a desired value. However, if the tension on the positive electrode plate 20, the negative electrode plate 21, and the separator 22 is too small, it causes a winding shift, and if the tension on the positive electrode plate 20, the negative electrode plate 21, and the separator 22 is extremely large, the positive electrode plate 20, the negative electrode plate 21, and the separator 22 are broken. Therefore, the tension on the positive electrode plate 20, the negative electrode plate 21, and the separator 22 may be about 20 to 300 gf / cm per unit length based on the length of the separator 22 in the first direction.

  In addition, as a method of forming the thin portion 220 and the thick portions 221 and 221 on the separator 22, the positive electrode plate 20, the negative electrode plate 21, and the separator 22 are wound in a stacked state, and then in a wound state. You may employ | adopt the method of pressing the board 20, the negative electrode plate 21, and the separator 22 completely (pressing to radial direction). In this way, the positive electrode plate 20 and the negative electrode plate 21 are pressed against the separator 22. Therefore, the area where the positive electrode plate 20 and the negative electrode plate 21 are pressed in the separator 22 becomes the thin portion 220, and the other area becomes the thick portion 221.

  As another method, after the positive electrode plate 20, the negative electrode plate 21, and the separator 22 are wound in a stacked state, they are housed in the case 4 to form a single power storage element 1, and then the power storage element 1 A method of pressing (Case 4) can also be adopted. In this way, the positive plate 20 and the negative plate 21 are pressed against the separator 22 by the compression of the case 4. Therefore, the area where the positive electrode plate 20 and the negative electrode plate 21 are pressed in the separator 22 becomes the thin portion 220, and the other area becomes the thick portion 221.

  DESCRIPTION OF SYMBOLS 1 ... Lithium ion battery (electric storage element), 2 ... Power generation element, 3 ... Current collector (current collector for positive electrode, current collector for negative electrode), 4 ... Case, 5 ... External terminal (external terminal for positive electrode, for negative electrode) External terminal), 6 ... Internal gasket (Positive electrode internal gasket, Negative electrode internal gasket), 7 ... External gasket (Positive electrode external gasket, Negative electrode external gasket), 8 ... Connection 杆 (Positive electrode connection 杆, Negative electrode connection 杆) ), 9... Shaft member (shaft member for positive electrode, shaft member for negative electrode), 20... Positive electrode plate, 21... Negative electrode plate, 22. Piece part 31 ... Power generation element connection part 32 ... Clip member 40 ... Case body 41 ... Cover body 50 ... Terminal part 51 ... Rotation part 60 ... Through hole 61 ... Cylindrical part 70 ... Through hole, 71 ... concave portion, 80 ... first hole, 81 ... second hole, 200 Positive electrode base layer, 201 ... positive electrode active material layer, 202 ... base layer exposed portion, 210 ... negative electrode base layer, 211 ... negative electrode active material layer, 212 ... base layer exposed portion, 220 ... thin wall portion, 221 ... thick wall portion, 222 ... base material layer 223 ... heat-resistant layer, 300 ... through hole, 400 ... opening, 410 ... through hole (through hole for positive electrode, through hole for negative electrode)

Claims (8)

A positive electrode plate including a positive electrode base layer having conductivity and a positive electrode active material layer formed on the positive electrode base layer;
A negative electrode plate comprising a negative electrode base layer having conductivity and a negative electrode active material layer formed on the negative electrode base layer, wherein the negative electrode active material layer is superimposed on the positive electrode plate in a state of facing the positive electrode active material layer Negative electrode plate,
A separator having electrical insulation properties and heat shrinkability, the separator disposed between the positive electrode plate and the negative electrode plate so as to exist in the entire region where the positive electrode plate and the negative electrode plate overlap; A power generation element having
The size of the separator is set larger than the size of the positive electrode active material layer and the size of the negative electrode active material layer,
The separator is
Including a base layer composed of a microporous film and a heat-resistant layer formed on the base layer;
Arranged so as to protrude on both sides of the positive electrode active material layer and the negative electrode active material layer,
At least a part of each of the portions protruding on both sides of the positive electrode active material layer and the negative electrode active material layer includes a thick portion thicker than the thickness of the portion facing the positive electrode active material layer and the negative electrode active material layer,
The heat-resistant layer is formed on at least one of both surfaces of the base material layer,
Each of the thick-walled portions has a protruding amount that is locked to at least one of the positive electrode active material layer and the negative electrode active material layer facing the heat resistant layer when the separator attempts to thermally shrink. The heat-resistant layer is formed so as to protrude and thereby protrude toward at least one of the positive electrode plate side and the negative electrode plate side, whereby the positive electrode active material layer and the negative electrode active material layer are projected. A power storage element present on both sides of at least one of the material layers. The electric storage element according to claim 1, wherein an interval between the thick portions existing on both sides of the active material layer is set to be equal to or larger than a size of the active material layer in a direction in which the separator protrudes from the active material layer. The size of the separator in the shrinkage characteristic direction to shrink by the heat shrinkability is set larger than the size of the positive electrode active material layer and the size of the negative electrode active material layer in the direction corresponding to the shrinkage characteristic direction,
The separator is
The positive electrode active material layer and the negative electrode active material layer in a direction corresponding to the shrinkage characteristic direction are disposed so as to protrude from both sides, and
The thick portion is provided in at least a part of each of the portions protruding on both sides of the positive electrode active material layer and the negative electrode active material layer in a direction corresponding to the shrinkage characteristic direction,
3. Each of the thick portions is present on both sides in a direction corresponding to the shrinkage characteristic direction in at least one of the positive electrode active material layer and the negative electrode active material layer. The electricity storage device described.   4. The power storage device according to claim 1, wherein the heat resistant layer is provided on a surface on the positive electrode plate side of both surfaces of the base material layer. 5. A gap is formed between at least one of the positive electrode active material layer and the negative electrode active material layer and each of the thick portions existing on both sides of the active material layer. 5. The electricity storage device according to any one of 1 to 4. The power storage device according to claim 1, wherein the heat-resistant layer includes an inorganic filler. At least one of the positive electrode base layer and the negative electrode base layer is formed of the positive electrode active material layer and the negative electrode active material layer in a direction in which the separator protrudes from the positive electrode active material layer and the negative electrode active material layer. The power storage element according to claim 1, wherein the power storage element is larger than a corresponding active material layer. A positive electrode plate including a positive electrode base layer having conductivity and a positive electrode active material layer formed on the positive electrode base layer;
A negative electrode plate comprising a negative electrode base layer having conductivity and a negative electrode active material layer formed on the negative electrode base layer, wherein the negative electrode active material layer is superimposed on the positive electrode plate in a state of facing the positive electrode active material layer Negative electrode plate,
Possess electrical insulating properties, and a separator comprising a microporous substrate layer composed of a film and the substrate layer a heat-resistant layer formed on the overlap of the positive electrode plate and the negative electrode plate area And a separator disposed between the positive electrode plate and the negative electrode plate so as to protrude from both sides of the positive electrode active material layer and the negative electrode active material layer. A method,
In the separator, at least a part of each of the positive electrode active material layer and the negative electrode active material layer protruding on both sides by pressing a portion facing the positive electrode active material layer and the negative electrode active material layer, the A thick portion thicker than the thickness of the portion facing the positive electrode active material layer and the negative electrode active material layer, wherein the separator is disposed between the positive electrode plate and the negative electrode plate; Thickness existing on both sides of at least one of the positive electrode active material layer and the negative electrode active material layer by projecting toward at least one of the negative electrode plate sides A meat part is formed,
Each of the thick-walled portions has a protruding amount that is locked to at least one of the positive electrode active material layer and the negative electrode active material layer facing the heat resistant layer when the separator attempts to thermally shrink. The heat-resistant layer is formed so as to protrude and thereby protrude toward at least one of the positive electrode plate side and the negative electrode plate side, whereby the positive electrode active material layer and the negative electrode active material layer are projected. A method for manufacturing a power storage element that is present on both sides of at least one of the material layers.

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