JP6726398B2 - Storage element - Google Patents

Description

The present invention relates to a power storage device including an electrode body in which an electrode and a separator having a heat resistant layer are laminated.

Conventionally, a non-aqueous electrolyte secondary battery including a wound electrode body having a separator having a layer containing inorganic particles has been known (see Patent Document 1). Specifically, this non-aqueous electrolyte secondary battery has a wound electrode body housed in a battery can and sealed with a battery lid.

As shown in FIG. 13, the wound electrode body has a separator 103 arranged between a negative electrode 101 and a positive electrode 102, and is wound so as to be housed in the battery can. The negative electrode 101 has a negative electrode active material layer 1011 in which a negative electrode active material is formed on a metal foil 1010 such as a copper foil, and a current collector foil exposed portion 1012 in which the negative electrode active material is not formed at one end in the width direction. There is. The positive electrode 102 includes a positive electrode active material layer 1021 formed by forming a positive electrode active material on a metal foil 1020 such as an aluminum foil, and a positive electrode active material on one end in the width direction of the negative electrode 101 opposite to the current collector foil exposed portion 1012. It has a collector foil exposed portion 1022 which is not formed. The separator 103 has a first layer 1032 which is a microporous film and a second layer 1031 which is a porous functional layer containing inorganic particles, which is formed on the first layer 1032.

In the non-aqueous electrolyte secondary battery, the current collector foil exposed portion 1012 of the negative electrode 101 and the current collector foil exposed portion 1022 of the positive electrode 102 of the wound electrode body are bundled together to form a negative electrode current collector and a positive electrode current collector. Each connected to the body.

In the non-aqueous electrolyte secondary battery, in a state where the collector foil exposed portion 1012 of the negative electrode 101 and the collector foil exposed portion 1022 of the positive electrode 102 are bound together, as shown in FIG. When the end portion of the layer 1031 (specifically, the corner portion of the inorganic layer) is in contact with the current collector foil exposed portion 1012 of the negative electrode 101, the inorganic layer (inorganic particles contained in the inorganic layer) is hard, The metal foil 1010 (collector foil exposed portion 1012) may be scraped by the end portion of the second layer 1031 due to vibration or the like to cause contamination such as metal powder.

JP, 2014-222669, A

Therefore, an object of the present embodiment is to provide a power storage element in which even if a separator having a heat-resistant layer is used in an electrode body, contamination due to contact between the metal foil contained in the electrode and the heat-resistant layer does not easily occur. ..

The power storage element of the present embodiment is
An electrode having a metal foil and an active material layer, and an electrode on which the metal foil and the active material layer are stacked in a state where one end of the metal foil in a predetermined direction projects from the active material layer, and a substrate And a heat-resistant layer containing an inorganic substance has a separator that is stacked, and an electrode body in which these electrodes and a separator are laminated,
The heat-resistant layer faces the active material layer, and is larger than the active material layer in the predetermined direction,
At least one of the electrode and the separator has a protective layer facing the other member,
The protective layer is disposed between the one end of the metal foil and the heat-resistant layer, and the heat-resistant layer from the edge position of the active material layer toward the one side in the predetermined direction. Extends to a position above the edge position.

According to this structure, the protective layer is arranged in the entire area in the predetermined direction between the metal foil (the end portion on one side of the metal foil) protruding from the active material layer in the electrode and the heat-resistant layer of the separator. Therefore, contact between the metal foil and the heat-resistant layer is prevented by the protective layer, and thus contamination due to contact between the metal foil of the electrode and the heat-resistant layer of the separator is less likely to occur.

In the storage element,
The electrode has the protective layer,
The protective layer may cover the surface of the one end of the metal foil.

According to such a configuration, since a part of the portion of the metal foil which is not covered with the active material layer is covered with the protective layer, the portion of the electrode where the metal foil is exposed is reduced, whereby the metal foil Occurrence of contamination caused by contact with other members can be suppressed.

in this case,
The protective layer may be fixed to the one end of the metal foil.

In this way, the protective layer is fixed to the metal foil (that is, arranged so as not to move relative to each other), so that even if the protective layer is arranged on the surface of the metal foil, rubbing between the protective layer and the metal foil, etc. Is prevented, so that contamination due to the rubbing or the like does not occur.

In the storage element,
One end surface of the heat resistant layer in the predetermined direction may be inclined or curved with respect to the surface of the base material so as to approach the base material toward the one end edge of the heat resistant layer.

According to such a configuration, at the one end of the heat-resistant layer, the angle formed by the surface forming the corner of the end becomes large (for example, see FIG. 8), or the corner does not exist at the end. Therefore, even if the end of the heat-resistant layer comes into contact with the metal foil, contamination due to the contact is less likely to occur.

Further, in the electric storage element,
The edge of the protective layer is located on the other side from the edge of the metal foil in the predetermined direction.
The edge of the base material may be located between the edge of the protective layer and the edge of the metal foil in the predetermined direction.

According to such a configuration, by locating the edge of the protective layer on the other side of the edge of the metal foil, a portion (a portion of the electrode where the metal foil is exposed) that is electrically connected to the other member is secured. .. Moreover, by positioning the edge of the base material between the edge of the protective layer and the edge of the metal foil, the protective layer and another electrode in the laminating direction of the electrode body (the electrode on which the protective layer is arranged) Since the base material is located between the metal foil of another electrode) and the metal foil of the other electrode, it becomes difficult to contact the metal foil of the other electrode with the metal foil of the other electrode. It is also possible to suppress the occurrence of contamination due to the contact of.

Further, in the electric storage element,
The electrode is arranged between the separators adjacent to each other in the stacking direction of the electrode and the separator,
The active material layer and the protective layer may be arranged on both surfaces of the metal foil, respectively.

With such a configuration, even if the separators (heat resistant layers) are arranged so as to sandwich the metal foil, it is possible to suppress the occurrence of contamination due to the contact between the heat resistant layer and the metal foil.

As described above, according to the present embodiment, it is possible to provide a power storage element in which even if a separator having a heat resistant layer is used in the electrode body, contamination due to contact between the metal foil contained in the electrode and the heat resistant layer does not easily occur. it can.

FIG. 1 is a perspective view of a power storage element according to this embodiment. FIG. 2 is an exploded perspective view of the storage element. FIG. 3 is a sectional view taken along the line III-III in FIG. FIG. 4 is a perspective view of an electrode body included in the power storage element. FIG. 5 is a schematic view of a cross section in a state where the positive electrode included in the electrode body is disassembled. FIG. 6 is a schematic view of a cross section in a state where the negative electrode included in the electrode body is disassembled. FIG. 7 is a schematic view of a cross section in a state in which the separator included in the electrode body is disassembled. FIG. 8 is a diagram for explaining the positional relationship between the respective constituents of the positive electrode, the negative electrode, and the separator. FIG. 9 is a diagram for explaining the position of the protective layer in the electrode body according to another embodiment. FIG. 10 is an enlarged cross-sectional view of the end portion in the width direction of the separator according to another embodiment. FIG. 11 is an enlarged cross-sectional view of the end portion in the width direction of the separator according to another embodiment. FIG. 12 is a perspective view of a power storage device including the power storage element according to the present embodiment. FIG. 13: is a figure for demonstrating the positional relationship of each structure of the conventional positive electrode, negative electrode, and separator. FIG. 14 is a schematic diagram for explaining a state in which the exposed portions of the negative electrode collector foil are bundled.

Hereinafter, an embodiment of a power storage device according to the present invention will be described with reference to FIGS. 1 to 8. The power storage element includes a primary battery, a secondary battery, a capacitor, and the like. In the present embodiment, a chargeable/dischargeable secondary battery will be described as an example of a power storage element. It should be noted that the names of the respective constituent members (respective constituent elements) of the present embodiment are those of the present embodiment and may differ from the names of the respective constituent members (respective constituent elements) of the background art.

The electricity storage device of this embodiment is a non-aqueous electrolyte secondary battery. More specifically, the power storage element is a lithium-ion secondary battery that utilizes electron transfer that occurs as lithium ions move. This type of power storage element supplies electric energy. The electric storage element is used alone or in plural. Specifically, the storage element is used alone when the required output and the required voltage are small. On the other hand, the power storage element is used in the power storage device in combination with another power storage element when at least one of the required output and the required voltage is large. In the power storage device, a power storage element used in the power storage device supplies electric energy.

As shown in FIGS. 1 to 4, the electricity storage device includes electrodes 23, 24 including metal foils 231, 241, and active material layers 232, 242 stacked on the metal foils 231, 241, a base material 251, and the base material. The electrode body 2 in which the separator 25 including the heat-resistant layer 252 that is stacked on the material 251 is laminated. In addition, the electricity storage device 1 includes a case 3 that houses the electrode body 2, an external terminal 4 that is at least partially disposed outside the case 3, and a current collector 5 that electrically connects the electrode body 2 and the external terminal 4. And an insulating member 6 that insulates the electrode body 2 and the case 3 from each other.

The electrode body 2 includes a winding core 21 and a lamination body 22 in which a positive electrode 23 and a negative electrode 24 are laminated in an insulated state, and the lamination body 22 is wound around the winding core 21. (See FIGS. 3 and 4). In the electrode body 2, lithium ions move between the positive electrode 23 and the negative electrode 24, so that the storage element 1 is charged and discharged.

The winding core 21 is usually made of an insulating material. The winding core 21 of the present embodiment has a tubular shape, more specifically, a flat tubular shape. The winding core 21 is formed by winding a flexible or thermoplastic sheet. The sheet of this embodiment is made of synthetic resin.

The electrodes 23 and 24 have metal foils 231 and 241 and active material layers 232 and 242, as shown in FIGS. 2 and 5 to 8. The metal foils 231 and 241 and the active material layers 232 and 242 are stacked in such a manner that one end of the metal foils 231 and 241 on one side in a predetermined direction protrudes from the active material layers 232 and 242. In the electricity storage device 1 of the present embodiment, the active material layer has the positive electrode active material layer 232 and the negative electrode active material layer 242, and the electrodes have the positive electrode 23 and the negative electrode 24. The details are as follows.

The positive electrode 23 includes a strip-shaped metal foil 231, a positive electrode active material layer 232 that is stacked on the metal foil 231, and a protective layer 233 that is stacked on the metal foil 231 and faces the separator 25. The metal foil 231 of this embodiment is, for example, an aluminum foil.

The positive electrode active material layer 232 is overlaid on the metal foil 231 at a portion (active material coating portion 2312) excluding an end portion 2311 on one side in the width direction (shorter direction: left-right direction in FIG. 5) of the metal foil 231. ing. Further, in the positive electrode 23 of the present embodiment, the positive electrode active material layers 232 are arranged on both sides of the metal foil 231, that is, in the positive electrode 23, the metal foil 231 is sandwiched by the positive electrode active material layers 232 in the thickness direction. Has been. The positive electrode active material layer 232 includes a positive electrode active material and a binder.

The positive electrode active material is, for example, lithium metal oxide. Specifically, the positive electrode active material is, for example, _a composite oxide (Li _a Co _y O ₂ , Li _a Ni _x ) represented by Li _a Me _b O _c (Me represents one or more transition metals). O ₂ , Li _a Mn _z O ₄ , Li _a Ni _x Co _y Mn _z O _2, etc.), Li _a Me _b (XO _c ) _d (Me represents one or more transition metals, and X represents, for example, P. , Si, B, a polyanion compounds represented by the representative of the _{V) (Li a Fe b PO} 4, Li a Mn b PO 4, Li a Mn b SiO 4, Li a Co b PO 4 F , etc.). The positive electrode active material of this embodiment is LiNi _1/3 Co _1/3 Mn _1/3 O ₂ .

The binder used for the positive electrode active material layer 232 is, for example, polyvinylidene fluoride (PVDF), a copolymer of ethylene and vinyl alcohol, polymethyl methacrylate, polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyacrylic acid, polymethacryl. Acid, styrene-butadiene rubber (SBR). The binder of this embodiment is polyvinylidene fluoride.

The positive electrode active material layer 232 may further include a conductive auxiliary agent such as Ketjen Black (registered trademark), acetylene black, or graphite. The positive electrode active material layer 232 of this embodiment has acetylene black as a conductive additive.

The protective layer 233 covers the surface of the end portion 2311 on one side of the metal foil 231. Like the positive electrode active material layer 232, the protective layers 233 of the present embodiment are arranged on both surfaces of the metal foil 231. That is, in the positive electrode 23, the metal foil 231 (specifically, the one end 2311) is sandwiched between the protective layers 233 in the thickness direction. The thickness dimension of the protective layer 233 of the present embodiment is smaller than the thickness dimension of the positive electrode active material layer 232. The protective layer 233 contains an insulator and a binder.

Examples of the insulator include oxide fine particles such as Al ₂ O ₃ (alumina) and SiO ₂ (silica), ionic crystal fine particles such as calcium fluoride and lithium fluoride, clay fine particles such as talc and montmorillonite, boehmite, zeolite, and the like. Examples include mineral resource-derived substances such as apatite and kaolin, and resin beads such as polyethylene and polypropylene.

The binder is, for example, ethylene-vinyl acetate copolymer, (meth)acrylic acid copolymer, fluorine rubber, styrene-butadiene rubber (SBR), polyvinyl alcohol (PVA), polyvinylidene fluoride, or the like. Note that only the binder may be applied to form the insulating film-like protective layer 233 (that is, the protective layer 233 may be composed of only the binder), but in order to support the thickness and strength, insulation It is preferable that particles are blended.

The protective layer 233 of the present embodiment contains an inorganic material. The protective layer 233 is fixed to the end portion 2311 on one side of the metal foil 231. More specifically, the protective layer 233 is disposed between the end portion 2311 on one side of the metal foil 231 and the heat resistant layer 252 of the separator 25, and the positive electrode active material layer 232 in the width direction of the metal foil 231. From one edge to the other side (see FIG. 8). The edge 233E on one side in the width direction of the protective layer 233 is on the other side (in FIG. 8) than the edge 231E on one side in the width direction of the metal foil 231 and the edge 25E on one side in the width direction of the separator 25. It is located on the left side). Note that the protective layer 233 may have a configuration that does not include an inorganic substance. Further, in the protective layer 233, the binder may also serve as an insulator.

The negative electrode 24 has a strip-shaped metal foil 241 and a negative electrode active material layer 242 stacked on the metal foil 241. The metal foil 241 of this embodiment is, for example, a copper foil.

The negative electrode active material layer 242 is a portion excluding the end portion 2411 on the other side (the side opposite to the non-covered portion of the metal foil 231 of the positive electrode 23) of the metal foil 241 in the width direction (shorter direction: left-right direction in FIG. 6). It is overlaid on the metal foil 241 in the (active material coating portion 2412). Further, in the negative electrode 24 of the present embodiment, the negative electrode active material layers 242 are arranged on both sides of the metal foil 241, respectively, that is, in the negative electrode 24, the metal foil 241 is sandwiched between the negative electrode active material layers 242 in the thickness direction. Has been. The dimension of the negative electrode active material layer 242 in the width direction of the present embodiment is larger than the dimension of the positive electrode active material layer 232 in the width direction (see FIG. 8 ). The negative electrode active material layer 242 has a negative electrode active material and a binder.

The negative electrode active material is, for example, a carbon material such as graphite, non-graphitizable carbon, and easily graphitizable carbon, or a material that causes an alloying reaction with lithium ions such as silicon (Si) and tin (Sn). The negative electrode active material of this embodiment is non-graphitizable carbon.

The binder used for the negative electrode active material layer 242 is the same as the binder used for the positive electrode active material layer 232. The binder of this embodiment is polyvinylidene fluoride.

The negative electrode active material layer 242 may further include a conductive auxiliary agent such as Ketjen Black (registered trademark), acetylene black, or graphite. The negative electrode active material layer 242 of this embodiment does not have a conductive additive.

In the electrode body 2 of this embodiment, the positive electrode 23 and the negative electrode 24 configured as described above are wound in a state of being insulated by the separator 25. That is, in the electrode body 2 of this embodiment, the laminated body 22 of the positive electrode 23, the negative electrode 24, and the separator 25 is wound.

The separator 25 is an insulating member and is arranged between the positive electrode 23 and the negative electrode 24. Thereby, in the electrode body 2 (specifically, the laminated body 22), the positive electrode 23 and the negative electrode 24 are insulated from each other. Further, the separator 25 holds the electrolytic solution in the case 3. This allows lithium ions to move between the positive electrodes 23 and the negative electrodes 24 that are alternately stacked with the separator 25 in between when the power storage device 1 is charged and discharged.

Specifically, the separator 25 has a strip shape and is made of, for example, a porous film of polyethylene, polypropylene, cellulose, polyamide, or the like. The separator 25 includes, for example, a base material 251 formed of a polyethylene porous film, and inorganic particles such as SiO ₂ particles, Al ₂ O ₃ particles, and boehmite (alumina hydrate) stacked on the base material 251. And a heat-resistant layer (inorganic layer) 252 containing the same. In the separator 25 of the present embodiment, the heat resistant layer 252 is overlaid on the surface of the base material 251 facing the positive electrode active material layer 232 (the lower surface in the example of FIG. 7). That is, the heat resistant layer 252 of the separator 25 faces the positive electrode active material layer 232.

As shown in FIG. 8, the separator 25 configured as described above is stacked in a state in which the positive electrode active material layer 232 and the negative electrode active material layer 242 are misaligned in the width direction so as to overlap in the thickness direction (stacking direction). It is arranged between the positive electrode 23 and the negative electrode 24. At this time, the end 2311 on one side in the width direction of the positive electrode 23 and the end 2411 on the other side in the width direction of the negative electrode 24 do not overlap. That is, the end portion 2311 on one side in the width direction of the positive electrode 23 projects in the width direction (direction orthogonal to the stacking direction) from the region where the positive electrode 23 and the negative electrode 24 overlap, and on the other side in the width direction of the negative electrode 24. The end portion 2411 projects in the width direction (direction opposite to the projecting direction of the end portion 2311 on one side of the positive electrode 23) from the region where the positive electrode 23 and the negative electrode 24 overlap.

The dimension of the base material 251 in the width direction is larger than the dimension of the negative electrode active material layer 242 in the width direction. Further, the widthwise dimension of the heat-resistant layer 252 is smaller than the widthwise dimension of the base material 251, and is larger than the widthwise dimension of the positive electrode active material layer 232. The edge on the other side (left side in FIG. 8) in the width direction of the heat-resistant layer 252 is located on one side (on the right side in FIG. 8) than the edge on the other side in the width direction of the base material 251. The edge of the heat-resistant layer 252 on the other side in the width direction is located on the other side of the edge of the metal foil 231 on the other side in the width direction and the edge of the positive electrode active material layer 232 on the other side in the width direction. doing. An edge 252E on one side in the width direction of the heat-resistant layer 252 is located on one side of an edge 232E on one side in the width direction of the positive electrode active material layer 232. The edge 252E on one side in the width direction of the heat-resistant layer 252 is located on the other side of the edge 233E on the one side in the width direction of the protective layer 233. That is, the protective layer 233 extends in the width direction from one end edge 232E of the positive electrode active material layer 232 to a position equal to or higher than the position of the one end edge 252E of the heat-resistant layer 252. The edge 251E on one side in the width direction of the base material 251 is located on one side of the edge 233E on the one side in the width direction of the protective layer 233. An edge 231E on one side in the width direction of the metal foil 231 is located on one side of an edge 233E on one side in the width direction of the protective layer 233 and an edge 251E on one side in the width direction of the base material 251. ..

As described above, from the edge 232E on one side in the width direction of the positive electrode active material layer 232, the edge 252E on one side of the heat-resistant layer 252 and the edge 233E on one side of the protective layer 233 are sequentially arranged toward the one side. The edge 251E on one side of the base material 251 and the edge 231E on one side of the metal foil 231 are lined up (see FIG. 8). In addition, from the edge on the other side in the width direction of the positive electrode active material layer 232 and the edge on the other side in the width direction of the metal foil 231, in order from the edge on the other side, the edge on the other side of the heat-resistant layer 252 and the base material. The other edge of 251 is lined up.

Further, the end surface 2520 on one side in the width direction of the heat resistant layer 252 is inclined with respect to the surface of the base material 251 so as to approach the base material 251 as it approaches the edge 252E on the one side in the width direction of the heat resistant layer 252. It is curved. The one end surface 2520 of the present embodiment is inclined with respect to the surface of the base material 251 (see FIGS. 7 and 8).

The electrode body 2 is formed by winding the positive electrode 23, the negative electrode 24, and the separator 25 (that is, the laminated body 22) that are laminated in the above state. In addition, in the electrode body 2 of the present embodiment, a portion 2314 of the end portion 2311 on one side of the positive electrode 23 excluding the region where the protective layer 233 is overlapped (protective layer coating portion 2313) or the other end of the negative electrode 24. The uncoated laminated portion 26 of the electrode body 2 is configured by the portion where only the portion 2411 is laminated.

The uncoated laminated portion 26 is a portion of the electrode body 2 that is electrically connected to the current collector 5. The uncoated laminated portion 26 of the present embodiment has two hollow portions 27 (see FIGS. 2 and 4) sandwiching the hollow portion 27 (see FIGS. 2 and 4) when viewed from the winding center axis C direction of the wound positive electrode 23, negative electrode 24, and separator 25. It is divided into two parts (divided uncoated laminated part) 261.

The uncovered laminated portion 26 configured as described above is provided on each electrode of the electrode body 2. That is, the uncoated laminated portion 26 in which only the portion 2314 of the end portion 2311 on one side of the positive electrode 23 excluding the protective layer covered portion 2313 is laminated constitutes the uncoated laminated portion of the positive electrode in the electrode body 2, and The uncoated laminated portion 26 in which only the end portion 2411 on the other side is laminated constitutes the negative electrode uncoated laminated portion in the electrode body 2.

The case 3 has a case body 31 having an opening, and a cover plate 32 that closes (closes) the opening of the case body 31. The case 3 accommodates the electrolytic solution in the internal space 33 (see FIG. 3) together with the electrode body 2, the current collector 5, and the like. The case 3 is made of a metal having resistance to the electrolytic solution. The case 3 of the present embodiment is formed of, for example, aluminum or an aluminum-based metal material such as an aluminum alloy.

The electrolytic solution is a non-aqueous solution type electrolytic solution. The electrolytic solution is obtained by dissolving an electrolyte salt in an organic solvent. The organic solvent is, for example, cyclic carbonic acid esters such as propylene carbonate and ethylene carbonate, and chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. The electrolyte salt is LiClO ₄ , LiBF ₄ , LiPF _6, or the like. The electrolytic solution of the present embodiment uses 1 mol/L of LiPF ₆ in a mixed solvent prepared by adjusting propylene carbonate, dimethyl carbonate, and ethyl methyl carbonate at a ratio of propylene carbonate:dimethyl carbonate:ethyl methyl carbonate=3:2:5. Is dissolved.

As shown in FIGS. 1 to 3, the case 3 is formed by joining the opening peripheral edge portion 34 of the case main body 31 and the peripheral edge portion of the lid plate 32 in an overlapped state. In the case 3, the case body 31 and the cover plate 32 define an internal space 33. In the case 3 of the present embodiment, the opening peripheral edge 34 of the case main body 31 and the peripheral edge of the lid plate 32 are joined by welding.

The case body 31 includes a plate-shaped closing portion 311 and a tubular body portion 312 connected to the peripheral edge of the closing portion 311.

The closing portion 311 is located at the lower end of the case body 31 when the case body 31 is arranged with the opening facing upward (that is, becomes the bottom wall of the case body 31 when the opening faces upward). ) Part. The closing portion 311 has a rectangular shape when viewed from the normal direction of the closing portion 311.

In the following, the long side direction of the closed portion 311 is the X axis direction, the short side direction of the closed portion 311 is the Y axis direction, and the normal direction of the closed portion 311 is the Z axis direction.

The body portion 312 has a rectangular tube shape, more specifically, a flat rectangular tube shape. The body portion 312 has a pair of long wall portions 313 extending from the long side at the peripheral edge of the closing portion 311 and a pair of short wall portions 314 extending from the short side at the peripheral edge of the closing portion 311.

As described above, the case main body 31 has a rectangular tube shape (that is, a bottomed rectangular tube shape) in which one end in the opening direction (Z-axis direction) is closed.

The cover plate 32 is a plate-shaped member that closes the opening of the case body 31. Specifically, the cover plate 32 has a contour shape corresponding to the opening peripheral edge portion 34 of the case body 31 when viewed from the Z-axis direction. That is, the cover plate 32 is a rectangular plate member that is long in the X-axis direction when viewed from the Z-axis direction. The cover plate 32 contacts the case body 31 so as to close the opening of the case body 31. More specifically, the peripheral edge of the cover plate 32 is overlapped with the peripheral edge 34 of the opening of the case body 31 so that the cover plate 32 closes the opening. The boundary between the lid plate 32 and the case body 31 is welded in a state where the opening peripheral edge portion 34 and the lid plate 32 are overlapped. This forms the case 3.

The external terminal 4 is a part electrically connected to an external terminal of another power storage element or an external device. The external terminal 4 is formed of a conductive member. For example, the external terminal 4 is formed of a metal material having high weldability such as an aluminum-based metal material such as aluminum or aluminum alloy, or a copper-based metal material such as copper or copper alloy. The external terminal 4 of this embodiment has a surface 41 to which a bus bar or the like can be welded.

The current collector 5 is arranged in the case 3 and is directly or indirectly connected to the electrode body 2 so as to be electrically conductive. As shown in FIGS. 2 and 3, the current collector 5 of this embodiment is electrically connected to the electrode body 2 via the clip member 55. That is, the electricity storage device 1 includes the clip member 55 that electrically connects the electrode body 2 and the current collector 5. The clip member 55 sandwiches the positive electrode 23 or the negative electrode 24 laminated in the uncoated laminated portion 26 (specifically, the divided uncoated laminated portion 261) of the electrode body 2 so as to bundle them. As a result, the clip member 55 excludes the positive electrode 23 laminated in the non-covered laminated portion 26 (specifically, the protective layer covering portion 2313 at the end 2311 on one side in the width direction of the metal foil 231 included in the positive electrode 23 is removed. The portions 2314) are electrically connected to each other or the negative electrodes 24 (specifically, the end portions 2411 on the other side in the width direction of the metal foil 241 included in the negative electrodes 24) are electrically connected to each other.

The current collector 5 is formed of a conductive member and is arranged along the inner surface of the case 3. The current collector 5 of this embodiment electrically connects the external terminal 4 and the clip member 55. Specifically, the current collector 5 has a first connection portion 51 that is electrically connected to the external terminal 4 and a second connection portion 52 that is electrically connected to the electrode body 2. In the current collector 5, the first connecting portion 51 extends in the X-axis direction along the lid plate 32 from the vicinity of the boundary between the lid plate 32 and the short wall portion 314 in the case 3, and the second connecting portion 52 forms the first connecting portion 52. The one connecting portion 51 extends in the Z-axis direction from the end portion on the boundary side along the short wall portion 314.

The current collectors 5 configured as described above are arranged on the positive electrode and the negative electrode of the electricity storage device 1, respectively. In the electricity storage device 1 of the present embodiment, the positive electrode non-covered laminated portion 26 and the negative electrode non-coated laminated portion 26 of the electrode body 2 are arranged in the case 3 respectively.

The positive electrode current collector 5 and the negative electrode current collector 5 are made of different materials. Specifically, the positive electrode current collector 5 is made of, for example, aluminum or an aluminum alloy, and the negative electrode current collector 5 is made of, for example, copper or a copper alloy.

As shown in FIGS. 2 and 3, the insulating member 6 is arranged between the case 3 (specifically, the case body 31) and the electrode body 2. The insulating member 6 of the present embodiment is formed in a bag shape by bending an insulating sheet-shaped member cut into a predetermined shape.

According to the above electricity storage device 1, the protective layer 233 has the metal foil 231 protruding from the positive electrode active material layer 232 in the positive electrode 23 (the end portion 2311 on one side in the width direction of the metal foil 231) and the heat resistance of the separator 25. It is arranged between the layers 252. Therefore, the protective layer 233 prevents contact between the metal foil 231 and the heat resistant layer 252. As a result, in the electricity storage device 1, contamination due to contact between the metal foil 231 of the positive electrode 23 and the heat resistant layer 252 of the separator 25 is less likely to occur.

In the electricity storage device 1 of the present embodiment, the protective layer 233 covers the surface of the end portion 2311 on one side in the width direction of the metal foil 231. Therefore, a part (protective layer covering part 2313) of the portion (end portion on one side) 2311 of the metallic foil 231 which is not covered with the positive electrode active material layer 232 is covered with the protective layer 233. The part where 231 is exposed is reduced. As a result, in the storage element 1, the occurrence of contamination caused by the contact of the metal foil 231 with another member is suppressed.

In addition, in the electricity storage device 1 of the present embodiment, the protective layer 233 contains an inorganic substance and is fixed to the end portion 2311 on one side in the width direction of the metal foil 231. In this way, the protective layer 233 is fixed to the metal foil 231 (that is, arranged so as not to move relative to each other), so that even if the protective layer 233 is arranged on the surface of the metal foil 231, the protective layer 233 is Rubbing with the metal foil 231 is prevented. As a result, even if the protective layer 233 containing an inorganic substance is arranged on the metal foil 231, the contamination due to the rubbing or the like does not occur or hardly occurs.

In the electricity storage device 1 of the present embodiment, the end surface 2520 on one side in the width direction of the heat resistant layer 252 approaches the base material 251 as it approaches the edge 252E on one side in the width direction of the heat resistant layer 252. 251 is inclined with respect to the surface. Thus, at one end of the heat-resistant layer 252 on the one side in the width direction, the angle formed by the faces forming the corners of the end (end face 2520 and the face of the heat-resistant layer 252 facing the positive electrode 23) is 90°. With the larger size, even if the end portion (the corner portion) in the width direction of the heat-resistant layer 252 comes into contact with the metal foil 231 of the positive electrode 23, contamination due to the contact is less likely to occur.

Further, in the electricity storage device 1 of the present embodiment, the one edge 233E in the width direction of the protective layer 233 is located on the other side of the one edge 231E in the width direction of the metal foil 231, and the base material. An edge 251E on one side in the width direction of 251 is located between an edge 233E on one side in the width direction of the protective layer 233 and an edge 231E on one side in the width direction of the metal foil 231 (FIG. 8).

In this way, by arranging the edge 233E on one side in the width direction of the protective layer 233 on the other side of the edge 231E on the one side in the width direction of the metal foil 231, the other member in the electrode body 2 (this embodiment In the example of the form, a portion (a portion of the positive electrode 23 where the metal foil 231 is exposed) that is electrically connected to the current collector 5) is secured. Moreover, the edge 251E on one side in the width direction of the base material 251 is located between the edge 233E on one side in the width direction of the protective layer 233 and the edge 231E on one side in the width direction of the metal foil 231. The base material 251 is positioned between the protective layer 233 and the metal foils 231 and 241 of the other electrodes (electrodes different from the positive electrode 23 on which the protective layer 233 is arranged) 23 and 24 in the stacking direction of the electrode body 2. To do. Therefore, it becomes difficult for the protective layer 233 and the metal foils 231 and 241 of the other electrodes 23 and 24 to come into contact with each other. As a result, in the storage element 1, the occurrence of contamination due to the contact between the protective layer 233 and the metal foils 231 and 241 of the other electrodes 23 and 24 can be suppressed.

Further, in the electricity storage device 1 of the present embodiment, the positive electrode 23 is arranged between the separators 25 in the electrode body 2, and the positive electrode active material layer 232 and the protective layer 233 are arranged on both surfaces of the metal foil 231 respectively. Thus, even if the separator 25 (heat resistant layer 252) is arranged so as to sandwich the metal foil 231, the protective layer 233 has the metal foil 231 (specifically, the end portion 2311 on one side in the width direction of the metal foil 231). Since the heat-resistant layer 252 and the metal foil 231 are in contact with each other, generation of contamination due to contact between the heat-resistant layer 252 and the metal foil 231 is suppressed.

It should be noted that the electricity storage device of the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the scope of the present invention. For example, the configuration of another embodiment can be added to the configuration of one embodiment, and a part of the configuration of one embodiment can be replaced with the configuration of another embodiment. In addition, some of the configurations of certain embodiments may be deleted.

In the electricity storage device 1 of the above embodiment, only the positive electrode 23 has the protective layer 233, but the configuration is not limited to this. Only the negative electrode 24 may have the protective layer 233, and each of the positive electrode 23 and the negative electrode 24 may have the protective layer 233. That is, the electrodes 23 and 24 facing the heat resistant layer 252 of the separator 25 may have the protective layer 233.

Further, in the electricity storage device 1 of the above-described embodiment, the protective layers 233 are arranged on both surfaces of the positive electrode 23, but the configuration is not limited to this. For example, the protective layer 233 may be arranged only on one surface of the electrode (the positive electrode 23 in the example of the above embodiment).

In the electricity storage device 1 of the above embodiment, the electrode (the positive electrode 23 in the example of the above embodiment) has the protective layer 233, but the configuration is not limited to this. For example, as shown in FIG. 9, the separator 25 may have a structure having a protective layer 233. In this case, the heat-resistant layer 252 is disposed in a region facing the metal foils 231 and 241 on the electrode-side surface (specifically, regions of the metal foils 231 and 241 where the active material layers 232 and 242 are not disposed).

In the electricity storage device 1 of the above embodiment, the end surface 2520 on one side of the heat resistant layer 252 is a surface (inclined surface) that is inclined with respect to the surface of the base material 251, but is not limited to this configuration. For example, as shown in FIG. 10, the end surface 2520 on one side of the heat resistant layer 252 may be a curved surface (curved surface) with respect to the surface of the base material 251. Even with this configuration, the corners of the end of the heat-resistant layer 252 are eliminated, so that even if the end contacts the metal foils 231 and 241 of the electrodes 23 and 24, contamination due to the contact is less likely to occur. The end surface 2520 on one side of the heat resistant layer 252 may be perpendicular or substantially perpendicular to the surface of the base material 251, as shown in FIG. 11.

Further, in the above embodiment, the case where the power storage element is used as a chargeable/dischargeable non-aqueous electrolyte secondary battery (for example, a lithium ion secondary battery) has been described, but the type and size (capacity) of the power storage element are arbitrary. Is. Further, in the above embodiment, the lithium ion secondary battery has been described as an example of the power storage element, but the present invention is not limited to this. For example, the present invention can be applied to various secondary batteries, other primary batteries, and electric storage elements for capacitors such as electric double layer capacitors.

The power storage element (for example, battery) 1 may be used for a power storage device (a battery module when the power storage element is a battery) 11 as shown in FIG. The power storage device 11 includes at least two power storage elements 1 and a bus bar member 12 that electrically connects the two (different) power storage elements 1 to each other. In this case, the technique of the present invention may be applied to at least one power storage element 1.

DESCRIPTION OF SYMBOLS 1... Electric storage element, 2... Electrode body, 21... Core, 22... Laminated body, 23... Positive electrode (electrode), 231... Metal foil, 231E... One edge of the metal foil in the width direction, 2311... Width direction One end, 2312... Active material coating portion, 2313... Protective layer coating portion, 2314... Portion excluding protective coating portion, 232... Positive electrode active material layer (active material layer), 232E... Positive electrode active material layer Edge on one side in the width direction, 233... Protective layer, 233E... Edge on one side in the width direction of the protective layer, 24... Negative electrode (electrode), 241... Metal foil, 2411... Edge on the other side in the width direction , 2412... Active material coating part, 242... Negative electrode active material layer, 25... Separator, 25E... Edge of separator on one side in width direction, 251... Base material, 251E... Edge of base material on one side in width direction , 252... Heat-resistant layer, 252E... One edge in the width direction of the heat-resistant layer, 2520... One end surface in the width direction, 26... Uncoated laminated portion, 261... Divided uncoated laminated portion, 27... Hollow Part, 3... Case, 31... Case main body, 311... Closure part, 312... Body part, 313... Long wall part, 314... Short wall part, 32... Lid plate, 33... Internal space, 34... Opening peripheral part, 4... External terminals, 41... Surface, 5... Current collector, 51... First connecting portion, 52... Second connecting portion, 55... Clip member, 6... Insulating member, 11... Power storage device, 12... Bus bar member, 101... Negative electrode 1011... Negative electrode active material layer, 1012... Current collector foil exposed part, 102... Positive electrode, 1021... Positive electrode active material layer, 1022... Current collector foil exposed part, 103... Separator, 1031... Inorganic layer forming part, 1032... Inorganic layer Non-formed part, C... Winding central axis

Claims (5)

An electrode having a metal foil and an active material layer, and an electrode on which the metal foil and the active material layer are stacked in a state where one end of the metal foil in a predetermined direction projects from the active material layer, and a substrate And a heat-resistant layer containing an inorganic substance has a separator that is stacked, and an electrode body in which these electrodes and a separator are laminated,
The heat-resistant layer faces the active material layer, and is larger than the active material layer in the predetermined direction,
The electrodes may have a protective layer facing the separator,
The protective layer is disposed between the one end of the metal foil and the heat-resistant layer, and the heat-resistant layer from the edge position of the active material layer toward the one side in the predetermined direction. edge position or position to extend Rutotomoni is fixed to an end portion of the one side of the metal foil, the electric storage element. Wherein one end surface of the in the predetermined direction of the heat-resistant layer is inclined or curved with respect to the surface of the substrate so as to approach the base material toward the said one side edge of said heat-resistant layer according to claim 1, The electric storage device according to. The edge of the protective layer is located on the other side from the edge of the metal foil in the predetermined direction.
Edge of the substrate, in the predetermined direction, located between the edge of the edge and the metal foil of the protective layer, electric storage element according to claim 1 or 2. The electrode is arranged between the separators adjacent to each other in the stacking direction of the electrode and the separator,
The active material layer and the protective layer, the are arranged on both sides of the metal foil, electric storage element according to any one of claims 1-3. The electric storage device according to claim 1, wherein the protective layer has a thickness smaller than that of the active material layer.