JP6885047B2 - Power storage element and manufacturing method of power storage element - Google Patents

Description

The present invention relates to a negative electrode plate, a power storage element including an electrode body having a positive electrode plate and a negative electrode plate, a method for manufacturing a negative electrode plate, and a method for manufacturing a power storage element.

The conversion from gasoline-powered vehicles to electric vehicles is becoming important as a global approach to environmental issues. For this reason, the development of electric vehicles using a power storage element such as a lithium ion secondary battery as a power source is underway.

Conventionally, as an electrode of a power storage element, for example, an electrode manufactured by forming an active material layer on a continuum of base material layers and then cutting (slitting) the active material layer to a predetermined length is widely used. It is known (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2009-163942

However, when an electrode obtained by cutting both the base material layer and the active material layer in this way is used, a part of the cut end portion (slit end portion) of the electrode falls off and is mixed as an impurity (contamination, hereinafter referred to as "contamination". Various problems may occur due to (described as "contamination"). Examples of such a defect include a decrease in performance such as a decrease in capacity and an increase in resistance, an internal short circuit, and the like.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a negative electrode plate, a power storage element, a method for manufacturing a negative electrode plate, and a method for manufacturing a power storage element capable of suppressing the occurrence of contamination. ..

In order to achieve the above object, the negative electrode plate according to one aspect of the present invention is a negative electrode plate provided on the electrode body of the power storage element, and a part or all of the base material layer and the base material layer are exposed. The peripheral portion of the negative electrode plate is arranged on the first side connected to the current collector of the power storage element, and the active material layer is not formed. It has a non-forming portion and a non-exposed portion that is arranged on a second side different from the first side and the active material layer is not exposed.

Here, in the electrode body in which the positive electrode plate and the negative electrode plate are laminated, the electrode body is pressed by the inner wall of the container of the power storage element, so that the portions of the positive electrode plate and the negative electrode plate facing each other are pressed against each other. Therefore, in the facing portion, the chips (cutting powder) of the base material layer and the floating of the active material layer can be suppressed by the compression, so that the cause of contamination can be suppressed. Generally, when a part of the cut end portion of the negative electrode plate falls off, a problem such as an internal short circuit is likely to occur. Therefore, in order to suppress the occurrence of contamination in the power storage element, it is particularly effective to suppress the occurrence of contamination caused by the negative electrode plate.

Therefore, according to the negative electrode plate according to the present embodiment, since the peripheral portion has an unexposed portion in which the active material layer is not exposed, it is possible to suppress the falling off of the active material in the peripheral portion of the negative electrode plate, and the occurrence of contamination occurs. Can be suppressed.

Further, the power storage element according to one aspect of the present invention includes an electrode body having the above-mentioned negative electrode plate and positive electrode plate.

According to this configuration, by arranging the unexposed portion where the active material layer is not exposed on the peripheral edge portion of the negative electrode plate, it is possible to suppress a part of the cut end portion of the negative electrode plate from falling off, so that the occurrence of contamination is suppressed. it can.

Further, the non-exposed portion is composed of at least one of a portion in which the base material layer is covered with a coating material attached to the base material layer and a portion in which the active material layer is not formed. It may be.

Here, when the base material layer is covered with a coating material that is not attached to the base material layer, there is a possibility that the end portion of the base material layer may fall off together with the coating material. That is, there is a possibility that contamination may occur due to the base material layer falling off together with the covering material. Therefore, by attaching the covering material to the base material layer, it is possible to suppress the falling off of the covering material and more reliably suppress the falling off of the base material layer, so that the occurrence of contamination can be suppressed more reliably.

Further, by arranging a portion where the active material layer is not arranged on the peripheral edge portion of the negative electrode plate, the portion where the active material layer is not formed can be cut to manufacture the negative electrode plate. Therefore, the occurrence of contamination can be suppressed.

Further, the non-exposed portion may be arranged on the short side of the negative electrode plate.

Since the non-exposed portion is arranged on the short side of the negative electrode plate in this way, a continuum of the negative electrode plates in which the active material layer is uniformly formed along the longitudinal direction (hereinafter, referred to as “negative electrode base material”). Even when the negative electrode plate is manufactured by cutting the negative electrode plate, the occurrence of contamination can be suppressed.

Further, the non-exposed portion may be composed of a portion covered with the base material layer by a coating material attached to the base material layer, and may be arranged on both short sides of the negative electrode plate.

Here, so-called intermittent coating, in which the active material layer is intermittently formed in the longitudinal direction of the negative electrode base material, may be difficult in manufacturing. Therefore, it is difficult to provide a portion on the short side of the negative electrode plate where the active material layer is not formed. Therefore, by forming the non-exposed portions arranged on both short sides of the negative electrode plate with the base material layer covered with a coating material, it is possible to suppress the cause of contamination on both short sides.

Further, the non-exposed portion may be arranged on the long side of the negative electrode plate.

Here, when the amount of chips in the base material layer and the amount of shedding of the active material layer generated per unit length are the same on the short side and the long side of the negative electrode plate, the chips on the long side and the said Dropout is likely to cause contamination. Therefore, by arranging the non-exposed portion on the long side of the negative electrode plate, the cause of contamination can be suppressed in the place where the factor of contamination is likely to occur.

Further, the non-exposed portion is composed of a portion in which the active material layer is not formed, and the non-formed portion is arranged on one of both long sides of the negative electrode plate, and the non-exposed portion is provided. May be arranged on the other long side of the two long sides.

Here, when the non-exposed portion arranged on the long side of the negative electrode plate is composed of, for example, a portion covered with the active material layer by a covering material, the thicknesses of both long sides of the negative electrode plate may be different from each other. For this reason, in the so-called winding type electrode body formed by winding the positive electrode plate and the negative electrode plate, the negative electrode plate meanders at the time of winding, so that the winding accuracy is lowered and the yield is deteriorated. There is a risk of Further, not only the winding type electrode body, but also the thickness of both long sides of the negative electrode plate is different from each other, which makes it difficult to control the dimensions of the electrode body, which makes it difficult to accommodate the electrode body in the container of the power storage element. Become. Therefore, by forming the non-exposed portion arranged on the long side of the negative electrode plate with the portion where the active material layer is not arranged, the dimensional control of the electrode body is facilitated, the yield is maintained, and the occurrence of contamination is suppressed. it can.

Further, the length of the short side of the negative electrode plate may be larger than the length of the short side of the positive electrode plate.

Here, in the electrode body in which the positive electrode plate and the negative electrode plate are laminated, the electrode body is pressed by the inner wall of the container of the power storage element, so that the portions of the positive electrode plate and the negative electrode plate facing each other are pressed against each other. Therefore, in the facing portion, the chips of the base material layer and the floating of the active material layer can be suppressed by the compression. However, since the length of the short side of the negative electrode plate is larger than that of the positive electrode plate, both ends of the negative electrode plate in the lateral direction do not face the positive electrode plate and are not easily pressed. Therefore, chips of the base material layer and the active material layer are likely to be lifted at both ends in the lateral direction of the negative electrode plate, which may cause contamination. Therefore, by arranging the non-exposed portion on the long side of the negative electrode plate, the cause of contamination can be suppressed in the place where the factor of contamination is likely to occur.

Further, the negative electrode plate may have a circumference larger than that of the positive electrode plate by combining both short sides and both long sides.

Here, on the short and long sides of the positive electrode plate and the negative electrode plate, when the amount of chips of the base material layer and the amount of shedding of the active material layer generated per unit length are the same, both short sides and the long side Contamination is likely to occur due to electrodes with a large circumference that combines both long sides. Therefore, by arranging the non-exposed portion on the peripheral edge of the negative electrode plate having a larger peripheral length than the positive electrode plate, it is possible to suppress the cause of contamination in the electrode where the cause of contamination is likely to occur.

Further, the base material layer may contain a metal that is dissolved by the potential of the positive electrode plate.

Here, when the base material layer of the negative electrode plate contains a metal that dissolves due to the potential of the positive electrode plate, when chips of the base material layer of the negative electrode plate are generated, the chips are melted and ionized in the positive electrode plate, and then the negative electrode plate. There is a possibility that an internal short circuit may occur due to precipitation in the form of dendrites. Therefore, by arranging the non-exposed portion on the peripheral edge of the negative electrode plate, it is possible to suppress the generation of chips in the base material layer of the negative electrode plate, so that the occurrence of an internal short circuit due to dendrite-like precipitation on the negative electrode plate can be suppressed.

The present invention can be realized not only as a negative electrode plate and a power storage element, but also as a method for manufacturing the negative electrode plate and a method for manufacturing the power storage element.

According to the present invention, it is possible to provide a negative electrode plate provided on an electrode body of a power storage element, such as a negative electrode plate capable of suppressing the occurrence of contamination.

It is a perspective view which shows typically the appearance of the power storage element which concerns on Embodiment 1 of this invention. It is a perspective view which shows the component arranged in the container of the power storage element which concerns on Embodiment 1 of this invention. It is a perspective view which shows the winding state of the electrode body which concerns on Embodiment 1 of this invention by partially developing. It is a top view which shows the structure of the electrode body which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the structure of the electrode body which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the structure of the unexposed part which concerns on Embodiment 1 of this invention. It is an enlarged view of the process of manufacturing the electrode body which concerns on Embodiment 1 of this invention, and a part thereof. It is sectional drawing which shows the structure of the unexposed part which concerns on the modification 1 of Embodiment 1 of this invention. It is a perspective view which shows the structure of the electrode body which concerns on the modification 2 of Embodiment 1 of this invention, and is a partially enlarged view thereof. It is a perspective view which shows the winding state of the electrode body which concerns on Embodiment 2 of this invention by partially developing. It is sectional drawing which shows the structure of the electrode body which concerns on Embodiment 2 of this invention. It is sectional drawing which shows the structure of the non-exposed part which concerns on other embodiment of this invention.

Hereinafter, a method for manufacturing the negative electrode plate, the power storage element, and the negative electrode plate, and a method for manufacturing the power storage element according to the embodiment of the present invention will be described with reference to the drawings. It should be noted that all of the embodiments described below show a preferred specific example of the present invention. Numerical values, shapes, materials, components, arrangement positions and connection forms of components, manufacturing processes, order of manufacturing processes, etc. shown in the following embodiments are examples, and are not intended to limit the present invention. Further, among the components in the following embodiments, the components not described in the independent claims indicating the highest level concept of the present invention will be described as arbitrary components constituting the more preferable form. Moreover, in each figure, the dimensions and the like do not exactly match.

(Embodiment 1)
First, the configuration of the power storage element 10 will be described.

FIG. 1 is a perspective view schematically showing the appearance of the power storage element 10 according to the first embodiment of the present invention. Further, FIG. 2 is a perspective view showing components arranged inside the container of the power storage element 10 according to the first embodiment of the present invention. Specifically, FIG. 2 is a perspective view showing a configuration in which the main body 111 of the container 100 is separated from the power storage element 10.

The power storage element 10 is a secondary battery capable of charging electricity and discharging electricity, and more specifically, a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. For example, the power storage element 10 is applied to an electric vehicle (EV), a hybrid electric vehicle (HEV), or a plug-in hybrid electric vehicle (PHEV). The power storage element 10 is not limited to the non-aqueous electrolyte secondary battery, and may be a secondary battery other than the non-aqueous electrolyte secondary battery, or may be a capacitor.

As shown in FIG. 1, the power storage element 10 includes a container 100, a positive electrode terminal 200, and a negative electrode terminal 300. Further, as shown in FIG. 2, the positive electrode current collector 120, the negative electrode current collector 130, and the electrode body 400 are housed inside the container 100.

In addition to the above components, spacers arranged on the sides of the positive electrode current collector 120 and the negative electrode current collector 130, a safety valve for releasing the pressure in the container 100 when the pressure rises, or An insulating film or the like that wraps the electrode body 400 or the like may be arranged. Further, although a liquid such as an electrolytic solution (non-aqueous electrolyte) is sealed inside the container 100 of the power storage element 10, the illustration of the liquid is omitted. The type of electrolytic solution sealed in the container 100 is not particularly limited as long as it does not impair the performance of the power storage element 10, and various types can be selected.

The container 100 is composed of a main body 111 having a rectangular tubular shape and a bottom, and a lid 110 which is a plate-shaped member that closes the opening of the main body 111. Further, the container 100 can be sealed inside by accommodating the electrode body 400 or the like inside and then welding the lid body 110 and the main body 111 or the like. The materials of the lid 110 and the main body 111 are not particularly limited, but are preferably weldable metals such as stainless steel, aluminum, and aluminum alloy.

The electrode body 400 includes a positive electrode plate (hereinafter, also simply referred to as a positive electrode), a negative electrode plate (hereinafter, also simply referred to as a negative electrode), and a separator, and is a member capable of storing electricity. The positive electrode is formed by forming a positive electrode active material layer on a long strip-shaped positive electrode base material layer made of aluminum, an aluminum alloy, or the like. The negative electrode is a negative electrode active material layer formed on a long strip-shaped negative electrode base material layer made of copper, a copper alloy, or the like. The separator is a microporous sheet made of resin. The detailed configuration of the electrode body 400 will be described later.

In FIG. 2, the shape of the electrode body 400 is an oval shape, but it may be a circular shape or an elliptical shape. Further, the shape of the electrode body 400 is not limited to the winding type, and may be a shape in which flat plate-shaped electrode plates are laminated, or a shape in which long strip-shaped electrode plates are laminated in a bellows shape by repeating mountain folds and valley folds. Good.

The positive electrode terminal 200 is an electrode terminal electrically connected to the positive electrode of the electrode body 400, and the negative electrode terminal 300 is an electrode terminal electrically connected to the negative electrode of the electrode body 400. That is, the positive electrode terminal 200 and the negative electrode terminal 300 lead the electricity stored in the electrode body 400 to the external space of the power storage element 10, and the electricity is stored in the internal space of the power storage element 10 in order to store electricity in the electrode body 400. It is a metal electrode terminal for introducing. Further, the positive electrode terminal 200 and the negative electrode terminal 300 are attached to a lid 110 arranged above the electrode body 400.

The positive electrode current collector 120 is arranged between the positive electrode of the electrode body 400 and the wall surface of the main body 111 of the container 100, and has conductivity and rigidity that are electrically connected to the positive electrode terminal 200 and the positive electrode of the electrode body 400. It is a provided member. The positive electrode current collector 120 is made of aluminum, an aluminum alloy, or the like, like the positive electrode base material layer of the electrode body 400.

The negative electrode current collector 130 is arranged between the negative electrode body 400 and the wall surface of the main body 111 of the container 100, and has conductivity and rigidity that are electrically connected to the negative electrode terminal 300 and the negative electrode body 400. It is a provided member. The negative electrode current collector 130 is made of copper, a copper alloy, or the like, like the negative electrode base material layer of the electrode body 400.

Specifically, the positive electrode current collector 120 and the negative electrode current collector 130 are metal plate-shaped members arranged in a bent state along the wall surface and the lid 110 from the wall surface of the main body 111 to the lid 110. Is. Further, the positive electrode current collector 120 and the negative electrode current collector 130 are fixedly connected to the lid body 110, and are fixedly connected to the positive electrode body 400 and the negative electrode body 400 by welding or the like, respectively. As a result, the electrode body 400 is held inside the container 100 in a state of being suspended from the lid body 110 by the positive electrode current collector 120 and the negative electrode current collector 130.

Next, the configuration of the electrode body 400 will be described in detail with reference to FIGS. 3 to 5.

FIG. 3 is a perspective view showing a partially developed winding state of the electrode body 400 according to the first embodiment of the present invention.

Further, FIG. 4 is a top view showing the configuration of the electrode body 400 according to the first embodiment of the present invention. Specifically, it is an enlarged view of the end portion of the negative electrode 420 in the winding direction and viewed from the plus side in the Z-axis direction. For convenience of explanation, the figure is a perspective view of the separator 430, in which the forming portion 410c, which is the region where the positive electrode active material layer of the positive electrode 410 is formed, and the unexposed portion 420b of the negative electrode 420 ( Hatching is applied to (described later) and the forming portion 420c, which is a region where the negative electrode active material layer is formed.

Further, FIG. 5 is a cross-sectional view showing the configuration of the electrode body 400 according to the first embodiment of the present invention. Specifically, the figure is a diagram showing a cross section when cut at the AA'cross section of FIG. Note that, in FIG. 5, only one set of a plurality of sets of the positive electrode 410, the negative electrode 420, and the separator 430, which are repeatedly laminated by being wound, is shown, and the illustration of the other sets is omitted.

As shown in FIGS. 3 to 5, the electrode body 400 is wound so that the positive electrode 410, the negative electrode 420, and the two separators 430 are arranged in the order of the separator 430, the negative electrode 420, the separator 430, and the positive electrode 410. Is formed.

The positive electrode 410 is an electrode plate in which a positive electrode active material layer is formed on the surface of a long strip-shaped conductive positive electrode current collecting foil made of aluminum or an aluminum alloy. Specifically, as shown in FIG. 5, the positive electrode 410 has a positive electrode base material layer 411 and positive electrode active material layers 412 and 413.

The positive electrode base material layer 411 is a long strip-shaped conductive current collecting foil made of, for example, aluminum or an aluminum alloy.

The positive electrode active material layers 412 and 413 are active material layers formed on the positive electrode base material layer 411 in a state where part or all of them are exposed (in the present embodiment, all of them are exposed).

Specifically, the positive electrode active material layer 412 is an active material layer arranged on the inner peripheral side (minus side in the Z-axis direction in FIG. 5) of the positive electrode base material layer 411, and the positive electrode active material layer 413 is a positive electrode group. It is an active material layer arranged on the outer peripheral side (minus side in the Y-axis direction in FIG. 5) of the material layer 411.

Here, the positive electrode active material layers 412 and 413 contain the positive electrode active material, the binder, and the conductive auxiliary agent. As the positive electrode active material used for the positive electrode active material layers 412 and 413, known materials can be appropriately used as long as they are positive electrode active materials capable of occluding and releasing lithium ions. For example, _{a composite oxide represented by Li x} MO _y (M represents at least one transition metal) (Li _x CoO ₂ , Li _x NiO ₂ , Li _x Mn ₂ O ₄ , Li _x MnO ₃ , Li _x Ni). _y Co _(1-y) O ₂ , Li _x N _y Mn _z Co _(1-y-z) O ₂ , Li _x N _y Mn _(2-y) O ₄ etc.), or Li _w Me _x (XO) _y ) _z (Me represents at least one transition metal, X represents, for example, P, Si, B, V) polyanionic compounds (LiFePO ₄ , LiMnPO ₄ , LiNiPO ₄ , LiCoPO ₄ , Li ₃ V ₂ (PO) ₄ ) ₃ , Li ₂ MnSiO ₄ , Li ₂ CoPO ₄ F, etc.) can be selected. Further, the element or polyanion in these compounds may be partially replaced with another element or anion species, and the surface is coated with a metal oxide such as _{ZrO 2} , MgO, Al ₂ O _{3 or carbon.} May be good. Further, examples thereof include, but are not limited to, conductive polymer compounds such as disulfide, polypyrrole, polyaniline, polyparastyrene, polyacetylene, and polyacene-based materials, and pseudo-graphite structural carbonaceous materials. Further, these compounds may be used alone or in combination of two or more.

The negative electrode 420 is an electrode plate in which a negative electrode active material layer is formed on the surface of a long strip-shaped conductive negative electrode current collecting foil made of copper or a copper alloy. Specifically, as shown in FIG. 5, the negative electrode 420 has a negative electrode base material layer 421 and negative electrode active material layers 422 and 423.

The negative electrode base material layer 421 is, for example, a long strip-shaped conductive current collecting foil made of copper or a copper alloy.

The negative electrode active material layers 422 and 423 are active material layers formed on the negative electrode base material layer 421 in a partially or completely exposed state. That is, the negative electrode active material layers 422 and 423 are formed in a state where at least a part of them is exposed on the negative electrode base material layer 421. Specifically, the negative electrode active material layer 422 is an active material layer arranged on the inner peripheral side (minus side in the Z-axis direction in FIG. 5) of the negative electrode base material layer 421, and the negative electrode active material layer 423 is a negative electrode group. This is an active material layer arranged on the outer peripheral side (plus side in the Z-axis direction in FIG. 5) of the material layer 421.

Here, the negative electrode active material layers 422 and 423 contain the negative electrode active material, the binder, and the conductive auxiliary agent. As the negative electrode active material used for the negative electrode active material layers 422 and 423, a known material can be appropriately used as long as it is a negative electrode active material capable of occluding and releasing lithium ions. For example, in addition to lithium metals and lithium alloys (lithium metal-containing alloys such as lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and wood alloys), lithium can be stored and released. Alloys, carbon materials (eg graphite, non-graphitizable carbon (hard carbon, coke, etc.), easily graphitized carbon, low temperature fired carbon, amorphous carbon, etc.), metal oxides, lithium metal oxides (Li ₄ Ti ₅ O) ₁₂ etc.), polyphosphate compounds and the like.

Further, as the binder used for the negative electrode active material layers 422 and 423, the same binder as that used for the positive electrode active material layers 412 and 413 can be applied.

The separator 430 is a microporous sheet made of resin, and is impregnated with an electrolytic solution containing an organic solvent and an electrolyte salt. Here, as the separator 430, a synthetic resin microporous film made of a woven fabric insoluble in an organic solvent, a non-woven fabric, or a polyolefin resin such as polyethylene is used, and a plurality of microporous films having different materials, weight average molecular weights, and porosity are used. Those that are laminated, those that contain appropriate amounts of additives such as various plasticizers, antioxidants, and flame retardants in these microporous films, and those that are coated with inorganic oxides such as silica on one or both sides. It may be a thing. In particular, a synthetic resin microporous membrane can be preferably used. Among them, polyolefin-based microporous membranes such as polyethylene and polypropylene microporous membranes, polyethylene and polypropylene microporous membranes composited with aramid and polypropylene, and microporous membranes composited of these are the thickness, film strength, and film. It is preferably used in terms of resistance and the like.

In this way, the electrode body 400 is formed by winding and laminating the positive electrode 410 and the negative electrode 420.

Here, the positive electrode 410 is an end portion on the minus side in the X-axis direction (the end portion of the positive electrode base material layer 411 in which the positive electrode active material layers 412 and 413 are not formed), which is a portion connected to the positive electrode current collector 120. A non-forming portion 410a is arranged so as to project from the separator 430, and is electrically and mechanically connected to the positive electrode current collector 120 at the protruding portion. That is, the peripheral portion of the positive electrode 410 has a non-formed portion 410a in which the positive electrode active material layers 412 and 413 are not formed, which are arranged on the side connected to the positive electrode current collector 120.

Specifically, the negative electrode 420 is the end portion on the positive side in the X-axis direction (the end portion of the negative electrode base material layer 421 in which the negative electrode active material layers 422 and 423 are not formed), which is a portion connected to the negative electrode current collector 130. ) Is disposed so as to project from the separator 430, and is electrically and mechanically connected to the negative electrode current collector 130 at the projecting portion. That is, the peripheral edge portion of the negative electrode 420 has a non-formed portion 420a on which the negative electrode active material layers 422 and 423 are not formed, which are arranged on the side connected to the negative electrode current collector 130.

Further, in the negative electrode 420, the end portion on the positive side in the Y-axis direction, which is the end portion in the winding direction, is arranged so as to project from the positive electrode 410, and the negative electrode active material layers 422 and 423 are not exposed in this protruding portion. It has an exposed portion 420b.

Here, when viewed from the thickness direction of the negative electrode 420 (viewed from the Z-axis direction), the negative electrode active material layers 422 and 423 are arranged larger than the positive electrode active material layers 412 and 413. That is, the positive electrode active material layers 412 and 413 are arranged so as to be included in the negative electrode active material layers 422 and 423 when viewed from the thickness direction.

Therefore, the length of the short side (length in the X-axis direction) of the negative electrode 420 is larger than the length of the short side of the positive electrode 410, and the length of the long side (length in the Y-axis direction in FIG. 4). Is also larger than the length of the long side of the positive electrode 410. That is, the negative electrode 420 is formed to have a circumference larger than that of the positive electrode 410 by combining both short sides (sides at both ends in the winding direction) and both long sides (sides at both ends in the winding axis direction). Here, the short side and the long side refer to the short side and the long side in the state before winding of the negative electrode 420. That is, the short side is the side of the innermost peripheral end portion or the side of the outermost outer peripheral end portion in the state after winding the negative electrode 420. The long side is a side of one end or a side of the other end in the winding axis direction in the state after winding the negative electrode 420.

As described above, the peripheral edge portion of the negative electrode 420 is arranged on the side (first side) connected to the negative electrode current collector 130, and the non-formed portion 420a in which the negative electrode active material layers 422 and 423 are not formed, and the negative electrode. The negative electrode active material layers 422 and 423 are arranged on a side (second side) different from the side connected to the current collector 130, and have an unexposed portion 420b in which the negative electrode active material layers 422 and 423 are not exposed. Specifically, the non-forming portion 420a is arranged on the long side of the long strip-shaped negative electrode 420, and the non-exposed portion 420b is arranged on the short side of the negative electrode 420.

Here, the “exposure” refers to a state in which the negative electrode 420 is visible from the outside (a state in which it is exposed on the surface) when the wound state of the electrode body 400 is expanded and the negative electrode 420 is viewed alone. Further, "not exposed" means that the negative electrode 420 is not exposed in either the thickness direction or the direction orthogonal to the thickness direction. That is, "not exposed" means a state in which the negative electrode 420 does not appear on the surface of the negative electrode 420 and cannot be seen from the outside even when the wound state of the electrode body 400 is expanded and the negative electrode 420 is viewed alone.

FIG. 6 is a cross-sectional perspective view showing the configuration of the non-exposed portion 420b according to the first embodiment of the present invention. Specifically, the figure is a cross-sectional perspective view of the negative electrode 420 on the BB'line of FIG.

As shown in the figure, in the present embodiment, the non-exposed portion 420b is a coating portion in which the negative electrode active material layers 422 and 423 are covered with the coating material 425 attached to the negative electrode base material layer 421. That is, the non-exposed portion 420b has a covering material 425 extending in the X-axis direction along the end of the winding end of the negative electrode 420 in the winding direction. As described above, since the negative electrode active material layers 422 and 423 are arranged in a state where the portion other than the portion covered with the coating material 425 is exposed, the negative electrode active material layers 422 and 423 are formed in a state where a part is exposed on the negative electrode base material layer 421. It can be said that it has been done.

The coating material 425 is a member that is attached to the negative electrode base material layer 421 and covers the negative electrode active material layers 422 and 423. For example, a tape that covers the negative electrode active material layers 422 and 423 while adhering to the negative electrode base material layer 421. Is. In the present embodiment, the covering material 425 covers both sides of the end portion (both sides in the Z-axis direction) and the end surface of the end portion (plus side in the Y-axis direction) so as to cover the end portion in the longitudinal direction of the negative electrode 420. Is placed on the surface). Specifically, the covering material 425 is a long strip-shaped tape extending in the X-axis direction, and is attached to the end surface (the surface on the plus side in the Y-axis direction) of the negative electrode base material layer 421.

Here, "attached" means that they are connected inseparably, and specifically, that they are bonded or joined. That is, a part of the covering material 425 is in contact with the negative electrode base material layer 421.

As the coating material 425, a tape formed of a resin such as polypropylene (PP), polyethylene (PE), polyphenylene sulfide (PPS), polyphenylene ether (PPE), polyimide (PI) or polyethylene terephthalate (PET) is used. Can be done. The material of the covering material 425 is not limited to this, and may be any material as long as it is insoluble in the electrolytic solution and does not react with the negative electrode 420.

As described above, the peripheral edge portion of the negative electrode 420 is arranged on the second side (short side in the present embodiment) different from the first side (long side in the present embodiment) connected to the negative electrode current collector 130. It has a non-exposed portion 420b. With this configuration, the power storage element 10 according to the present embodiment can suppress the occurrence of contamination.

The reason for this will be described after describing the factors that cause contamination in the following description of the process of manufacturing the electrode body 400. In the following, a method of manufacturing the negative electrode plate 420 and a method of manufacturing the power storage element 10 will be described. That is, the method for manufacturing the negative electrode plate 420 includes a negative electrode plate forming step of forming the negative electrode active material layers 422 and 423 on the negative electrode base material layer 421 with a part or all exposed. Then, in the negative electrode plate forming step, the non-forming portion 420a is arranged on the first side connected to the negative electrode current collector 130 of the power storage element 10 and the negative electrode active material layers 422 and 423 are not formed, and the first A negative electrode plate 420 is formed which is arranged on a second side different from the side of the above and has an unexposed portion 420b in which the negative electrode active material layers 422 and 423 are not exposed at the peripheral edge portion. Further, in the method of manufacturing the power storage element 10, the negative electrode plate forming step included in the manufacturing method of the negative electrode plate 420, and the negative electrode plate 420 and the positive electrode plate 410 formed in the negative electrode plate forming step are laminated to form the electrode body 400. Includes an electrode body forming step of forming the above.

FIG. 7 is a schematic view showing a process of manufacturing the electrode body 400 according to the first embodiment of the present invention, and a partially enlarged view of the schematic diagram. Specifically, (a) in the figure is a schematic view showing a cutting step (slit step) and a winding step in the steps of manufacturing the electrode body 400, and (b) in the figure is (a). It is a figure which shows typically the cutting process of the negative electrode 420 shown by). In the figure, only one of the two separators 430 is shown, and the other one is the same, so the illustration is omitted.

As shown in the figure, in the cutting step, the cutters 21 to 23 use the cutters 21 to 23 to describe a continuous body of the positive electrode 410 (hereinafter, referred to as “positive electrode base material”) and a continuous body of the negative electrode 420 (hereinafter, referred to as “negative electrode base material”). ) And each of the continuum of the separator 430 (hereinafter, referred to as "separator base material") are cut (slit) to a predetermined length. Specifically, in the cutting step, the positive electrode base material, the negative electrode base material, and the separator base material formed in the winding axis direction (X-axis direction) to a predetermined length (predetermined width) are wound. By cutting to a predetermined length in the direction (Y-axis direction), a positive electrode 410, a negative electrode 420, and a separator 430 having a predetermined length in the winding direction are formed.

After that, in the winding step, the positive electrode 410, the negative electrode 420, and the separator 430 formed to a predetermined length in the cutting step are wound, and further, the coating material 425 is provided at the end of the winding end of the negative electrode 420 to form an electrode. Form body 400. The covering material 425 may be attached by adhering the covering material 425 after winding.

Here, in the cutting step, the cutters 21 and 22 cut both the active material layer and the base material layer of the positive electrode 410 and the negative electrode 420. That is, the cutters 21 and 22 cut the positive electrode base material and the negative electrode base material uniformly coated with the active material layer except for the non-formed portion 410a and the non-formed portion 420a.

For example, as shown in (b) of the figure, the cutter 22 cuts the negative electrode base material layer 421 in which the negative electrode active material layers 422 and 423 are formed on both sides together with the negative electrode active material layers 422 and 423. A negative electrode 420 having a predetermined length in the winding direction is formed.

When both the active material layer and the base material layer are cut in this way, the end portion in the winding direction of the positive electrode 410, which is the portion cut by the cutters 21 and 22, and the end portion in the winding direction of the negative electrode 420. In, the following problems may occur.

That is, at the end portion (hereinafter referred to as "cutting end portion"), the active material layer may be lifted from the base material layer due to stress such as stress applied at the time of cutting, or the active material layer and the base material layer may be separated from each other. The peel strength may decrease. In this case, after the electrode body 400 is housed in the container 100, the active material layer at the cut end portion may fall off and penetrate the separator 430, which may cause a problem such as an internal short circuit.

Further, at the cut end portion, the base material layer is cut together with the active material layer by the cutters 21 and 22, which may cause metal sagging or burrs of the base material layer. In this case, after the electrode body 400 is housed in the container 100, metal drips, burrs, and the like may fall off to form minute metal debris called chips, which may cause problems such as an internal short circuit.

Further, in general, a shellac-like relatively hard material is used as the active material in the active material layer, and the active material layer is formed thicker than the base material layer. Therefore, the cutters 21 and 22 that cut both the base material layer and the active material layer are liable to be worn or chipped. Metal sagging, burrs, and the like are likely to occur on the base material layer cut by the cutters 21 and 22 that have been worn or chipped, so that contamination is likely to occur.

Here, the generation of contamination due to chips is particularly problematic for chips caused by the negative electrode base material layer 421 of the negative electrode 420.

Specifically, the negative electrode base material layer 421 is made of, for example, copper or a copper alloy as described above. This is determined by the requirements required for the negative electrode base material layer 421 (for example, it does not form an alloy with lithium metal and has high electrical conductivity, etc.).

At this time, since copper is melted by the potential of the positive electrode 410 (for example, 4 V vs. Li ^/ Li +), copper chips are generated at the negative electrode 420, and the chips are dissolved and ionized up to the positive electrode 410. .. After that, when the ions reach the negative electrode 420, copper precipitates in the negative electrode 420 in a dendrite shape (dendritic shape) and penetrates the separator 430, which may cause a problem such as an internal short circuit.

It should be noted that the occurrence of contamination due to dendrite-like precipitation in the negative electrode 420 is not limited to the case where copper or a copper alloy is used for the negative electrode base material layer 421, as long as it is a metal that is dissolved by the potential of the positive electrode 410. It can also occur in metal.

Further, in both the positive electrode 410 and the negative electrode 420, the higher the hardness of the active material contained in the active material layer, the more easily the cutters 21 and 22 are worn by cutting the active material layer. That is, the sharpness of the cutters 21 and 22 tends to decrease. When the base material layer is cut by the cutters 21 and 22 having such reduced sharpness, metal sagging, burrs, and the like are more likely to occur in the base material layer at the cut end portion.

In particular, in the negative electrode 420, amorphous carbon (non-graphitized carbon) having high hardness such as hard carbon and coke may be used as the negative electrode active material contained in the negative electrode active material layers 422 and 423. In this case, the sharpness of the cutter 22 is significantly reduced, and metal sagging, burrs, and the like are particularly likely to occur in the negative electrode base material layer 421 of the cut end portion. Therefore, in this case, contamination due to the negative electrode 420 is particularly likely to occur.

Further, in the electrode body 400 in which the positive electrode 410 and the negative electrode 420 are laminated, the electrode body 400 is pressed by the inner wall of the container 100 of the power storage element 10, so that the portions of the positive electrode 410 and the negative electrode 420 facing each other are pressed against each other. .. Therefore, in the facing portion, the chips of the base material layer and the floating of the active material layer can be suppressed by the compression, so that the cause of contamination can be suppressed. However, since the negative electrode 420 is larger than the positive electrode 410, the peripheral edge of the negative electrode 420 is less likely to be compressed, and it is difficult to suppress the cause of contamination.

Therefore, in order to suppress the generation of contamination in the power storage element 10, it is particularly effective to suppress the generation of contamination caused by the negative electrode 420.

Therefore, according to the power storage element 10 according to the present embodiment, the non-exposed portion 420b in which the negative electrode active material layers 422 and 423 are not exposed is arranged on the peripheral edge of the negative electrode 420, so that the peripheral edge of the negative electrode 420 falls off. Can be suppressed, so that the occurrence of contamination can be suppressed. Specifically, when both the negative electrode base material layer 421 and the negative electrode active material layers 422 and 423 are cut in the manufacturing process of the negative electrode 420, the chips of the negative electrode base material layer 421 and the negative electrode active material layer 422 and the negative electrode active material layer 422 are cut at the cut portion. There is a risk that the 423 will be lifted. These are factors that cause the above-mentioned contamination. Therefore, when the negative electrode active material layers 422 and 423 are arranged on the peripheral edge of the negative electrode 420, that is, when both the negative electrode base material layer 421 and the negative electrode active material layers 422 and 423 are cut in the manufacturing process, By covering the active material in the peripheral portion, the cause of the contamination can be suppressed. Further, when the negative electrode active material layers 422 and 423 are not arranged on the peripheral edge of the negative electrode 420, that is, when only the negative electrode base material layer 421 is cut in the manufacturing process, the cause of contamination that occurs at the time of cutting can be suppressed. .. As described above, in the present embodiment, the occurrence of contamination can be suppressed by arranging the non-exposed portion 420b in which the negative electrode active material layers 422 and 423 are not exposed on the peripheral edge portion of the negative electrode 420.

The non-exposed portion 420b is a portion (covered portion) in which the negative electrode active material layers 422 and 423 are covered by the coating material 425 attached to the negative electrode base material layer 421.

Here, when the negative electrode active material layers 422 and 423 are covered with the coating material not attached to the negative electrode base material layer 421, the coating material may fall off together with the negative electrode active material layers 422 and 423. That is, there is a possibility that contamination may occur due to the negative electrode active material layers 422 and 423 falling off together with the coating material. Therefore, in the present embodiment, by attaching the coating material 425 to the negative electrode base material layer 421, the coating material 425 is suppressed from falling off, and the negative electrode active material layers 422 and 423 are more reliably suppressed from falling off. The occurrence of contamination can be suppressed more reliably.

Further, since the non-exposed portion 420b is arranged on the short side of the negative electrode 420, the negative electrode 420 is formed by cutting the negative electrode base material in which the negative electrode active material layers 422 and 423 are uniformly formed along the longitudinal direction. Even in the case of manufacturing, the occurrence of contamination can be suppressed.

Specifically, the negative electrode active material layers 422 and 423 are uniformly formed along a predetermined direction, and the negative electrode active material layers 422 and 423 are formed in a stripe shape in a direction orthogonal to the predetermined direction. When the negative electrode 420 is formed by using the negative electrode base material (striped negative electrode base material) which is the layer 421, the negative electrode base material is cut along the predetermined direction, and then the cut negative electrode base material is used. Each negative electrode 420 is formed by cutting with a cutter 22 so as to have a predetermined length in a predetermined direction. That is, in FIG. 7, each negative electrode 420 is formed by cutting the negative electrode base material sent toward the electrode body 400 at a predetermined speed with a cutter 22 at predetermined time intervals. Therefore, since the cutter 22 is cut without moving, the time required for manufacturing the negative electrode 420 can be shortened.

At this time, the cutter 22 cuts both the negative electrode base material layer 421 and the negative electrode active material layers 422 and 423. For example, after the cutting step, the negative electrode 420 end is covered with the unexposed portion 420b of the negative electrode 420. By arranging it on the peripheral edge portion, it is possible to suppress the chips of the negative electrode base material layer 421 and the floating of the negative electrode active material layers 422 and 423 by coating. Therefore, even when the negative electrode base material coated with stripes is used, the occurrence of the above-mentioned contamination can be suppressed.

Further, when the amount of chips of the negative electrode base material layer 421 and the amount of shedding of the negative electrode active material layers 422 and 423 generated per unit length on the short side and the long side of each of the positive electrode 410 and the negative electrode 420 are the same. , Electrodes with a large circumference, which is the sum of both short sides and both long sides, are prone to contamination. Therefore, by arranging the non-exposed portion 420b on the peripheral edge of the negative electrode 420 having a circumference larger than that of the positive electrode 410, the cause of contamination can be suppressed in the electrode where the cause of contamination is likely to occur.

Further, when the negative electrode base material layer 421 contains a metal that dissolves due to the potential of the positive electrode 410, when chips of the negative electrode base material layer 421 are generated, the chips are dissolved and ionized at the positive electrode 410, and then dendrite at the negative electrode 420. Internal short circuit may occur due to the precipitation in the form. Therefore, by arranging the non-exposed portion 420b on the peripheral edge of the negative electrode 420, the generation of chips in the negative electrode base material layer 421 can be suppressed, so that the occurrence of an internal short circuit due to dendrite-like precipitation in the negative electrode 420 can be suppressed.

(Modification 1 of Embodiment 1)
Next, a modification 1 of the first embodiment of the present invention will be described. In the first embodiment, the non-exposed portion 420b is a portion where the negative electrode active material layers 422 and 423 are covered with the coating material 425. On the other hand, in this modification, the non-exposed portion is composed of a portion in which the negative electrode active material layers 422 and 423 are not formed.

FIG. 8 is a cross-sectional perspective view showing the configuration of the unexposed portion 420Ab according to the first modification of the first embodiment of the present invention. Specifically, the figure is a cross-sectional perspective view when the negative electrode 420A according to the present modification is cut along the line corresponding to the BB'line of FIG.

As shown in the figure, the negative electrode active material layers 422 and 423 are not formed on the peripheral portion of the negative electrode 420A of the present modification as the unexposed portion 420Ab in which the negative electrode active material layers 422 and 423 are not exposed. A part is provided. In the non-exposed portion 420Ab, not only the negative electrode active material layers 422 and 423 are not formed on the negative electrode base material layer 421, but also other members may not be provided. That is, in the non-exposed portion 420Ab, the negative electrode base material layer 421 may be exposed in the thickness direction of the negative electrode 420.

Specifically, in the non-exposed portion 420Ab, the negative electrode active material layers 422 and 423 are not formed along the end of the winding end of the negative electrode 420A in the winding direction, and the negative electrode base material layer 421 is formed in the X-axis direction. This is the exposed part. That is, the negative electrode active material layers 422 and 423 are formed in a state where all of them are exposed on the negative electrode base material layer 421.

According to the power storage element according to the present modification configured as described above, the same effect as that of the first embodiment can be obtained. That is, as described in the first embodiment, when both the negative electrode base material layer 421 and the negative electrode active material layers 422 and 423 are cut in the manufacturing process of the negative electrode 420A, the chips of the negative electrode base material layer 421 are cut at the cut portion. And the negative electrode active material layers 422 and 423 may be lifted. These can be factors that cause the above contamination. Therefore, in this modification, by arranging the unexposed portion 420Ab in which the negative electrode active material layers 422 and 423 are not arranged on the peripheral portion of the negative electrode 420A, the portion where the negative electrode active material layers 422 and 423 are not formed is cut. The negative electrode 420A can be manufactured. Therefore, the occurrence of the above-mentioned contamination can be suppressed.

Specifically, the negative electrode 420 according to the present modification uses a negative electrode base material (negative electrode base material intermittently coated) in which the negative electrode active material layers 422 and 423 are formed intermittently in the longitudinal direction. It is manufactured by cutting the portion where the negative electrode active material layers 422 and 423 are not formed.

However, when the electrode body is formed by winding the negative electrode base material in which the negative electrode active material layers 422 and 423 are intermittently coated and the positive electrode base material in which the positive electrode active material layers 412 and 413 are intermittently coated. When a large amount of electrode bodies are wound, the following problems may occur. Specifically, due to the influence of the coating accuracy of the active material layer, the winding accuracy, the thickness variation of the electrodes, etc., the non-forming portion of the active material layer at the end in the winding direction is between the negative electrode 420A and the positive electrode. There is a risk of misalignment.

Therefore, in the process of manufacturing the wound electrode body, it is preferable to cut the negative electrode base material on which the negative electrode active material layers 422 and 423 are uniformly formed in the longitudinal direction to manufacture each negative electrode. That is, in the winding type electrode body, it is preferable that the winding direction end portion of the negative electrode is composed of a portion in which the negative electrode active material layers 422 and 423 are covered with a coating material. As a result, in the winding type electrode body, it is possible to reduce defects due to misalignment between the positive electrode 410 and the negative electrode 420 in the winding direction.

(Modification 2 of Embodiment 1)
Next, a modification 2 of the first embodiment of the present invention will be described. In the first embodiment, the non-exposed portion 420b is arranged at the end of the winding end of the negative electrode 420 in the winding direction. On the other hand, in this modification, the non-exposed portion is arranged at the end of the winding start of the negative electrode in the winding direction. Further, in the first embodiment, it is assumed that the non-exposed portion 420b is composed of a covering portion which is a portion where the negative electrode active material layers 422 and 423 are covered with the covering material 425. On the other hand, in this modification, the non-exposed portion is composed of a winding core and a portion in which the negative electrode active material layers 422 and 423 are covered by the protrusions of the winding core.

FIG. 9 is a perspective view showing the configuration of the electrode body 400B according to the second modification of the first embodiment of the present invention, and a partially enlarged view of the perspective view. Specifically, (a) of the figure is a perspective view of the electrode body 400B, and (b) of the figure is an enlarged view showing a part of (a) of the figure in an enlarged manner.

The electrode body 400B shown in the figure is formed by winding a separator 430, a negative electrode 420B, and a positive electrode 410 around a winding core 500.

Here, the negative electrode 420B is provided with a winding core 500 and an unexposed portion 420Bb covered with a protrusion 500a arranged so as to project outward from the winding core 500 at the end of the winding start in the winding direction. There is.

The protrusion 500a is formed integrally with the winding core 500, and covers and sandwiches the longitudinal end of the negative electrode 420B on the outer peripheral surface (the surface on the plus side in the Z-axis direction) and the end. It is arranged on the end surface (the surface on the minus side in the Y-axis direction). That is, the protrusion 500a is attached to the end surface (the surface on the minus side in the Y-axis direction) of the negative electrode base material layer 421 by pressing the end of the negative electrode 420B at the start of winding.

According to the power storage element according to the present modification configured as described above, the same effect as that of the first embodiment can be obtained. That is, since the winding start end portion of the negative electrode 420B is covered with the winding core 500 and the protrusion 500a of the winding core 500, chips of the negative electrode base material layer 421 and the negative electrode active material layers 422 and 423 at the end portion are covered. Can be suppressed from rising. Therefore, the occurrence of contamination can be suppressed as in the first embodiment.

In this modification, the non-exposed portion 420Bb provided at the end of the negative electrode 420B at the beginning of winding is a coated portion covered with the winding core 500 and the protruding portion 500a, but is covered as in the first embodiment. It may be a covering portion covered with the material 425.

(Embodiment 2)
Next, Embodiment 2 of the present invention will be described. In the first embodiment, the non-exposed portion 420b is arranged on the short side of the negative electrode 420. On the other hand, in the present embodiment, the non-exposed portion is arranged on the long side of the negative electrode 420. Further, in the first embodiment, the non-exposed portion 420b is assumed to be a covering portion. On the other hand, in the present embodiment, the non-exposed portion is composed of the portions where the negative electrode active material layers 422 and 423 are not formed, as in the modification 1 of the first embodiment.

FIG. 10 is a perspective view showing a partially developed winding state of the electrode body 400C according to the second embodiment of the present invention.

Further, FIG. 11 is a cross-sectional view showing the configuration of the electrode body 400C according to the second embodiment of the present invention. Specifically, the figure is a diagram showing a cross section when cut at the CC'cross section of FIG. In FIG. 11, only one set of a plurality of sets of the positive electrode 410, the negative electrode 420C, and the separator 430, which are repeatedly laminated by being wound, is shown, and the other sets are not shown.

As shown in FIGS. 10 and 11, the peripheral edge of the negative electrode 420C is arranged on the side (first side) connected to the negative electrode current collector 130, and the negative electrode active material layers 422 and 423 are not formed. It has a forming portion 420a and an unexposed portion 420Cb that is arranged on a side (second side) different from the side connected to the negative electrode current collector 130 and in which the negative electrode active material layers 422 and 423 are not exposed.

Here, in the present embodiment, the non-exposed portion 420Cb is arranged on the long side of the negative electrode 420. Further, the non-exposed portion 420Cb is composed of portions in which the negative electrode active material layers 422 and 423 are not formed, and the non-formed portion 420a and the non-exposed portion 420Cb are arranged on both long sides of the negative electrode 420C. In other words, the non-forming portion 420a is arranged on one long side of both long sides of the negative electrode 420, and the non-exposed portion 420Cb is arranged on the other long side of both long sides. That is, the negative electrode 420C in the present embodiment has portions on both sides of the electrode body 400 in the winding axis direction (both sides in the X-axis direction) in which the negative electrode active material layers 422 and 423 are not formed.

According to the power storage element according to the present embodiment configured as described above, the same effect as that of the first embodiment can be obtained. That is, in the first embodiment, the reason why contamination occurs has been described by giving an example in which the short side of the negative electrode is cut in the cutting step. However, the long side of the negative electrode may be cut in the manufacturing process. Therefore, in the negative electrode manufacturing process, when both the negative electrode base material layer 421 and the negative electrode active material layers 422 and 423 are cut on the long side of the negative electrode, the negative electrode base material layer is cut at the cut portion (long side end face of the negative electrode). There is a risk that 421 chips and the negative electrode active material layers 422 and 423 may be lifted. These can be factors that cause the above contamination.

Therefore, in the present embodiment, by arranging the unexposed portion 420Cb in which the negative electrode active material layers 422 and 423 are not arranged on the long side of the negative electrode 420C, the portion where the negative electrode active material layers 422 and 423 are not formed is formed. The negative electrode 420C can be manufactured by cutting. Therefore, the occurrence of the above-mentioned contamination can be suppressed.

Further, when the short side and the long side of the negative electrode 420C have the same amount of chips of the negative electrode base material layer 421 and the negative electrode active material layers 422 and 423 generated per unit length, the long side has the same amount. The chips and the falling off are likely to cause contamination. Therefore, by arranging the non-exposed portion 420Cb on the long side of the negative electrode 420C, the cause of contamination can be suppressed in a place where the factor of contamination is likely to occur.

Further, when the non-exposed portion 420Cb arranged on the long side of the negative electrode 420C is composed of, for example, a portion where the negative electrode active material layers 422 and 423 are covered with a coating material, the thickness of both long sides of the negative electrode 420C is increased. Can be different from each other. Therefore, in the winding type electrode body, the negative electrode 420C meanders at the time of winding, which may reduce the winding accuracy and the yield. Further, not only the winding type electrode body but also the negative electrode 420C has different thicknesses on both long sides, which makes it difficult to control the dimensions of the electrode body. Therefore, the electrode body can be accommodated in the container 100 of the power storage element 10. It becomes difficult. Therefore, in the present embodiment, by arranging the non-exposed portion 420Cb in which the negative electrode active material layers 422 and 423 are not formed on the long side of the negative electrode 420C, the dimensional control of the electrode body 400C is facilitated and the yield is maintained. At the same time, the occurrence of contamination can be suppressed.

Further, in the electrode body 400C in which the positive electrode 410 and the negative electrode 420C are laminated, the electrode body 400C is pressed by the inner wall of the container 100, so that the portions of the positive electrode 410 and the negative electrode 420C facing each other are pressed against each other. Therefore, in the facing portion, the chips of the negative electrode base material layer 421 and the floating of the negative electrode active material layers 422 and 423 can be suppressed by the compression. However, since the length of the short side (size in the X-axis direction) of the negative electrode 420C is larger than that of the positive electrode 410, both ends of the negative electrode 420C in the lateral direction (both ends in the X-axis direction) are compressed without facing the positive electrode 410. It is hard to be done. Therefore, chips of the negative electrode base material layer 421 and the negative electrode active material layers 422 and 423 are likely to be lifted at both ends of the negative electrode 420C in the lateral direction, which may cause contamination. Therefore, by arranging the non-exposed portion 420Cb on the long side of the negative electrode 420C, the cause of contamination can be suppressed in a place where the factor of contamination is likely to occur.

(Other embodiments)
Although the power storage element according to the embodiment of the present invention and the modified example thereof has been described above, the present invention is not limited to the embodiment and the modified example thereof.

That is, it should be considered that the embodiments disclosed this time and examples thereof are examples in all respects and are not restrictive. The scope of the present invention is shown not by the above description but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

For example, the configuration of the first embodiment may be combined with the configuration of the second modification of the first embodiment. That is, non-exposed portions formed by the portions covered with the negative electrode active material layers 422 and 423 by the coating material attached to the negative electrode base material layer 421 may be arranged on both short sides of the negative electrode. With this configuration, even when the negative electrode is manufactured by cutting the negative electrode base material in which the negative electrode active material layers 422 and 423 are formed in stripes, the occurrence of contamination can be further suppressed. That is, so-called intermittent coating, in which the negative electrode active material layers 422 and 423 are intermittently formed in the longitudinal direction of the negative electrode base material, may be difficult in manufacturing. Therefore, it is difficult to provide a portion on the short side of the negative electrode where the negative electrode active material layers 422 and 423 are not formed. Therefore, by adopting a configuration in which the negative electrode base material layer 421 is covered with a coating material on the non-exposed portions arranged on both short sides of the negative electrode, it is possible to suppress the cause of contamination on both short sides. For example, the covering material 425 of the first embodiment is used as the covering material on one short side, and the winding core 500 and the protrusion 500a of the modified example 2 of the first embodiment are used as the covering material on the other short side. You may.

Of the non-exposed portions 420b arranged on both short sides, one is composed of a portion (covered portion) covered with a covering material 425, and the other is a portion (a portion in which the negative electrode active material layers 422 and 423 are not formed). It may be composed of a non-formed portion). This also makes it possible to suppress the occurrence of contamination, as in the above description.

Further, the configuration of the first embodiment may be combined with the configuration of the second embodiment. That is, the non-forming portion is arranged on one long side of both long sides of the negative electrode 420, the non-exposed portion is arranged on the other long side, and the non-exposed portion is arranged on both short sides of the negative electrode 420. You may decide. In this case, both long sides of the negative electrode 420 are composed of portions where the negative electrode active material layers 422 and 423 are not formed, and both short sides of the negative electrode 420 are any of the first embodiment and the first and second modifications. It is conceivable to make this configuration. For example, when all of both the long sides and the short sides of the negative electrode 420 are composed of the portions where the negative electrode active material layers 422 and 423 are not formed, the peripheral edge of the negative electrode 420 is not arranged and the covering material 425 or the like is not arranged. It is possible to suppress the dropout of the active material around the entire circumference, thereby suppressing the decrease in capacity, the increase in resistance, the occurrence of internal short circuit, and the like. However, even in this case, sagging or cutting may occur at the end of the base material layer after the slit due to wear of the slit blade (cutter) or the like. Therefore, in such a case, by covering at least one side of both short sides of the negative electrode 420 with a covering material 425 (or a protrusion 500a of the winding core 500), detachment of the metal piece and generation of internal resistance are suppressed. can do.

Further, in the above description, it is assumed that the non-exposed portion is composed of either a coated portion or a non-formed portion. However, the configuration of the non-exposed portion is not limited to this, and a part of the non-exposed portion 420b may be composed of a covering portion and the other portion may be composed of a non-forming portion. Further, the non-exposed portion may be arranged on a side different from the side to which the negative electrode current collector 130 is connected, and the negative electrode active material layers 422 and 423 may not be exposed. It does not matter if it is configured. This also makes it possible to suppress the occurrence of contamination, as in the above description.

Here, the coating portion is not limited to the portion where the negative electrode active material layers 422 and 423 are covered by the coating material 425 attached to the negative electrode base material layer 421, and the negative electrode is not limited to the portion covered by the coating material attached to the negative electrode base material layer 421. It may be a portion where the base material layer 421 is covered.

FIG. 12 is a cross-sectional perspective view showing the configuration of such a non-exposed portion 420Db. Specifically, the figure is a cross-sectional perspective view when the negative electrode 420D according to the present embodiment is cut along a line corresponding to the BB'line of FIG.

As shown in the figure, the negative electrode active material layers 422 and 423 are not formed in the non-exposed portion 420Db as compared with the non-exposed portion 420b of the first embodiment, and the non-exposed portion 420Db is covered with the covering material 425D. Similar to the covering material 425, the covering material 425D covers both sides of the end portion (both sides in the Z-axis direction) and the end surface of the end portion (plus in the Y-axis direction) so as to cover the end portion in the longitudinal direction of the negative electrode 420. It is placed on the side surface). Further, the covering material 425D is attached to the end surface (the surface on the plus side in the Y-axis direction) of the negative electrode base material layer 421. That is, the covering material 425D is attached to the negative electrode base material layer 421 and is arranged so as to cover the negative electrode base material layer 421.

Since the material of the covering material 425D is the same as that of the covering material 425, the description thereof will be omitted.

Even a power storage element having a negative electrode 420D configured as described above can achieve the same effect as that of the first embodiment. Specifically, even when the negative electrode active material layers 422 and 423 are not formed on the peripheral edge of the negative electrode 420, if there is metal sagging or burrs on the peripheral edge of the negative electrode base material layer 421, these metals There is a risk that dripping or burrs will fall off and contamination will occur. Therefore, by covering the negative electrode base material layer 421 with the coating material 425D, the occurrence of contamination can be suppressed.

Further, in the second embodiment, the non-exposed portion 420Cb is composed of a non-forming portion in which the negative electrode active material layers 422 and 423 are not formed, and the non-forming portion 420a and the non-exposed portion 420Cb have both lengths of the negative electrode 420C. It was assumed that it was placed on the side. However, the non-exposed portion 420b arranged on the long side may be composed of a covering portion. Even with this, although the winding accuracy may be lowered and the yield may be slightly deteriorated, the occurrence of contamination can be suppressed.

Further, in the above description, it is assumed that the length of the short side of the negative electrode is larger than that of the positive electrode 410. However, the negative electrode may have a short side length of 410 or less as the positive electrode. In this case, since the lateral end of the negative electrode is pressed by the positive electrode 410, contamination due to the negative electrode is less likely to occur. Therefore, although the effect is somewhat small, the occurrence of contamination can be suppressed by arranging the non-exposed portion on the peripheral edge of the negative electrode.

Further, in the above description, it is assumed that the peripheral length of the negative electrode, which is the sum of both short sides and both long sides, is larger than that of the positive electrode 410. However, the negative electrode may have a peripheral length of 410 or less as the positive electrode. In this case, since contamination due to the negative electrode is less likely to occur, the effect is somewhat reduced, but the occurrence of contamination can be suppressed by arranging the non-exposed portion on the peripheral edge of the negative electrode.

Further, in the above description, the negative electrode base material layer 421 contains a metal that is dissolved by the potential of the positive electrode 410. However, the negative electrode base material layer 421 may not contain the metal. For example, the negative electrode base material layer 421 may contain a metal that is difficult to dissolve due to the potential of the positive electrode 410. In this case, although an internal short circuit due to dendrite-like precipitation on the negative electrode is less likely to occur, there is a possibility that an internal short circuit or the like may occur due to chips of the negative electrode base material layer 421 penetrating the separator 430, for example. Therefore, even in this case, by arranging the non-exposed portion on the peripheral edge of the negative electrode, the generation of chips can be suppressed, so that internal short circuits such as minute short circuits due to chips can be suppressed. ..

Further, in the above description, it is assumed that the negative electrode is connected to the negative electrode current collector 130 of the power storage element 10 on the long side. However, the negative electrode may be connected to the negative electrode current collector 130 on the short side. That is, the side on which the non-forming portion 420a is arranged (first side) and the side on which the non-exposed portion is arranged (second side) may be sides different from each other of the negative electrode, and the short side of the negative electrode and the short side of the negative electrode It does not matter which side is the long side. Further, the side on which the non-exposed portion is arranged (second side) may be a side other than the side on which the non-forming portion 420a is arranged (first side), and may be a plurality of sides. .. Further, the non-exposed portion does not have to be arranged on all of the second side, and may be arranged on at least a part of the second side.

Further, in the above description, it is assumed that each of the positive electrode and the negative electrode has a long strip shape. However, each of the positive electrode and the negative electrode may have a rectangular shape, and the lengths of the four sides forming the rectangular shape may be the same.

Further, a form constructed by arbitrarily combining the above-described embodiment and its modifications is also included in the scope of the present invention. Further, the configuration may be a combination of the above-described embodiments and partial configurations of the modifications thereof as appropriate. For example, as described above, the configuration may be a combination of the configuration of the first embodiment and the configuration of the modified example 2 of the first embodiment, or the configuration may be a combination of the first embodiment and the configuration of the second embodiment. It doesn't matter if there is one.

Since the present invention can provide a power storage element capable of suppressing the occurrence of contamination, it can be applied to a power storage element or the like mounted on an automobile or the like where high quality and high output are required.

10 Power storage element 21, 22, 23 Cutter 100 Container 110 Lid 111 Main body 120 Positive electrode current collector 130 Negative electrode current collector 200 Positive electrode terminal 300 Negative electrode terminal 400, 400B, 400C Electrode body 410 Positive electrode 411 Positive electrode base material layer 412, 413 Positive electrode Active material layer 410a, 420a Non-forming part 420b, 420Ab, 420Bb, 420Cb, 420Db Non-exposed part 420, 420A, 420B, 420C, 420D Negative electrode 421 Negative electrode base material layer 422, 423 Negative electrode active material layer 425, 425D Coating material 430 Separator 500 winding core 500a protrusion

Claims (7)

A power storage element including an electrode body having a negative electrode plate and a positive electrode plate.
The negative electrode plate is
It has a base material layer and an active material layer formed on the base material layer in a partially or completely exposed state.
The peripheral edge of the negative electrode plate is
A non-forming portion arranged on the first side connected to the current collector of the power storage element and on which the active material layer is not formed, and a non-forming portion.
Disposed on a second side different from the first side, it possesses a non-exposed portion to which the active material layer is not exposed,
The non-exposed portion is composed of a portion where the active material layer is not formed.
The non-formed portion is arranged on one long side of both long sides of the negative electrode plate, and the non-exposed portion is arranged on the other long side of both long sides.
Power storage element . A power storage element including an electrode body having a negative electrode plate and a positive electrode plate.
The negative electrode plate is
It has a base material layer and an active material layer formed on the base material layer in a partially or completely exposed state.
The peripheral edge of the negative electrode plate is
A non-forming portion arranged on the first side connected to the current collector of the power storage element and on which the active material layer is not formed, and a non-forming portion.
Disposed on a second side different from the first side, it possesses a non-exposed portion to which the active material layer is not exposed,
The electrode body is formed by winding the negative electrode plate and the positive electrode plate around a winding core.
The non-exposed portion is arranged at the end of the winding start of the negative electrode plate in the winding direction, and is composed of the winding core and a portion covered by a protrusion protruding from the winding core.
Power storage element . The power storage element according to claim 1 or 2 , wherein the negative electrode plate has a short side length larger than the short side length of the positive electrode plate. The power storage element according to any one of claims 1 to 3 , wherein the negative electrode plate has a circumference of both short sides and both long sides larger than that of the positive electrode plate. The power storage element according to any one of claims 1 to 4 , wherein the base material layer contains a metal that is dissolved by the potential of the positive electrode plate. A method for manufacturing a power storage element including an electrode body having a negative electrode plate and a positive electrode plate.
A negative electrode plate forming step of forming an active material layer on the base material layer of the negative electrode plate with a part or all exposed.
The present invention includes an electrode body forming step of laminating the negative electrode plate and the positive electrode plate formed in the negative electrode plate forming step to form an electrode body.
In the negative electrode plate forming step, a non-forming portion that is arranged on the first side connected to the current collector of the power storage element and does not have the active material layer formed, and a second side that is different from the first side. A negative electrode plate arranged on the side and having an unexposed portion where the active material layer is not exposed is formed on the peripheral portion.
In the negative electrode plate forming step, the non-exposed portion is composed of a portion where the active material layer is not formed, and the non-formed portion is formed on one of the long sides of the negative electrode plate. The non-exposed portion is arranged, and the unexposed portion is arranged on the other long side of the two long sides.
Manufacturing method of power storage element. A method for manufacturing a power storage element including an electrode body having a negative electrode plate and a positive electrode plate.
A negative electrode plate forming step of forming an active material layer on the base material layer of the negative electrode plate with a part or all exposed.
The present invention includes an electrode body forming step of laminating the negative electrode plate and the positive electrode plate formed in the negative electrode plate forming step to form an electrode body.
In the negative electrode plate forming step, a non-forming portion that is arranged on the first side connected to the current collector of the power storage element and does not have the active material layer formed, and a second side that is different from the first side. A negative electrode plate arranged on the side and having an unexposed portion where the active material layer is not exposed is formed on the peripheral portion.
In the electrode body forming step, the negative electrode body and the positive electrode plate are wound around a winding core to form the electrode body.
In the negative electrode plate forming step, the non-exposed portion is arranged at the end of the winding start of the negative electrode plate in the winding direction, and the non-exposed portion is covered with the winding core and a protrusion protruding from the winding core. Consists of broken parts
Manufacturing method of power storage element.

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