JPWO2018123088A1 - Winding battery - Google Patents

Abstract

In a wound battery including an electrode body formed by winding a positive electrode, a negative electrode, and a separator, and the negative electrode contains a metal alloyed with Li, by suppressing the occurrence of deflection inside the electrode body due to expansion of the negative electrode , Preventing deterioration of battery characteristics. The wound battery 1 has a positive electrode 31, a negative electrode 32, and a separator 33 that are wound in an overlapped state, thereby forming an electrode body 30 having a flat cross section and a battery case in which the electrode body 30 is enclosed. 2 is provided. The negative electrode 32 has a negative electrode portion 51 containing an element that can be alloyed with Li, and a negative electrode end portion 52. The electrode body 30 includes a spacer portion 53 that is located at least partly between the negative electrode end portions 52 adjacent to each other in the radial direction of the electrode body 30 and has a thickness larger than the thickness of the positive electrode 31.

Description

  The present invention relates to a wound battery having an electrode body formed by winding a positive electrode, a negative electrode, and a separator, each formed in a strip shape, in an overlapped state.

  2. Description of the Related Art Conventionally, a wound battery having an electrode body that is wound in a state where a positive electrode, a negative electrode, and a separator each formed in a strip shape are overlapped is known. In such a wound battery, for example, in Patent Document 1, a cylindrical electrode is obtained by winding a positive electrode plate, a negative electrode plate, and a separator interposed between both electrode plates using a winding core. A method of obtaining a flat spiral electrode body by producing a body and pressing the electrode body is disclosed.

  Here, in a secondary battery having a flat spiral electrode body as described above, both positive and negative electrode plates repeat expansion and contraction due to insertion and extraction of lithium ions by charging and discharging. The expansion / contraction of the electrode plate is limited by an adhesive or tape that fixes the winding end of the flat spiral electrode body, and the flat spiral electrode body is bent so that the electrode plate is folded back. Displacement of the spiral electrode body outward in the radial direction is limited. As a result, the electrode plate expands inward of the flat spiral electrode body. Therefore, the electrode plate is deflected. This deflection causes a problem that the thickness of the battery increases.

  On the other hand, in Patent Document 1, in a secondary battery provided with a flat spiral electrode body, a cylindrical electrode body is produced, and then the electrode body is rotated in the same direction as the winding direction to be wound up. A process of loosening the process is disclosed. In the configuration disclosed in Patent Document 1, the flat spiral electrode body is obtained by pressing the electrode body obtained in this step. Thereby, when the flat spiral electrode body is cut in a direction perpendicular to the central axis, the distance from the inner surface of the innermost circumference of the wound electrode body located on the major axis to the outermost circumference surface on the major axis in the cross section D1 / D2 ≧ 1.1 is established between D1 and the shortest distance D2 from the innermost winding electrode body side surface to the outermost surface on the short axis in the cross section.

  In the configuration disclosed in Patent Document 1, the loosened body moves in the vicinity of the corner portion of the flat spiral electrode body by pressing the electrode body whose winding state has been loosened. As a result, when the electrode plate expands due to occlusion of lithium ions by charging, the electrode plate is deformed in a direction to fill this looseness, and the occurrence of the deflection of the electrode plate can be prevented. Therefore, an increase in battery thickness can be suppressed, and no gap is generated between the positive electrode plate and the negative electrode plate even when the charge / discharge cycle is repeated. Therefore, cycle deterioration is reduced.

Japanese Patent No. 4778984

  By the way, in the battery having the configuration disclosed in Patent Document 1, a process of loosening the winding state of the electrode body is necessary in the manufacturing process. However, when the winding state of the electrode body is loosened in this way, it is difficult to accurately manage the amount of looseness. Therefore, manufacturing management of the battery becomes difficult.

  In particular, when the expansion of the electrode plate is large, the electrode body is not bent inward even if the electrode plate expands only by the process of loosening the winding state of the electrode body as described above. It is difficult to provide looseness with high accuracy.

  As a battery having a large expansion of the electrode plate as described above, for example, a configuration in which the negative electrode includes a metal (for example, Al, Si, Sn, etc.) alloyed with Li is known. In the negative electrode, when the battery is charged, the metal and Li are alloyed, so that the negative electrode expands greatly in the thickness direction.

  An object of the present invention is to provide a wound battery including an electrode body formed by winding a positive electrode, a negative electrode, and a separator, each formed in a strip shape, and the negative electrode contains a metal alloyed with Li. An object of the present invention is to prevent deterioration of battery characteristics by suppressing the occurrence of deflection inside the electrode body due to the expansion of the negative electrode.

  In a wound battery according to an embodiment of the present invention, a positive electrode, a negative electrode, and a separator each formed in a strip shape are wound so that the separator is positioned between the positive electrode and the negative electrode, An electrode body having an elongated columnar shape and a flat cross section perpendicular to the axial direction is provided, and an exterior body in which the electrode body is sealed. The negative electrode is provided in at least one of the negative electrode portion disposed so as to overlap the positive electrode across the separator when viewed from the thickness direction, and in the short direction of the negative electrode with respect to the negative electrode portion, As viewed from the thickness direction, it has a negative electrode end portion that does not overlap the positive electrode. The negative electrode portion includes an element that can be alloyed with Li. The electrode body is located in at least a part between the negative electrode end portions adjacent to each other in the radial direction of the electrode body in a cross section orthogonal to the axial direction of the electrode body, and is larger than the thickness of the positive electrode The spacer portion has a thickness.

  According to the wound battery according to the embodiment of the present invention, the negative electrode overlaps with the positive electrode with the separator interposed therebetween when viewed from the thickness direction, and includes a negative electrode portion including an element that can be alloyed with Li, the positive electrode, Have negative electrode ends that do not overlap. The electrode body having a flat cross section, which is configured by winding the positive electrode, the negative electrode, and the separator, is located at least at a part between the negative electrode end portions adjacent to each other in the radial direction of the electrode body, And it has the spacer part which has thickness larger than the thickness of the said positive electrode. Thereby, when a negative electrode part expand | swells by charge of a battery, it can suppress that a deflection | deviation arises inside an electrode body. Therefore, deterioration of battery characteristics can be prevented.

FIG. 1 is a perspective view illustrating a schematic configuration of the wound battery according to the embodiment. 2 is a cross-sectional view of the wound battery before charging, taken along the line II-II in FIG. FIG. 3 is a diagram schematically showing the arrangement of the positive electrode, the negative electrode, and the separator. FIG. 4 is a diagram schematically illustrating a state where the positive electrode, the negative electrode, and the separator are wound in a state where they are stacked in the thickness direction. FIG. 5 is a perspective view showing a schematic configuration of the electrode body. FIG. 6 is an enlarged cross-sectional view showing a part of the electrode body before charging (X portion in FIG. 2) in an enlarged manner. FIG. 7 is an enlarged view corresponding to FIG. 6 showing an enlarged part of the electrode body after charging. FIG. 8 is a diagram schematically showing a cross section of the electrode body when the spacer portion is not provided. FIG. 9 is a view corresponding to FIG. 8 schematically showing a cross section of the electrode body in the case where the spacer portion is provided. FIG. 10 is a diagram showing the relationship between the thickness of the spacer portion and the strain in the electrode body. FIG. 11 is an enlarged view corresponding to FIG. 6 illustrating a part of the electrode body in the case where the spacer portion is provided on both surfaces of the negative electrode. FIG. 12 is a view corresponding to FIG. 4 when the negative electrode end portion is integrally provided with a convex portion. FIG. 13 is a perspective view showing a schematic configuration of a wound battery according to another embodiment.

  In a wound battery according to an embodiment of the present invention, a positive electrode, a negative electrode, and a separator each formed in a strip shape are wound so that the separator is positioned between the positive electrode and the negative electrode, An electrode body having an elongated columnar shape and a flat cross section perpendicular to the axial direction is provided, and an exterior body in which the electrode body is sealed. The negative electrode is provided in at least one of the negative electrode portion disposed so as to overlap the positive electrode across the separator when viewed from the thickness direction, and in the short direction of the negative electrode with respect to the negative electrode portion, As viewed from the thickness direction, it has a negative electrode end portion that does not overlap the positive electrode. The negative electrode portion includes an element that can be alloyed with Li. The electrode body is located in at least a part between the negative electrode end portions adjacent to each other in the radial direction of the electrode body in a cross section orthogonal to the axial direction of the electrode body, and is larger than the thickness of the positive electrode A spacer portion having a thickness is provided (first configuration).

  Thereby, even when the negative electrode part containing an element that can be alloyed with Li expands when an alloy with Li is generated during charging of the battery, it is possible to prevent the bending of the electrode body. That is, by providing a spacer portion having a thickness larger than the thickness of the positive electrode between negative electrode end portions adjacent to each other in the radial direction of the electrode body, a space is formed between the negative electrode portions adjacent in the radial direction of the electrode body. Is formed. Thereby, even when the negative electrode portion expands as described above, an increase in thickness due to the expansion of the negative electrode portion can be absorbed by the space. As a result, in the electrode body in which deformation to the radially outer side is suppressed by the outer peripheral side portion of the electrode body, the positive electrode, the negative electrode, and the separator constituting the electrode body are expanded by the expansion of the negative electrode portion as described above. Thus, it is possible to suppress the application of a force that causes the electrode body to be displaced inward. Therefore, with the above-described configuration, it is possible to suppress the occurrence of deflection inside the electrode body. Therefore, it can suppress that the distance between electrodes becomes non-uniform inside an electrode body, and a battery characteristic falls.

  In particular, as described above, when an alloy of Li and an element that can be alloyed with Li is formed in the negative electrode portion, the negative electrode portion expands greatly. Therefore, by providing the spacer portion as described above, it is possible to effectively suppress the occurrence of deflection in the electrode body.

  And the battery characteristic of a winding type battery can be improved by the above-mentioned structure. In the electrode body in which the spacer portion is not provided as described above, the positive electrode and the negative electrode are overlapped with almost no gap through the separator. Therefore, it takes time until the nonaqueous electrolytic solution is uniformly infiltrated into the electrode body. On the other hand, by providing a spacer portion larger than the thickness of the positive electrode between the negative electrode end portions adjacent to each other in the radial direction of the electrode body as in the configuration described above, the negative electrode portion adjacent to the radial direction in the state before charging. Is larger than the thickness of the positive electrode. Therefore, a gap is formed between the positive electrode and the negative electrode part. Thereby, a nonaqueous electrolyte can be easily infiltrated to the inside of an electrode body. Therefore, the battery performance of the wound battery can be improved.

  In the first configuration, the electrode body has a bent portion that is bent so that the positive electrode, the negative electrode, and the separator are folded in the thickness direction in the cross section. The spacer portion is positioned between the adjacent negative electrode end portions in the bent portion of the electrode body (second configuration).

  In the electrode body, in a bent portion that is bent so that the positive electrode, the negative electrode, and the separator are folded back in the thickness direction, even if the negative electrode expands inside the electrode body, displacement in the radially outward direction is restricted. Therefore, when the negative electrode portion expands, the bent portion is not deformed, and the portion other than the bent portion of the electrode body is affected by the expansion of the negative electrode portion. That is, in the electrode body, when the negative electrode portion expands, deflection occurs in a portion other than the bent portion.

  On the other hand, as described above, in the bent portion of the electrode body, the positive electrode, the negative electrode, and the separator of the electrode body are caused by the expansion of the negative electrode portion by positioning the spacer portion between the adjacent negative electrode end portions. On the other hand, it is possible to more reliably suppress the application of a force that causes the electrode body to be displaced inward. Thereby, it can suppress more reliably that a bending arises inside the said electrode body.

  In the first or second configuration, the spacer portion has a thickness greater than or equal to the sum of the thickness of the positive electrode and the difference between the thickness of the negative electrode portion and the thickness of the negative electrode end (third configuration). .

  Accordingly, when the negative electrode portion expands when the battery is charged, the spacer portion applies a force to be displaced inward of the electrode body to the positive electrode, the negative electrode, and the separator of the electrode body. It can be reliably suppressed. Therefore, even when the wound battery is repeatedly charged and discharged, it is possible to more reliably suppress the occurrence of deflection in the electrode body.

  In the first or second configuration, the spacer portion has a thickness less than the total of the thickness of the positive electrode and the difference between the thickness of the negative electrode portion and the thickness of the negative electrode end (fourth configuration). .

  When the thickness of the spacer portion is increased, the interelectrode distance between the positive electrode and the negative electrode portion is increased, and the battery characteristics may be deteriorated. On the other hand, by setting the thickness of the spacer portion to the above-described thickness, the interelectrode distance between the positive electrode and the negative electrode portion can be within an appropriate range while suppressing the occurrence of deflection inside the electrode body. it can. That is, with the above-described configuration, it is possible to achieve both suppression of the occurrence of deflection inside the electrode body and prevention of deterioration of battery characteristics of the wound battery.

  In any one of the first to fourth configurations, the spacer portion is provided on at least one of the negative electrode end and the separator (fifth configuration). Thereby, a spacer part can be easily provided between the negative electrode edge parts adjacent to the radial direction of an electrode body.

  In the fifth configuration, the spacer portion is provided in at least one of the negative electrode end portion and the separator from one end portion in the longitudinal direction to the other end portion (sixth configuration). Thereby, the negative electrode part adjacent to the radial direction of an electrode body can be more reliably spaced apart by the spacer part over the whole electrode body.

  In the fifth or sixth configuration, the spacer portion is provided on a radially outer peripheral side of at least one of the negative electrode end and the separator in the electrode body (seventh configuration).

  In the electrode body, when a spacer part is provided on at least one radial inner peripheral side of the negative electrode end part and the separator, when the positive electrode, the negative electrode, and the separator are wound in a state of being stacked in the thickness direction, the spacer part is slackened. And deformation such as wrinkles may occur. On the other hand, as described above, by providing a spacer portion on the radially outer peripheral side of at least one of the negative electrode end portion and the separator, the positive electrode, the positive electrode, The negative electrode and the separator can be wound. Therefore, deformation such as sagging and wrinkles can be prevented from occurring in the spacer portion. Thereby, the space | interval of the negative electrode part adjacent to the radial direction of the said electrode body can be ensured more reliably.

  In the fifth or sixth configuration, the spacer portion is provided on at least one surface of the negative electrode end portion and the separator, and the spacer portion of the spacer portion adjacent to the electrode body in the radial direction is provided. The total thickness is larger than the thickness of the positive electrode (eighth configuration).

  Thereby, compared with the case where a spacer part is provided in at least one surface of a negative electrode edge part and a separator, the thickness of each spacer part can be made small. Therefore, when winding the positive electrode, the negative electrode, and the separator while being stacked in the thickness direction, it is possible to more reliably prevent sagging and wrinkling from occurring in the spacer portion.

  In any one of the fifth to eighth configurations, the spacer portion is configured by a member different from the negative electrode end portion and the separator (a ninth configuration). Thereby, the thickness of a spacer part can be adjusted easily.

  In any one of the fifth to eighth configurations, the spacer portion is integrally provided on at least one of the negative electrode end portion and the separator (tenth configuration). Thus, by providing the spacer portion integrally with at least one of the negative electrode end portion and the separator, the spacer portion of the present invention can be easily obtained without using a separate member. Therefore, the configuration of the wound battery of the present invention can be easily obtained.

  In any one of the first to tenth configurations, the negative electrode portion includes a Li—Al alloy as a negative electrode active material after charging the battery (an eleventh configuration). Thus, when the Li—Al alloy is generated from the Al alloy by charging the battery in the negative electrode part, the negative electrode part expands in the thickness direction. Even when such expansion occurs, it is possible to effectively suppress the occurrence of deflection inside the electrode body by applying the above first to tenth configurations.

  In the eleventh configuration, the negative electrode is a laminate having a metal base layer that is not alloyed with Li and a metal surface layer bonded to at least one of the metal base layers in the thickness direction. At least the surface side of the metal surface layer in the negative electrode portion includes the Li—Al alloy after charging the battery (a twelfth configuration).

  Even in the above-described configuration, by applying the above-described first to tenth configurations, the expansion of the negative electrode portion caused when the Li-Al alloy is generated on the metal surface layer by charging the battery, the electrode body It is possible to suppress the occurrence of internal deflection.

  In any one of the first to twelfth configurations, the spacer portion is made of a resin material that does not contribute to a battery reaction (a thirteenth configuration). Thereby, a spacer part can be formed between the negative electrode edge parts adjacent to the radial direction of an electrode body, without affecting a battery characteristic.

  In any one of the first to thirteenth configurations, the exterior body includes an exterior can that houses the electrode body (a 14th configuration). Thus, when the exterior body which accommodates an electrode body is an exterior can, the said electrode body is further controlled by the said exterior can in the deformation | transformation to radial direction outward. Therefore, when the negative electrode portion expands due to charging, the stress inside the electrode body tends to increase. As described above, when the stress inside the electrode body is increased, the electrodes of the positive electrode and the negative electrode part in the electrode body when the spacer portions as in the first to thirteenth structures are not provided. The distance between them becomes narrower. Therefore, a short circuit is likely to occur inside the electrode body. In contrast, as in the first to thirteenth configurations described above, by providing a spacer portion between the negative electrode end portions adjacent to each other in the radial direction of the electrode body, the inter-electrode distance can be reduced within the electrode body. The predetermined interval can be set so as not to cause a short circuit. Therefore, the occurrence of a short circuit inside the electrode body can be prevented.

  In any one of the first to thirteenth configurations, the exterior body includes a laminate film exterior body that houses the electrode body (a 15th configuration). Thus, even in the configuration in which the electrode body is housed in the laminate film exterior body, the occurrence of deflection in the electrode body due to the expansion of the negative electrode portion can be suppressed by applying the above first to thirteenth configurations. Can do.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals and description thereof will not be repeated.

(overall structure)
FIG. 1 is a perspective view showing a schematic configuration of a wound battery 1 according to an embodiment of the present invention. The wound battery 1 includes a bottomed cylindrical outer can 10, a cover plate 20 that covers an opening of the outer can 10, and an electrode body 30 that is accommodated in the outer can 10. By attaching the cover plate 20 to the outer can 10, a rectangular parallelepiped battery case 2 (exterior body) having a rectangular parallelepiped space is formed. In addition to the electrode body 30, a non-aqueous electrolyte is also enclosed in the battery case 2.

  The outer can 10 is a bottomed cylindrical member made of an aluminum alloy, and constitutes the battery case 2 together with the cover plate 20. As shown in FIG. 1, the outer can 10 is a bottomed cylindrical member having a rectangular bottom surface 11 in a top view. Specifically, the outer can 10 includes a bottom surface 11 and a flat cylindrical side wall 12. That is, the outer can 10 is formed in a flat shape such that the dimension in the thickness direction corresponding to the short side direction of the bottom surface 11 is smaller than the width direction corresponding to the long side direction of the bottom surface 11. Further, since the outer can 10 is joined to a lid plate 20 connected to a positive electrode lead (not shown), it also serves as a positive electrode terminal of the wound battery 1. A positive electrode 31 described later of the electrode body 30 is connected to the lid plate 20 by a positive electrode lead (not shown).

  The cover plate 20 is joined to the opening of the outer can 10 by welding so as to cover the opening of the outer can 10. Thereby, the upper surface of the battery case 2 is formed by the cover plate 20. Similar to the outer can 10, the lid plate 20 is made of a member made of an aluminum alloy and is formed in a rectangular shape so as to be fitted inside the opening of the outer can 10. Moreover, the through-hole 20a is formed in the center part of the longitudinal direction at the cover board 20 (refer FIG. 2).

  As shown in FIG. 2, an insulating packing 21 made of polypropylene and a negative electrode terminal 22 made of stainless steel are inserted into the through hole 20 a of the lid plate 20. Specifically, a substantially cylindrical insulating packing 21 into which a substantially columnar negative electrode terminal 22 is inserted is fitted to the peripheral edge of the through hole 20a. The negative electrode terminal 22 has a configuration in which flat portions are integrally formed at both ends of a cylindrical shaft portion. The negative electrode terminal 22 is arranged with respect to the insulating packing 21 so that the flat surface portion is exposed to the outside and the shaft portion is positioned in the insulating packing 21. A stainless steel lead plate 27 is connected to the negative terminal 22. Thereby, the negative electrode terminal 22 is electrically connected to the negative electrode 32 of the electrode body 30 via the lead plate 27 and the negative electrode lead 35 described later. An insulator 26 is disposed between the lead plate 27 and the lid plate 20.

  Between the negative electrode terminal 22 attached to the cover plate 20 and the electrode body 30, a resin insulating plate 36 is disposed. A negative electrode lead 35 penetrates the insulating plate 36. Note that a positive electrode lead (not shown) extends to the lid plate 20 through the insulating plate 36 or through the side of the insulating plate 36.

  As shown in FIG. 2, a non-aqueous electrolyte inlet 24 is formed in the lid plate 20 along with the negative electrode terminal 22. The injection port 24 is formed in a substantially circular shape in plan view. The injection port 24 has a small diameter portion and a large diameter portion so that the diameter changes in two steps in the thickness direction of the lid plate 20. The injection port 24 is sealed by a sealing plug 25 formed in a step shape corresponding to a change in the diameter of the injection port 24. The outer peripheral portion on the large diameter side of the sealing plug 25 and the peripheral portion of the injection port 24 are joined by laser welding so that no gap is generated between the sealing plug 25 and the peripheral portion of the injection port 24. Has been. The inlet 24 and the sealing plug 25 are not limited to the above-described configuration, and may have any configuration as long as it can be sealed after injecting the nonaqueous electrolytic solution into the battery case 2. .

(Electrode body)
The electrode body 30 is formed in a state in which the positive electrode 31 and the negative electrode 32 formed in a strip shape are overlapped with each other so that the separators 33 are positioned between them and below the positive electrode 31 (see FIG. 3). The wound electrode body is formed by winding the positive electrode 31, the negative electrode 32, and the separator 33 in the direction of the white arrow in FIG. A state in which the electrode body 30 is configured by winding the positive electrode 31, the negative electrode 32, and the separator 33 is schematically shown in FIG. The electrode body 30 is formed in a flat shape after being wound in a state where the positive electrode 31, the negative electrode 32, and the separator 33 are overlapped (see FIG. 5). That is, the electrode body 30 is obtained by crushing a cylindrical wound body extending along the axis L to make it flat. As shown in FIG. 2, the flat electrode body 30 is accommodated in the battery case 2.

  As shown in FIG. 5, the electrode body 30 formed in a flat shape as described above includes a pair of bent portions 30a bent so that the positive electrode 31, the negative electrode 32, and the separator 33 are folded back in the thickness direction. The pair of bent portions 30a are located at the ends in the width direction when the electrode body 30 is viewed from the side.

  Note that the electrode body 30 shown in FIG. 2 is shown only for several layers on the outer peripheral side. However, in FIG. 2, the illustration of the inner peripheral side portion of the electrode body 30 is omitted, and naturally, the positive electrode 31, the negative electrode 32, and the separator 33 are also present on the inner peripheral side of the electrode body 30. .

  Further, in FIG. 3, in order to illustrate a state in which the positive electrode 31, the negative electrode 32, and the separator 33 are overlapped, the positions of the positive electrode 31, the negative electrode 32, and the separator 33 are moved from the actual arrangement and shown in perspective. In FIG. 3, in order to distinguish the positive electrode 31, the negative electrode 32, and the separator 33, the positive electrode 31 and the negative electrode 32 are hatched although they are not cross sections.

  In the following description, the axial direction of the electrode body 30 means a direction along the axis L. The radial direction of the electrode body 30 means a direction along the thickness direction of the positive electrode 31, the negative electrode 32, and the separator 33 constituting the electrode body 30.

  As shown in FIG. 6, the positive electrode 31 has a positive electrode active material layer 42 containing a positive electrode active material provided on one or both sides of a positive electrode current collector 41 made of a metal foil such as aluminum (see FIG. 6). In the example shown, the positive electrode active material layer 42 is provided on both surfaces of the positive electrode current collector 41). Specifically, the positive electrode 31 has a positive electrode active material that is a lithium-containing oxide capable of occluding and releasing lithium ions, a positive electrode mixture containing a conductive additive and a binder on a positive electrode current collector 41 made of aluminum foil or the like. It is formed by applying and drying.

Examples of the lithium-containing oxide that is the positive electrode active material include Li _{1 + x} M ¹ O ₂ (−0.1 <x <0.1, M ¹ : Co, Ni, Mn, Al, Mg, Ti, Zr, and the like. Lithium-containing composite oxide having a layered structure represented by one or more selected elements), LiMn ₂ O ₄ or a lithium manganese composite oxide having a spinel structure in which a part of the element is substituted with another element, Li _{4 / 3} Ti _5/3 O ₄ and a lithium manganese composite oxide synthesized at a low temperature represented by a composition such as a lithium titanium composite oxide having a spinel structure in which part of the element is substituted with another element, LiMn ₃ O ₆ And an olivine type compound represented by LiM ² PO ₄ (M ² : one or more elements selected from Co, Ni, Mn, Fe, etc.). Examples of the lithium-containing composite oxide having a layered structure include lithium cobalt oxide such as LiCoO ₂ , LiNi _1-a Co _ab Al _b O ₂ (0.1 ≦ a ≦ 0.3, 0.01 ≦ b ≦ 0.2), an oxide containing at least Co, Ni and Mn (LiMn _1/3 Ni _1/3 Co _1/3 O ₂ , LiMn _5/12 Ni _5/12 Co _1/6 O ₂ , LiNi _3/5 Examples thereof include lithium-containing nickel composite oxides such as Mn _1/5 Co _1/5 O ₂ . Note that only one type of material may be used as the positive electrode active material, or two or more types of materials may be used. Further, the positive electrode active material is not limited to the above-described materials.

  When the positive electrode active material of the secondary battery is a material with a large irreversible capacity, the battery is assembled using a laminate of the negative electrode current collector and the Al layer as the negative electrode precursor, and the assembled battery is charged to form the negative electrode It is preferable to generate a Li—Al alloy of this type because part or all of the irreversible capacity of the positive electrode can be offset by the negative electrode.

  Examples of binders for the positive electrode mixture include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), and imide binders (polyamideimide, polyimide, etc.), An amide binder (polyamide, aramid, etc.) can be used.

  In addition, conductive assistants related to the positive electrode mixture include graphite (graphite carbon material) such as natural graphite (flaky graphite), artificial graphite; acetylene black, ketjen black, channel black, furnace black, lamp black, Carbon materials such as carbon black such as thermal black; carbon fiber; and the like can be used.

  Further, the positive electrode 31 having the positive electrode active material layer 42 and the positive electrode current collector 41 includes, for example, a positive electrode active material, a conductive additive, a binder, and the like in water or an organic solvent such as N-methyl-2-pyrrolidone (NMP). Disperse to prepare a positive electrode mixture-containing composition (slurry, paste, etc.) (the binder may be dissolved in a solvent), which is applied onto the positive electrode current collector 41 and dried, and if necessary It can manufacture by passing through the process of performing press processes, such as a calendar process.

  The content of the positive electrode active material in the positive electrode mixture is preferably 80 to 98.8% by mass. Moreover, it is preferable that content of the conductive support agent in a positive mix is 1.5-10 mass%. Furthermore, the binder content in the positive electrode mixture is preferably 0.3 to 10% by mass. The thickness of the positive electrode active material layer 42 (thickness per one side of the current collector) is preferably 30 to 300 μm.

  As the positive electrode current collector 41, a metal foil such as Al or an Al alloy, a punching metal, a net, an expanded metal, or the like can be used. Usually, an Al foil is preferably used. The thickness of the positive electrode current collector 41 is preferably 10 to 30 μm.

  Although not particularly illustrated, the positive electrode lead is connected to a portion of the positive electrode current collector 41 where the positive electrode mixture is not applied, that is, a portion where the positive electrode current collector 41 is exposed.

  As shown in FIG. 6, the negative electrode 32 includes a metal base layer 45 containing a copper alloy, and a metal surface layer 46 located on both surfaces of the metal base layer 45 and containing an aluminum alloy. The negative electrode 32 is made of, for example, a clad material composed of a layer containing a copper alloy and a layer containing an aluminum alloy positioned on both surfaces of the layer. The negative electrode 32 is larger in dimensions in the longitudinal direction and the short direction than the positive electrode 31 in plan view.

  The negative electrode 32 has a negative electrode part 51 and a negative electrode end part 52. The negative electrode part 51 is provided in the electrode body 30 at a position overlapping the positive electrode active material layer 42 of the positive electrode 31 in the thickness direction. The negative electrode part 51 functions as an electrode of the negative electrode 32 with respect to the positive electrode 31.

  The negative electrode end portion 52 is provided on both sides of the negative electrode portion 51 in the short direction of the negative electrode 32. That is, the negative electrode end portion 52 is provided at both ends in the short direction of the negative electrode 32 and is provided at a position in the electrode body 30 that does not overlap the positive electrode active material layer 42 of the positive electrode 31 in the thickness direction. .

  The negative electrode portion 51 includes a Li—Al alloy on at least the surface side of the portion of the metal surface layer 46 that overlaps the positive electrode active material layer 42 of the positive electrode 31 in the thickness direction after the winding type battery 1 is charged. That is, the negative electrode 32 including the metal base layer 45 and the metal surface layer 46 is used as a precursor to charge the wound battery 1 assembled together with the positive electrode 31 described above, whereby the positive electrode 31 of the metal surface layer 46 is charged. The portion overlapping the positive electrode active material layer 42 in the thickness direction is electrochemically reacted with Li ions in the non-aqueous electrolyte. As a result, a Li—Al alloy is generated at least on the surface side of the portion of the metal surface layer 46 of the negative electrode portion 51 that overlaps the positive electrode active material layer 42 of the positive electrode 31 in the thickness direction. The portion where the Li—Al alloy is generated becomes the Al active layer.

  The metal base layer 45 may be made of nickel or the like. The metal substrate layer 45 may be laminated with the metal surface layer 46 by pressure bonding or the like. The metal surface layer 46 may be provided only on one side of the metal base layer 45. Further, instead of the metal surface layer 46, a metal layer containing an element that can be alloyed with Li (for example, Si or Sn) may be provided on one side or both sides of the metal base layer 45.

  In the metal surface layer 46, the thickness of the layer provided on one surface of the metal base layer 45 is preferably 5 μm or more, more preferably 10 μm or more, and further preferably 15 μm or more. The metal surface layer 46 has a thickness of 150 μm or less, more preferably 70 μm or less, and more preferably 50 μm or less, on the one surface of the metal base layer 45. preferable.

  The negative electrode 32 is provided with a spacer portion 53 at the negative electrode end portion 52 for suppressing the occurrence of deflection in the electrode body 30 when a Li—Al alloy is generated in the negative electrode portion 51 by charging. A detailed configuration of the spacer portion 53 will be described later.

  The separator 33 preferably has a property (that is, a shutdown function) in which the pores are blocked at 80 ° C. or higher (more preferably 100 ° C. or higher) and 170 ° C. or lower (more preferably 150 ° C. or lower). Moreover, the separator 33 can use the separator used for the normal nonaqueous electrolyte secondary battery etc., for example, the microporous film made from polyolefin, such as polyethylene (PE) and polypropylene (PP). The microporous membrane constituting the separator 33 may be, for example, one using only PE or one using only PP, or a laminate of a PE microporous membrane and a PP microporous membrane. It may be. The thickness of the separator 33 is preferably 10 to 30 μm, for example.

  In addition, in order to improve heat resistance, a laminated separator in which a heat-resistant porous layer containing an inorganic filler or the like is provided on the surface of a polyolefin microporous film as described above, or tetrafluoroethylene-perfluoro Fluorine resins such as alkoxyethylene copolymers (PFA), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polybutylene terephthalate (PBT), polymethylpentene, cellulose, aramid, polyimide, polyamideimide, and other heat resistant resins A non-woven fabric separator or the like can also be used.

  Next, the nonaqueous electrolyte in the nonaqueous electrolytic solution used in the wound battery 1 according to this embodiment will be described.

The phosphoric acid compound having a group represented by the following general formula (1) in the molecule is added to the non-aqueous electrolyte in a non-aqueous electrolyte battery using a carbon material as a negative electrode active material. It is known to have an effect of increasing

  On the other hand, in the battery using at least one negative electrode active material selected from the group consisting of Li (metal Li), Li alloy, an element alloyable with Li, and a compound containing the element, the phosphoric acid compound is added. It was found that when the non-aqueous electrolyte was used, the load characteristics in a low temperature environment after high temperature storage could be maintained high.

  In addition, in the secondary battery using the negative electrode active material, it was found that when the nonaqueous electrolyte added with the phosphoric acid compound is used, the initial charge / discharge efficiency can be improved.

  The phosphoric acid compound is known to form a SEI (Solid Electrolyte Interface) film on the surface of the positive electrode in a non-aqueous electrolyte battery using a carbon material as a negative electrode active material. In the nonaqueous electrolyte battery using the negative electrode active material as described above, it is considered that the phosphoric acid compound also acts on the negative electrode. However, it is considered that the phosphoric acid compound forms a thin and high-quality film on the surface of the negative electrode active material, unlike a compound known to form a film on the negative electrode surface such as vinylene carbonate. . Therefore, it is considered that the deterioration of the negative electrode during high-temperature storage can be suppressed and the decrease in load characteristics due to the formation of the surface film can be suppressed. Therefore, it is presumed that a battery having excellent load characteristics can be configured in a low temperature environment even after high temperature storage.

  Further, since the surface film becomes thinner, the amount of Li required for forming the film is reduced. Therefore, in the secondary battery (non-aqueous electrolyte secondary battery) having the negative electrode active material, it is estimated that the irreversible capacity of the negative electrode is reduced, so that the charge / discharge efficiency can be improved.

  As described above, in the wound battery 1 according to this embodiment, a solution (nonaqueous electrolyte) prepared by dissolving a lithium salt in the following nonaqueous solvent is used. The nonaqueous electrolyte is used by containing a phosphate compound having a group represented by the general formula (1) in the molecule.

  The phosphoric acid compound has a structure in which at least one of hydrogen atoms of phosphoric acid is substituted with a group represented by the general formula (1).

In the general formula (1), X is Si, Ge or Sn, but Si is more preferable. That is, the phosphoric acid compound is more preferably a phosphoric acid silyl ester. In the general formula (1), R ¹ , R ² and R ³ are each independently an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms. Among them, a methyl group or an ethyl group is more preferable. In addition, part or all of the hydrogen atoms possessed by R ¹ , R ² and R ³ may be substituted with fluorine. The group represented by the general formula (1) is particularly preferably a trimethylsilyl group.

  Moreover, in the said phosphoric acid compound, only one of the hydrogen atoms which phosphoric acid may have may be substituted by the group represented by the said General formula (1). Two of the hydrogen atoms of phosphoric acid may be substituted with a group represented by the general formula (1). All three hydrogen atoms of phosphoric acid may be substituted with a group represented by the general formula (1). It is more preferable that all three hydrogen atoms of phosphoric acid are substituted with the group represented by the general formula (1).

  Examples of the phosphoric acid compound include mono (trimethylsilyl) phosphate, di (trimethylsilyl) phosphate, tris (trimethylsilyl) phosphate, dimethyltrimethylsilyl phosphate, methylbis (trimethylsilyl) phosphate, diethyltrimethylsilyl phosphate, Examples thereof include diphenyl phosphate (trimethylsilyl), trisphosphate (triethylsilyl), and trisphosphate (vinyldimethylsilyl). Among these, the phosphoric acid compound is preferably mono (trimethylsilyl) phosphate, di (trimethylsilyl) phosphate, tris (trimethylsilyl) phosphate, dimethyltrimethylsilyl phosphate, or methylbis (trimethylsilyl) phosphate. Furthermore, the phosphoric acid compound is particularly preferably tris (trimethylsilyl) phosphate.

  The content of the phosphoric acid compound having the group represented by the general formula (1) in the molecule in the non-aqueous electrolyte used in the battery is 0 from the viewpoint of ensuring the above-described effects more effectively. It is preferably 1% by mass or more, more preferably 0.3% by mass or more, particularly preferably 0.5% by mass or more, and most preferably 0.7% by mass or more. If the content is too large, the thickness of the SEI film that can be formed at the electrode interface increases, which may increase resistance and reduce load characteristics. Therefore, the content of the phosphoric acid compound having a group represented by the general formula (1) in the molecule in the nonaqueous electrolyte used for the battery is preferably 8% by mass or less, and 7% by mass or less. Is more preferably 5% by mass or less, and most preferably 3% by mass or less.

  Nonaqueous electrolyte solvents include, for example, ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), and lactone rings. Compounds having 1,2-dimethoxyethane (DME), tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), 1,3-dioxolane, formamide, dimethylformamide (DMF), nitromethane, methyl formate, methyl acetate, ethyl acetate An aprotic organic solvent such as phosphoric acid triester (trimethyl phosphate, triethyl phosphate, etc.), trimethoxymethane, sulfolane, 3-methyl-2-oxazolidinone, diethyl ether, etc. Hydrofuran, etc.) and the like can be used as alone in a mixed solvent or a mixture of two or more. In order to make the effect of the phosphoric acid compound more likely to occur, propylene carbonate is preferably contained in an amount of 10% by volume or more, more preferably 20% by volume or more, in all the solvents.

The lithium salt according to the non-aqueous electrolyte, for _{example, LiClO 4, LiPF 6, LiBF4} , LiAsF 6, LiSbF 6, LiCF 3 SO 3, LiCF 3 CO 2, Li 2 C 2 F 4 (SO 3) 2, LiN ( FSO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiC _n F _{2n + 1} SO ₃ (n ≧ 2), LiN (RfOSO ₂ ) ₂ [where Rf is a fluoroalkyl group] And at least one selected from the above. The concentration of the nonaqueous electrolyte of these lithium salts is preferably 0.6 to 1.8 mol / l, and more preferably 0.9 to 1.6 mol / l. Two or more lithium salts can be used in combination. In that case, what is necessary is just to adjust so that the sum total of the density | concentration of each lithium salt may become the said range.

  In addition, it is preferable that the nonaqueous electrolyte contains a compound having a lactone ring because the discharge characteristics at a low temperature of the battery can be improved. Examples of the compound having a lactone ring include γ-butyrolactone and lactones having a substituent at the α-position.

  The lactone having a substituent at the α-position is preferably, for example, a 5-membered ring (having 4 carbon atoms constituting the ring). The α-position substituent of the lactone may be one or two.

  Examples of the substituent include a hydrocarbon group and a halogen group (fluoro group, chloro group, bromo group, iodo group) and the like. As the hydrocarbon group, an alkyl group, an aryl group, and the like are preferable, and the number of carbon atoms is preferably 1 or more and 15 or less (more preferably 6 or less), and part or all of the hydrogen atoms of the hydrocarbon group are fluorine. May be substituted. When the substituent is a hydrocarbon group, a methyl group, an ethyl group, a propyl group, a butyl group, a phenyl group, and the like are more preferable.

  Specific examples of lactones having a substituent at the α-position include α-methyl-γ-butyrolactone, α-ethyl-γ-butyrolactone, α-propyl-γ-butyrolactone, α-butyl-γ-butyrolactone, α-phenyl. -Γ-butyrolactone, α-fluoro-γ-butyrolactone, α-chloro-γ-butyrolactone, α-bromo-γ-butyrolactone, α-iodo-γ-butyrolactone, α, α-dimethyl-γ-butyrolactone, α, α -Diethyl-γ-butyrolactone, α, α-diphenyl-γ-butyrolactone, α-ethyl-α-methyl-γ-butyrolactone, α-methyl-α-phenyl-γ-butyrolactone, α, α-difluoro-γ-butyrolactone , Α, α-dichloro-γ-butyrolactone, α, α-dibromo-γ-butyrolactone, α, α-diiodo-γ-butyrolac Emissions, and the like, may be used only one of these may be used in combination of two or more. Among these, α-methyl-γ-butyrolactone is more preferable.

  In the case of using a compound having a lactone ring, the content of the compound having a lactone ring in the total organic solvent used for the non-aqueous electrolyte is 0.1 from the viewpoint of favorably ensuring the effect of the use. It is preferably at least mass%, more preferably at least 0.5 mass%, particularly preferably at least 1 mass%. On the other hand, in order not to inhibit the action of the phosphate compound having the group represented by the general formula (1) in the molecule, it is preferably 30% by mass or less, more preferably 10% by mass or less, It is particularly preferably 5% by mass or less.

  The nonaqueous electrolyte preferably contains a nitrile compound. The nitrile compound in the non-aqueous electrolyte forms a film mainly on the surface of the positive electrode in the battery, and suppresses elution of transition metals (Co, Mn, etc.) in the positive electrode active material. Therefore, by using the nitrile compound together with the phosphoric acid compound having the group represented by the general formula (1) in the molecule, the high-temperature storage characteristics of the battery can be further improved.

  Specific examples of the nitrile compound include mononitriles such as acetonitrile, propionitrile, butyronitrile, valeronitrile, benzonitrile, acrylonitrile; malononitrile, succinonitrile, glutaronitrile, adiponitrile, 1,4-dicyanoheptane, 1,5 -Dicyanopentane, 1,6-dicyanohexane, 1,7-dicyanoheptane, 2,6-dicyanoheptane, 1,8-dicyanooctane, 2,7-dicyanooctane, 1,9-dicyanononane, 2,8-dicyanononane 1,10-dicyanodecane, 1,6-dicyanodecane, dinitriles such as 2,4-dimethylglutaronitrile; cyclic nitriles such as benzonitrile; alkoxy-substituted nitriles such as methoxyacetonitrile; 1 of May be used alone, or in combination of two or more kinds. Among these nitrile compounds, adiponitrile is more preferable.

  The content of the nitrile compound in the non-aqueous electrolyte used in the battery is preferably 1% by mass or more, more preferably 2% by mass or more, from the viewpoint of ensuring the above-mentioned effect better. However, since the nitrile compound has high reactivity with the negative electrode (lithium), it is preferable to limit the amount of the nitrile compound used to some extent to suppress an excessive reaction between them. Therefore, the content of the nitrile compound in the non-aqueous electrolyte used for the battery is preferably 8% by mass or less, and more preferably 5% by mass or less.

  In addition, to these nonaqueous electrolytes, for the purpose of further improving various characteristics of the battery, vinylene carbonates, cyclic sultone compounds such as 1,3-propane sultone, 1,3-propene sultone, disulfide compounds such as diphenyl disulfide, Benzene compounds such as cyclohexylbenzene, biphenyl, fluorobenzene, t-butylbenzene, fluorine-substituted cyclic carbonates such as 4-fluoro-1,3-dioxolan-2-one (FEC), lithium tetrakis (acetate) borate, Additives such as lithium organic borate such as lithium bis (oxalate) borate (LiBOB) can be added as appropriate. In particular, the use of a cyclic sultone compound or an organic borate lithium salt together with a phosphoric acid compound having in its molecule the group represented by the general formula (1) is considered to form a suitable surface coating on the positive electrode or the negative electrode. It is done. Thereby, it is considered that the high-temperature storage characteristics of the battery can be further improved.

  Further, as the non-aqueous electrolyte, the above-mentioned solution (non-aqueous electrolyte) may be made into a gel (gel electrolyte) using a known polymer or other gelling agent.

(Spacer part)
As described above, by charging the wound battery 1, at least the surface side of the portion of the metal surface layer 46 of the negative electrode portion 51 that faces the positive electrode active material layer 42 with the separator 33 interposed therebetween is Li -An Al alloy is produced. Thus, when the Li—Al alloy is generated on the metal surface layer 46 of the negative electrode portion 51, the portion where the Li—Al alloy is generated expands in the thickness direction. Therefore, the thickness of the negative electrode portion 51 after charging is larger than the negative electrode end portion 52 where no Li—Al alloy is generated.

  The winding type battery 1 is charged after the electrode body 30 is formed by winding the positive electrode 31, the negative electrode 32, and the separator 33 and the electrode body 30 is accommodated in the battery case 2. In this case, the electrode body 30 is constrained on the outer part by the battery case 2, and deformation on the outer peripheral side is restricted by the bent portion 30 a of the electrode body 30. Therefore, even when the negative electrode portion 51 expands in the thickness direction as described above by charging the wound battery 1, the deformation of the electrode body 30 outward in the radial direction is restricted.

  Therefore, the expansion of the negative electrode portion 51 inside the electrode body 30 affects the inside of the electrode body 30. That is, since the deformation due to the expansion of the negative electrode portion 51 pushes the positive electrode 31, the negative electrode 32, and the separator 33 toward the inside of the electrode body 30, in the configuration of the conventional electrode body, as shown in FIG. Deflection occurs inside the electrode body 230. As described above, when the deflection occurs in the electrode body 230, the distance between the positive electrode and the negative electrode varies, and sufficient battery characteristics cannot be obtained. FIG. 8 is a view of the conventional electrode body 230 as seen from the axial direction. In FIG. 8, for simplicity of illustration, a state in which the positive electrode, the negative electrode, and the separator are stacked in the thickness direction is illustrated as one sheet.

  On the other hand, in this embodiment, as shown in FIGS. 2 to 4, 6, and 7, the negative electrode end 52 of the negative electrode 32 is interposed between the negative electrode ends 52 adjacent to each other in the radial direction of the electrode body 30. A spacer portion 53 is provided so as to be positioned. The spacer portion 53 is formed of a tape or resin as will be described later, and is a member different from the negative electrode 32. Thereby, the thickness of the spacer part 53 can be adjusted easily.

  The spacer portion 53 is provided at the negative electrode end portion 52 so as to extend in the longitudinal direction of the negative electrode 32. A pair of spacer portions 53 are provided on the negative electrode end portions 52 located on both sides of the negative electrode portion 51 in the short direction, that is, so as to sandwich the negative electrode portion 51 in the short direction. As shown in FIGS. 2 to 4, 6, and 7, the spacer portion 53 is preferably provided at an end portion in the short direction of the negative electrode 32, but is not limited thereto, and is not limited to the negative end portion 52. Any position may be used as long as it is provided.

  The spacer portion 53 is made of a resin tape (polyethylene terephthalate (PET) tape, polypropylene (PP) tape, polyphenylene sulfide resin (PPS) tape, polyimide tape, etc.), or various resins or ultraviolet curable resins that are cured by ultraviolet rays. It is made of a material that does not contribute to the battery reaction, such as a molded member or an adhesive made of various resins. Thereby, it is possible to prevent the spacer portion 53 from affecting the battery characteristics of the wound battery 1.

  The spacer portion 53 has a thickness X that is larger than the thickness of the positive electrode 31. Thereby, in the electrode body 30 before charging, the interval between the negative electrode portions 51 adjacent in the radial direction can be made larger than the thickness of the positive electrode 31. Therefore, even when the negative electrode portion 51 expands in the thickness direction due to the charging of the wound battery 1, the occurrence of deflection inside the electrode body 30 can be suppressed.

  The spacer portion 53 has a thickness that is equal to or greater than the sum of the thickness of the positive electrode 31 and the thickness of the negative electrode portion 51 (the difference between the thickness of the negative electrode portion 51 and the thickness of the negative end portion 52). preferable. Thereby, the space | interval of the negative electrode part 51 adjacent to radial direction in the electrode body 30 before charge can be made into the space | interval more than the sum total of the thickness of the positive electrode 31, and the thickness of the expansion of the negative electrode part 51. Therefore, even when the negative electrode portion 51 expands in the thickness direction due to the charging of the wound battery 1, it is possible to more reliably suppress the occurrence of deflection inside the electrode body 30.

  In addition, the spacer portion 53 has a thickness less than the sum of the thickness of the positive electrode 31 and the thickness of the negative electrode portion 51 (the difference between the thickness of the negative electrode portion 51 and the thickness of the negative electrode end portion 52). May be. When the thickness of the spacer portion 53 is increased, the inter-electrode distance between the positive electrode 31 and the negative electrode portion 52 is increased, and battery characteristics may be deteriorated. On the other hand, by setting the thickness of the spacer portion 53 to the above-described thickness, the interelectrode distance between the positive electrode 31 and the negative electrode portion 52 is within an appropriate range while suppressing the occurrence of deflection inside the electrode body 30. can do. That is, with the above-described configuration, it is possible to achieve both suppression of the occurrence of deflection within the electrode body 30 and prevention of deterioration of the battery characteristics of the wound battery 1.

  In FIG. 9, the figure which looked at the electrode body 30 after charge from the axial direction is shown. In FIG. 9, as in FIG. 8, for simplicity of illustration, a state in which the positive electrode, the negative electrode, and the separator are stacked in the thickness direction is described as one sheet. As shown in FIG. 9, in the electrode body 30 of the present embodiment provided with the spacer portion 53 as described above, it is possible to suppress the occurrence of deflection inside the electrode body 30 even after charging.

  That is, by providing the spacer portion 53 as described above, even when the negative electrode portion 51 expands due to charging as shown in FIG. 7, the positive electrode 31, the negative electrode 32, and the separator 33 have a diameter of the electrode body 30 due to the expansion. It can prevent being pushed inward in the direction. Therefore, the interval T between the negative electrodes 32 adjacent to each other in the electrode body 30 hardly changes in FIGS. Thereby, it is possible to suppress the occurrence of deflection inside the electrode body 30.

  The spacer portion 53 is provided on the outer peripheral side of the negative electrode 32 in the electrode body 30. That is, as shown in FIG. 4, when the spacer portion 53 is wound in a state where the negative electrode 32, the positive electrode 31 and the separator 33 are stacked in the thickness direction, the outer surface of the negative electrode 32 in the radial direction of the electrode body 30. (A surface located on the separator 33 and the positive electrode 31 side). Accordingly, when the negative electrode 32, the positive electrode 31, and the separator 33 are wound in a state where they are stacked in the thickness direction, a tensile force acts on the spacer portion 53 in the longitudinal direction of the negative electrode 32. Therefore, the electrode body 30 can be formed without the spacer portion 53 being bent. In addition, when the spacer part 53 is formed of resin or the like instead of a tape, it is preferably provided on the inner peripheral side of the negative electrode 32 in the radial direction of the electrode body 30 from the viewpoint of preventing the spacer part 53 from peeling off.

  The spacer portion 53 may be divided in the thickness direction and provided on both sides of the negative electrode 32. That is, as shown in FIG. 11, spacer portions 53a and 53b may be provided on both sides of the negative electrode 32, respectively. In the case of the configuration shown in FIG. 11, the spacer portions 53a and 53b constitute the spacer portion of the present invention. The spacer portions 53a and 53b may each be half the thickness of the spacer portion 53. If the total thickness of the spacer portions 53a and 53b is the same as that of the spacer portion 53, the thickness of the spacer portions 53a and 53b is May be different. The total thickness of the spacer portions 53 a and 53 b adjacent to each other in the radial direction of the electrode body 30 is larger than the thickness of the positive electrode 31. Thereby, compared with the case where the spacer part 53 is provided in the surface of one side of the negative electrode 32, the thickness of the spacer parts 53a and 53b can be made small, respectively. Therefore, when the negative electrode 32, the positive electrode 31, and the separator 33 are wound in a state where they are stacked in the thickness direction, it is possible to more reliably prevent sagging and wrinkles from occurring in the spacer portions 53a and 53b.

  Moreover, the spacer part may be comprised by the convex part 252a integrally formed in the negative electrode edge part 252 as shown in FIG. Thus, by providing the convex part 252a which protrudes in the thickness direction in a part of the negative electrode end part 252, the spacer part can be easily configured without configuring the spacer part by another member. Therefore, the electrode body of this embodiment can be obtained easily. In FIG. 12, reference numeral 232 indicates a negative electrode, reference numeral 251 indicates a negative electrode portion, and reference numeral 252 indicates a negative electrode end.

  In the present embodiment, the spacer portion 53 is provided on the negative electrode 32, but is not limited thereto, and may be provided on the separator 33. When the spacer portion 53 is provided on the separator 33, another member may be formed on the separator 33 as in the case where the spacer portion 53 is provided on the negative electrode 32, or a convex portion may be provided integrally on the separator 33. The spacer portion 53 may be provided on both the negative electrode 32 and the separator 33.

  In the wound battery 1 according to this embodiment, an Al active layer containing a Li—Al alloy can be formed on the negative electrode portion 51 of the negative electrode 32 having the metal surface layer 46 by charging the battery. Thereby, the winding type battery 1 with high heat resistance is obtained.

  In addition, in the electrode body 30 having a flat cross section, the spacer portion 53 is provided at the negative electrode end portion 52 that does not overlap the positive electrode 31 in the thickness direction, whereby the negative electrode portion 51 that overlaps the positive electrode 31 in the thickness direction is charged by charging the battery. Even when the negative electrode portion 51 expands when the Li—Al alloy is generated, it is possible to suppress the occurrence of deflection in the electrode body 30.

  That is, the above-described expansion in the negative electrode portion 51 of the negative electrode 32 can be absorbed by the space formed between the negative electrodes adjacent to each other in the radial direction of the electrode body 30 by the spacer portion 53. Therefore, it is possible to suppress the force that causes the positive electrode 32, the negative electrode 31, and the separator 33 from being displaced inward in the radial direction of the electrode body 30 due to the above-described expansion of the negative electrode portion 51. Thereby, it is possible to suppress the deflection of the positive electrode 31, the negative electrode 32, and the separator 33 in the electrode body 30. Therefore, in the wound battery 1 in which the Li—Al alloy is generated on the negative electrode 32 by charging the battery as described above, it is possible to suppress the inter-electrode distance from becoming uneven inside the electrode body 30, and the battery characteristics are improved. A decrease can be prevented.

  And the battery characteristic of the winding type battery 1 can be improved by the above-mentioned structure. That is, by providing the spacer part 53 larger than the thickness of the positive electrode 31 between the negative electrode end parts 52 adjacent to each other in the radial direction of the electrode body 30 as described above, the radial direction is adjacent to the radial direction in the state before charging. The interval between the matching negative electrode portions 51 is larger than the thickness of the positive electrode 31. Therefore, a gap is formed between the positive electrode 31 and the negative electrode part 51. Thereby, the non-aqueous electrolyte can be easily infiltrated into the electrode body 30.

  Furthermore, by making the thickness of the spacer portion 53 equal to or greater than the sum of the thickness of the positive electrode 31 and the thickness of the negative electrode portion 51, the amount of expansion of the negative electrode portion 51 can be more reliably absorbed. Therefore, the occurrence of deflection in the electrode body 30 can be more reliably suppressed, and the deterioration of the battery characteristics of the wound battery 1 can be more reliably prevented.

  Further, by providing the spacer portion 53 from one end portion to the other end portion in the longitudinal direction of the negative electrode 32, it is possible to more reliably suppress the occurrence of deflection within the electrode body 30.

In addition, as the nonaqueous electrolytic solution of the wound battery 1, a nonaqueous electrolytic solution containing a phosphoric acid compound having a group represented by the following general formula (1) in the molecule in an amount of 8% by mass or less is used. Thus, a battery having good load characteristics at a low temperature after high-temperature storage can be obtained. Moreover, in the configuration capable of suppressing the occurrence of deflection in the electrode body 30 as in the present embodiment, the reaction in the electrode body 30 is made uniform by using the non-aqueous electrolyte as described above. As the process proceeds, gas generation in the wound battery 1 can be effectively suppressed. Therefore, the wound battery 1 having high heat resistance and improved battery characteristics can be obtained.

In the general formula (1), X is Si, Ge or Sn, and R ¹ , R ² and R ³ are each independently an alkyl group having 1 to 10 carbon atoms or an alkenyl having 2 to 10 carbon atoms. Represents a group or an aryl group having 6 to 10 carbon atoms, and part or all of the hydrogen atoms may be substituted with fluorine.

(Other embodiments)
While the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and the above-described embodiment can be appropriately modified and implemented without departing from the spirit of the invention.

  In the embodiment, the electrode body 30 is accommodated in the rectangular parallelepiped battery case 2. However, the electrode body 30 may be accommodated in an exterior body having another configuration. For example, the electrode body 30 may be accommodated in the laminate film exterior body, or may be accommodated in a battery case having another can structure.

  As an example of another exterior body in which the electrode body 30 is accommodated, FIG. 13 shows an example of a wound battery 101 in which the electrode body 30 is accommodated in a laminate film exterior body 110 (exterior body).

  The wound battery 101 is a secondary battery having a rectangular shape in a plan view in which the electrode body 30 is covered with the laminate film exterior body 110. The wound battery 101 includes an electrode body 30 and a laminate film exterior body 110 that covers the electrode body 30. The wound battery 101 includes a positive electrode connection terminal 121 and a negative electrode connection terminal 122 that are electrically connected to the positive electrode 31 and the negative electrode 32 of the electrode body 30, respectively. In addition, a non-aqueous electrolyte similar to that in the above-described embodiment is also enclosed in the wound battery 1.

  The laminate film exterior body 110 is made of a material in which one side of an aluminum metal foil is covered with nylon and the other side is covered with polypropylene. That is, the laminate film exterior body 110 is made of a material obtained by laminating aluminum with nylon and polypropylene. Thereby, the laminate film exterior body 110 is welded by applying pressure while heating in a state where the laminate film exterior bodies 110 are overlapped. The metal foil is not limited to aluminum but may be formed of other metal materials such as stainless steel.

  Moreover, the laminate film exterior body 110 is formed in a substantially rectangular shape. With the electrode body 30 sandwiched between the pair of laminate film exterior bodies 110, the outer peripheral sides of the laminate film exterior body 110 are welded together to form a bulging portion 101a and a seal portion 101b as shown in FIG. The That is, the bulging portion 101a is formed by covering the electrode body 30 with the laminate film exterior body 110, and the bulging portion 101a is surrounded by welding the laminate film exterior body 110 around the bulging portion 101a. The seal portion 101b is formed.

  In the portion of the seal portion 101b located on the end side in the longitudinal direction of the wound battery 101, the positive electrode connection terminal 121 and the negative electrode connection terminal 122 are laminated with the pair of laminate film exterior bodies 110 sandwiched therebetween. The film exterior bodies 110 are fixed by welding. The positive electrode connection terminal 121 and the negative electrode connection terminal 122 are respectively connected to a positive electrode lead and a negative electrode lead 35 attached to the electrode body 30. Thereby, the electrode body 30 covered with the laminate film exterior body 110 can be electrically connected to the outside.

  In the above description, the configuration in which the outer peripheral sides of the pair of laminate film exterior bodies 110 are welded to each other has been described. However, the present invention is not limited to this, and one laminate film exterior body is folded back so as to sandwich the electrode body 30 therebetween. It may be welded. The direction in which the laminate film exterior body is folded back may be the extending direction of the positive electrode connection terminal 121 and the negative electrode connection terminal 122 with respect to the electrode body 30 or the width direction.

  Even in the configuration in which the electrode body 30 is covered with the laminate film exterior body 110 as described above, by providing the spacer portion 53 on the negative electrode 32 as in the above-described embodiment, the negative electrode portion 51 is expanded during battery charging. It is possible to suppress the occurrence of deflection inside the electrode body 30.

  Further, by placing a non-aqueous electrolyte containing the same non-aqueous electrolyte as in the above-described laminate film outer package 110, a wound battery having high heat resistance and capable of suppressing gas generation is obtained. It is done.

  In the embodiment, the spacer 53 is provided from one end in the longitudinal direction of the negative electrode 32 to the other end. However, the spacer portion 53 may be provided only in a part of the negative electrode 32 in the longitudinal direction. For example, the spacer portion 53 may be provided only in a portion of the negative electrode 32 that is located in the bent portion 30 a of the electrode body 30, or may be provided at a predetermined interval in the longitudinal direction of the negative electrode 32. In the bent portion 30 a of the electrode body 30, deformation of the electrode body 30 outward in the radial direction due to expansion of the negative electrode portion 51 is restricted by the outer peripheral side of the electrode body 30. For this reason, the positive electrode 31 and the like are pushed inward of the electrode body 30, and deflection occurs at a portion other than the bent portion 30 a of the electrode body 30. On the other hand, as described above, by providing the spacer portion 53 in the negative electrode 32 at a portion located in the bent portion 30a of the electrode body 30, even when the negative electrode portion 51 expands in the bent portion 30a, the positive electrode 31. Etc. are not pushed inward of the electrode body 30. Therefore, it is possible to suppress the occurrence of deflection inside the electrode body 30.

  In the embodiment, the spacer portions 53 are respectively provided on the negative electrode end portions 52 on both sides of the negative electrode portion 51 in the short direction, that is, so as to sandwich the negative electrode portion 51 in the short direction. However, the spacer portion 53 may be provided on only one side of the negative electrode end portion 52 located on one side of the negative electrode portion 32 in the short side direction, that is, on both sides of the negative electrode portion 51 in the short side direction. Further, the negative electrode end portion 52 may be provided only on one side of the negative electrode portion 51 in the short direction. In addition, it is preferable to provide the spacer part 53 in the both sides of the transversal direction of the negative electrode part 51, ie, each negative electrode edge part 52, respectively. Thereby, in the electrode body 30, the space | interval of the negative electrode part 51 adjacent to radial direction can be ensured more reliably.

  In the embodiment, the negative electrode 32 is constituted by a clad material composed of the metal base layer 45 and the metal surface layer 46. However, the negative electrode 32 may have a configuration other than the clad material as long as it has a metal base layer and a metal surface layer. The negative electrode 32 is formed by combining a powder containing an element that can be alloyed with Li with a binder or the like, and applying the mixture onto the surface of a metal foil (metal substrate layer) that serves as a current collector. Also good. In such a configuration, a powder containing an element that can be alloyed with Li may be used in combination with a negative electrode active material (for example, a carbon material such as graphite) capable of inserting and extracting Li ions.

  In the embodiment, the negative electrode 32 has the metal surface layer 46 on both surfaces of the metal base layer 45. However, the metal surface layer 46 may be provided only on one surface of the metal base layer 45. In this case, the positive electrode may be disposed so that the positive electrode active material layer is positioned at a position facing the metal surface layer 46 with the separator 33 interposed therebetween.

  In the embodiment, the positive electrode 31 and the negative electrode 32 each formed in a strip shape are overlapped with the separator 33 such that the separator 33 is positioned between the two and the lower side of the positive electrode 31, for example. However, the order in which the positive electrode 31, the negative electrode 32, and the separator 33 are stacked may be any order as long as the secondary battery can be configured.

  In the embodiment, the positive electrode 31 of the electrode body 30 is electrically connected to the outer can 10, but the present invention is not limited thereto, and the negative electrode 32 may be electrically connected to the outer can 10.

  In the said embodiment, the phosphoric acid compound which has group represented by the said General formula (1) in a molecule | numerator is contained and used for a nonaqueous electrolyte. However, any non-aqueous electrolyte solution may be used as long as it is capable of causing a battery reaction by alloying lithium at the negative electrode.

  Hereinafter, the effect of the spacer portion in the wound battery according to the embodiment will be described. Specifically, the amount of deformation of the electrode body and the battery case when the thickness of the spacer portion was changed was confirmed before and after charging of the wound battery manufactured as follows. However, the following examples do not limit the present invention.

<Preparation of positive electrode>
LiNi _0.8 Co _0.15 Al _0.05 O _{2 as} a positive electrode active material: 97 parts by mass, acetylene black as a conductive auxiliary agent: 1.5 parts by mass, PVDF as a binder: 1.5 parts by mass Is applied to both surfaces of a 12 μm-thick Al foil, dried, and subjected to a press treatment, whereby approximately 12.7 mg / ml is applied to one surface of the Al foil current collector. A positive electrode active material layer having a mass of cm ² (per one side) was formed. Furthermore, the positive electrode active material layer was pressed to produce a strip-like positive electrode having a length of 974 mm and a width of 40 mm. An aluminum lead body was attached to the positive electrode. The positive electrode had a thickness of 90 μm where the positive electrode active material layer was formed.

<Production of negative electrode>
A clad material (laminated metal foil) having a size of 988 mm × 44 mm obtained by laminating an Al foil having a thickness of 20 μm on both surfaces of a 35 μm thick Cu foil was used for the production of the negative electrode. A nickel lead body for conductive connection with the outside of the battery was attached to the clad material. The negative electrode had a thickness of 75 μm.

  A PET tape having a predetermined thickness was attached to both ends of the negative electrode on both sides in the short direction from one end to the other end in the longitudinal direction of the negative electrode.

  The positive electrode and the negative electrode were laminated via a separator made of PE microporous film with a thickness of 16 μm, wound in a spiral shape, and then crushed to form a flat electrode body. In the production of the electrode body, the separator was disposed so that the surface side to which the boehmite of the separator was bound was opposed to the positive electrode.

Further, LiBF ₄ was dissolved at a concentration of 1.2 mol / l in a mixed solvent of propylene carbonate (PC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DEC) at a volume ratio of 17:63:20, and adiponitrile was further added. : 5 mass%, Tris (trimethylsilyl) phosphate (TMSP): The nonaqueous electrolyte solution was prepared by adding in the quantity used as 2 mass%.

  A rectangular nonaqueous electrolyte solution having the structure shown in FIGS. 1 and 2 is formed by enclosing the electrode body and the nonaqueous electrolyte solution in an aluminum alloy outer can having a size of 103450 and a thickness of 0.8 mm. The next battery was obtained. The obtained battery was 9.8 mm in thickness in the short direction before being charged (before chemical conversion).

  As a chemical conversion treatment of the battery obtained as described above, the battery was charged so that the amount of expansion in the thickness direction of the negative electrode was 30 μm. The presence or absence of distortion (deflection) in the electrode body after charging (after chemical conversion) and the change in the thickness of the entire battery were examined.

  The case where the total thickness of the PET tape attached to both surfaces of the negative electrode is 90 μm is a comparative example, and the cases where the total thickness is 100 μm, 110 μm, 120 μm, and 130 μm are examples 1 to 4, respectively.

  FIG. 10 shows the presence or absence of strain (deflection) in the electrode body and the change in battery thickness after the battery is charged (after formation) when the thickness of the spacer portion is changed. The strain (deflection) in the electrode body is a result of confirming the inside of the electrode body after charging by CT (Computed Tomography) in the state of the battery, that is, in a state where the electrode body is disposed in the battery case.

  As shown in FIG. 10, when the thickness of the spacer portion was the same as the thickness of the positive electrode (Comparative Example 1), the strain (deflection) in the electrode body was large and the thickness of the entire battery was also large. On the other hand, when the thickness of the spacer portion is larger than the thickness of the positive electrode (in the case of Examples 1 to 4), the strain (deflection) in the electrode body and the battery thickness are the same as the thickness of the positive electrode. Compared to the same case (Comparative Example 1), it was smaller.

  In addition, when the thickness of the spacer portion was equal to or greater than the sum of the thickness of the positive electrode and the thickness of the negative electrode due to charging (110 μm), no distortion (deflection) occurred in the electrode body.

  Thereby, it is preferable that the thickness of a spacer part is larger than the thickness of a positive electrode, and more than the sum total of the thickness of a positive electrode and the expansion part of the negative electrode by charge is more preferable.

  INDUSTRIAL APPLICABILITY The present invention can be used for a wound battery in which an electrode body formed by winding a positive electrode, a negative electrode, and a separator is housed in an exterior body.

Claims (15)

Each of the positive electrode, the negative electrode, and the separator each formed in a strip shape is wound so that the separator is positioned between the positive electrode and the negative electrode, and the cross section orthogonal to the axial direction is a flat columnar shape extending in the axial direction Electrode body,
An exterior body in which the electrode body is enclosed;
The negative electrode is
A negative electrode portion disposed so as to overlap the positive electrode across the separator as viewed from the thickness direction;
A negative electrode end portion that is provided in at least one of the short sides of the negative electrode with respect to the negative electrode portion and does not overlap with the positive electrode when viewed from the thickness direction;
The negative electrode portion includes an element that can be alloyed with Li,
The electrode body is located in at least a part between the negative electrode end portions adjacent to each other in the radial direction of the electrode body in a cross section orthogonal to the axial direction of the electrode body, and is larger than the thickness of the positive electrode A wound battery having a spacer portion having a thickness. The wound battery according to claim 1,
The electrode body has a bent portion bent so that the positive electrode, the negative electrode, and the separator are folded in the thickness direction in the cross section;
The said spacer part is a winding type battery located between the said adjacent negative electrode edge parts in the said bending part of the said electrode body. The wound battery according to claim 1 or 2,
The said spacer part is a winding type battery which has thickness more than the sum total of the thickness of the said positive electrode, and the difference of the thickness of the said negative electrode part, and the thickness of the said negative electrode edge part. The wound battery according to claim 1 or 2,
The spacer part is a wound battery having a thickness less than the total of the thickness of the positive electrode and the difference between the thickness of the negative electrode part and the thickness of the negative electrode end part. In the wound battery according to any one of claims 1 to 4,
The spacer portion is a wound battery provided in at least one of the negative electrode end and the separator. The wound battery according to claim 5, wherein
The said spacer part is a winding type battery provided in the at least one of the said negative electrode edge part and the said separator ranging from one edge part of the longitudinal direction to the other edge part. The wound battery according to claim 5 or 6,
The said spacer part is a winding type battery provided in the said electrode body in the radial direction outer peripheral side of at least one of the said negative electrode edge part and the said separator. The wound battery according to claim 5 or 6,
The spacer portion is provided on at least one side of the negative electrode end portion and the separator, and the total thickness of the spacer portions adjacent to each other in the radial direction of the electrode body is greater than the thickness of the positive electrode. Large, wound battery. The wound battery according to any one of claims 5 to 8,
The said spacer part is a winding type battery comprised by the member different from the said negative electrode edge part and the said separator. The wound battery according to any one of claims 5 to 8,
The spacer unit is a wound battery provided integrally with at least one of the negative electrode end and the separator. The wound battery according to any one of claims 1 to 10,
The said negative electrode part is a winding type battery which contains a Li-Al alloy as a negative electrode active material after charge of a battery. The wound battery according to claim 11, wherein
The negative electrode is a laminate having a metal base layer that is not alloyed with Li and a metal surface layer bonded to at least one of the thickness directions of the metal base layer.
At least the surface side of the metal surface layer in the negative electrode portion is a wound battery including the Li-Al alloy after the battery is charged. The wound battery according to any one of claims 1 to 12,
The said spacer part is a winding type battery comprised with the resin material which does not contribute to a battery reaction. The wound battery according to any one of claims 1 to 13,
The exterior body is a wound battery including an exterior can that houses the electrode body. The wound battery according to any one of claims 1 to 13,
The outer package includes a laminate film outer package that houses the electrode assembly.

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