JP2013097980A - Nonaqueous electrolyte secondary battery and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery manufacturing method which can impregnate a nonaqueous electrolyte into the wound coated part of a flat wound electrode body in a short time without deteriorating the cycle charge-discharge characteristic of the battery.SOLUTION: Lower uncoated parts 155f, 156f, of wound coated parts 155d, 156d, which are located below a position at which current collector terminal members 120 and 130 are to be welded or have been welded when a flat wound electrode body 150A is housed in a battery case 160 are cut off. The battery case 160 used here is the one in which counter faces 112b, 112f opposed in an axis direction AX to cut faces 150b, 150c of the flat wound electrode body 150 which has had the lower uncoated parts 155f, 156f cut off are located to the inside in the battery case 160 with respect to the axis direction AX from the inner faces 112c, 112g opposed in the axis direction AX to the end faces of the wound coated parts 155d, 156d at an upper position than those.

Description

  The present invention relates to a non-aqueous electrolyte secondary battery and a manufacturing method thereof.

  Non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries are attracting attention as power sources for portable devices and power sources for electric vehicles and hybrid vehicles. In recent years, various nonaqueous electrolyte secondary batteries have been proposed (see, for example, Patent Document 1).

JP 2006-128132 A

  Patent Document 1 discloses a flat wound electrode body (electrode group) formed by winding a positive electrode, a negative electrode, and a separator into a flat shape, a rectangular parallelepiped battery case that houses the flat wound electrode body, and a current collecting terminal A secondary battery including a member (lead element) is disclosed. The current collecting terminal member has a positive electrode mixture layer uncoated part (plain part) and a negative electrode mixture layer uncoated part (plain part) at the positions of both ends in the axial direction of the flat wound electrode body. It is welded to the wound uncoated part which is wound respectively. In detail, the current collection terminal member is welded to the flat part located in the center of the winding non-coating part.

  Further, in Patent Document 1, after cutting both ends of the uncoated portion of the wound (upper and lower end portions where the composite material layer uncoated portion has an arc shape), it is positioned at the center of the uncoated portion of the wound. The form which welds a current collection terminal member to the flat part to perform is disclosed. It is described that the current collecting terminal member can be connected in a good state to the flat part located at the center of the wound uncoated part by cutting off the end of the wound uncoated part. Yes.

  By the way, in the non-aqueous electrolyte secondary battery of Patent Document 1 or the like, the non-aqueous electrolyte is impregnated in the wound coating portion of the flat wound electrode body. Specifically, first, after the flat wound electrode body is accommodated in the battery case, a nonaqueous electrolyte is injected into the battery case in which the flat wound electrode body is accommodated in the liquid injection process. Thereafter, in the impregnation step, the non-aqueous electrolyte injected into the battery case is impregnated into the wound coating portion of the flat wound electrode body. Here, the wound coating portion refers to a portion formed by winding the positive electrode mixture layer coating portion, the negative electrode mixture layer coating portion, and the separator.

  The nonaqueous electrolyte injected into the rectangular battery case that accommodates the flat wound electrode body enters the inside of the wound coating part through both axial end faces (left and right end faces) of the wound coating part. Furthermore, the entrance of the non-aqueous electrolyte into the wound coating part is only the axial end faces (left and right end faces) of the wound coating part. In addition, the wound coating portion is wound with a positive electrode (a mixture layer coating portion), a negative electrode (a mixture layer coating portion), and a separator wound tightly (with almost no gap). It was difficult for the non-aqueous electrolyte to penetrate into the inside of the coating part, and as a result, it took a long time to complete the impregnation of the non-aqueous electrolyte into the winding part.

  As described above, the entrance of the non-aqueous electrolyte to the inside of the wound coating portion is both end surfaces (left and right end surfaces) in the axial direction of the wound coating portion. Therefore, in order to impregnate the non-aqueous electrolyte in the wound coating portion in a short time, it is necessary to increase the area of the portion where the non-aqueous electrolyte is in contact with both axial end surfaces of the wound coating portion. preferable. For this purpose, for example, a method of injecting a large amount of non-aqueous electrolyte to raise the liquid level of the non-aqueous electrolyte in the liquid injection step can be considered.

  However, since the amount of non-aqueous electrolyte impregnated inside the wound coating portion is limited, if the amount of non-aqueous electrolyte injected is increased, the excess electrolyte does not penetrate into the wound coating portion The amount of liquid increases. When the amount of the excess electrolyte increases, the cycle charge / discharge characteristics of the battery are greatly deteriorated. For this reason, it was not preferable to inject an excessive non-aqueous electrolyte into the battery case.

  The present invention has been made in view of the present situation, and impregnates the non-aqueous electrolyte in the wound coating portion of the flat wound electrode body in a short time without deteriorating the cycle charge / discharge characteristics of the battery. An object of the present invention is to provide a method for producing a non-aqueous electrolyte secondary battery that can be used, and a non-aqueous electrolyte secondary battery having good cycle charge / discharge characteristics.

  One aspect of the present invention includes a flat wound electrode body obtained by winding a positive electrode, a negative electrode, and a separator into a flat shape, a rectangular battery case that accommodates the flat wound electrode body, and the flat wound electrode body A non-aqueous electrolyte impregnated in the electrode, and a current collecting terminal member, wherein the flat wound electrode body comprises the positive electrode mixture layer coating portion, the negative electrode mixture layer coating portion, and The wound coating part formed by winding the separator, and the axially opposite ends of the flat wound electrode body, the positive electrode mixture layer uncoated part and the negative electrode mixture layer uncoated A non-aqueous electrolyte secondary battery produced by welding the winding terminal member to the winding non-coated portion. A winding step of winding the positive electrode, the negative electrode, and the separator into a flat shape to form a flat wound electrode body, and the flat Of the wound uncoated portion of the wound electrode body, when the flat wound electrode body is in a posture to be accommodated in the battery case, the current collector terminal member is to be welded or below the welded portion. An excision step of excising the lower uncoated part located in the step, a step of accommodating the flat wound electrode body excised from the lower uncoated part in the battery case, and the flat wound electrode body Injecting the non-aqueous electrolyte into the battery case accommodated, and an impregnation step of impregnating the non-aqueous electrolyte injected into the battery case into the wound coating part, As the battery case, a cutting surface of the flat wound electrode body obtained by excising the lower uncoated portion of the inner side surface of the battery case and a facing surface facing the axial direction are positioned at a position above the upper surface. Opposite to the end face of the uncoated part in the axial direction Than the inner surface, a method of manufacturing a nonaqueous electrolyte secondary battery using the battery case in a form is positioned on the inside of the battery case for the axial direction.

  In the above-described manufacturing method, in the cutting process, the lower uncoated part (the lower positive electrode uncoated part and the lower part) among the wound uncoated parts (the positive electrode wound uncoated part and the negative electrode wound uncoated part) Cut off the negative electrode uncoated part). Here, the lower uncoated portion is a portion to be welded or welded to the current collecting terminal member of the wound uncoated portion when the flat wound electrode body is accommodated in the battery case. It is a part located below (the bottom side of the battery case). Therefore, in a conventional non-aqueous electrolyte secondary battery (that is, a battery in which the wound uncoated part is not cut), the position of the wound uncoated part on the bottom side (downward) of the battery case is The material layer uncoated portion corresponds to a portion located on the bottom surface side (downward) from the portion where the current collecting terminal member is welded.

  In the nonaqueous electrolyte secondary battery manufactured by the above-described manufacturing method, the flat wound electrode body is accommodated in the battery case in a posture in which the axial direction is aligned with the left-right direction (horizontal direction). Of the wound electrode body, portions where the positive electrode and the like form an arc are disposed on the upper end side and the lower end side of the flat wound electrode body. Therefore, when the flat wound electrode body after winding is in a posture to be accommodated in the battery case, the portion where the mixed material layer uncoated part of the wound uncoated part has an arc shape is flat wound. It arrange | positions at the upper end side and lower end side of an electrode body (winding non-coating part).

  The excision step may be performed before the current collecting terminal member is welded to the wound uncoated portion, or may be performed after the current collecting terminal member is welded to the wound uncoated portion. When performing the excision process before welding the current collecting terminal member to the wound uncoated part, when the flat wound electrode body is placed in the battery case, the “collected part of the wound uncoated part” The lower uncoated portion located below the “scheduled portion for welding the electric terminal member” is cut off. Also, when performing the excision process after welding the current collecting terminal member to the wound uncoated part, when the flat wound electrode body is placed in a battery case, The lower uncoated portion located below the “part where the current collecting terminal member is welded” is cut off.

  In addition, a positive electrode has a positive electrode current collection member (for example, metal foil) and the positive mix layer coated on the surface. Accordingly, the positive electrode mixture layer uncoated portion refers to a portion made only of a positive electrode current collecting member (for example, metal foil) constituting the positive electrode without having a positive electrode mixture layer containing a positive electrode active material. On the other hand, a portion having a positive electrode mixture layer (a portion having a positive electrode current collecting member and a positive electrode mixture layer) in the positive electrode is referred to as a positive electrode mixture layer coating portion.

  Moreover, a negative electrode has a negative electrode current collection member (for example, metal foil) and the negative mix layer coated on the surface. Therefore, the negative electrode mixture layer uncoated portion refers to a portion made only of a negative electrode current collecting member (for example, a metal foil) constituting the negative electrode without having a negative electrode mixture layer containing a negative electrode active material. On the other hand, a portion having a negative electrode mixture layer (a portion having a negative electrode current collecting member and a negative electrode mixture layer) in the negative electrode is referred to as a negative electrode mixture layer coating portion.

  The flat wound electrode body includes a positive electrode mixture layer coating portion, a negative electrode mixture layer coating portion, a wound coating portion in which a separator is wound, and a positive electrode adjacent to one end thereof. The wound uncoated part (the part where only the positive electrode mixture layer uncoated part is wound) and the negative electrode wound uncoated part adjacent to the other end (only the negative electrode mixture layer uncoated part) A portion formed by rotation). A positive electrode current collecting terminal member is welded to the positive electrode winding uncoated portion, and a negative electrode current collecting terminal member is welded to the negative electrode winding uncoated portion.

  The portion where the current collecting terminal member is not welded in the wound uncoated portion does not affect the battery characteristics even if it is excised, and therefore the lower uncoated portion is excised in the above-described manufacturing method. By cutting away the lower uncoated portion, the internal space of the battery case where the lower uncoated portion is conventionally disposed becomes unnecessary.

  Therefore, in the above-described manufacturing method, as a battery case, a cut surface of a flat wound electrode body (a cut surface facing the axial direction of the flat wound electrode body) obtained by cutting a lower uncoated portion of the inner surface of the battery case. And the surface facing the axial direction of the flat wound electrode body (referred to as the facing surface) above this (on the opposite side to the bottom side) and the end surface of the wound uncoated part and the axial direction (left and right) The battery case has a configuration in which it is positioned on the inner side (center side) of the battery case with respect to the axial direction rather than the inner side surface (which is referred to as the upper inner side surface) facing the direction.

  That is, in the battery case, the first opposed surface that faces the first cut surface of the flat wound electrode body in which the lower positive electrode uncoated portion is cut out of the inner surface of the battery case and the axial direction is positioned above the first opposed surface. The axial direction is positioned on the inner side of the battery case from the first upper inner surface facing the end surface of the positive electrode winding uncoated portion in the axial direction. Furthermore, the second cut surface of the flat wound electrode body in which the lower negative electrode uncoated portion is cut out of the inner side surface of the battery case and the second facing surface facing the axial direction above the negative electrode It is located inside the battery case in the axial direction from the second upper inner surface facing the end face of the uncoated portion in the axial direction.

  In such a battery case, the capacity per unit height (battery case) of the internal space of the battery case from the bottom surface (lower surface) of the battery case to the upper end of the opposing surface (first opposing surface and second opposing surface). Can be made smaller than the capacity per unit height of the internal space above this (corresponding to the bottom area of a conventional rectangular parallelepiped battery case).

  Thereby, in a liquid injection process, when a fixed amount (regulated amount) of non-aqueous electrolyte is injected into the battery case, the battery case of the above-described form has a conventional rectangular parallelepiped battery case (inner surface is a rectangular parallelepiped shape). In comparison, the liquid level of the non-aqueous electrolyte can be increased. Therefore, by using the above-described battery case, compared to the case of using a conventional battery case, the area of the portion where the non-aqueous electrolyte contacts with each other in the axial direction of both ends of the wound coating portion of the flat wound electrode body (Hereinafter also referred to as a liquid contact area) can be increased.

  The winding uncoated part (positive winding uncoated part and negative winding uncoated part) of the flat wound electrode body has a relatively large current collecting member (positive current collecting member and negative current collecting member). It is wound around a gap. For this reason, when the non-aqueous electrolyte is injected into the battery case, the non-aqueous electrolyte immediately enters the wound uncoated portions (the positive electrode wound uncoated portion and the negative electrode wound uncoated portion). On the other hand, since the wound coating part is wound densely (with almost no gap), the injected non-aqueous electrolyte slowly enters (penetrates) into the wound coating part.

  For this reason, when a non-aqueous electrolyte is injected into the battery case, first, non-aqueous electrolysis is performed in the internal space of the wound uncoated portion and the outside of the flat wound electrode body (that is, outside the wound coated portion). Liquid accumulates. Thereafter, the non-aqueous electrolyte accumulated outside the wound coating portion slowly permeates into the inside of the wound coating portion through both axial end surfaces of the wound coating portion.

  Therefore, the larger the liquid contact area at the end surface of the wound coating portion, the faster the non-aqueous electrolyte penetrates into the wound coating portion, and the impregnation is completed (the non-aqueous electrolyte solution is wound. The time until it reaches the entire interior of the department) can be shortened. Therefore, in the above-described manufacturing method, the non-aqueous electrolyte can be impregnated in the wound coating portion in a short time in the impregnation step.

In addition, in the above-described manufacturing method, it is not necessary to inject excess nonaqueous electrolyte into the battery case in order to increase the liquid level of the nonaqueous electrolyte (in order to increase the liquid contact area). Cycle charge / discharge characteristics are not deteriorated.
As mentioned above, according to the above-mentioned manufacturing method, the non-aqueous electrolyte can be impregnated in the wound coating portion of the flat wound electrode body in a short time without deteriorating the cycle charge / discharge characteristics of the battery.

  In the impregnation step, the operation of depressurizing the inside of the battery case and then pressurizing may be repeated a plurality of times. This is because the impregnation rate of the non-aqueous electrolyte into the wound coating portion can be increased, and the non-aqueous electrolyte can be impregnated into the wound coating portion in a shorter time.

The operation of “depressurizing and pressurizing” the inside of the battery case includes, for example, an operation of depressurizing the inside of the battery case from the atmospheric pressure state and then increasing (opening to the atmosphere) to the atmospheric pressure.
Further, in the impregnation step, after the operation of depressurizing and pressurizing the inside of the battery case is repeated a plurality of times, the inside of the battery case may be left in a constant pressure state (for example, atmospheric pressure state) for a predetermined time. good.

  Furthermore, in the method for manufacturing a non-aqueous electrolyte secondary battery described above, the battery case has an upper wall portion in which the facing wall portion having the facing surface among the wall portions of the battery case has the upper inner side surface. In the non-aqueous electrolyte 2, the opposing surface is positioned on the inner side of the battery case with respect to the axial direction than the upper inner surface by adopting a configuration in which the axial direction is recessed toward the inner side of the battery case. A secondary battery manufacturing method is preferable.

  In the battery case used in the above-described manufacturing method, the opposing wall portion having a facing surface (a surface facing the cut surface of the flat wound electrode body in the axial direction) among the wall portions of the battery case is an upper inner surface (from the facing surface). The upper wall portion having a surface facing the end surface of the wound uncoated portion at the upper position in the axial direction is recessed in the battery case in the axial direction (left-right direction). By setting it as such a form, an opposing surface can be appropriately located inside a battery case about an axial direction rather than an upper inner surface.

  Further, in the method for manufacturing the non-aqueous electrolyte secondary battery, the battery case is located at a position facing the cut surface of the flat wound electrode body in the axial direction within a rectangular parallelepiped case. The spacer includes a spacer, and a side surface of the spacer that is opposed to the cut surface in the axial direction is located inside the battery case in the axial direction from the upper inner surface. A method for manufacturing a non-aqueous electrolyte secondary battery is preferable.

  The battery case used in the manufacturing method described above includes a cut surface of the flat wound electrode body (cut surface obtained by cutting away the lower uncoated portion) and an axial direction (left-right direction) of the flat wound electrode body in the case of the rectangular parallelepiped shape. ) Is provided at a position opposite to the spacer. In such a battery case, the opposing surface can be appropriately positioned inside the battery case in the axial direction with respect to the upper inner surface. Specifically, of the side surfaces of the spacer, the surface facing the cut surface of the flat wound electrode body in the axial direction is the facing surface. Thereby, an opposing surface can be appropriately located inside a battery case about an axial direction rather than an upper inner surface. The spacer is a part (component) of the battery case.

  Another aspect of the present invention includes a flat wound electrode body obtained by winding a positive electrode, a negative electrode, and a separator into a flat shape, a rectangular battery case that accommodates the flat wound electrode body, and the flat wound electrode. A non-aqueous electrolyte impregnated in the body, and a current collecting terminal member, wherein the flat wound electrode body includes the positive electrode mixture layer coating portion, the negative electrode mixture layer coating portion, and A wound coating portion formed by winding the separator, and axially opposite ends of the flat wound electrode body, the positive electrode mixture layer uncoated portion and the negative electrode mixture layer uncoated A non-aqueous electrolyte secondary battery formed by welding a wound uncoated portion formed by winding each of the working portions, and the current collecting terminal member being welded to the wound uncoated portion, Of the winding uncoated part, the lower uncoated part located below the part where the current collecting terminal member is welded is cut off, The cutting surface of the flat wound electrode body obtained by excising the lower uncoated portion of the inner surface of the battery case and the facing surface facing the axial direction are positioned above the wound uncoated portion. It is a non-aqueous electrolyte secondary battery which is located inside the battery case in the axial direction from the upper inner surface facing the end surface of the battery in the axial direction.

  The non-aqueous electrolyte secondary battery described above has a cut surface of a flat wound electrode body obtained by cutting a lower uncoated portion of the inner side surface of the battery case as the battery case (facing the axial direction of the flat wound electrode body). The end face of the wound uncoated part and the above axis at a position above this (the opposite face) and the face facing the axial direction of the flat wound electrode body (this is called the facing face) A battery case is used that is positioned on the inner side (center side) of the battery case in the axial direction than the inner side surface (referred to as the upper inner side surface) facing the direction (left-right direction).

  That is, in the battery case, the first opposed surface that faces the first cut surface of the flat wound electrode body in which the lower positive electrode uncoated portion is cut out of the inner surface of the battery case and the axial direction is positioned above the first opposed surface. The axial direction is positioned on the inner side of the battery case from the first upper inner surface facing the end surface of the positive electrode winding uncoated portion in the axial direction. Furthermore, the second cut surface of the flat wound electrode body in which the lower negative electrode uncoated portion is cut out of the inner side surface of the battery case and the second facing surface facing the axial direction above the negative electrode It is located inside the battery case in the axial direction from the second upper inner surface facing the end face of the uncoated portion in the axial direction.

  As described above, by using such a battery case, the non-aqueous electrolyte can be impregnated in the wound coating portion in a short time in the impregnation step when the battery is manufactured. Therefore, since the battery manufacturing time is shortened, the non-aqueous electrolyte secondary battery described above is an inexpensive battery. Moreover, the non-aqueous electrolyte secondary battery described above has good cycle charge / discharge characteristics.

  Further, in the above non-aqueous electrolyte secondary battery, the opposing wall portion having the opposing surface among the wall portions of the battery case is more in the axial direction than the upper wall portion having the upper inner surface. By adopting a form that is recessed inside the battery case, the non-aqueous electrolyte secondary battery may be configured such that the facing surface is located inside the battery case in the axial direction with respect to the upper inner surface.

  By using the battery case having the above-described form, when the battery is manufactured, the non-aqueous electrolyte can be impregnated in the wound coating portion in a short time in the impregnation step. Therefore, since the battery manufacturing time is shortened, the non-aqueous electrolyte secondary battery described above is an inexpensive battery. Moreover, the non-aqueous electrolyte secondary battery described above has good cycle charge / discharge characteristics.

  Further, in the nonaqueous electrolyte secondary battery, the battery case is disposed at a position facing the cut surface of the flat wound electrode body in the axial direction within a rectangular parallelepiped case. Non-aqueous electrolysis comprising a spacer, wherein the opposing surface which is a side surface of the spacer and faces the cut surface in the axial direction is located inside the battery case in the axial direction with respect to the upper inner surface A liquid secondary battery is preferred.

  By using the battery case having the above-described form, when the battery is manufactured, the non-aqueous electrolyte can be impregnated in the wound coating portion in a short time in the impregnation step. Therefore, since the battery manufacturing time is shortened, the non-aqueous electrolyte secondary battery described above is an inexpensive battery. Moreover, the non-aqueous electrolyte secondary battery described above has good cycle charge / discharge characteristics.

1 is a cross-sectional view of a non-aqueous electrolyte secondary battery according to Example 1. FIG. It is a perspective view of the case main-body part of the nonaqueous electrolyte secondary battery. It is a perspective view of the flat wound electrode body of the nonaqueous electrolyte secondary battery. It is a figure which shows the positive electrode which comprises a flat wound electrode body. It is a figure which shows the negative electrode which comprises a flat wound electrode body. 3 is a flowchart showing a flow of a method for manufacturing a non-aqueous electrolyte secondary battery according to Examples 1 and 2. It is a figure explaining the winding process of Example 1. FIG. It is a perspective view of the flat wound electrode body formed in the same winding process. FIG. 2 is a diagram for explaining the accommodation process, the liquid injection process, and the impregnation process of Example 1, and is a cross-sectional view of the assembly 101. 6 is a cross-sectional view of a non-aqueous electrolyte secondary battery according to Example 2. FIG. It is a perspective view of the case main-body part of the nonaqueous electrolyte secondary battery. 3 is a cross-sectional view of a non-aqueous electrolyte secondary battery according to Comparative Example 1. FIG. It is a perspective view of the case main-body part of the nonaqueous electrolyte secondary battery.

Example 1
First, the nonaqueous electrolyte secondary battery 100 of the first embodiment will be described.
As shown in FIG. 1, the nonaqueous electrolyte secondary battery 100 is a rectangular sealed lithium ion secondary battery including a rectangular battery case 160, a positive electrode external terminal 121, and a negative electrode external terminal 131.

  Among these, the battery case 160 is a hard case having a metal case main body 110 and a metal lid 170 that form a square accommodation space. A flat wound electrode body 150 and the like are accommodated inside the battery case 160 (case body 110).

  The flat wound electrode body 150 is a flat wound electrode body in which a sheet-like positive electrode 155, a negative electrode 156, and a separator 157 are wound into a flat shape (see FIGS. 3 to 5). In the first embodiment, the flat wound electrode body 150 is accommodated in the battery case 160 in a posture in which the axis AX direction is aligned with the left-right direction (horizontal direction) (see FIG. 1). Therefore, portions 150 f and 150 g of the flat wound electrode body 150 in which the positive electrode 155, the negative electrode 156, and the separator 157 form an arc shape are disposed on the upper end side and the lower end side of the flat wound electrode body 150.

  As shown in FIG. 4, the positive electrode 155 has a strip shape extending in the longitudinal direction DA, and is disposed in a strip shape extending in the longitudinal direction DA on both sides of the positive electrode current collecting member 151 made of aluminum foil and the positive electrode current collecting member 151. And two positive electrode mixture layers 152. The positive electrode mixture layer 152 includes a positive electrode active material 153, a conductive material made of acetylene black, and PVdF (binder) in a ratio of 89: 8: 3 (weight ratio).

A portion of the positive electrode 155 where the positive electrode mixture layer 152 is applied is referred to as a positive electrode mixture layer coating portion 155c. On the other hand, a portion made only of the positive electrode current collecting member 151 without having the positive electrode mixture layer 152 is referred to as a positive electrode mixture layer uncoated portion 155b. The positive electrode mixture layer uncoated portion 155 b extends in a band shape in the longitudinal direction DA of the positive electrode 155 along one long side of the positive electrode 155. This positive electrode mixture layer uncoated portion 155b is wound to form a spiral shape, and has one end (right end in FIGS. 1 and 3) in the axial direction (left and right direction in FIG. 1) of the flat wound electrode body 150. Is located.
In the present embodiment, LiNi _1/3 Co _1/3 Mn _1/3 O ₂ is used as the positive electrode active material 153.

  Further, as shown in FIG. 5, the negative electrode 156 has a strip shape extending in the longitudinal direction DA. The negative electrode current collecting member 158 made of copper foil and strips extending in the longitudinal direction DA on both surfaces of the negative electrode current collecting member 158, respectively. It has two negative electrode mixture layers 159 arranged. The negative electrode mixture layer 159 includes the negative electrode active material 154, SBR (binder), and CMC (thickener) at a ratio of 98: 1: 1 (weight ratio).

A portion of the negative electrode 156 where the negative electrode mixture layer 159 is applied is referred to as a negative electrode mixture layer coating portion 156c. On the other hand, a portion including only the negative electrode current collector 158 without having the negative electrode mixture layer 159 is referred to as a negative electrode mixture layer uncoated portion 156b. The negative electrode mixture layer uncoated portion 156 b extends in a strip shape in the longitudinal direction DA of the negative electrode 156 along one long side of the negative electrode 156. The negative electrode mixture layer uncoated portion 156b is wound to form a spiral shape, and is located at the other end portion in the axial direction of the flat wound electrode body 150 (the left end portion in FIGS. 1 and 3).
In the present embodiment, graphite is used as the negative electrode active material 154.

  In the flat wound electrode body 150, a portion where the positive electrode mixture layer uncoated portion 155b is wound is referred to as a positive electrode wound uncoated portion 155d (see FIG. 3). In addition, a portion of the flat wound electrode body 150 where the negative electrode mixture layer uncoated portion 156b is wound is referred to as a negative electrode wound uncoated portion 156d. The positive electrode winding uncoated portion 155d and the negative electrode winding uncoated portion 156d are located at the axial ends of the flat wound electrode body 150.

  Further, in the flat wound electrode body 150, a portion where the positive electrode mixture layer coating portion 155c, the negative electrode mixture layer coating portion 156c, and the separator 150 are wound is referred to as a wound coating portion 150d ( (See FIG. 3). The wound coating portion 150d is located between the positive electrode winding uncoated portion 155d and the negative electrode winding uncoated portion 156d. The wound coating part 150d is impregnated with a non-aqueous electrolyte solution 140 having lithium ions.

  The separator 157 is a separator composed of three layers of PP (polypropylene) / PE (polyethylene) / PP (polypropylene). The separator 157 is interposed between the positive electrode 155 and the negative electrode 156 to separate them.

The non-aqueous electrolyte 140 is prepared by mixing lithium hexafluorophosphate (LiPF ₆ ) and EC (ethylene carbonate) which are Li salts in a non-aqueous solvent in which DMC (dimethyl carbonate), EMC (ethyl methyl carbonate) and an additive are mixed. ) And a non-aqueous electrolyte solution. In addition, the molar concentration of LiPF ₆ in the nonaqueous electrolytic solution 140 is 1.1 mol / L. In the first embodiment, 124 g of the nonaqueous electrolyte solution 140 is injected into the battery case 160.

  Further, the positive electrode current collecting terminal member 120 formed by processing a metal plate is welded to the positive electrode 155 (specifically, the positive electrode winding uncoated portion 155d) of the flat wound electrode body 150 (FIG. 1). reference). Specifically, the positive electrode current collector connection part 122 of the positive electrode current collector terminal member 120 is welded to the center and upper side portions of the positive electrode winding uncoated part 155d as viewed in the vertical direction. A positive external terminal 121 is integrally formed at the upper end of the positive current collecting terminal member 120.

  Further, the negative electrode current collecting terminal member 130 formed by processing a metal plate is welded to the negative electrode 156 (specifically, the negative electrode winding uncoated portion 156d) of the flat wound electrode body 150 (FIG. 1). reference). Specifically, the negative electrode current collector connection part 132 of the negative electrode current collector terminal member 130 is welded to the center and the upper part of the negative electrode winding uncoated part 156d as viewed in the vertical direction. Note that a negative electrode external terminal 131 is integrally formed at the upper end of the negative electrode current collecting terminal member 130.

  By the way, in the present Example 1, the part (lower positive electrode uncoated part 155f, lower positive electrode uncoated part 155f, lower part than the part (terminal welded part 155g) where the positive electrode current collecting terminal member 120 is welded in the positive electrode wound uncoated part 155d 8) is cut out (see FIG. 3). Further, a portion (lower negative electrode uncoated portion 156f, see FIG. 8) located below the portion where the negative electrode current collector terminal member 130 is welded (terminal welded portion 156g) in the negative electrode wound uncoated portion 156d is excised. doing.

  In addition, a cut surface (a cut surface facing the axis AX direction of the flat wound electrode body 150, a cut surface facing the right direction in FIG. 1) obtained by cutting out the lower positive electrode uncoated portion 155 f of the flat wound electrode body 150. The first cut surface 150b. Further, a cut surface (a cut surface facing the axis AX direction of the flat wound electrode body 150, a cut surface facing the left direction in FIG. 1) obtained by cutting out the lower negative electrode uncoated portion 156 f of the flat wound electrode body 150. This is referred to as a second cut surface 150c. The axis AX direction refers to a direction along the axis AX of the flat wound electrode body 150.

  Even if the portion where the positive electrode current collector terminal member 120 is not welded in the positive electrode winding uncoated portion 155d is cut off, the battery characteristics are not affected. Similarly, even if a portion of the negative electrode wound uncoated portion 156d where the negative electrode current collecting terminal member 130 is not welded is excised, the battery characteristics are not affected. For this reason, in the present Example 1, the lower positive electrode uncoated part 155f and the lower negative electrode uncoated part 156f are excised. Thereby, in the internal space of the conventional rectangular parallelepiped battery case (for example, the battery case 560 in FIG. 12), the space portion where the lower positive electrode uncoated portion 155f and the lower negative electrode uncoated portion 156f are arranged is It becomes unnecessary.

  Therefore, in the first embodiment, the shape of the battery case 160 is different from the first cut surface 150b of the flat wound electrode body 150 in the inner side surface 112 of the battery case 160 (case main body 110) and the axis AX direction (FIG. 1). The first facing surface 112b facing in the left-right direction in FIG. 5 is more axially in the direction of the axis AX than the first upper inner surface 112c facing the end surface of the positively wound uncoated portion 155d in the axis AX direction at a position above this. The battery case 160 (case body 110) is positioned inside (left side in FIG. 1) (see FIGS. 1 and 2).

  Further, the second facing surface 112f facing the second cut surface 150c of the flat wound electrode body 150 in the axis AX direction (left-right direction in FIG. 1) is at a position above this, the negative-wound uncoated portion 156d. The inner surface (right side in FIG. 1) of the battery case 160 (case main body 110) in the axis AX direction with respect to the second upper inner side surface 112g facing the end surface of the battery in the axis AX direction (FIG. 1, FIG. 2).

  Specifically, for the battery case 160 (case body 110), the first opposing wall 111b having the first opposing surface 112b of the wall 111 of the battery case 160 (case body 110) is the first upper inner surface. The first upper wall portion 111c having 112c is recessed toward the inner side (left side in FIGS. 1 and 2) of the battery case 160 in the axis AX direction (left and right direction in FIGS. 1 and 2).

  Further, with respect to the battery case 160 (case body 110), the second opposing wall 111f having the second opposing surface 112f is more in the axis AX direction (see FIG. 5) than the second upper wall 111g having the second upper inner surface 112g. 1 and in the left-right direction in FIG. 2, the battery case 160 is recessed on the inner side (right side in FIGS. 1 and 2).

  In the first embodiment, the internal dimensions of the case main body 110 of the battery case 160 are as follows. Specifically, with reference to FIG. 2, the inner dimension A in the width direction (the direction corresponding to the axial direction of the flat wound electrode body 150) is 152 mm, and the inner dimension A is in the depth direction (the vertical direction in FIG. 2). The dimension B is 88 mm, and the inner dimension C of the depth is 24 mm.

  Further, the height dimension D (vertical dimension in FIG. 2) of the first facing surface 112b is 35 mm, and the recess dimension E of the first facing surface 112b (axis AX direction from the first upper inner surface 112c to the first facing surface 112b) (Corresponding to the distance) is 15 mm. Further, the height dimension F (vertical dimension in FIG. 2) of the second facing surface 112f is 35 mm, and the recess dimension G of the second facing surface 112b (axis AX direction from the second upper inner surface 112g to the second facing surface 112f) (Corresponding to the distance) is 15 mm.

  In such a battery case 160 (case body 110), an internal space S1 (D, in FIG. 2) from the bottom surface 115 (lower surface) of the battery case 160 to the upper ends of the first opposing surface 112b and the second opposing surface 112f. The capacity per unit height (the space of the height dimension portion indicated by F) (corresponding to the bottom area of the battery case 160) is the capacity per unit height of the internal space S2 above this (the conventional rectangular parallelepiped shape) Less than the bottom area of the battery case). Therefore, the battery case 160 of Example 1 has a lower capacity (bottom side) than the conventional rectangular parallelepiped battery case 560 (see FIGS. 12 and 13).

  As a result, when a certain amount (specified amount) of the non-aqueous electrolyte solution 140 is injected into the battery case in the liquid injection step described later, the battery case 160 of the first embodiment has a conventional rectangular parallelepiped battery case 560 ( The liquid surface of the non-aqueous electrolyte 140 can be made higher than the inner surface of a rectangular parallelepiped. Therefore, by using the battery case 160 of the first embodiment, compared to the case of using the conventional battery case 560, the portion of the end portion in the axial direction of the wound coating portion 150d that is in contact with the nonaqueous electrolyte solution 140 is reduced. The area (liquid contact area) can be increased.

  In the positive electrode winding uncoated portion 155d and the negative electrode winding uncoated portion 156d, the positive electrode current collecting member 151 and the negative electrode current collecting member 158 are wound with a relatively large gap. For this reason, when the nonaqueous electrolyte solution 140 is injected into the battery case 160, the nonaqueous electrolyte solution 140 immediately enters the positive electrode winding uncoated portion 155d and the negative electrode winding uncoated portion 156d. On the other hand, since the wound coating part 150d is wound densely (with almost no gap), the injected non-aqueous electrolyte 140 slowly enters (penetrates) the wound coating part 150d. become.

  For this reason, when the non-aqueous electrolyte 140 is injected into the battery case 160, first, the internal space of the positively wound non-coated portion 155d and the negatively wound non-coated portion 156d and the outside of the flat wound electrode body 150 (that is, The non-aqueous electrolyte 140 is accumulated outside the wound coating part 150d. Thereafter, the non-aqueous electrolyte 140 accumulated outside the wound coating part 150d slowly permeates into the inside of the wound coating part 150d through both axial end surfaces of the wound coating part 150d. .

  Accordingly, the larger the liquid contact area at both axial end surfaces of the wound coating portion 150d, the faster the nonaqueous electrolyte 140 penetrates into the wound coating portion 150d, and the impregnation is completed (non-aqueous). The time until the electrolytic solution 140 reaches the entire inside of the wound coating portion 150d) can be shortened. Therefore, in the present Example 1, the non-aqueous electrolyte solution 140 can be impregnated in the wound coating part 150d in a short time in the impregnation step described later.

  In addition, in order to increase the liquid level of the non-aqueous electrolyte 140 (in order to increase the liquid contact area), it is not necessary to inject the excessive non-aqueous electrolyte 140 into the battery case 160. The characteristics are not deteriorated.

Next, a method for manufacturing the non-aqueous electrolyte secondary battery according to Example 1 will be described.
FIG. 6 is a flowchart illustrating the flow of the method for manufacturing the nonaqueous electrolyte secondary battery according to the first embodiment. First, in step S1 (winding step), the positive electrode 155, the negative electrode 156, and the separator 157 are wound into a flat shape to form a flat wound electrode body 150A (see FIG. 8).

  Specifically, as shown in FIG. 4, a positive electrode 155 is prepared in which a positive electrode mixture layer 152 is coated on the surface (both sides) of a strip-shaped positive electrode current collecting member 151. Further, as shown in FIG. 5, a negative electrode 156 in which a negative electrode mixture layer 159 is coated on the surface (both sides) of a strip-shaped negative electrode current collecting member 158 is prepared.

  Next, as shown in FIG. 7, the separator 157, the negative electrode 156, the separator 157, and the positive electrode 155 are wound so as to overlap in this order. Specifically, the positive electrode mixture layer uncoated portion 155b of the positive electrode 155 and the negative electrode mixture layer uncoated portion 156b of the negative electrode 156 are positioned on opposite sides in the width direction (left-right direction in FIG. 7). Then, the separator 157, the negative electrode 156, the separator 157, and the positive electrode 155 are wound into a flat shape to form a flat wound electrode body 150A (see FIG. 8).

Subsequently, it progresses to step S2 (cutting process), and the lower uncoated part 155f of the positive electrode winding uncoated part 155d and the lower uncoated part 156f of the negative electrode winding uncoated part 156d are cut off. Here, the lower uncoated portion 155f of the positive electrode winding uncoated portion 155d is a posture in which the flat wound electrode body 150A is accommodated in the battery case 160 of the positive electrode winding uncoated portion 155d (FIG. 8). (Position shown in FIG. 8) is a portion located below a portion (referred to as terminal welded portion 155g) where the positive electrode current collecting terminal member 120 is welded (see FIG. 8). In addition, the lower uncoated portion 156f of the negative electrode wound uncoated portion 156d is a posture in which the flat wound electrode body 150A is accommodated in the battery case 160 in the negative electrode wound uncoated portion 156d. This is a part located below the part where the negative electrode current collecting terminal member 130 is welded (referred to as terminal welded part 156g).
Thereby, the flat wound electrode body 150 (see FIG. 3) in which the lower uncoated portions 155f and 156f are cut off is completed.

  In the non-aqueous electrolyte secondary battery 100, as described above, the flat wound electrode body 150 is housed in the battery case 160 in a posture in which the axis AX direction is aligned with the left-right direction (horizontal direction). Parts 150 f and 150 g in which the positive electrode 155 and the like form an arc shape in the flat wound electrode body 150 are disposed on the upper end side and the lower end side of the flat wound electrode body 150. Accordingly, when the flat wound electrode body 150A is placed in the battery case 160, the portion 155j, 155k in which the positive electrode mixture layer uncoated portion 155b of the positive electrode wound uncoated portion 155d has an arc shape. Are arranged on the upper end side and the lower end side of the flat wound electrode body (winding uncoated portion), and the negative electrode mixture layer uncoated portion 156b of the negative electrode wound uncoated portion 156d has an arc shape. The portions 156j and 156k are disposed on the upper end side and the lower end side of the flat wound electrode body (the wound uncoated portion) (see FIG. 8).

  Then, it progresses to step S3 (welding process), and the positive electrode current collection terminal member 120 is welded to the positive electrode winding uncoated part 155d of the flat wound electrode body 150. FIG. Specifically, the positive electrode current collector connection portion 122 of the positive electrode current collector terminal member 120 is welded to the terminal weld portion 155g of the positive electrode winding uncoated portion 155d. Further, the negative electrode current collector terminal member 130 is welded to the negative electrode wound uncoated portion 156 d of the flat wound electrode body 150. Specifically, the negative electrode current collector connection part 132 of the negative electrode current collector terminal member 130 is welded to the terminal weld part 156g of the negative electrode winding uncoated part 156d.

  Next, proceeding to step S4 (accommodating step), the flat wound electrode body 150 to which the positive electrode current collector terminal member 120 and the negative electrode current collector terminal member 130 are welded is accommodated in the case body 110. Thereafter, the lid 170 closes the opening of the case body 110, and in this state, the lid 170 and the case body 110 are welded. Thereby, the assembly 101 in which the flat wound electrode body 150 is accommodated in the battery case 160 is completed (see FIG. 9). A liquid injection hole 170 b that penetrates the lid 170 is formed at the center of the lid 170.

Next, the process proceeds to step S <b> 5 (the liquid injection process), and the nonaqueous electrolytic solution 140 is injected into the battery case 160 through the liquid injection hole 170 b of the assembly 101. In Example 1, the injection amount of the non-aqueous electrolyte solution 140 is set to 124 g (153.8 mL).
In addition, the injected nonaqueous electrolyte solution 140 is a space outside the wound coating portion 150d of the flat wound electrode body 150 in the inner space of the battery case 160 (inside the positive winding uncoated portion 155d). And the internal space of the negative-winding uncoated portion 156d).

  Since the positive electrode winding uncoated portion 155d and the negative electrode winding uncoated portion 156d are wound with a relatively large gap between the positive electrode current collecting member 151 and the negative electrode current collecting member 158, the inside of the battery case 160 When the non-aqueous electrolyte solution 140 is injected into the non-aqueous electrolyte solution 140, the non-aqueous electrolyte solution 140 immediately enters the positive electrode winding uncoated portion 155d and the negative electrode winding uncoated portion 156d. On the other hand, since the wound coating part 150d is wound densely (with almost no gap), the injected nonaqueous electrolytic solution 140 is then slowly wound in the step S6 (impregnation step). It will enter (penetrate) into the interior of 150d.

  Next, it progresses to step S6 (impregnation process) and is made to impregnate the inside of the nonaqueous electrolyte solution 140 and the winding coating part 150d which were inject | poured in the battery case 160. FIG. Specifically, the operation of depressurizing the inside of the battery case 160 and then pressurizing is repeatedly performed a plurality of times (for example, five times). Specifically, using a vacuum pump (not shown), the gas in the battery case 160 is discharged to the outside through the liquid injection hole 170b of the battery case 160, and the inside of the battery case 160 is depressurized (for example, from atmospheric pressure to 100 kPa). ) Next, the inside of the battery case 160 is raised to atmospheric pressure (open to the atmosphere). This operation is repeated a plurality of times (for example, 5 times). Thereby, the impregnation speed of the non-aqueous electrolyte solution 140 into the flat wound electrode body 150 can be increased. Thereafter, by leaving the battery case 160 in an atmospheric pressure state for a certain time, the non-aqueous electrolyte solution 140 can be impregnated in the wound coating portion 150d.

Next, after sealing the liquid injection hole 170b with the liquid injection lid 175, the process proceeds to step S7 (initial charging step), and the non-aqueous electrolyte secondary battery is initially charged. For example, charging is performed at a constant current of 1 C until the battery voltage value reaches 4.1 V, and then charging is performed while the battery voltage value is maintained at 4.1 V. When the charging current value is reduced to 0.1 A, Stop charging. As a result, the non-aqueous electrolyte secondary battery is made 100% SOC.
As described above, the non-aqueous electrolyte secondary battery 100 is completed.

  Note that 1C is a current value at which discharge is completed in 1 hour after a battery having a rated capacity value (nominal capacity value) is discharged at a constant current. Since the rated capacity (nominal capacity) of the nonaqueous electrolyte secondary battery 100 of Example 1 is 22.8 Ah, 1C = 22.8A.

(Comparative Example 1)
In Comparative Example 1, a non-aqueous electrolyte secondary battery 500 was manufactured using a conventional rectangular parallelepiped battery case 560 (see FIG. 12) as a battery case.

  The battery case 560 is different from the battery case 160 of Example 1 in that the wall portion of the case body is not recessed inward, and the others are the same (FIGS. 12 and 13). reference). Specifically, as shown in FIG. 13, the inner dimension A in the width direction, the inner dimension B in the depth direction, and the inner dimension C in the depth direction of the case body 510 are the same as those in the case body 110 of the first embodiment. , 152 mm, 88 mm, and 24 mm. Therefore, the battery case 560 of Comparative Example 1 has a larger capacity on the lower side (bottom side) than the battery case 160 of Example 1.

  Further, in Comparative Example 1, as the flat wound electrode body, the lower uncoated portion 155f of the positive electrode wound uncoated portion 155d and the lower uncoated portion 156f of the negative electrode wound uncoated portion 156d are excised. Instead, the flat wound electrode body 150A is used. Other than that was carried out similarly to Example 1, and manufactured the non-aqueous-electrolyte secondary battery 500. FIG.

  In this comparative example 1, since the rectangular battery case 560 (see FIG. 12) is used, when a specified amount (specifically, 124 g) of the nonaqueous electrolyte solution 140 is injected into the battery case in the liquid injection process. Compared with Example 1 (battery case 160), the liquid level of the nonaqueous electrolyte solution 140 is lowered. Therefore, the area (liquid contact area) of the portion in contact with the non-aqueous electrolyte 140 in both axial end faces of the wound coating portion 150d is reduced as compared with the first embodiment. For this reason, as will be described later, in Comparative Example 1, the completion time of impregnation with the nonaqueous electrolytic solution 140 was longer than that in Example 1.

(Comparative Example 2)
In Comparative Example 2, as in Comparative Example 1, a conventional rectangular parallelepiped battery case 560 (see FIG. 12) is used as the battery case. Further, similarly to Comparative Example 1, as a flat wound electrode body, a lower uncoated portion 155f of the positive electrode wound uncoated portion 155d and a lower uncoated portion 156f of the negative electrode wound uncoated portion 156d are provided. The flat wound electrode body 150A is used without excision.

However, in Comparative Example 2, unlike Example 1 and Comparative Example 1, 128 g (158.7 mL) of nonaqueous electrolyte solution 140 was injected into the battery case in the liquid injection process. Thus, by injecting excess (4 g more than the specified amount) non-aqueous electrolyte solution 140 into the battery case, the non-aqueous electrolyte solution 140 was injected into the battery case as compared with Comparative Example 1. The liquid level can be increased. Therefore, the area (liquid contact area) of the portion in contact with the non-aqueous electrolyte 140 in both axial end faces of the wound coating portion 150d can be made larger than that in Comparative Example 1. For this reason, as will be described later, in this comparative example 2, the time for completing the impregnation of the nonaqueous electrolytic solution 140 is shorter than in the comparative example 1.
A nonaqueous electrolyte secondary battery 500 of Comparative Example 2 was manufactured in the same manner as Example 1 except for the above.

(Investigation of impregnation completion time)
About Example 1 and Comparative Examples 1 and 2, the non-aqueous electrolyte impregnation completion time was investigated as follows.

  In Example 1, the time from the completion of pouring 124 g of the non-aqueous electrolyte 140 into the battery case 160 until the impregnation of the non-aqueous electrolyte 140 into the wound coating portion 150 d (impregnation) Surveyed). Specifically, a large number of batteries were assembled using the battery case 160 and the flat wound electrode body 150 described above, and the nonaqueous electrolyte solution 140 was injected into each of these batteries. After that, after performing the decompression and pressurization operation as described above for each battery, the batteries are extracted one by one every time a certain time elapses, and non-aqueous electrolysis is performed inside the wound coating unit 150d. It was investigated whether the impregnation of the liquid 140 was completed.

  Whether or not the impregnation has been completed is determined by performing initial charging on the extracted battery, then disassembling and analyzing the battery, and Li is deposited on the surface of the negative electrode mixture layer coating portion 156c or the separator 157. Judging by whether or not. When Li is detected, it can be determined that the impregnation of the nonaqueous electrolytic solution 140 into the wound coating portion 150d has not yet been completed. On the other hand, when Li is not detected, it can be determined that the impregnation of the nonaqueous electrolytic solution 140 into the wound coating portion 150d is completed. Thus, for a battery in which Li was not detected, the elapsed time from when the non-aqueous electrolyte 140 was completely injected into the battery case 160 until the battery was extracted (until the initial charge was started) was And impregnation completion time. The results are shown in Table 1.

  Further, for Comparative Example 1 and Comparative Example 2, the impregnation completion time of the nonaqueous electrolyte solution 140 was investigated as described above. These results are also shown in Table 1.

  As a result, in Comparative Example 1, the impregnation completion time was 32 hours. That is, 32 hours were spent from injecting the nonaqueous electrolyte solution 140 into the battery case 560 until the impregnation of the nonaqueous electrolyte solution 140 into the wound coating portion 150d was completed.

  In Comparative Example 2, the impregnation completion time was 20 hours. That is, 20 hours were spent from injecting the non-aqueous electrolyte 140 into the battery case 560 until the impregnation of the non-aqueous electrolyte 140 into the wound coating portion 150d was completed.

  Thus, in Comparative Example 2, the impregnation completion time was shortened by 12 hours compared to Comparative Example 1. The reason is that in Comparative Example 2, a larger amount (4 g more than the specified amount) of nonaqueous electrolyte solution 140 was injected into battery case 560 in Comparative Example 2 in the liquid injection process. Thereby, in the comparative example 2, compared with the comparative example 1, the liquid level height when inject | pouring the non-aqueous electrolyte 140 in a battery case can be made high, As a result, the winding coating part 150d It can be said that the area (liquid contact area) of the portion in contact with the nonaqueous electrolyte solution 140 in both axial end faces can be made larger than that in Comparative Example 1. For this reason, in Comparative Example 2, it can be said that the completion time of impregnation with the nonaqueous electrolytic solution 140 is shorter than that in Comparative Example 1.

  In Example 1, the impregnation completion time was 12 hours. That is, 12 hours were spent from injecting the nonaqueous electrolyte solution 140 into the battery case 160 until the impregnation of the nonaqueous electrolyte solution 140 into the wound coating portion 150d was completed.

  Thus, in Example 1, compared with Comparative Example 1, the impregnation completion time could be shortened by 20 hours. The reason for this is that in Example 1, for the battery case 160 (case body 110), the first opposing wall 111b having the first opposing surface 112b of the wall 111 of the battery case 160 (case body 110) is This is because the first upper wall 111c having the first upper inner surface 112c is recessed in the battery case 160 in the axis AX direction. Furthermore, since the second opposing wall portion 111f having the second opposing surface 112f is recessed toward the inner side of the battery case 160 in the axis AX direction than the second upper wall portion 111g having the second upper inner surface 112g. (See FIGS. 1 and 2).

  Thereby, the battery case 160 of Example 1 has the capacity | capacitance of the downward side (bottom surface side) made small compared with the battery case 560 (refer FIG. 12, FIG. 13) of the conventional rectangular parallelepiped shape. As a result, when the nonaqueous electrolytic solution 140 was injected into the battery case, the nonaqueous electrolytic solution 140 was compared with the comparative example 1 in Example 1, although the injection amount was the same amount (124 g). The liquid level could be increased.

  Thereby, in Example 1, compared with the comparative example 1, the area (liquid contact area) of the part which the non-aqueous electrolyte solution 140 contacts among the axial direction both ends of the winding coating part 150d can be increased. It was. As a result, in Example 1, compared with Comparative Example 1, the speed at which the nonaqueous electrolyte 140 penetrates into the wound coating portion 150d is increased, and the impregnation is completed (the nonaqueous electrolyte 140 is wound). It can be said that the time until the entire interior of the coating part 150d) was shortened.

In addition, the impregnation completion time is shorter in Example 1 than in Comparative Example 2 in which the amount of liquid injection is larger than in Example 1.
From the above, in Example 1, it can be said that the non-aqueous electrolyte 140 can be impregnated in the wound coating part 150d in a short time. Thereby, since the manufacturing time of a battery is shortened, the nonaqueous electrolyte secondary battery 100 of Example 1 becomes an inexpensive battery.

(Cycle charge / discharge test)
Next, a cycle charge / discharge test was performed on the nonaqueous electrolyte secondary batteries of Example 1 and Comparative Examples 1 and 2.

  Specifically, each secondary battery was subjected to a charge / discharge cycle in a temperature environment of 25 ° C. Specifically, each secondary battery is brought into a state where the SOC is 20%, and first, charging is performed for 10 seconds at a constant current value of 200 A (8.8 C). Next, after resting for 5 seconds, discharging is performed for 10 seconds at a constant current value of 200 A (8.8 C). Then pause for 5 seconds. This charging / discharging was made into 1 cycle, and charging / discharging of multiple cycles was performed about each secondary battery. Thus, in this test, the charge / discharge cycle is performed at a high rate (8.8 C).

  In this cycle charge / discharge test, the IV resistance value of each secondary battery is measured every predetermined cycle, and the measured IV resistance value is 1.5 times the initial IV resistance value (before the cycle charge / discharge test). The number of cycles at the time was determined as the number of deterioration cycles. The results are shown in Table 1.

  The IV resistance value is obtained as follows. Specifically, each secondary battery is adjusted to a SOC of 20%, discharged at a constant current value of 1 C for 10 seconds in a temperature environment of 25 ° C., and the battery voltage value at the end of discharge is measured. did. Furthermore, only the discharge current value was different from 3C, 5C, and 10C, and discharge was performed under the same conditions as above, and the battery voltage value at the end of discharge for 10 seconds was measured according to each discharge current value. .

  Thereafter, for each secondary battery, the data obtained by the above discharge was plotted on a coordinate plane with the horizontal axis representing the discharge current value and the vertical axis representing the battery voltage value at the end of discharge. And about each secondary battery, the approximate straight line (primary formula) was computed by the least squares method based on these plot data. The inclination was obtained as the IV resistance value of each secondary battery.

  As shown in Table 1, in Comparative Example 1, the number of deterioration cycles was 7500. That is, by performing high-rate charge / discharge of 7500 cycles, the IV resistance value of the battery increased to 1.5 times the initial value.

  On the other hand, in Comparative Example 2, the number of deterioration cycles was 2400. That is, by performing high-rate charge / discharge of 2400 cycles, the IV resistance value of the battery increased to 1.5 times the initial value. Thus, in the comparative example 2, compared with the comparative example 1, the deterioration cycle number fell to 1/3 or less, and the cycle charging / discharging characteristic fell very large.

  The reason for this is that in Comparative Example 2, in order to increase the liquid level when the nonaqueous electrolytic solution 140 is injected into the battery case, the amount is higher than that of Comparative Example 1 (4 g more than the specified amount). That is, the nonaqueous electrolyte solution 140 is injected into the battery case. It is considered that the internal resistance (IV resistance) of the battery was raised early due to the high-rate charge / discharge cycle due to the presence of excess nonaqueous electrolyte solution 140 in the battery.

  On the other hand, in Example 1, the number of degradation cycles was 7800 cycles. That is, by performing high-rate charge / discharge for 7800 cycles, the IV resistance value of the battery increased to 1.5 times the initial value. As described above, in Example 1, the number of deterioration cycles exceeded that of Comparative Example 1, and the cycle charge / discharge characteristics were improved.

  From the above results, in the manufacturing method of Example 1, the non-aqueous electrolyte solution was flattened in a short time without reducing the cycle charge / discharge characteristics of the battery (specifically, improving the cycle charge / discharge characteristics). It can be said that the wound coating part of the electrode body could be impregnated (see Table 1). Moreover, it can be said that the battery of Example 1 is an inexpensive battery having good cycle charge / discharge characteristics.

(Example 2)
Next, the nonaqueous electrolyte secondary battery 200 of Example 2 will be described. The non-aqueous electrolyte secondary battery 200 of the second embodiment is different from the non-aqueous electrolyte secondary battery 100 of the first embodiment in the form of the case body of the battery case, and the others are the same ( (Refer FIG. 10, FIG. 11).

  Specifically, the battery case 260 (case main body 210) of the second embodiment has a first cut surface 150b of the flat wound electrode body 150 and an axis AX direction (in FIG. 10) in the inside of the rectangular parallelepiped case. A spacer 216 is provided at a position facing the left and right direction. The spacer 216 is integrated with the case main body 210 and constitutes a part of the wall 212 of the case main body 210.

  The spacer 216 is made of polyphenylene sulfide (PPS) resin and has a rectangular parallelepiped shape. The outer dimension of the spacer 216 is 14 mm (width direction dimension of the battery case 260, horizontal dimension in FIG. 10) × 35 mm (height direction dimension of the battery case 260, vertical dimension in FIG. 10) × 24 mm (battery case 260 dimension). It is a dimension in the depth direction, a dimension in a direction perpendicular to the paper surface in FIG. The depth dimension of the spacer 216 coincides with the inner depth dimension (C dimension in FIG. 11) of the battery case 260 (case main body 210).

  In such a battery case 260 as well, similarly to the battery case 160 of the first embodiment, the first facing surface 212b is appropriately placed on the inner side of the battery case (on the left side in FIG. 10) in the axis AX direction with respect to the first upper inner surface 212c. ). Specifically, of the side surfaces of the spacer 216, the surface facing the first cut surface 150b of the flat wound electrode body 150 in the axis AX direction (the surface facing the left side in FIG. 10) is the first facing surface 212b. . The first opposing surface 212b is located on the inner side of the battery case in the axis AX direction than the first upper inner surface 212c (see FIG. 10).

  Furthermore, the battery case 260 (case body portion 210) of the second embodiment has the second cut surface 150c of the flat wound electrode body 150 and the axis AX direction (the left-right direction in FIG. 10) in the inside of the rectangular parallelepiped battery case. A spacer 217 is also provided at a position opposite to. The spacer 217 also forms a part of the wall 212 of the case body 210 together with the case body 210. The spacer 217 is equivalent to the spacer 216 and has the same shape.

  Thus, similarly to the battery case 160 of the first embodiment, the second facing surface 212f is appropriately positioned on the inner side (right side in FIG. 10) of the second upper inner surface 212g in the axis AX direction. Can do. Specifically, of the side surfaces of the spacer 217, the surface facing the second cut surface 150c of the flat wound electrode body 150 in the axis AX direction (the surface facing the right side in FIG. 10) is the second facing surface 212f. The second facing surface 212f is located on the inner side of the battery case in the axis AX direction than the second upper inner surface 212g (see FIG. 10).

  In the second embodiment, the internal dimensions of the case body 210 of the battery case 260 are as follows. Specifically, with reference to FIG. 11, the inner dimension A in the width direction (the direction corresponding to the axial direction of the flat wound electrode body 150) is 152 mm, and the inner dimension A is in the depth direction (the vertical direction in FIG. 11). The dimension B is 88 mm, and the inner dimension C of the depth is 24 mm.

Furthermore, the height dimension D (vertical direction dimension in FIG. 11) of the first facing surface 212b is 35 mm, and the projecting dimension E of the first facing surface 112b (the axis AX direction from the first upper inner side surface 212c to the first facing surface 212b) (Corresponding to the distance) is 14 mm. Furthermore, the height dimension F (vertical dimension in FIG. 11) of the second facing surface 212f is 35 mm, and the protruding dimension G of the second facing surface 212b (axis AX direction from the second upper inner surface 212g to the second facing surface 212f) (Corresponding to the distance) is 14 mm.
In short, the battery case 260 of the second embodiment corresponds to a case where the spacers 216 and 217 are arranged inside the battery case 560 of the first comparative example.

  In such a battery case 260 (case body portion 210) as well as the battery case 160 of Example 1, the internal space from the bottom surface 215 (lower surface) to the upper ends of the first opposing surface 212b and the second opposing surface 212f. The capacity per unit height (corresponding to the bottom area of the case body 210) of S1 (the space of the height dimension portion indicated by D and F in FIG. 11) is the unit height of the internal space S2 above this. It can be made smaller than the hit capacity (corresponding to the bottom area of the battery case 560 of Comparative Example 1). Therefore, the battery case 260 of Example 2 has a lower capacity (bottom side) than the conventional rectangular battery case 560 (see FIGS. 12 and 13).

  Thereby, also in the present Example 2, when a fixed amount (a prescribed amount) of the non-aqueous electrolyte solution 140 is injected into the battery case 260 in the injection process, as in Example 1, a conventional rectangular parallelepiped battery case Compared to 560 (inner surface is a rectangular parallelepiped shape), the liquid level of the non-aqueous electrolyte 140 can be increased. Therefore, by using the battery case 260 of the second embodiment, compared to the case of using the conventional battery case 560, the area of the portion where the nonaqueous electrolyte solution 140 is in contact with each other in the axial direction both end faces of the wound coating portion. (Liquid contact area) can be increased.

  Therefore, in the second embodiment, in the impregnation step, the non-aqueous electrolyte 140 can be impregnated in the wound coating portion 150d in a short time. In addition, in order to increase the liquid level of the non-aqueous electrolyte 140 (in order to increase the liquid contact area), it is not necessary to inject an excessive amount of the non-aqueous electrolyte 140 into the battery case 260. The characteristics are not deteriorated.

(Investigation of impregnation completion time)
Also in Example 2, the completion time of impregnation with the nonaqueous electrolyte solution 140 was investigated by the same method as in Example 1. The results are shown in Table 2. For comparison with Example 2, the results of Comparative Examples 1 and 2 are also shown in Table 2.

  In Example 2, as in Example 1, the impregnation completion time was 12 hours. That is, 12 hours were spent from injecting the nonaqueous electrolyte solution 140 into the battery case 260 until the impregnation of the nonaqueous electrolyte solution 140 into the wound coating portion 150d was completed.

  Thus, in Example 2, compared with Comparative Example 1, the impregnation completion time could be shortened by 20 hours. The reason is the same as in the first embodiment. Specifically, by using the battery case 260 (the case main body portion 210) having the above-described form, the non-aqueous electrolyte solution 140 of both end surfaces in the axial direction of the wound coating portion 150d is compared with Comparative Example 1. It is because the area (liquid contact area) of the part which contacts can be increased. As a result, in Example 2, compared with Comparative Example 1, the speed at which the nonaqueous electrolyte 140 penetrates into the wound coating portion 150d is increased, and the impregnation is completed (the nonaqueous electrolyte 140 is wound). It can be said that the time until the entire interior of the coating part 150d) was shortened.

In addition, the impregnation completion time is shorter in Example 2 than in Comparative Example 2 in which the amount of liquid injection is larger than in Example 2.
From the above, in Example 2, it can be said that the non-aqueous electrolyte 140 can be impregnated in the wound coating part 150d in a short time. Thereby, since the manufacturing time of the battery is shortened, the nonaqueous electrolyte secondary battery 200 of Example 2 is an inexpensive battery.

(Cycle charge / discharge test)
In Example 2, cycle charge / discharge is performed in the same manner as in Example 1, and the IV resistance value of the battery is 1.5 times the initial IV resistance value (before the cycle charge / discharge test). The number of cycles was determined as the number of deterioration cycles. The results are also shown in Table 2.

  In Example 2, the number of deterioration cycles was 7500. That is, by performing high-rate charge / discharge of 7500 cycles, the IV resistance value of the battery increased to 1.5 times the initial value. Thus, in Example 2, while the impregnation completion time was significantly shortened compared with Comparative Example 1, the number of deteriorated cycles was equivalent to that of Comparative Example 1, and the cycle charge / discharge characteristics were good.

  From the above results, it can be said that in Example 2, the non-aqueous electrolyte solution could be impregnated in the wound coating portion of the flat wound electrode body in a short time without reducing the cycle charge / discharge characteristics of the battery ( (See Table 2). Moreover, it can be said that the battery of Example 2 is an inexpensive battery having good cycle charge / discharge characteristics.

  In the above, the present invention has been described with reference to the first and second embodiments. However, the present invention is not limited to the above-described embodiments, and it can be applied as appropriate without departing from the scope of the present invention. Nor.

100, 200 Nonaqueous electrolyte secondary battery 160, 260 Battery case 110, 210 Case main body 111, 211 Wall 111b First opposing wall 111c First upper wall 111f Second opposing wall 111g Second upper wall 112, 212 Inner side surfaces 112b, 212b First opposing surface 112c, 212c First upper inner side surface 112f, 212f Second opposing surface 112g, 212g Second upper inner side surface 120 Positive electrode current collecting terminal member 130 Negative electrode current collecting terminal member 170 Lid 170b Injection hole 140 Nonaqueous electrolyte 150 Flat wound electrode body 150b First cut surface 150c Second cut surface 150d Winding coating portion 155 Positive electrode 155b Positive electrode mixture layer uncoated portion 155c Positive electrode mixture layer coating portion 155d Positive electrode winding uncoated portion 155f Lower positive electrode uncoated portion 156 Negative electrode 156b Negative electrode mixture layer uncoated portion 156c Negative electrode mixture layer coated portion 56d Fukyokumeku times uncoated portion 156f lower negative electrode uncoated portion 157 a separator 216, 217 spacer AX axis

Claims (6)

A flat wound electrode body obtained by winding a positive electrode, a negative electrode, and a separator into a flat shape;
A rectangular battery case that houses the flat wound electrode body;
A non-aqueous electrolyte impregnated in the flat wound electrode body;
A current collecting terminal member,
The flat wound electrode body is
A positive electrode mixture layer coating portion, a negative electrode mixture layer coating portion, and a wound coating portion formed by winding the separator;
A wound uncoated portion that is located at both ends in the axial direction of the flat wound electrode body, and in which the positive electrode mixture layer uncoated portion and the negative electrode mixture layer uncoated portion are respectively wound. And having
In the method for producing a non-aqueous electrolyte secondary battery, the current collecting terminal member is welded to the wound uncoated portion.
A winding step of winding the positive electrode, the negative electrode, and the separator into a flat shape to form a flat wound electrode body;
Of the uncoated portion of the flat wound electrode body, when the flat wound electrode body is in a posture to be accommodated in the battery case, the current collecting terminal member is to be welded or welded. An excision step of excising the lower uncoated part located below,
Storing the flat wound electrode body with the lower uncoated portion removed in the battery case; and
Injecting the non-aqueous electrolyte into the battery case containing the flat wound electrode body,
An impregnation step of impregnating the wound coating portion with the non-aqueous electrolyte injected into the battery case, and
As the battery case, a cutting surface of the flat wound electrode body obtained by excising the lower uncoated portion of the inner side surface of the battery case and a facing surface facing the axial direction are positioned at a position above the upper surface. A non-aqueous electrolyte secondary battery manufacturing method using a battery case in a form that is positioned on the inner side of the battery case in the axial direction rather than an upper inner surface facing the end surface of the uncoated part in the axial direction. A method for producing a non-aqueous electrolyte secondary battery according to claim 1,
The battery case is configured such that, of the wall portions of the battery case, the facing wall portion having the facing surface is recessed toward the inner side of the battery case in the axial direction than the upper wall portion having the upper inner surface. By this, the manufacturing method of the non-aqueous electrolyte secondary battery which makes the said opposing surface be located inside the said battery case about the said axial direction rather than the said upper inner surface. A method for producing a non-aqueous electrolyte secondary battery according to claim 1,
The battery case is
A spacer disposed in a position facing the cut surface of the flat wound electrode body and the axial direction among the inside of a rectangular parallelepiped case,
A nonaqueous electrolyte secondary battery in which a side surface of the spacer and the facing surface facing the cut surface in the axial direction is located inside the battery case in the axial direction with respect to the upper inner surface. Production method. A flat wound electrode body obtained by winding a positive electrode, a negative electrode, and a separator into a flat shape;
A rectangular battery case that houses the flat wound electrode body;
A non-aqueous electrolyte impregnated in the flat wound electrode body;
A current collecting terminal member,
The flat wound electrode body is
A positive electrode mixture layer coating portion, a negative electrode mixture layer coating portion, and a wound coating portion formed by winding the separator;
A wound uncoated portion that is located at both ends in the axial direction of the flat wound electrode body, and in which the positive electrode mixture layer uncoated portion and the negative electrode mixture layer uncoated portion are respectively wound. And having
In the nonaqueous electrolyte secondary battery formed by welding the current collecting terminal member to the wound uncoated portion,
Of the winding uncoated part, the lower uncoated part located below the part where the current collecting terminal member is welded is cut off,
A cut surface of the flat wound electrode body obtained by excising the lower uncoated portion of the inner side surface of the battery case and a facing surface facing the axial direction are positioned above the wound uncoated portion. A non-aqueous electrolyte secondary battery that is located inside the battery case in the axial direction from the upper inner surface that faces the end surface of the battery in the axial direction. The nonaqueous electrolyte secondary battery according to claim 4,
The opposing wall portion having the opposing surface among the wall portions of the battery case is configured to be recessed inward of the battery case with respect to the axial direction rather than the upper wall portion having the upper inner surface. A non-aqueous electrolyte secondary battery in which a surface is located inside the battery case in the axial direction with respect to the upper inner surface. The nonaqueous electrolyte secondary battery according to claim 4,
The battery case is
A spacer disposed in a position facing the cut surface of the flat wound electrode body and the axial direction among the inside of a rectangular parallelepiped case,
A non-aqueous electrolyte secondary battery in which a side surface of the spacer that is opposed to the cut surface in the axial direction is located inside the battery case in the axial direction with respect to the upper inner surface.

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