JP2015210944A - Square secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a square secondary battery for which the difference in electrical resistance caused by the inter-electrode distance difference of a wound electrode body can be reduced to suppress progress of deterioration of the square secondary battery.SOLUTION: A square secondary battery 100 has a wound group 3 obtained by winding first and second separators 33, 35 interposed between a positive electrode 34 and a negative electrode 32, a battery can 1 in which the wound group 3 is mounted, and a first insulation protection sheet 109 which is disposed between the wound group 3 and the battery can 1 and covers the wound groove 3 along a winding direction. The second separator 35 is disposed on the outermost periphery of the wound group 3, and a winding terminal end portion 35a is covered by the first insulation protection sheet 109. In the winding direction, a first fixing portion 140 and a second fixing portion 141 for fixing the first insulation protection sheet 109 and the second separator 35 are provided at both the sides sandwiching the winding terminal end portion 35a therebetween.

Description

  The present invention relates to a prismatic secondary battery used for in-vehicle applications, for example.

  In recent years, prismatic secondary batteries with large capacity (Wh) have been developed as power sources for hybrid electric vehicles and pure electric vehicles, among which prismatic lithium ion secondary with high energy density (Wh / kg). Batteries are attracting attention.

  In a rectangular lithium ion secondary battery, a flat-shaped wound group in which a positive electrode foil coated with a positive electrode active material, a negative electrode foil coated with a negative electrode active material, and a separator for insulating each other are wound together ( That is, the wound electrode body is electrically connected to the positive external terminal and the negative external terminal provided on the lid. Then, the wound group is accommodated in a battery can, and the opening of the battery can is sealed with a lid. Furthermore, after injecting electrolyte from the liquid injection port provided in the lid, a liquid injection stopper is inserted and sealed by laser welding to produce a rectangular secondary battery.

  In such a prismatic lithium ion secondary battery, winding tension is always applied to the winding group. Therefore, if the separator is not fixed, it may cause loosening or loosening. If the loosening or unraveling is caused, the deterioration of the prismatic lithium ion secondary battery proceeds. Therefore, by fixing the separator with a tacking tape, it is possible to prevent the winding group from being loosened or unraveled. For example, Patent Document 1 describes a prismatic secondary battery including a wound group in which a separator is fixed by a tacking tape.

JP 2012-54024 A

  However, if the wound group is pressed against the inner wall of the battery can due to the expansion of the wound group during charging / discharging in the prismatic secondary battery or the relationship between the thickness of the wound group and the distance between the inner walls of the battery can, There is a difference in the distance between the electrodes in the wound group between the portion with and without the tape, and a difference in electrical resistance occurs. That is, the electrical resistance of the part with the tacking tape is lower than the part without the tacking tape. Therefore, there is a problem in that current concentration locally occurs in a portion having a low electric resistance, lithium is precipitated, and deterioration of the prismatic secondary battery is caused.

  The present invention has been made in view of the above points, and can reduce the difference in electrical resistance due to the inter-electrode distance difference of the wound electrode body and suppress the progress of deterioration of the rectangular secondary battery. An object is to provide a secondary battery.

  The prismatic secondary battery of the present invention that solves the above problems is a flat wound electrode body that is wound by interposing a separator between a positive electrode and a negative electrode, and placing the separator on the outermost periphery, A square secondary having a battery can that accommodates the wound electrode body, and an insulating protective sheet that is disposed between the wound electrode body and the battery can and covers the wound electrode body along at least the winding direction. In the battery, the winding end end of the outermost separator is covered with the insulating protective sheet, and the insulating end is disposed on both sides of the winding end end of the outermost separator in the winding direction. The protective sheet and the outermost separator are fixed to each other.

  According to the present invention, the insulating protective sheet and the outermost separator are respectively fixed on both sides of the outermost separator, so that the wound electrode body is prevented from being loosened or unraveled. In addition, the difference in electrical resistance due to the difference in distance between the electrodes of the wound electrode body can be reduced as compared with the conventional method in which the separator is fixed with the tacking tape. Therefore, the occurrence of current concentration can be reliably suppressed locally, and lithium deposition due to current concentration can be prevented. As a result, it becomes possible to effectively suppress the progress of deterioration of the prismatic secondary battery.

The perspective view which shows the square secondary battery which concerns on 1st Embodiment. The disassembled perspective view which shows the square secondary battery which concerns on 1st Embodiment. The perspective view which shows a battery cover and an electric power generation element. The expansion | deployment perspective view of a winding group. (A) Sectional drawing along the AA line in FIG. 1, (b) Cross-sectional schematic diagram. (A) Sectional drawing of the square secondary battery which concerns on 2nd Embodiment, (b) Cross-sectional schematic diagram. (A) Sectional drawing of the square secondary battery which concerns on 3rd Embodiment, (b) Cross-sectional schematic diagram. (A) Sectional drawing of the square secondary battery which concerns on 4th Embodiment, (b) Cross-sectional schematic diagram. (A) Sectional drawing of the square secondary battery which concerns on 5th Embodiment, (b) Cross-sectional schematic diagram. (A) Sectional drawing of the square secondary battery which concerns on 6th Embodiment, (b) Cross-sectional schematic diagram. (A) Sectional drawing of the square secondary battery which concerns on 7th Embodiment, (b) Cross-sectional schematic diagram.

  Hereinafter, embodiments of a square secondary battery according to the present invention will be described with reference to the drawings. In the following embodiments, a case of a lithium ion secondary battery used in a hybrid vehicle or an electric vehicle will be described as an example of a square secondary battery. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

<First Embodiment>
FIG. 1 is a perspective view showing a prismatic secondary battery according to the first embodiment, FIG. 2 is an exploded perspective view showing the prismatic secondary battery according to the first embodiment, and FIG. 3 shows a battery lid / power generation element. It is a perspective view shown.

  A rectangular secondary battery 100 according to this embodiment is configured by housing a wound group (winding electrode body) 3 in a flat battery container 2 including a battery lid 6 and a battery can 1. . A non-aqueous electrolyte (not shown) is injected into the battery container 2. The battery lid 6 and the battery can 1 are made of, for example, a conductive metal material such as aluminum, iron, and stainless steel.

  A positive electrode current collector 180, a negative electrode current collector 190, and the like are integrally assembled with the battery lid 6. The battery lid 6, the positive electrode current collector 180, the negative electrode current collector 190, and the like constitute a lid assembly 107. The positive electrode current collector 180 and the negative electrode current collector 190 are respectively joined to the positive electrode foil 34c or the negative electrode foil 32c (see FIG. 4) of the wound group 3 by, for example, ultrasonic welding. As shown in FIG. 3, the battery lid / power generation element 50 includes a lid assembly 107 and a wound group 3. The battery lid / power generation element 50 is inserted into and accommodated in the battery can 1 through the opening at the upper end of the battery can 1. Further, as shown in FIG. 2, the wound group 3 is covered with an insulating protective sheet 108 so as not to directly touch the battery can 1 and is electrically insulated from the battery can 1.

The battery lid 6 is provided with a liquid injection port 7 for injecting a non-aqueous electrolyte into the battery container 2 and a gas discharge valve 10 for discharging the gas in the battery container 2 to the outside. The liquid injection port 7 is closed by a fitted liquid injection stopper 11 after injecting a non-aqueous electrolyte into the battery container 2. In the non-aqueous electrolyte, lithium hexafluorophosphate (LiPF ₆ ) was dissolved at a concentration of 1 mol / liter in a mixed solution in which ethylene carbonate and dimethyl carbonate were mixed at a volume ratio of 1: 2. Things can be used. The liquid injection stopper 11 is firmly joined to the inlet 7 by, for example, laser welding.

  The gas discharge valve 10 plays a role of reducing the pressure inside the battery container 2 by discharging the gas inside the battery container 2 to the outside when the pressure inside the battery container 2 exceeds a reference value due to overcharge or the like. The battery lid 6 seals the battery container 2 by joining to the battery can 1 by laser welding.

  FIG. 4 is a developed perspective view of the wound group. The winding group 3 is formed by winding a positive electrode 34 and a negative electrode 32 around an axis (not shown) with a first separator 33 and a second separator 35 interposed therebetween. ing. As shown in FIG. 3, the winding group 3 has a flat shape, and includes a flat surface portion 3b extending in the winding direction, and a pair of folded portions 3c located at both ends of the flat surface portion 3b. ing. Of the pair of folded portions 3 c, the lower folded portion 3 c is covered with the insulating protective sheet 108 and disposed on the bottom side of the battery can 1. Reference numeral 3 a in FIG. 3 is a hollow portion having a width corresponding to the thickness of the axis of the wound group 3.

  The positive electrode 34 is obtained by, for example, applying a positive electrode mixture layer 34a to both front and back surfaces of a positive foil 34c made of an aluminum foil or the like. A positive foil exposed portion (a portion where the positive electrode mixture layer 34a is not applied) 34b in which the positive foil 34c is exposed is formed at one edge portion in the width direction (that is, the winding axis L direction) of the positive foil 34c. . The negative electrode 32 is obtained by, for example, applying a negative electrode mixture layer 32a to both front and back surfaces of a negative foil 32c made of copper foil or the like. In the winding axis L direction, a negative electrode foil exposed portion (negative electrode mixture layer 32a uncoated portion) 32b in which the negative electrode foil 32c is exposed is formed at the edge of the negative electrode foil 32c opposite to the positive electrode foil exposed portion 34b. Yes. Thereby, the positive electrode foil exposed part 34b and the negative electrode foil exposed part 32b are arranged so as to face each other along the winding axis L direction.

The positive electrode mixture layer 34a is prepared by adding 10 parts by weight of a conductive material and 10 parts by weight of a binder to 100 parts by weight of the positive electrode active material, adding a dispersion solvent thereto, and kneading. And the positive mix layer 34a is apply | coated leaving the positive electrode foil exposed part 34b on both surfaces of the 20-micrometer-thick aluminum foil. Thereafter, drying, pressing, and cutting are performed to obtain the positive electrode 34. The thickness of the positive electrode 34 is preferably 90 μm (the total of both the front and back surfaces) of the positive electrode active material application part not including the aluminum foil. In addition, lithium manganate (chemical formula LiMn ₂ O ₄ ) as a positive electrode active material, scaly graphite as a conductive material, polyvinylidene fluoride (hereinafter referred to as PVDF) as a binder, and N-methylpyrrolidone (hereinafter referred to as NMP) as a dispersion solvent. ).

  The negative electrode mixture layer 32a is prepared by adding 10 parts by weight of a binder to 100 parts by weight of the negative electrode active material, further adding a dispersion solvent thereto, and kneading. The negative electrode mixture layer 32a is applied on both sides of a 10 μm thick copper foil leaving the negative electrode foil exposed portions 32b. Thereafter, drying, pressing, and cutting are performed to obtain the negative electrode 32. The thickness of the negative electrode 32 is preferably 70 μm of the thickness of the negative electrode active material application part not including the copper foil (total of both front and back surfaces). Note that amorphous carbon powder is used as the negative electrode active material, PVDF is used as the binder, and NMP is used as the dispersion solvent.

  In order to form the wound group 3, first, the tip portions of the first separator 33 and the second separator 35 are welded to the shaft core. Next, the winding start end portion of the negative electrode 32 is disposed between the first separator 33 and the second separator 35 so as to be located inside the winding start end portion of the positive electrode 34 and wound. . At that time, the positive electrode foil exposed portion 34b and the negative electrode foil exposed portion 32b are arranged on the respective side edges so as to be opposite in the width direction (direction of the winding axis L). As shown in FIG. 4, the width of the negative electrode mixture layer 32a (that is, the length in the winding axis L direction) is formed wider than the width of the positive electrode mixture layer 34a. The width of the first separator 33 is such that the positive foil exposed portion 34b of the positive electrode 34 is exposed to the outside on one edge side in the winding axis L direction. The width of the second separator 35 is such that the negative electrode foil exposed portion 32b of the negative electrode 32 is exposed to the outside on the other edge side in the winding axis L direction.

  A hollow portion 3a (see FIGS. 3 and 4) is formed on the winding start side of the winding group 3 (that is, on the axial core side). On the winding end side of the winding group 3, the second separator 35 is disposed on the outermost periphery, and the negative electrode 32 is disposed on the inner side of the second separator 35. Therefore, the positive electrode mixture layer 34a is covered with the negative electrode mixture layer 32a over the entire length and the entire width from the starting side to the end side. By doing in this way, the mixture layer lamination | stacking area | region 3d where the positive mix layer 34a of the positive electrode 34 and the negative mix layer 32a of the negative electrode 32 were laminated | stacked and laminated | stacked in the center position of the winding axis L direction. Is formed. The positive electrode foil exposed portion 34b of the positive electrode foil 34c is arranged on one side in the winding axis L direction and exposed to the outside, and the negative electrode foil exposed portion 32b of the negative electrode foil 32c is exposed on the other side in the winding axis L direction. Arranged and exposed to the outside.

  As illustrated in FIG. 3, the lid assembly 107 includes a battery lid 6, a positive electrode side terminal component 60, and a negative electrode terminal component 70. The positive electrode side terminal component 60 includes a positive electrode bolt 14, a positive electrode connection terminal 62, a positive electrode external terminal 63, a positive electrode side external insulator 24, a gasket (not shown), and a positive electrode current collector 180. The positive electrode bolt 14, the positive electrode connection terminal 62, the positive electrode external terminal 63, the gasket and the positive electrode current collector 180 are integrally fixed and attached to the battery lid 6.

  The positive electrode side terminal component 60 is manufactured as follows. First, the positive electrode current collector 180 is crimped to the positive electrode connection terminal 62. Subsequently, the positive electrode side external insulator 24 is disposed in the through hole of the battery lid 6 so that the through hole of the battery lid 6 and the through hole of the positive electrode side external insulator 24 are aligned. Next, the positive electrode bolt 14 is inserted into a through hole provided in the positive electrode external terminal 63 and fixed to the positive electrode external terminal 63 on the positive electrode side external insulator 24. The positive bolt 14 may be crimped to the positive external terminal 63. Further, the gasket is disposed on the back side of the battery lid 6 by aligning the positive and negative through holes of the battery lid 6 and the through holes of the gasket.

  Then, the positive electrode current collector 180 and the crimped positive electrode connection terminal 62 are inserted from the back side of the battery lid 6 into the through holes of the gasket, the battery lid 6, the positive electrode side external insulator 24, and the positive electrode external terminal 63. The tip end portion of the positive electrode connection terminal 62 has a cylindrical shape slightly smaller than the through hole of the positive electrode external terminal 63. By caulking the tip portion of the positive electrode connection terminal 62, the positive electrode side terminal component 60 becomes a battery. The lid 6 is assembled integrally. In this state, the positive electrode current collector 180, the positive electrode connection terminal 62, the positive electrode external terminal 63, and the positive electrode bolt 14 are electrically connected. Further, the positive electrode current collector 180, the positive electrode connection terminal 62, the positive electrode external terminal 63, and the positive electrode bolt 14 are electrically insulated from the battery lid 6 by the positive electrode side external insulator 24 and the gasket.

  The negative electrode side terminal component 70 includes the negative electrode bolt 12, the negative electrode connection terminal 72, the negative electrode external terminal 73, the negative electrode side external insulator 22, a gasket (not shown), and a negative electrode current collector 190. The negative electrode side terminal component 70 has the same structure as the positive electrode terminal component 60. The negative electrode bolt 12, the negative electrode external terminal 73, the negative electrode connection terminal 72, the gasket and the negative electrode current collector 190 are fixed integrally and attached to the battery lid 6. In this state, the negative electrode current collector 190, the negative electrode connection terminal 72, the negative electrode external terminal 73, and the negative electrode bolt 12 are electrically connected. Further, the negative electrode current collector 190, the negative electrode connection terminal 72, the negative electrode external terminal 73, and the negative electrode bolt 12 are electrically insulated from the battery lid 6 by the negative electrode side external insulator 22 and the gasket.

  The prismatic secondary battery 100 can charge and discharge external electronic devices connected to the positive electrode bolt 14 and the negative electrode bolt 12 by joining the positive and negative electrode current collectors 180 and 190 to the wound group 3. It becomes.

  The positive electrode current collector 180 is made of aluminum or an aluminum alloy. The positive electrode current collector 180 includes a flat plate-shaped seat surface portion 181 attached along the lower surface of the battery lid 6 and a pair of plane portions bent downward at approximately 90 ° at both ends in the width direction of the seat surface portion 181. 182. At the lower ends of the pair of flat portions 182, a pair of joined flat portions 183 that are each processed into a flat shape are formed. Each joining plane part 183 is joined to the winding group 3 by ultrasonic welding.

  Further, the pair of bonding flat portions 183 are bent at an angle inclined with respect to the flat portion 182. Specifically, the pair of joining plane portions 183 are formed in a square shape so as to be separated from each other as they go from the inside to the outside along the winding axis L direction, and are line symmetric. The inclined angle is the same with respect to the center plane. As shown in FIG. 2, the positive electrode foil exposed portion 34b of the wound group 3 is inserted between the pair of joining plane portions 183, and the positive foil exposed portion 34b of the wound group 3 is opened in a letter C shape. In this state, the positive electrode foil exposed portion 34b is joined by ultrasonic welding.

  The negative electrode current collector 190 is made of copper or a copper alloy and has the same structure as the positive electrode current collector 180. That is, the negative electrode current collector 190 includes a pair of flat seat surface portions 191 attached along the lower surface of the battery lid 6 and a pair of portions bent downward at approximately 90 ° at both ends in the width direction of the seat surface portions 191. A planar portion 192. At the lower ends of the pair of flat portions 192, a pair of joined flat portions 193 each formed into a flat shape is formed. Each joining plane part 193 is joined to the winding group 3 by ultrasonic welding.

  Further, the pair of bonding flat portions 193 are bent at an angle inclined with respect to the flat portion 192, respectively. Specifically, the pair of joining plane portions 193 are formed in a square shape so as to be separated from each other as they go from the inside to the outside along the winding axis L direction, and are line symmetric. The inclined angle is the same with respect to the center plane. As shown in FIG. 2, the negative electrode foil exposed portion 32b of the wound group 3 is inserted between the pair of joining plane portions 193, and the negative foil exposed portion 32b of the wound group 3 is opened in a C shape. In this state, it is joined to the negative electrode foil exposed portion 32b by ultrasonic welding.

Next, the configuration of the insulating protective sheet 108 will be described with reference to FIGS.
2 is an exploded perspective view showing the prismatic secondary battery according to the first embodiment. Specifically, FIG. 2 is an exploded perspective view showing a state in which the prismatic secondary battery 100 of FIG. 5A is a cross-sectional view taken along line AA in FIG. 1, and FIG. 5B is a schematic cross-sectional view.

  The insulation protection sheet 108 is housed in the battery can 1 together with the winding group 3 in a state of covering the winding group 3 from the surroundings, and is interposed between the winding group 3 and the inner wall of the battery can 1 to wind the winding. The group 3 and the battery can 1 are electrically isolated. The insulation protection sheet 108 includes a first insulation protection sheet 109 covering the winding group 3 mainly along the winding direction (direction wound around the axis), and both left and right sides along the winding axis L direction. The second insulation protection sheets 110 and 111 covering the winding group 3 are provided.

  Specifically, the first insulating protective sheet 109 is formed between the mixture layer stacking region 3d of the wound group 3 and the battery can 1, and between the positive and negative electrode current collectors 180 and 190 and the battery can 1. It is intervened in a part. The second insulating protective sheets 110 and 111 are provided between the positive and negative electrode foil exposed portions 34 b and 32 b of the wound group 3 and the battery can 1, and between the positive and negative electrode current collectors 180 and 190 and the battery can 1. Intervened. The second insulating protective sheets 110 and 111 are formed thicker than the first insulating protective sheet 109.

  The first insulating protective sheet 109 is made of a synthetic resin material having flexibility and insulating properties. By using the resin material in this manner, the first insulating protective sheet 109 can be manufactured at a low cost. As shown in FIG. 2, the first insulating protective sheet 109 is formed by folding one rectangular sheet member into two and covering the wound group 3 from below the battery lid / power generation element 50. The winding group 3 is covered across the ends on both sides in the winding axis L direction. That is, the first insulating protective sheet 109 extends downward from the vicinity of the lower surface of the battery lid 6 along one side of the flat surface portion 3b of the wound group 3 and is folded at the lower folded portion 3c on the lower side of the wound group 3. It makes a U-turn, extends upward along the other side of the flat portion 3 b, and reaches the vicinity of the lower surface of the battery lid 6. The first insulating protective sheet 109 has the same width as that of the mixture layer laminated region 3d of the wound group 3.

  The first insulating protective sheet 109 is fixed to the wound group 3 by being thermally welded to the outermost second separator 35. The first insulating protective sheet 109 is housed in the battery can 1 together with the winding group 3 while being fixed to the winding group 3, so that the mixture layer stacking region 3d of the winding group 3 and the battery can 1 is interposed.

  When the thickness of the battery can 1 is constant, if the thickness of the first insulating protective sheet 109 is increased, the thickness (number of cells) of the mixture layer laminated region 3d of the wound group 3 must be reduced. Therefore, in order to ensure a large battery capacity, it is necessary to make the thickness of the first insulating protective sheet 109 as small as possible. In addition, the active material layer of the wound group 3 expands and contracts due to charging / discharging of the battery, and the battery can 1 expands due to the expansion. Therefore, the swelling of the battery can 1 can be prevented by reducing the thickness of the first insulating protective sheet 109.

  When the first insulating protective sheet 109 was not provided, the second separator 35 located on the outermost periphery of the wound group 3 was formed of a porous, thin and soft resin film. There is a risk that the outermost second separator 35 may be damaged when inserted into the outer periphery. The breakage of the second separator 35 may lead to problems such as an internal short circuit of the square secondary battery 100. Furthermore, a large sliding friction between the outermost second separator 35 and the battery can 1 during insertion also causes damage to the second separator 35, leading to a decrease in productivity.

  Considering this, the first insulating protective sheet 109 is required between the mixture layer laminated region 3d of the wound group 3 and the battery can 1. Furthermore, in order to ensure a large battery capacity, it is preferable to reduce the thickness of the sheet as much as possible. The thickness of the first insulating protective sheet 109 is preferably 100 to 150 μm, but the thickness may be changed according to the battery configuration conditions and the like.

  The second insulating protective sheets 110 and 111 are formed in a U-shaped cross section so as to cover the positive and negative electrode foil exposed portions 34b and 32b. The second insulating protective sheets 110 and 111 are made of a synthetic resin thicker than the first insulating protective sheet 109, and may be formed by bending a sheet member, or formed by injection molding, vacuum molding, or the like. May be.

  The second insulating protective sheet 110 is attached to the end of the winding group 3 on the positive electrode side in the winding axis L direction. The second insulating protective sheet 110 includes a facing surface portion 110a facing the positive end face of the winding group 3, a pair of side surface portions 110b and 110b facing each other with the winding group 3 interposed therebetween, and a winding group. 3 has a bottom surface portion 110c facing the lower folded portion 3c. Note that the upper side (battery cover 6 side) of the second insulating protective sheet 110 is opened to avoid interference with the seating surface portion 181 and the pair of flat surface portions 182 of the positive electrode current collector 180.

  The facing surface portion 110a has a rectangular shape extending with a constant width from the folded portion 3c on the battery lid 6 side to the folded portion 3c on the bottom side. The pair of side surface portions 110b and 110b are vertically formed from both sides in the width direction of the facing surface portion 110a, and the end portions of the flat surface portions 3b of the wound group 3 (that is, the positive foil exposed portions 34b are stacked in a planar shape. Part). Each side surface part 110b has a dimension substantially the same width as the positive electrode foil exposed part 34b, and covers the outermost periphery of the positive electrode foil exposed part 34b.

  The second insulating protective sheet 111 is attached to the negative electrode side end of the wound group 3 in the winding axis L direction. The second insulating protective sheet 111 includes a facing surface portion 111a facing the negative electrode side end surface of the wound group 3, a pair of side surface portions 111b and 111b facing each other with the wound group 3 interposed therebetween, and a wound group. 3 and a bottom surface portion 111c facing the folded portion 3c on the bottom side. In addition, the upper side (battery cover 6 side) of the second insulating protective sheet 111 is opened in order to avoid interference with the seating surface portion 191 and the pair of flat surface portions 192 of the negative electrode current collector 190.

  The facing surface portion 111a has a rectangular shape extending at a constant width from the folded portion 3c on the battery lid 6 side to the folded portion 3c on the bottom side. The pair of side surface portions 111b and 111b are vertically formed from both sides in the width direction of the opposing surface portion 111a, and the end portion of the flat surface portion 3b of the wound group 3 (that is, the negative foil exposed portion 32b is laminated in a flat shape. Part). Each side part 111b has the dimension of substantially the same width as the negative electrode foil exposed part 32b, and covers the outermost periphery of the negative electrode foil exposed part 32b.

  The second insulating protective sheets 110 and 111 are accommodated in the battery can 1 together with the winding group 3 in a state of being fixed to the winding group 3, thereby exposing the positive and negative electrode foil exposed portions 34 b and 32 b of the winding group 3. It is interposed between the battery can 1 and between the positive and negative electrode current collectors 180 and 190 and the battery can 1. Since the second insulation protective sheets 110 and 111 are interposed between the positive and negative electrode foil exposed portions 34b and 32b and the battery can 1, the positive and negative current collectors are applied when an external force is applied to the battery body or the terminal portion. 180 and 190 may be deformed, and the second insulating protective sheets 110 and 111 may be sandwiched between the positive and negative electrode current collectors 180 and 190 and the battery can 1 and strongly pressed against each other. Further, when the second insulating protective sheets 110 and 111 are inserted into the battery can 1 together with the wound group 3, the positive and negative electrode current collectors 180 and 190 are inserted into the battery can via the second insulating protective sheets 110 and 111. There is a possibility of contact with 1 and rubbing. Furthermore, the positive and negative electrode current collectors 180 and 190 may become hot when a large current flows.

  Therefore, the second insulating protective sheets 110 and 111 are required to withstand external force and high temperature. Therefore, it is preferable that the thickness of the second insulating protective sheets 110 and 111 is as large as possible. The thickness of the second insulating protective sheets 110 and 111 is preferably 100 to 300 μm, but the thickness may be changed according to the battery configuration conditions and the like.

  The insulating protection sheet 108 is formed by bending a sheet-like insulating material. A suitable insulating material used for the insulating protective sheet 108 is preferably a synthetic resin material that has good insulation properties, is difficult to wrinkle, and has high heat resistance. For example, a polyolefin-based material such as polypropylene and polyethylene Examples thereof include resin materials, polyester, polyphenylene sulfide, polyimide, and the like. In addition, the first insulating protective sheet 109 disposed between the active material layer region of the wound group 3 and the battery can 1, and the exposed portion of the positive and negative electrode foils 34 c and 32 c and the battery can 1 are disposed. The second insulating protective sheets 110 and 111 need not be the same material, and can be a combination of the materials described above.

  As shown in FIG. 5 (b), the winding end portion 35a of the outermost second separator 35 is disposed in the vicinity of the half height position S of the wound group 3, and the first insulating protective sheet 109 Covered. In the winding direction, the first insulating protective sheet 109 and the outermost second separator 35 are respectively fixed to both sides of the outermost end 35a of the outermost second separator 35.

  Specifically, the first insulating protective sheet 109 has a first fixing portion 140 and a second fixing portion 141 that are fixed to the outermost second separator 35. Among these fixing portions, the first fixing portion 140 is disposed at a position higher than the half height position S of the wound group 3. On the other hand, the second fixing portion 141 is disposed on the opposite side of the first fixing portion 140 with the winding end portion 35a of the second separator 35 interposed therebetween. That is, the first fixing portion 140 and the second fixing portion 141 are arranged at positions separated on one side and the other side in the winding direction via the winding end portion 35 a of the second separator 35. In addition, the distance from the second fixing portion 141 to the winding end portion 35a is shorter than the distance from the first fixing portion 140 to the winding end portion 35a of the second separator 35.

  Hereinafter, an assembling operation of the prismatic secondary battery 100 having the above-described insulating protective sheet 108 will be described. First, the first insulating protective sheet 109 is folded in two so as to cover the wound group 3 from below the battery lid / power generation element 50. Thereby, the winding group 3 is covered with the first insulating protective sheet 109 across the end portions on both sides in the winding axis direction.

  Next, the first insulation protective sheet 109 and the second separator 35 are disposed above the separation end portion 35a of the second separator 35 and in the vicinity of the separation start end portion 109c of the first insulation protection sheet 109. Fix by heat welding. By this heat welding, the first fixing part 140 is formed. At that time, the location of the heat welding is selected so that the position of the first fixing portion 140 is above the half height position S of the wound group 3. When the second separator 35 and the first insulating protective sheet 109 are fixed by a thermal welding method, the fixing operation can be easily performed.

  Subsequently, the first insulating protective sheet 109 and the second separator 35 are thermally welded to a position on the opposite side of the first fixing portion 140 in the vicinity of the end 35a of the second separator 35. A second fixing part 141 is formed. At that time, heat is applied so that the distance from the second fixing portion 141 to the winding end portion 35a is shorter than the distance from the first fixing portion 140 to the winding end portion 35a of the second separator 35. Select the welding location. The first insulating protective sheet 109 is fixed to the wound group 3 by the first and second fixing portions 140 and 141.

  In order to fix the first insulating protective sheet 109 and the second separator 35 by heat welding, the first insulating protective sheet 109 is more preferable than the second separator 35 disposed on the outermost periphery of the wound group 3. Is preferably formed thick. In this way, it is possible to reduce the influence on the first insulating protective sheet 109 and the second separator 35 due to heat welding. In the present embodiment, the thickness of the first insulating protective sheet 109 is 100 to 150 μm, and the thickness of the second separator 35 is 10 to 20 μm. Furthermore, the outermost second separator 35 has a resin layer and a heat-resistant layer, and the resin layer is preferably located on the outermost side of the wound group 3. In this way, it is possible to reliably suppress the influence on the second separator 35 due to heat welding.

  Next, the second insulating protection sheets 110 and 111 are approached from both the left and right sides in the winding axis L direction of the winding group 3, and the winding group 3 is interposed between the pair of side surface portions 110b, 110b, 111b, and 111b. The second insulating protective sheets 110 and 111 are fixed to the wound group 3 by sandwiching the positive and negative electrode foil exposed portions 34 b and 32 b and the end portions of the first insulating protective sheet 109. As a result, the wound group 3 is covered with the insulating protective sheet 108.

  Subsequently, the winding group 3 is inserted into the battery can 1 from above, the opening of the battery can 1 is closed with the battery lid 6, and the battery can 1 and the battery lid 6 are sealed by laser welding. To do. Next, after pouring electrolyte solution into the battery can 1 from the liquid injection port 7, the liquid injection port 7 is closed with a liquid injection stopper 11 and sealed by laser welding.

  In the prismatic secondary battery 100 according to the present embodiment, the first insulating protective sheet 109 is interposed between the mixture layer stacking region 3d of the wound group 3 and the battery can 1, and the positive and negative foils of the wound group 3 The second insulation protective sheets 110 and 111 are interposed between the exposed portions 34b and 32b and the battery can 1 and between the positive and negative electrode current collectors 180 and 190 and the battery can 1, so that the first insulation The second insulating protective sheets 110 and 111 are thicker than the protective sheet 109. Then, by reducing the thickness of the first insulating protective sheet 109, the thickness (number of ridges) of the mixture layer laminated region 3d of the wound group 3 can be increased. Therefore, a large battery capacity can be secured and the volume energy density of the wound group 3 can be increased.

  In addition, by reducing the thickness of the first insulating protective sheet 109, the clearance with the battery can 1 can be increased, and the battery generated by the expansion and contraction of the active material layer accompanying charging / discharging of the battery The swelling of the can 1 can be prevented. Further, by arranging the first insulating protective sheet 109 between the mixture layer stacking region 3 d of the winding group 3 and the battery can 1, the winding group 3 is inserted into the battery can 1. 3 can be smoothly inserted without damaging the second outermost separator 35.

  Further, the second insulating protective sheets 110 and 111 can improve the sheet strength by increasing the sheet thickness. Therefore, for example, the positive and negative electrode current collectors 180 and 190 are deformed by the application of an external force to the battery body or the terminal portion, and the second insulation sandwiched between the positive and negative electrode current collectors 180 and 190 and the battery can 1. Even when the protective sheets 110 and 111 are strongly pressed, the second insulating protective sheets 110 and 111 are not damaged, and the space between the positive and negative foil exposed portions 34b and 32b of the wound group 3 and the battery can 1 is not damaged. Alternatively, the insulation between the positive and negative electrode current collectors 180 and 190 and the battery can 1 can be reliably maintained.

  Further, it is preferable to increase the thickness of the second insulating protective sheets 110 and 111. This prevents the positive and negative electrode current collectors 180 and 190 from rubbing against the battery can 1 when the wound group 3 is inserted into the battery can 1 together with the second insulating protective sheets 110 and 111. be able to. Furthermore, by increasing the thickness of the second insulating protective sheets 110 and 111, even if a large current flows through the positive and negative electrode current collectors 180 and 190 and the temperature rises, the second insulating protective sheets 110 and 111 Can withstand that high temperature.

  According to the prismatic secondary battery 100 having the above-described configuration, the first insulating protection sheet 109 and the second separator 35 are fixed on both sides of the outermost end portion 35a of the second separator 35. Since the first fixing part 140 and the second fixing part 141 are provided respectively, it is possible to prevent the winding group 3 from being loosened or unraveled without using a winding tape. Moreover, compared with the conventional method of fixing the separator with the tacking tape, the difference in electrical resistance due to the distance between the electrodes of the wound group 3 can be reduced. Therefore, the occurrence of current concentration can be reliably suppressed locally, and lithium deposition due to current concentration can be prevented. Therefore, it is possible to effectively suppress the progress of deterioration of the prismatic secondary battery 100.

  In addition, since the first fixing portion 140 is at a position higher than the half height position S of the wound group 3, the first fixing portion 140 is a free end of the first insulating protection sheet 109 from the first fixing portion 140. By shortening the distance to the start end portion 109c, the unstable state of the first insulating protective sheet 109 can be suppressed, and the first insulating protective sheet 109 together with the wound group 3 can be smoothly moved by the battery can 1. Can be inserted into. Furthermore, since the distance from the second fixing portion 141 to the winding end portion 35a is shorter than the distance from the first fixing portion 140 to the winding end portion 35a of the second separator 35, the winding end portion 35a. Can be suppressed by the second fixing portion 141.

  In the present embodiment, the width of the first insulating protective sheet 109 is the same as the lateral width of the mixture layer laminated region 3d of the wound group 3, but the positive and negative electrode current collectors 180 and 190 and the positive and negative electrode foil exposed portion 34b. The first insulating protective sheet 109 may further extend in the direction of the positive and negative electrode foil exposed portions 34b and 32b within a range that does not hinder the welding with 32b. In this case, it is possible to expand an allowable range of positional deviation and winding deviation between the first insulating protective sheet 109 and the winding group 3, and accordingly, it is possible to reduce assembly costs.

  In addition, although the first insulating protective sheet 109 and the second separator 35 are fixed by heat welding, the method for fixing both is not limited to this, and may be fixed by adhesion using an adhesive or the like. Moreover, although the fixing part of the 1st insulation protective sheet and the winding group 3 was made into two places (the 1st fixing part 140 and the 2nd fixing part 141), it is a fixing part further along the winding axis L direction. May increase. Further, in the schematic cross-sectional view of FIG. 5B, the first fixing portion 140 and the second fixing portion 141 are shown to be large in an elliptical shape for the sake of explanation, but actually the fixing portion is formed to be small. Yes. Moreover, about the shape of a fixing | fixed part, various shapes, such as linear, a round shape, a rectangle, a polygon, a star shape, can be taken. Further, in the schematic cross-sectional view of FIG. 5B, a large gap is provided between the first insulating protective sheet 109 and the second separator 35 and between the adjacent second separators 35 for the sake of explanation. However, in practice, the first insulating protective sheet 109, the second separator 35, and the adjacent second separators 35 are in close contact with each other without a gap.

Second Embodiment
Hereinafter, the square secondary battery according to the second embodiment will be described. The prismatic secondary battery 200 according to this embodiment differs from the first embodiment in the positions of the first fixing portion and the second fixing portion. Since other structures and the like are the same as those of the first embodiment, redundant description is omitted.

  FIG. 6A is a cross-sectional view of the prismatic secondary battery according to the second embodiment, and FIG. 6B is a schematic cross-sectional view. As shown in FIG. 6B, the winding end portion 35a of the outermost second separator 35 is disposed in the vicinity of the folded portion 3c on the bottom side of the winding group 3, and the first insulating protective sheet 109 Covered. Then, in the winding direction, the first fixing for fixing the first insulating protective sheet 109 and the outermost second separator 35 to both sides sandwiching the winding end portion 35a of the outermost second separator 35. The part 240 and the second fixing part 241 are respectively arranged.

  The first fixing portion 240 is located above the half height position S of the wound group 3 and in the vicinity of the winding start end portion 109 c of the first insulating protective sheet 109, the first insulating protective sheet 109. And the second separator 35 are formed by heat welding. On the other hand, the second fixing portion 241 is in the vicinity of the end portion 35a of the second separator 35 and on the opposite side of the first fixing portion 240, and the first insulating protective sheet 109 and the second separator. 35 and is heat-welded. Further, as shown in FIG. 6B, compared to the distance from the first fixing portion 240 to the winding end portion 35a of the second separator 35, the distance from the second fixing portion 241 to the winding end portion 35a. The distance is short.

  In the present embodiment, the second fixing portion 241 is disposed in the vicinity of the folded portion 3 c on the can bottom side of the winding group 3. The first insulating protective sheet 109 is fixed to the wound group 3 by the first and second fixing portions 240 and 241. Further, in the present embodiment, the end of rolling of the second separator 35 from the second fixing portion 241 is greater than the distance from the end of end 35a of the outermost second separator 35 to the first fixing portion 240. The distance to the part 35a is short.

  The square secondary battery 200 according to the present embodiment has the same effects as those of the first embodiment, and the winding end portion 35a of the second separator 35 is near the folded portion 3c on the bottom side of the winding group 3. Since it is arranged, compared with the case where the winding end end portion 35a is arranged on the flat surface portion 3b of the winding group 3, the winding end end portion 35a does not affect the thickness of the winding group 3.

<Third Embodiment>
Hereinafter, the square secondary battery according to the third embodiment will be described. The prismatic secondary battery 300 according to this embodiment is different from the first embodiment in the positions of the first fixing portion and the second fixing portion. Since other structures and the like are the same as those of the first embodiment, redundant description is omitted.

  Fig.7 (a) is sectional drawing of the square secondary battery which concerns on 3rd Embodiment, FIG.7 (b) is a cross-sectional schematic diagram. As shown in FIG. 7B, the end portion 35a of the outermost second separator 35 is covered with a first insulating protective sheet 109. Then, in the winding direction, the first fixing for fixing the first insulating protective sheet 109 and the outermost second separator 35 to both sides sandwiching the winding end portion 35a of the outermost second separator 35. The part 340 and the second fixing part 341 are respectively arranged.

  The first fixing portion 340 is located above the half height position S of the wound group 3 and in the vicinity of the winding start end portion 109 c of the first insulating protective sheet 109, the first insulating protective sheet 109. And the second separator 35 are formed by heat welding. On the other hand, the second fixing portion 341 includes the first insulating protective sheet 109 and the second insulating portion in the vicinity of the end portion 35a of the second separator 35 and the end portion 109d of the first insulating protective sheet 109. The separator 35 is thermally welded. And this 2nd fixing | fixed part 341 is arrange | positioned in the position above the half height position S of the winding group 3 similarly to the 1st fixing | fixed part 340. As shown in FIG. Further, as shown in FIG. 7B, compared to the distance from the first fixing portion 340 to the winding end portion 35a of the second separator 35, the distance from the second fixing portion 341 to the winding end portion 35a. The distance is short.

  The prismatic secondary battery 300 according to the present embodiment has the same effects as those of the first embodiment, and the first insulating protection sheet 109 has a first end portion 109c and a first end portion 109d near the end portion 109d. By providing each of the fixing portion 340 and the second fixing portion 341, the distance from the first fixing portion 340 to the winding start end portion 109c that is the free end of the first insulating protective sheet 109, and the second fixing portion By shortening the distance from the winding end portion 109d, which is a free end, the unstable state of the first insulating protective sheet 109 can be reliably suppressed, and the first insulation together with the winding group 3 can be suppressed. The protective sheet 109 can be smoothly inserted into the battery can 1.

<Fourth embodiment>
Hereinafter, the square secondary battery according to the fourth embodiment will be described. The square secondary battery 400 according to this embodiment is different from the first embodiment in the positions of the first fixing portion and the second fixing portion. Since other structures and the like are the same as those of the first embodiment, redundant description is omitted.

  FIG. 8A is a cross-sectional view of a prismatic secondary battery according to the fourth embodiment, and FIG. 8B is a schematic cross-sectional view. As shown in FIG. 8 (b), the winding end portion 35 a of the outermost second separator 35 is covered with a first insulating protective sheet 109. Then, in the winding direction, the first fixing for fixing the first insulating protective sheet 109 and the outermost second separator 35 to both sides sandwiching the winding end portion 35a of the outermost second separator 35. The part 440 and the second fixing part 441 are arranged.

  The first fixing portion 440 includes the first insulating protective sheet 109 and the second separator in the vicinity of the rolling end portion 35a of the second separator 35 and the winding start end portion 109c of the first insulating protective sheet 109. 35 and is heat-welded. The second fixing portion 441 is formed by thermally welding the first insulating protective sheet 109 and the second separator 35 in the vicinity of the end portion 109d of the first insulating protective sheet 109. And the 1st fixing | fixed part 440 and the 2nd fixing | fixed part 441 are arrange | positioned in the position above the half height position S of the winding group 3, respectively.

  The prismatic secondary battery 400 according to the present embodiment has the same effects as those of the first embodiment, and the first insulating protective sheet 109 has a first end portion 109c and a first end portion 109d in the vicinity of the first end portion 109d. By providing each of the fixing portion 440 and the second fixing portion 441, the distance from the first fixing portion 440 to the winding start end portion 109c that is the free end of the first insulating protective sheet 109, and the second fixing portion The distance from 441 to the winding end portion 109d, which is a free end, can be shortened. Accordingly, the unstable state of the first insulating protective sheet 109 can be reliably suppressed, and the first insulating protective sheet 109 together with the wound group 3 can be smoothly inserted into the battery can 1.

<Fifth Embodiment>
Hereinafter, the square secondary battery according to the fifth embodiment will be described. The prismatic secondary battery 500 according to this embodiment is different from the first embodiment in the positions of the first fixing portion and the second fixing portion. Since other structures and the like are the same as those of the first embodiment, redundant description is omitted.

  Fig.9 (a) is sectional drawing of the square secondary battery which concerns on 5th Embodiment, FIG.9 (b) is a cross-sectional schematic diagram. As shown in FIG. 9B, the winding end portion 35a of the outermost second separator 35 is disposed in the vicinity of the folded portion 3c on the bottom side of the wound group 3, and the first insulating protective sheet 109 Covered. Then, in the winding direction, the first fixing for fixing the first insulating protective sheet 109 and the outermost second separator 35 to both sides sandwiching the winding end portion 35a of the outermost second separator 35. The part 540 and the second fixing part 541 are arranged.

  The first fixing portion 540 is formed by thermally welding the first insulating protective sheet 109 and the second separator 35 in the vicinity of the starting start end portion 109 c of the first insulating protective sheet 109. The second fixing portion 541 is formed by thermally welding the first insulating protective sheet 109 and the second separator 35 in the vicinity of the end portion 109 d of the first insulating protective sheet 109. And the 1st fixing | fixed part 440 and the 2nd fixing | fixed part 441 are arrange | positioned in the position above the half height position S of the winding group 3, respectively. Further, as shown in FIG. 9B, compared with the distance from the first fixing portion 540 to the end-of-stripping end portion 35a of the second separator 35, from the second fixing portion 541 to the end-of-stripping end portion 35a. The distance is short.

  The prismatic secondary battery 500 according to the present embodiment has the same effects as those of the first embodiment, and the first insulating protection sheet 109 has a first end portion 109c and a first end portion 109d in the vicinity of the end portion 109d. Since the fixing portion 540 and the second fixing portion 541 are provided, the distance from the first fixing portion 540 to the winding start end portion 109c that is the free end of the first insulating protective sheet 109, and the second fixing portion 541 The distance from the winding end portion 109d, which is a free end, can be shortened. Accordingly, the unstable state of the first insulating protective sheet 109 can be reliably suppressed, and the first insulating protective sheet 109 together with the wound group 3 can be smoothly inserted into the battery can 1. Further, since the winding end end portion 35 a of the second separator 35 is disposed in the vicinity of the folded portion 3 c on the bottom side of the winding group 3, the winding end end portion 35 a is disposed on the flat surface portion 3 b of the winding group 3. Compared to the case, there is no influence on the thickness of the wound group 3 by the winding end portion 35a.

<Sixth Embodiment>
Hereinafter, the square secondary battery according to the sixth embodiment will be described. The prismatic secondary battery 600 according to this embodiment is different from the first embodiment in the number of fixing parts and the position of the fixing parts. Since other structures and the like are the same as those of the first embodiment, redundant description is omitted.

  FIG. 10A is a cross-sectional view of a prismatic secondary battery according to the sixth embodiment, and FIG. 10B is a schematic cross-sectional view. As shown in FIG. 10 (b), the winding end portion 35 a of the outermost second separator 35 is covered with a first insulating protective sheet 109. In the winding direction, the first insulating protection sheet 109 and the outermost second separator 35 are fixed at three positions on both sides of the outermost end portion 35a of the outermost second separator 35. Yes.

  Specifically, the first insulating protective sheet 109 includes a first fixing portion 640, a second fixing portion 641, and a third fixing portion 642 that are fixed to the outermost second separator 35. . Among them, the first fixing portion 640 is formed by thermally welding the first insulating protective sheet 109 and the second separator 35 in the vicinity of the rolling start end portion 109c of the first insulating protective sheet 109. . The second fixing portion 641 is formed by thermally welding the first insulating protective sheet 109 and the second separator 35 in the vicinity of the end portion 35a of the second separator 35. The second fixing portion 641 is disposed on the opposite side of the first fixing portion 640 with the winding end portion 35a of the second separator 35 interposed therebetween. Further, as shown in FIG. 10 (b), compared to the distance from the first fixing portion 640 to the end portion 35a of the second separator 35, the distance from the second fixing portion 641 to the end portion 35a. The distance is short.

  The third fixing portion 642 is formed by thermally welding the first insulating protective sheet 109 and the second separator 35 in the vicinity of the end end portion 109d of the first insulating protective sheet 109. The first fixing part 640 and the third fixing part 642 are each arranged at a position higher than the half height position S of the wound group 3. Further, the second fixing portion 641 is located between the third fixing portion 642 and the winding end portion 35 a of the second separator 35.

  The prismatic secondary battery 600 according to the present embodiment has the same effects as those of the first embodiment, and the first insulating protection sheet 109 has a first end portion 109c and a first end portion 109d near the end portion 109d. In order to provide the fixing portion 640 and the third fixing portion 642, and further to provide the second fixing portion 641 in the vicinity of the end portion 35a of the second separator 35, the first insulating protective sheet 109 and the second separator The first insulation protective sheet 109 can be smoothly inserted into the battery can 1 together with the wound group 3. In addition, since the second fixing portion 641 is located between the third fixing portion 642 and the end portion 35a of the second separator 35, the unstable state of the end portion 35a is changed to the first state. Therefore, the operation of inserting the battery can 1 into the battery can 1 can be performed more smoothly.

<Seventh embodiment>
Hereinafter, the square secondary battery according to the seventh embodiment will be described. The prismatic secondary battery 700 according to this embodiment is different from the first embodiment in the number of fixed portions and the positions of the fixed portions. Since other structures and the like are the same as those of the first embodiment, redundant description is omitted.

  FIG. 11A is a cross-sectional view of a prismatic secondary battery according to the seventh embodiment, and FIG. 11B is a schematic cross-sectional view. As shown in FIG. 11 (b), the winding end portion 35 a of the outermost second separator 35 is disposed in the vicinity of the folded portion 3 c on the bottom side of the wound group 3, and the first insulating protective sheet 109 Covered. In the winding direction, the first insulating protection sheet 109 and the outermost second separator 35 are fixed at three positions on both sides of the outermost end portion 35a of the outermost second separator 35. Yes.

  Specifically, the first insulating protective sheet 109 has a first fixing portion 740, a second fixing portion 741, and a third fixing portion 742 that are fixed to the outermost second separator 35. . Among them, the first fixing portion 740 is formed by thermally welding the first insulating protective sheet 109 and the second separator 35 in the vicinity of the starting start end portion 109 c of the first insulating protective sheet 109. . The second fixing portion 741 is formed by thermally welding the first insulating protective sheet 109 and the second separator 35 in the vicinity of the end portion 35a of the second separator 35. The second fixing portion 741 is disposed on the opposite side of the first fixing portion 740 across the winding end portion 35a of the second separator 35 and in the vicinity of the folded portion 3c on the can bottom side of the winding group 3. ing. Further, as shown in FIG. 11 (b), compared to the distance from the first fixing portion 740 to the end portion 35a of the second separator 35, the second fixing portion 741 to the end portion 35a. The distance is short.

  The third fixing portion 742 is formed by thermally welding the first insulating protective sheet 109 and the second separator 35 in the vicinity of the end end portion 109d of the first insulating protective sheet 109. The first fixing part 740 and the third fixing part 742 are respectively arranged at positions higher than the half height position S of the wound group 3. Further, the second fixing portion 741 is located between the third fixing portion 742 and the winding end portion 35 a of the second separator 35.

  The square secondary battery 700 according to the present embodiment has the same effects as those of the first embodiment, and the first insulating protection sheet 109 has a first end portion 109c and a first end portion 109d near the end portion 109d. Since the fixing portion 740 and the third fixing portion 742 are provided, and the second fixing portion 741 is provided in the vicinity of the end portion 35a of the second separator 35, the first insulating protective sheet 109 and the second separator The first insulation protective sheet 109 can be smoothly inserted into the battery can 1 together with the wound group 3.

  Further, since the winding end end portion 35 a of the second separator 35 is disposed in the vicinity of the folded portion 3 c on the bottom side of the winding group 3, the winding end end portion 35 a is disposed on the flat surface portion 3 b of the winding group 3. Compared to the case, there is no influence on the thickness of the wound group 3 by the winding end portion 35a. Furthermore, since the second fixing portion 741 is positioned between the third fixing portion 742 and the end portion 35a of the second separator 35, the unstable state of the end portion 35a is determined as the second state. Therefore, the insertion operation into the battery can 1 can be performed more smoothly.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to the one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

1 Battery can 3 Winding group (winding electrode body)
3a Cavity part 3b Flat part 3c Folding part 3d Mixture layer lamination region 6 Battery cover 7 Liquid inlet 10 Gas discharge valve 11 Liquid stopper 32 Negative electrode 33 First separator 34 Positive electrode 35 Second separator 35a Portions 140, 240, 340, 440, 540, 640, 740 First fixing portions 141, 241, 341, 441, 541, 641, 741 Second fixing portions 642, 742 Third fixing portions 108 Insulating protective sheet 109 First insulating protective sheet 109c First insulating protective sheet rolling start end portion 109d First insulating protective sheet rolling end end portion 110 Second insulating protective sheet 110a Opposing surface portion 110b Side surface portion
110c Bottom face part 111 Second insulating protective sheet 111a Opposing face part 111b Side face part 111c Bottom face part 100, 200, 300, 400, 500, 600, 700 Square secondary battery L Winding axis S Half height position of winding group

Claims (12)

A flat wound electrode body wound with a separator interposed between the positive electrode and the negative electrode and disposed on the outermost periphery, a battery can containing the wound electrode body, and the wound A prismatic secondary battery that is disposed between the electrode body and the battery can and has an insulating protective sheet that covers at least the wound electrode body along the winding direction,
The end edge of the outermost separator is covered with the insulating protective sheet,
In the winding direction, the insulating protection sheet and the outermost separator are respectively fixed to both sides sandwiching the end-of-winding end portion of the outermost separator.   The insulation protective sheet has a plurality of fixing portions to be fixed to the outermost peripheral separator, and the first fixing portion of the plurality of fixing portions is located at a half height position of the wound electrode body. 2. The prismatic secondary battery according to claim 1, wherein the prismatic secondary battery is in an upper position.   The prismatic secondary battery according to claim 2, wherein the insulating protective sheet is thicker than the outermost separator.   The prismatic secondary battery according to claim 3, wherein the insulating protective sheet is made of resin.   The wound electrode body has a flat portion extending in the winding direction and a folded portion located at an end of the flat portion, and the folded portion covered with the insulating protective sheet is The prismatic secondary battery according to claim 4, wherein the prismatic secondary battery is disposed on a bottom side of the battery can.   The second fixing portion among the plurality of fixing portions is disposed on the opposite side of the first fixing portion with a winding end portion of the outermost peripheral separator interposed therebetween. The square secondary battery as described in any one of -5.   The distance from the second fixing part to the end of the outermost separator is shorter than the distance from the first fixing part to the end of the outermost separator. The square secondary battery according to claim 6.   The prismatic secondary battery according to claim 6, wherein the second fixing portion is located at a position higher than a half height position of the wound electrode body.   Of the plurality of fixing portions, a third fixing portion is disposed on the opposite side of the first fixing portion across the end portion of the outermost separator, and the winding electrode body The prismatic secondary battery according to claim 6, wherein the prismatic secondary battery is located at a position higher than a half height position.   10. The prismatic secondary battery according to claim 9, wherein the second fixing portion is located between the third fixing portion and a winding end portion of the outermost separator. 11.   3. The prismatic secondary battery according to claim 2, wherein the plurality of fixing portions are formed by heat-welding or bonding the outermost peripheral separator and the insulating protective sheet.   The prismatic secondary battery according to claim 11, wherein the outermost separator has a resin layer and a heat-resistant layer, and the resin layer is located on the outermost side of the wound electrode body. .

Images