JP2013093287A - Unit cell and battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent: short circuit between positive and negative electrode terminals due to dew condensation water; and thermal deformation of an insulating seal member due to heat input when a bus bar is welded to the positive and negative electrode terminals.SOLUTION: A unit cell includes: positive and negative electrode terminals 141 and 151 attached to a through hole 102h of a battery lid 102; and a gasket 130 that is disposed between the positive and negative electrode terminals 141 and 151 and the through hole 102h, and provides insulation between the positive and negative electrode terminals 141 and 151 and the battery lid 102. The positive and negative electrode terminals 141 and 151 are respectively provided with external terminal parts 142 and 152 to which a bus bar 110 for establishing an electrical connection between unit cells is welded. The gasket 130 includes a covering part 130c that covers tightly outer peripheral surfaces of the external terminal parts 142 and 152 of the positive and negative electrode terminals 141 and 151 protruding outward from the through hole 102h of the battery lid 102. The front end of the covering part 130c is located further closer to the battery lid than bus bar contact surfaces 142a and 152a of the external terminal parts 142 and 152.

Description

  The present invention relates to a battery cell and a battery pack in which a plurality of battery cells are electrically connected.

  In recent years, secondary batteries with large capacity (Wh) have been developed as power sources for hybrid electric vehicles and pure electric vehicles. Among them, prismatic lithium ion secondary batteries with high energy density (Wh / kg) are of particular interest. Has been.

  In a rectangular lithium ion secondary battery, a flat wound electrode group is formed by winding a positive electrode and a negative electrode with a separator interposed therebetween. The wound electrode group is electrically connected to a positive electrode terminal and a negative electrode terminal attached to the through hole of the battery lid via an insulating seal member. The wound electrode group is accommodated in a battery can of the battery container, and the opening of the battery can is sealed and welded with a battery lid. The secondary battery is formed by injecting an electrolytic solution from a liquid injection hole of a battery container containing a wound electrode group, inserting a liquid injection stopper, and sealing and welding by laser welding.

  An assembled battery is formed by electrically connecting the positive electrode terminals and the negative electrode terminals of the plurality of square secondary batteries (single cells) with a conductive member such as a bus bar. Patent Document 1 describes a secondary battery including a disk-shaped external terminal suitable for welding a bus bar.

JP 2005-142026 A

  For example, in a usage environment in which a temperature difference occurs between the secondary battery and the outside air, water vapor contained in the outside air may condense in the battery container and form water droplets. When water droplets adhere to the battery container due to condensation, the terminal and the battery container are electrically connected by the condensed water, and a short circuit may occur between the positive and negative terminals via the battery container. In the secondary battery described in Patent Document 1, no consideration is given to a short circuit due to the condensed water adhering to the battery container, and there is a risk of a short circuit between the positive and negative electrode terminals caused by the condensed water.

  Further, in the secondary battery described in Patent Document 1, the effect of heat generated when welding the bus bar to the terminal on the insulating seal member interposed between the terminal and the battery lid is not considered. The insulation seal member may be deformed by welding heat input.

The invention according to claim 1 includes a wound electrode group in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, a battery can that houses the wound electrode group, and a battery lid that seals the battery can. A positive electrode terminal, a negative electrode terminal, a positive electrode terminal, a negative electrode terminal, and a through hole that are electrically connected to each of the battery container and the positive and negative electrode electrodes and attached to each of a pair of through holes provided in the battery lid Between each of the positive electrode terminal and the negative electrode terminal and an insulating seal member that insulates the battery cover, and each of the positive and negative electrode terminals has a bus bar for electrically connecting the cells. A welded busbar welded portion is provided, and the insulating seal member has a cover portion that closely contacts and covers the outer peripheral surfaces of the positive and negative electrode terminals protruding outward from the through hole of the battery lid. The tip is a bus It is a single cell, characterized by being located on the battery cover side of the top surface of the over weld.
The invention according to claim 2 is the unit cell according to claim 1, wherein the dimension from the tip of the cover to the battery lid is a creepage distance for preventing electrical conduction between the positive and negative electrode terminals and the battery container, It is determined in consideration of heat input when the bus bar is welded to the bus bar welded portion.
According to a third aspect of the present invention, in the unit cell according to the first or second aspect, each of the positive and negative electrode terminals protrudes from one end of the cylindrical bus bar welded portion toward the battery lid side and penetrates the battery lid. Each of the positive and negative terminals is formed such that the outer diameter of the through portion is smaller than the outer diameter of the bus bar welded portion, and the insulating seal member includes a through portion and a cylindrical through portion that penetrates the hole. A cylindrical tube portion disposed between the through hole of the battery lid and an annular shape extending outward from one end of the tube portion and disposed between one end surface of the bus bar welded portion and the battery cover The cover part is formed in the cylindrical shape which stands | starts up from the outer edge of a collar part, It is characterized by the above-mentioned.
According to a fourth aspect of the present invention, in the unit cell according to the first or second aspect, each of the positive and negative electrode terminals protrudes from one end of the rectangular column-shaped bus bar welded portion toward the battery lid side, and Each of the positive and negative terminals is formed such that the outer diameter of the through portion is smaller than the outer size of the bus bar welded portion, and the insulating seal member includes a through portion and a cylindrical through portion that penetrates the through hole. A cylindrical tube portion disposed between the through hole of the battery lid and an annular flange extending outward from one end of the tube portion and disposed between one end surface of the bus bar welded portion and the battery lid The cover part is formed in the rectangular cylinder shape which stands | starts up from the outer edge of a collar part, It is characterized by the above-mentioned.
According to a fifth aspect of the present invention, there is provided the single battery according to the third or fourth aspect, wherein a positive electrode current collector having an electrode connection portion connected to the positive electrode and a terminal connection portion fixed to the positive electrode terminal, and a negative electrode A negative electrode current collector having an electrode connection part connected to the electrode, a terminal connection part fixed to the negative electrode terminal, and a terminal connection part of the positive and negative electrode current collector and the battery cover, Each of the positive and negative electrode current collectors is provided with an insulating member that insulates the battery lid, and each of the positive and negative electrode terminals includes a cylindrical protrusion protruding from one end of the through portion toward the wound electrode group. Each of the positive and negative electrode terminals is fixed to each of the positive and negative electrode current collectors by caulking the projecting portion to the terminal connection portion.
An invention according to claim 6 is an assembled battery comprising a plurality of the unit cells according to any one of claims 1 to 5, wherein the plurality of unit cells are electrically connected to each other by a bus bar. The dimension from the front end to the battery cover is determined in consideration of the shortest distance between the weld metal formed between the bus bar and the positive and negative electrode terminals and the cover portion.

  ADVANTAGE OF THE INVENTION According to this invention, while preventing the short circuit between positive / negative electrode terminals resulting from condensed water, the thermal deformation of the insulating seal member resulting from the heat input when welding a bus bar to a positive / negative electrode terminal can be prevented.

The perspective view of the assembled battery which concerns on the 1st Embodiment of this invention. The perspective view which shows the external appearance of the cell which comprises the assembled battery of FIG. The disassembled perspective view which shows the structure of the single battery of FIG. FIG. 4 is a perspective view showing the wound electrode group of FIG. 3. (A) is the VV sectional view taken on the line of FIG. 2, (b) is the A section enlarged view of FIG. 5 (a). The fracture | rupture perspective view which shows the positive electrode terminal of FIG. (A) is a plane schematic diagram which shows the welding position of a bus bar, (b) is a conceptual diagram which shows the connection structure of the positive electrode terminal of a single battery which comprises the assembled battery of FIG. 1, and a bus bar. The perspective view of the assembled battery which concerns on the 2nd Embodiment of this invention. The conceptual diagram which shows the connection structure of the positive electrode terminal of the cell which comprises the assembled battery of FIG. 8, and a bus-bar. The conceptual diagram which shows the connection structure of the positive electrode terminal and bus bar of the cell which comprise the assembled battery which concerns on the modification of this invention.

Hereinafter, with reference to the drawings, the present invention is an assembled battery incorporated in a power storage device mounted on a hybrid vehicle or a pure electric vehicle, and includes a plurality of prismatic lithium ion secondary batteries (hereinafter referred to as single cells). An embodiment applied to an assembled battery will be described.
-First embodiment-
FIG. 1 is a perspective view of an assembled battery according to the first embodiment of the present invention. As shown in FIG. 1, the assembled battery includes a plurality of single cells 100A to 100C. The cells 100A to 100C have a flat rectangular parallelepiped shape, and are arranged side by side so that the wide surfaces 101a having a large area among the side surfaces face each other. As illustrated, the single cells 100A and 100C have a positive electrode terminal 141 disposed on the left side in the drawing, and the single cell 100B has a negative electrode terminal 151 disposed on the left side in the drawing. That is, the plurality of unit cells 100A to 100C arranged side by side are reversed in direction so that the positions of the positive electrode terminal 141 and the negative electrode terminal 151 attached to the battery cover 102 of each of the unit cells 100A to 100C are reversed. Has been placed.

  As shown in FIG. 1, the positive electrode terminal 141 on the left side of the cell 100 </ b> A and the negative electrode terminal 151 on the left side of the cell 100 </ b> B are electrically connected by a bus bar 110. Similarly, the positive electrode terminal 141 on the right side of the cell 100B in the drawing and the negative electrode terminal 151 on the right side of the cell 100C in the drawing are electrically connected by the bus bar 110.

  The bus bar 110 that electrically connects the cells is a metal rectangular flat plate-shaped conductive member having a thickness of about 1 to 2 mm, and a columnar positioning convex portion 144 provided on the positive electrode terminal 141 is inserted therethrough. A positioning hole 110h1 and a positioning hole 110h2 through which a cylindrical positioning convex portion 154 provided in the negative electrode terminal 151 is inserted are provided.

  In the present embodiment, the positioning hole 110h1 is a circular through hole, and the positioning hole 110h2 is a long hole. The bus bar 110 can be easily positioned by inserting the positioning convex portion 144 into the positioning hole 110h1 and inserting the positioning convex portion 154 into the positioning hole 110h2. The bus bar 110 is placed on bus bar contact surfaces 142a and 152a of positive and negative terminals 141 and 151, which will be described later, and the bus bar contact surfaces 142a and 152a and the lower surface of the bus bar 110 are in contact with each other. The bus bar 110 and the positive and negative terminals 141 and 151 are laser welded by irradiating a laser perpendicular to the surface of the bus bar 110. The position of laser welding will be described later.

  A negative electrode terminal 151 on the right side of the cell 100A shown in FIG. 1 and a positive electrode terminal 141 on the left side of the cell 100C in FIG. 1 are electrically conductive members (not shown) electrically connected in series or in parallel to other batteries (not shown). Or is connected to a power extraction terminal (not shown) by a conductive member (not shown).

  A single battery constituting the assembled battery will be described. Since each of the unit cells 100A to 100C has the same structure, the unit cell 100A will be described below as a representative. FIG. 2 is an external perspective view showing the unit cell 100A, and FIG. 3 is an exploded perspective view showing the configuration of the unit cell 100A.

  As shown in FIG. 2, the unit cell 100 </ b> A includes a battery container including a battery can 101 and a battery lid 102. The material of the battery can 101 and the battery lid 102 is aluminum or an aluminum alloy. As shown in FIG. 3, the wound electrode group 170 is accommodated in the battery can 101. The battery can 101 has a pair of wide surfaces 101a, a pair of narrow surfaces 101b, and a bottom surface 101c, and is formed in a rectangular box shape with an upper surface opened. The wound electrode group 170 is accommodated in the battery can 101 while being covered with the insulating case 108. The material of the insulating case 108 is an insulating resin such as polypropylene. Thereby, the inner surface of the battery can 101 and the wound electrode group 170 are electrically insulated.

  As shown in FIGS. 2 and 3, the battery lid 102 has a rectangular flat plate shape and is welded so as to close the opening of the battery can 101. That is, the battery lid 102 seals the battery can 101. The battery lid 102 has a positive electrode terminal 141 and a negative electrode terminal 151 electrically connected to the positive electrode 174 and the negative electrode 175 of the wound electrode group 170 via the positive electrode current collector 180 and the negative electrode current collector 190, respectively. It is arranged.

  The positive electrode terminal 141 is electrically connected to the positive electrode 174 of the wound electrode group 170 via the positive electrode current collector 180, and the negative electrode terminal 151 is connected to the negative electrode 175 of the wound electrode group 170 via the negative electrode current collector 190. Since it is electrically connected, power is supplied to the external load via the positive electrode terminal 141 and the negative electrode terminal 151, or external generated power is supplied to the wound electrode group 170 via the positive electrode terminal 141 and the negative electrode terminal 151. And charged.

As shown in FIG. 3, the battery lid 102 is provided with a liquid injection hole 106a for injecting an electrolytic solution into the battery container. The liquid injection hole 106a is sealed by a liquid injection plug 106b after the electrolytic solution is injected. As the electrolytic solution, for example, a non-aqueous electrolytic solution in which a lithium salt such as lithium hexafluorophosphate (LiPF ₆ ) is dissolved in a carbonate-based organic solvent such as ethylene carbonate can be used.

  As shown in FIG. 2, the battery cover 102 is provided with a gas discharge valve 103. The gas discharge valve 103 is formed by partially thinning the battery lid 102 by press working. The gas discharge valve 103 is formed with a cleavage groove so that a large opening is formed at the time of cleavage. The gas discharge valve 103 generates heat due to abnormalities such as overcharging of the unit cell, generates gas, and when the pressure in the battery container rises and reaches a predetermined pressure, the gas discharge valve 103 is opened and discharges the gas from the inside. To reduce the pressure in the battery container.

  The wound electrode group 170 will be described with reference to FIG. FIG. 4 is a perspective view showing the wound electrode group 170. As shown in FIG. 4, the wound electrode group 170 that is a power storage element is obtained by winding a long positive electrode 174 and a negative electrode 175 in a flat shape around a winding axis W with a separator 173 interposed therebetween. It is a laminated structure.

  The positive electrode 174 includes a positive electrode foil 171 and a positive electrode active material mixture layer 176 formed by coating a positive electrode active material mixture in which a binder (binder) is mixed with a positive electrode active material on both surfaces of the positive electrode foil 171. Have The negative electrode 175 includes a negative electrode foil 172 and a negative electrode active material mixture layer 177 formed by coating a negative electrode active material mixture in which a binder (binder) is mixed with a negative electrode active material on both surfaces of the negative electrode foil 172. Have Charging / discharging is performed between the positive electrode active material and the negative electrode active material.

  The positive foil 171 is an aluminum alloy foil having a thickness of about 20 to 30 μm, and the negative foil 172 is a copper alloy foil having a thickness of about 15 to 20 μm. The material of the separator 173 is a porous polyethylene resin. The positive electrode active material is a lithium-containing transition metal double oxide such as lithium manganate, and the negative electrode active material is a carbon material such as graphite capable of reversibly occluding and releasing lithium ions.

  One end of both ends of the wound electrode group 170 in the width direction (winding axis W direction orthogonal to the winding direction) is an uncoated portion where the positive electrode active material mixture layer 176 is not formed (exposure of the positive electrode foil 171). Part) is a part where the negative electrode active material mixture layer 177 is not formed, and the other part is a part where the uncoated part (exposed part of the negative electrode foil 172) is laminated. The laminated body of the positive electrode side uncoated part and the laminated body of the negative electrode side uncoated part are respectively crushed in advance, and are respectively positive electrode current collector 180 and negative electrode current collector 190 (see FIG. 3) of battery lid assembly 107 described later. And the ultrasonic bonding.

  As shown in FIG. 3, the battery lid assembly 107 includes a battery lid 102, a positive terminal 141 and a negative terminal 151 attached to each of a pair of through holes 102 h provided in the battery lid 102, and a positive current collector. 180 and the negative electrode current collector 190, a pair of gaskets 130, and a pair of insulating members 160.

  The material of the positive electrode terminal 141 and the positive electrode current collector 180 is an aluminum alloy. The positive electrode terminal 141 is electrically connected to the positive electrode current collector 180. The material of the negative electrode terminal 151 and the negative electrode current collector 190 is a copper alloy. The negative electrode terminal 151 is electrically connected to the negative electrode current collector 190. The material of the insulating member 160 and the gasket 130 is an insulating resin such as polybutylene terephthalate, polyphenylene sulfide, perfluoroalkoxy fluororesin.

  5A is a cross-sectional view taken along the line VV in FIG. 2, and FIG. 5B is an enlarged view of a portion A in FIG. 5A. Although FIG. 5 shows the configuration on the positive electrode side, the positive electrode side and the negative electrode side have the same shape and configuration, and therefore, for convenience, reference numerals of components on the negative electrode side are given in parentheses. In FIG. 5A, the bus bar 110 is indicated by a two-dot chain line.

  As shown in FIG. 5A, the battery lid 102 is provided with a pair of circular through holes 102 h and a pair of circular convex portions 102 c that protrude toward the inside of the battery can 101. The through-holes 143 and 153 of the positive and negative electrode terminals 141 and 151 are inserted through the through-hole 102h through a gasket 130 described later. The circular convex portion 102c is fitted into a circular concave portion 167 of the insulating member 160 described later. The circular convex portion 102 c is formed into a bottomed cylindrical shape by being pressed from the outer surface of the battery lid 102 toward the inside.

  As shown in FIG. 3, the positive electrode current collector 180 is bent at a substantially right angle from a rectangular flat terminal connection portion 181 disposed along the inner surface of the battery lid 102 and a long side portion of the terminal connection portion 181. A flat plate 182 extending toward the bottom surface 101c of the battery can 101 along the wide surface 101a of the battery can 101, and a joint 183 connected by a connecting portion 186 provided at the lower end of the flat plate 182. Yes. The joint portion 183 is a portion that is electrically connected to the positive electrode 174 of the wound electrode group 170 by ultrasonic bonding, and has a joint surface 183 a with the positive electrode 174. The terminal connection portion 181 is provided with a circular through hole 184 into which a protrusion 145 of the positive electrode terminal 141 described later is inserted. As shown in FIG. 5A, the positive terminal 141 is fixed to the terminal connecting portion 181 by caulking and welding.

  Similarly, as illustrated in FIG. 3, the negative electrode current collector 190 includes a rectangular plate-like terminal connection portion 191 disposed along the inner surface of the battery lid 102 and a substantially right angle from the long side portion of the terminal connection portion 191. A flat plate 192 extending toward the bottom surface 101c of the battery can 101 along the wide surface 101a of the battery can 101, and a joint 193 connected by a connecting portion 196 provided at the lower end of the flat plate 192. It has. The bonding portion 193 is a portion that is electrically connected to the negative electrode 175 of the wound electrode group 170 by ultrasonic bonding, and has a bonding surface 193 a with the negative electrode 175. The terminal connection portion 191 is provided with a circular through hole 194 into which a protrusion 155 of a negative electrode terminal 151 described later is inserted. As shown in FIG. 5A, the negative terminal 151 is fixed to the terminal connecting portion 191 by caulking and welding.

  As shown in FIG. 5A, an insulating member 160 is disposed between the terminal connecting portions 181 and 191 of the positive and negative current collectors 180 and 190 and the battery lid 102. The insulating member 160 includes a base portion 161 interposed between each of the terminal connection portions 181 and 191 of the positive and negative electrode current collectors 180 and 190 and the battery lid 102, and one end portion of the base portion 161 in the longitudinal direction of the battery lid 102. The position restricting portion 166 formed so as to protrude from the winding electrode group 170 toward the winding electrode group 170 and the other end portion of the base portion 161 in the longitudinal direction of the battery lid 102 so as to protrude toward the winding electrode group 170 side. And an engagement wall 164 formed.

  Since the base portion 161 of the insulating member 160 having an insulating property is interposed between each of the terminal connection portions 181 and 191 of the positive and negative current collectors 180 and 190 and the battery cover 102, the positive and negative current collector 180. , 190 and the battery lid 102 are electrically insulated.

  The position restricting portion 166 has a position restricting surface 166 a that comes into contact with the wound electrode group 170. The wound electrode group 170 is ultrasonically bonded to the positive and negative electrode current collectors 180 and 190 while being in surface contact with the position regulating surface 166a.

  The insulating member 160 has a recess 162 formed by a base portion 161, an engagement wall 164, and a position restricting portion 166. The terminal connection portions 181 and 191 of the positive and negative current collectors 180 and 190 are fitted in the recesses 162 of the insulating member 160, respectively.

  As shown in FIG. 3, the base portion 161 of the insulating member 160 has circular through holes 161h into which through portions 143 and 153 (see FIG. 5A) of positive and negative electrode terminals 141 and 151 described later are inserted. Is provided. As shown in FIG. 5A, the position restricting portion 166 is provided with a circular concave portion 167 so as to open the battery lid 102 side at a position facing the circular convex portion 102c of the battery lid 102. The circular recess 167 has a circular bottom surface in plan view and an inner peripheral surface that rises perpendicularly from the bottom surface.

  As shown in FIG. 5A, the circular convex portion 102 c of the battery lid 102 is fitted into the circular concave portion 167 of the insulating member 160. When the circular convex portion 102 c is fitted into the circular concave portion 167, the outer peripheral surface of the circular convex portion 102 c comes into contact with the inner peripheral surface of the circular concave portion 167.

  FIG. 6 is a cutaway perspective view showing the positive electrode terminal 141. Although FIG. 6 shows the positive electrode terminal 141, the positive electrode terminal 141 and the negative electrode terminal 151 differ only in material and have the same shape. Therefore, for convenience, the reference numerals of the components of the negative electrode terminal 151 are indicated in parentheses. It is attached.

  As shown in FIG. 6, the positive electrode terminal 141 is provided with a cylindrical external terminal portion 142, protruding from one end of the external terminal portion 142 toward the battery lid 102, and the above-described through-hole 102 h and the battery lid 102. A cylindrical penetrating portion 143 penetrating through the through-hole 161h of the insulating member 160 and a cylindrical projecting portion 145 projecting from one end of the penetrating portion 143 toward the wound electrode group 170 side are provided. The positive electrode terminal 141 is formed such that the outer diameter size of the through portion 143 is smaller than the outer diameter size of the external terminal portion 142, and the outer diameter size of the protrusion 145 is smaller than the outer diameter size of the through portion 143. .

  As shown in FIG. 5A, the external terminal portion 142 is a portion to which the bus bar 110 is welded, and its top surface is a bus bar abutting surface 142a against which the bus bar 110 abuts. The external terminal portion 142 is provided with a cylindrical positioning convex portion 144 so as to protrude outward from the bus bar abutting surface 142a. The positioning convex portion 144 is provided for easily positioning the bus bar 110 and can be omitted. The bus bar 110 is laser-welded while being in contact with the bus bar contact surface 142a.

  The through portion 143 of the positive terminal 141 is inserted into the through hole 102h of the battery lid 102 with the gasket 130 attached. An annular end surface of the external terminal portion 142 is a surface that comes into contact with a flange portion 130b of the gasket 130, which will be described later, and the annular end surface includes an annular first protrusion 142b and a second projection as shown in FIG. A protrusion 142c is provided.

  Similarly, as shown in FIG. 6, the negative electrode terminal 151 is provided with a cylindrical external terminal portion 152, and protrudes from one end of the external terminal portion 152 toward the battery lid 102, and penetrates the battery lid 102 described above. A cylindrical penetrating portion 153 that passes through the hole 102h and the through hole 161h of the insulating member 160, and a cylindrical projecting portion 155 that protrudes from one end of the penetrating portion 153 toward the wound electrode group 170 side. Yes. The negative electrode terminal 151 is formed such that the outer diameter size of the through portion 153 is smaller than the outer diameter size of the external terminal portion 152, and the outer diameter size of the protrusion 155 is smaller than the outer diameter size of the through portion 153. .

  As shown in FIG. 5A, the external terminal portion 152 is a portion to which the bus bar 110 is welded, and its top surface is a bus bar abutting surface 152a against which the bus bar 110 abuts. The external terminal portion 152 is provided with a cylindrical positioning convex portion 154 so as to protrude outward from the bus bar contact surface 152a. The positioning convex portion 154 is provided for easily positioning the bus bar 110 and can be omitted. The bus bar 110 is laser-welded while being in contact with the bus bar contact surface 152a.

  The through portion 153 of the negative electrode terminal 151 is inserted into the through hole 102h of the battery lid 102 with the gasket 130 attached. An annular end surface of the external terminal portion 152 is a surface that comes into contact with a flange portion 130b of a gasket 130, which will be described later, and the annular end surface includes an annular first protrusion 152b and a second projection as shown in FIG. A protrusion 152c is provided.

  As shown in FIG. 5A, the gasket 130 includes a cylindrical tube portion 130a, an annular flange portion 130b extending outward from the upper end of the tube portion 130a, and an upper edge from the outer edge of the flange portion 130b. And a cylindrical cover portion 130c that rises.

  The cylindrical protrusion 145 of the positive electrode terminal 141 is inserted into a through hole 184 formed in the terminal connection portion 181 of the positive electrode current collector 180. A cylindrical protrusion with the flange 130b of the gasket 130 sandwiched between the lower end surface of the external terminal portion 142 and the outer surface of the battery lid 102, and the lower end surface of the through portion 143 being in contact with the terminal connection portion 181. The tip of 145 is caulked to the terminal connection portion 181 of the positive electrode current collector 180.

  As a result, as shown in FIG. 5A, the terminal connection portion 181 of the positive electrode current collector 180 is sandwiched between the crimping portion 145s and the lower end surface of the through portion 143, and the insulating member 160, the battery lid 102, and the gasket 130 The part 130 b is sandwiched between the terminal connection part 181 and the lower end surface of the external terminal part 142. The caulking portion 145s and the terminal connection portion 181 are spot-welded by laser after being caulked and fixed.

  Similarly, the cylindrical protrusion 155 of the negative electrode terminal 151 is inserted into a through hole 194 formed in the terminal connection portion 191 of the negative electrode current collector 190. A cylindrical protrusion with the flange 130b of the gasket 130 sandwiched between the lower end surface of the external terminal portion 152 and the outer surface of the battery lid 102 and the lower end surface of the through portion 153 in contact with the terminal connection portion 191. The tip of 155 is caulked to the terminal connection portion 191 of the negative electrode current collector 190.

  As a result, as shown in FIG. 5A, the terminal connection portion 191 of the negative electrode current collector 190 is sandwiched between the crimping portion 155s and the lower end surface of the through portion 153, and the insulating member 160, the battery lid 102, and the gasket 130 The part 130 b is sandwiched between the terminal connection part 191 and the lower end surface of the external terminal part 152. The caulking portion 155s and the terminal connecting portion 191 are spot-welded by a laser after being caulked and fixed.

  Thus, the positive electrode terminal 141 is fixed to the terminal connection part 181 of the positive electrode current collector 180 by caulking and welding, and the negative electrode terminal 151 is fixed to the terminal connection part 191 of the negative electrode current collector 190 by caulking and welding. Yes. Thereby, the positive electrode current collector 180 and the positive electrode terminal 141 are electrically connected, and the negative electrode current collector 190 and the negative electrode terminal 151 are electrically connected.

  As shown in FIG. 5A, the cylindrical portion 130 a of the gasket 130 is disposed so as to be interposed between the through portions 143 and 153 of the positive and negative electrode terminals 141 and 151 and the through hole 102 h of the battery lid 102. Has been. The flange 130b of the gasket 130 is pressed by the first protrusions 142b and 152b and the second protrusions 142c and 152c and compressed by a predetermined amount, and the outer surface of the battery lid 102 and the external terminal portions of the positive and negative terminals 141 and 151 It arrange | positions so that it may interpose between the annular | circular shaped end surfaces of 142,152.

  Thereby, between each of the positive / negative terminal 141,151 and the battery cover 102 is sealed, and the airtightness of the battery container is ensured. Since the gasket 130 has an insulating property as described above, each of the positive and negative electrode terminals 141 and 151 and the battery cover 102 are electrically insulated.

  Since the flange 130b is compressed over the entire circumference of the flange 130b of the gasket 130 by the annular first protrusions 142b and 152b and the second protrusions 142c and 152c, even if the compression amount is uneven, The contact between the flange portion 130b of the gasket 130 and the first protrusions 142b and 152b and the second protrusions 142c and 152c can be maintained over the entire circumference, thereby ensuring the stability of the airtightness of the battery container.

  As shown in FIG. 5B, the external terminal portions 142 and 152 of the positive and negative terminals 141 and 151 protrude outward from the through hole 102 h of the battery lid 102. The cover portion 130c of the gasket 130 is in close contact with the external terminal portions 142 and 152 so as to cover the battery cover side outer peripheral surfaces of the external terminal portions 142 and 152, respectively. As shown in FIG. 5B, the tip of the cover 130c is located closer to the battery lid 102 than the bus bar contact surfaces 142a and 152a.

  The design dimension L11 from the tip of the cover part 130c of the gasket 130 to the outer surface of the battery cover 102 is the minimum dimension L12 obtained from the creeping distance for preventing conduction between the positive and negative terminals 141 and 151 and the battery cover 102. And a separation dimension L13 obtained from the shortest distance between the weld metal formed between the bus bar 110 and the external terminal portions 142 and 152 and the gasket 130.

  The minimum dimension L12 from the tip of the cover part 130c to the outer surface of the battery lid 102 is to ensure insulation, that is, from the viewpoint of creepage distance to prevent conduction between the positive and negative terminals 141, 151 and the battery container. To be determined. For example, the minimum dimension L12 can be determined with reference to the relationship value between the voltage and creepage distance indicated in various safety standards such as the DIN standard. In the present embodiment, the creepage distance was determined from the standard document (DIN VDE 0110b: 1972-02) with the DC voltage of the unit cell set to 5V. The creepage distance is 2.3 mm as a reference value with the minimum DC voltage in the specification table being 15 V and the application being the insulation group D. The minimum dimension L12 is determined in consideration of the creepage distance obtained as a reference value.

  The front end of the cover portion 130c is separated from the bus bar abutting surfaces 142a and 152a by a predetermined distance so that the gasket 130 is not thermally deformed by heat input when the bus bar 110 is welded. The separation dimension L13 from the bus bar abutting surfaces 142a, 152a, which are the top surfaces of the external terminal portions 142, 152, to the tip of the cover portion 130c of the gasket 130 is such that the bus bar 110 is connected to the external terminal portions 142, 152 of the positive and negative terminals 141, 151. It is determined from the viewpoint of protecting the gasket 130 from heat input when laser welding is performed.

  The separation dimension L13 considers the size of the positive and negative terminals 141, 151, the material of the bus bar 110, the thickness of the bus bar 110, the welding speed, the welding energy, the welding area, the welding position, the material of the gasket 130 (heat resistance), and the like. Can be determined. In the present embodiment, the separation dimension L13 is determined in consideration of the shortest distance between the weld metal formed by laser welding and the cover 130c of the gasket 130.

  FIG. 7A is a schematic plan view showing the welding position of the bus bar 110. FIG. 7B is a conceptual diagram showing a connection structure between the positive electrode terminal 141 of the single battery constituting the assembled battery and the bus bar 110, and schematically shows a cross section taken along line BB in FIG. 7A. . 7B shows the connection structure on the positive electrode side, but since the negative electrode side has the same configuration, the reference numerals of the components on the negative electrode side are given in parentheses for convenience, and the negative electrode side is attached. Fig. 7 schematically shows a cut surface taken along the line C-C of Fig. 7A.

  With reference to Fig.7 (a) and FIG.7 (b), the welding position of the bus-bar 110 and the shortest distance L10 between a weld metal and the gasket 130 are demonstrated. As shown in FIGS. 7A and 7B, the positioning convex portions 144 and 154 of the positive and negative terminals 141 and 151 and the inner peripheral surfaces of the positioning holes 110h1 and 110h2 of the bus bar 110 are butt welded. . The laser is irradiated on the bus bar 110 from above, perpendicular to the surface of the bus bar 110.

  As shown in FIGS. 7A and 7B, on the positive electrode side, laser is irradiated from the tip side of the positioning convex portion 144 of the positive terminal 141, and laser welding is performed over the entire circumference of the positioning convex portion 144. The weld metal w11 is formed. On the negative electrode side, laser is irradiated from the tip side of the positioning convex portion 154 of the negative electrode terminal 151, and laser welding is performed on a part of the circumference of the positioning convex portion 154 to form a weld metal w12. In addition, the penetration depth h1 of the weld metals w11 and w12 does not reach the bus bar contact surfaces 142a and 152a of the external terminal portions 142 and 152.

  The shortest distance L10 between the weld metals w11 and w12 and the gasket 130 shown in FIG. 7B is desirably 2 mm or more. The separation dimension L13 is determined in consideration of the shortest distance L10 being 2 mm or more. When the separation dimension L13 is obtained, the maximum dimension L15 from the front end of the cover 130c to the battery lid 102 is obtained by subtracting the separation dimension L13 from the dimension L14 from the outer surface of the battery lid 102 to the bus bar contact surfaces 142a and 152a. It is determined (L15 = L14-L13).

  As described above, the minimum dimension L12 is determined in consideration of the creepage distance for preventing conduction between the positive and negative terminals 141 and 151 and the battery case, and the bus bar 110 is welded to the external terminal portions 142 and 152. The maximum dimension L15 is determined in consideration of heat input. When the minimum dimension L12 and the maximum dimension L15 are determined, the design dimension from the tip of the cover 130c of the gasket 130 to the outer surface of the battery lid 102 is equal to or greater than the minimum dimension L12 and equal to or less than the maximum dimension L15. L11 is determined (L12 ≦ L11 ≦ L15).

According to this embodiment described above, the following operational effects can be achieved.
The gasket 130 is provided with a cover portion 130c that tightly covers the outer peripheral surfaces of the external terminal portions 142 and 152 of the positive and negative electrode terminals 141 and 151 protruding outward from the through hole 102h of the battery lid 102. The dimensions from the tip of the cover 130 c to the battery lid 102 are the creepage distance to prevent conduction between the positive and negative terminals 141, 151 and the battery lid 102, and the bus bar 110 is welded to the external terminal portions 142, 152. The gasket 130 was formed so that the front end of the cover portion 130c was positioned closer to the battery lid 102 than the bus bar contact surfaces 142a and 152a of the external terminal portions 142 and 152. As a result, even if water droplets adhere to the battery lid 102 due to condensation or the like, it is possible to ensure insulation between the positive and negative electrode terminals 141 and 151 and the battery lid 102 and also due to heat input when the bus bar 110 is welded. Thermal deformation of the gasket 130 can be prevented.

  On the other hand, in the prior art described in Patent Document 1, a cover portion that tightly covers the external terminal portion is not provided in the gasket on the disk-shaped external terminal portion. Therefore, in the conventional technology, in a usage environment in which a temperature difference occurs between the battery and the outside air, water vapor contained in the outside air is condensed into water droplets in the battery container, and the terminal and the battery container are electrically connected by the dew condensation water. There is a possibility that a short circuit may occur between the positive and negative electrode terminals via the battery container.

  When the positive and negative terminals 141 and 151 are on the gas discharge path of the gas or electrolyte solution jetted from the gas discharge valve 103, the electrolyte solution jetted from the gas discharge valve 103 is transferred to another unit on the gas discharge path. Although it may adhere to the battery container of the battery, according to the present embodiment, the continuity between the positive and negative electrode terminals 141 and 151 and the battery container is prevented by the cover 130c, so that the gas discharge valve 103 is cleaved. Sometimes, the insulation between the positive and negative terminals 141 and 151 and the battery cover 102 can be secured.

-Second embodiment-
A secondary battery (unit cell) and an assembled battery according to the second embodiment will be described with reference to FIGS. 8 and 9. FIG. 8 is a perspective view of an assembled battery according to the second embodiment of the present invention. FIG. 9 is a conceptual diagram showing a connection structure between the positive electrode terminal 241 of the unit cell constituting the assembled battery and the bus bar 210, and schematically shows a cross section taken along line IX-IX in FIG. Although FIG. 9 shows the connection structure on the positive electrode side, since the negative electrode side has the same configuration, for convenience, reference numerals of components on the negative electrode side are also given in parentheses. In the figure, the same reference numerals are given to the same or corresponding parts as those in the first embodiment, and the differences will be mainly described.

  In the second embodiment, the shape of the external terminal portions 242 and 252 of the positive and negative terminals 241, 251 and the shape of the cover portion 230c of the gasket 230 that covers the outer peripheral surface of the external terminal portions 242, 252 and the flange portion 230b. Although the shape is different from that of the first embodiment, other configurations are the same as those of the first embodiment. In the second embodiment, the external terminal portions 242 and 252 are not provided with positioning projections, and the bus bar 210 is not provided with positioning holes.

  As shown in FIG. 8, rectangular column-shaped external terminal portions 242 and 252 are provided on the positive and negative terminals 241 and 251 of each of the unit cells 200A to 200C constituting the assembled battery according to the second embodiment. ing. The external terminal portions 242 and 252 are portions to which the bus bar 210 is welded, and the top surfaces thereof are bus bar abutting surfaces 242a and 252a with which the lower surface of the bus bar 210 abuts.

  As shown in FIG. 9, cylindrical penetrating portions 143 and 153 project from the lower ends of the external terminal portions 242 and 252 as in the first embodiment, and from the lower ends of the penetrating portions 143 and 153, respectively. Cylindrical protrusions 145 and 155 are projected. Each of the positive and negative terminals 241 and 251 has an outer diameter of the through-portions 143 and 153 smaller than the outer dimensions (width and length) of the external terminals 242 and 252, and the outer diameters of the protrusions 145 and 155. Is formed to be smaller than the outer diameter of the through-holes 143 and 153. The positive and negative electrode terminals 241 and 251 are fixed to the positive and negative electrode current collectors 180 and 190, respectively, by projecting the protrusions 145 and 155 to the terminal connection portions 181 and 191 (not shown).

  The flange portion 230b of the gasket 230 is formed in an annular shape having a rectangular shape in plan view, extends outward from the upper end of the cylindrical tube portion 130a, the lower end surfaces of the external terminal portions 242, 252 and the battery lid 102. It is arranged between. The cover portion 230c of the gasket 230 is formed in a rectangular cylindrical shape rising from the outer edge of the flange portion 230b, and covers the outer peripheral surfaces of the external terminal portions 242, 252 in close contact with each other.

  As shown in FIG. 8, the bus bar 210 and the positive and negative terminals 241 and 251 are overlapped and welded by laser when the laser is irradiated on the surface of the bus bar 210 vertically from above. When the bus bar 210 is welded to the positive terminal 241, a pair of weld metals w <b> 21 that are parallel to each other in a plan view are formed. Similarly, when the bus bar 210 is welded to the negative electrode terminal 251, a pair of weld metals w22 that are parallel to each other in a plan view are formed.

  As shown in FIG. 9, the weld metals w <b> 21 and w <b> 22 reach the bus bar abutting surfaces 242 a and 252 a at the center, and the weld metals w <b> 21 and w <b> 22 form a conduction path between the positive and negative terminals 241 and 251 and the bus bar 210. doing. The penetration depth of the weld metals w21 and w22 becomes deeper toward the center of the positive and negative terminals 241 and 251.

  The shortest distance L20 between the weld metals w21, w22 and the gasket 230 is preferably 2 mm or more. The separation dimension L23 from the bus bar contact surfaces 242a and 252a, which are the top surfaces of the external terminal portions 242 and 252, to the tip of the cover portion 230c of the gasket 230 is determined in consideration of the shortest distance L20 being 2 mm or more. . When the separation dimension L23 is obtained, the maximum dimension L25 from the front end of the cover 230c to the battery lid 102 is obtained by subtracting the separation dimension L23 from the dimension L24 from the outer surface of the battery lid 102 to the bus bar contact surfaces 242a and 252a. It is determined (L25 = L24-L23).

  The minimum dimension L22 from the front end of the cover 230c to the outer surface of the battery lid 102 is the creepage distance for preventing conduction between the positive and negative terminals 241 and 251 and the battery container, as in the first embodiment. Is determined in consideration of

  As described above, the minimum dimension L22 is determined in consideration of the creepage distance for preventing conduction between the positive and negative terminals 241 and 251 and the battery case, and the bus bar 210 is welded to the external terminal portions 242 and 252. The maximum dimension L25 is determined in consideration of heat input. When the minimum dimension L22 and the maximum dimension L25 are determined, the design dimension from the tip of the cover 230c of the gasket 230 to the outer surface of the battery lid 102 is equal to or greater than the minimum dimension L22 and not greater than the maximum dimension L25. L21 is determined (L22 ≦ L21 ≦ L25).

  According to the second embodiment, as in the first embodiment, the insulation between the positive and negative terminals 241 and 251 and the battery cover 102 is ensured even if water droplets adhere to the battery cover 102 due to condensation or the like. In addition, it is possible to prevent thermal deformation of the gasket 230 due to heat input when the bus bar 210 is welded.

  Furthermore, in the second embodiment, the external terminal portions 242 and 252 are formed in a rectangular column shape, and the bus bar contact surfaces 242a and 252a are formed in a rectangular shape in plan view. Therefore, in the second embodiment, compared to the first embodiment, the contact area between the bus bar 210 and the bus bar abutting surfaces 242a, 252a is large, and the weld metal forming region serving as a conduction path is formed in the first embodiment. Since it can be secured wider than in the embodiment, the electrical resistance between each of the positive and negative terminals 241 and 251 and the bus bar 210 can be reduced.

The following modifications are also within the scope of the present invention, and one or a plurality of modifications can be combined with the above-described embodiment.
[Modification]

  (1) In the first embodiment, the positioning convex portions 144 and 154 are provided, and the outer peripheral surfaces of the positioning convex portions 144 and 154 and the inner peripheral surfaces of the positioning holes 110h1 and 110h2 of the bus bar 110 are butt welded by laser. In the second embodiment, the bus bar 210 and the external terminal portions 242 and 252 are overlapped and welded by laser, but the present invention is not limited to this. For example, as shown in FIG. 10, a laser may be irradiated from the side, and the lower surface of the bus bar 310 and the bus bar abutting surfaces 342a and 352a of the external terminal portions 342 and 352 may be butt welded by the laser. FIG. 10 is a conceptual diagram showing a connection structure between a positive electrode terminal 341 and a bus bar 310 of a unit cell constituting an assembled battery according to a modification of the present invention. In FIG. 10, the connection structure on the positive electrode side is shown, but since the negative electrode side has the same configuration, the reference numerals of the components on the negative electrode side are given in parentheses for convenience.

  As shown in FIG. 10, the weld metals w31 and w32 are formed along the bus bar contact surfaces 342a and 352a. The shortest distance L30 between the weld metals w31, w32 and the gasket 130 is preferably 2 mm or more. The distance L33 from the bus bar contact surfaces 342a and 352a, which are the top surfaces of the external terminal portions 342 and 352, to the tip of the cover portion 130c of the gasket 130 is determined so that the shortest distance L30 is 2 mm or more. When the separation dimension L33 is obtained, the maximum dimension L35 from the tip of the cover 330c to the battery lid 102 is obtained by subtracting the separation dimension L33 from the dimension L34 from the outer surface of the battery lid 102 to the bus bar contact surfaces 342a and 352a. It is determined (L35 = L34-L33).

  The minimum dimension L32 from the front end of the cover 130c to the outer surface of the battery lid 102 is the creepage distance for preventing conduction between the positive and negative terminals 341 and 351 and the battery container, as in the first embodiment. Is determined in consideration of The design dimension L31 from the tip of the cover 330c of the gasket 330 to the outer surface of the battery lid 102 is determined to be not less than the minimum dimension L32 and not more than the maximum dimension L35 (L32 ≦ L31 ≦ L35).

  (2) In the first embodiment, the positioning protrusions 144 and 154 are provided so as to protrude outward from the bus bar contact surfaces 142a and 152a, but the present invention is not limited to this. For example, as shown in FIG. 10, positioning concave portions 344 and 354 having a circular shape in plan view may be provided so as to be recessed from the bus bar abutting surfaces 342a and 352a toward the battery lid 102 side. In this case, the bus bar 310 is formed with positioning convex portions 310c to be inserted into the positioning concave portions 344 and 354 of the positive and negative terminals 341 and 351.

  (3) The shapes of the positioning convex portions 144 and 154 and the positioning concave portions 344 and 354 are not limited to a circular shape in plan view.

  (4) Although the positioning convex portions 144 and 154 are formed on the positive and negative electrode terminals 141 and 151, respectively, the positioning convex portion may be provided on only one of the positive and negative electrode terminals 141 and 151. The positioning recesses 344 and 354 are formed in the positive and negative electrode terminals 341 and 351, respectively, but the positioning recess may be provided in only one of the positive and negative electrode terminals 341 and 351. A positioning convex part may be provided on one of the positive and negative terminals, and a positioning concave part may be provided on the other.

  (5) Although the lithium ion single battery has been described as an example of the secondary battery, the present invention can also be applied to other secondary batteries such as a nickel metal hydride battery.

  (6) The materials of the positive terminals 141, 241, 341, the positive current collector 180, and the positive foil 171 are not limited to aluminum alloys, and may be aluminum. The material of the negative electrode terminals 151, 251 and 351, the negative electrode current collector 190 and the negative electrode foil 172 is not limited to a copper alloy, and may be copper.

  (7) In the above-described embodiment, the assembled battery mounted on the hybrid electric vehicle or the pure electric vehicle has been described, but the present invention is not limited to this. The present invention is applied to an assembled battery that can be used for power storage devices such as other electric vehicles, such as railway vehicles such as hybrid trains, passenger cars such as buses, cargo vehicles such as trucks, and industrial vehicles such as battery-powered forklift trucks. Also good.

  (8) In the above-described embodiment, the bus bars 110, 210, 310 and the positive and negative terminals 141, 151, 241, 251, 341, 351 are connected by laser welding, but the present invention is not limited to this. For example, the bus bars 110, 210, and 310 may be connected to the positive and negative terminals 141, 151, 241, 251, 341, and 351 by electron beam welding.

  The present invention is not limited to the embodiment described above, and can be freely changed and improved without departing from the gist of the invention.

100A to 100C single cell, 101 battery can, 102 battery lid, 102h through hole, 103 gas discharge valve, 110 bus bar, 130 gasket, 130a cylinder, 130b collar, 130c cover, 141 positive terminal, 142 external terminal, 142a Bus bar abutting surface, 143 penetrating portion, 145 projecting portion, 145s caulking portion, 151 negative electrode terminal, 152 external terminal portion, 152a bus bar abutting surface, 153 penetrating portion, 155 projecting portion, 155s caulking portion, 160 insulating member, 161 Base part, 161h Through-hole, 170 wound electrode group, 173 separator, 174 positive electrode, 175 negative electrode, 180 positive electrode current collector, 181 terminal connection part, 183 joint part, 190 negative electrode current collector, 191 terminal connection part, 193 Joint, 200A-200C cell, 210 bus bar, 230 Gasket 230b collar part, 230c cover part, 241 positive terminal, 242 external terminal part, 242a bus bar contact surface, 251 negative terminal, 252 external terminal part, 252a bus bar contact surface, 310 bus bar, 330 gasket, 330c cover part, 341 Positive terminal, 342 External terminal, 342a Bus bar contact surface, 351 Negative terminal, 352 External terminal, 352a Bus bar contact surface

Claims (6)

A wound electrode group in which a positive electrode and a negative electrode are wound with a separator interposed therebetween;
A battery container comprising a battery can that houses the wound electrode group and a battery lid that seals the battery can;
A positive terminal and a negative terminal electrically connected to each of the positive and negative electrodes and attached to each of a pair of through holes provided in the battery lid;
An insulating seal member interposed between each of the positive electrode terminal and the negative electrode terminal and the through-hole to insulate each of the positive electrode terminal and the negative electrode terminal and the battery lid;
Each of the positive and negative terminals is provided with a bus bar welding portion to which a bus bar for electrically connecting the cells is welded,
The insulating seal member has a cover portion that tightly covers and covers each outer peripheral surface of the positive and negative electrode terminals protruding outward from the through hole of the battery lid,
The single cell according to claim 1, wherein a tip of the cover portion is located closer to a battery lid than a top surface of the bus bar welded portion. The single battery according to claim 1,
The dimensions from the front end of the cover part to the battery cover are the creepage distance to prevent conduction between the positive and negative electrode terminals and the battery container, and the heat input when welding the bus bar to the bus bar welded part. A single battery characterized by being determined. The single battery according to claim 1 or 2,
Each of the positive and negative terminals includes a cylindrical penetrating portion that protrudes from one end of the cylindrical bus bar welded portion toward the battery lid side and penetrates the through hole of the battery lid,
Each of the positive and negative terminals is formed such that the outer diameter dimension of the through portion is smaller than the outer diameter dimension of the bus bar welded portion,
The insulating seal member includes a cylindrical tube portion disposed between the through portion and the through hole of the battery lid, and extends outward from one end of the tube portion, and one end surface of the bus bar welded portion. And an annular collar disposed between the battery lid and the battery lid,
The cell is characterized in that the cover part is formed in a cylindrical shape rising from an outer edge of the flange part. The single battery according to claim 1 or 2,
Each of the positive and negative terminals includes a cylindrical penetrating portion that protrudes from one end of the rectangular bar-shaped bus bar welded portion toward the battery lid side and penetrates the through hole of the battery lid,
Each of the positive and negative terminals is formed such that the outer diameter dimension of the through portion is smaller than the outer dimension of the bus bar welded portion,
The insulating seal member includes a cylindrical tube portion disposed between the through portion and the through hole of the battery lid, and extends outward from one end of the tube portion, and one end surface of the bus bar welded portion. And an annular collar disposed between the battery lid and the battery lid,
The cell is characterized in that the cover part is formed in a rectangular cylindrical shape rising from an outer edge of the flange part. The single battery according to claim 3 or 4,
A positive electrode current collector having an electrode connection portion connected to the positive electrode and a terminal connection portion fixed to the positive electrode terminal;
A negative electrode current collector having an electrode connection part connected to the negative electrode and a terminal connection part fixed to the negative electrode terminal;
An insulating member interposed between each of the terminal connection portions of the positive and negative electrode current collectors and the battery lid, and insulating each of the positive and negative electrode current collectors and the battery lid;
Each of the positive and negative terminals includes a cylindrical protrusion protruding from one end of the penetrating part toward the wound electrode group,
Each of the positive and negative electrode terminals is fixed to each of the positive and negative electrode current collectors by caulking the protruding portion to the terminal connection portion. A battery pack comprising a plurality of the unit cells according to any one of claims 1 to 5, wherein the plurality of unit cells are electrically connected by a bus bar,
The dimension from the front end of the cover part to the battery cover is determined in consideration of the shortest distance between the weld metal formed between the bus bar and the positive and negative terminals and the cover part. A battery pack featuring the features.

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