JP7118907B2 - Secondary battery and insulating cover for secondary battery - Google Patents

Description

The present invention relates to a secondary battery and an insulating cover for the secondary battery.

One structure of a secondary battery includes a case, an electrode body housed in the case, and a lid that seals the opening of the case. The electrode assembly includes a positive electrode plate having a positive electrode mixture on a base material, a negative electrode plate having a negative electrode mixture applied to a base material, and a separator. As the structure of the electrode body, there is a wound type in which a positive electrode plate, a negative electrode plate, and a separator interposed therebetween are wound, and a plurality of positive electrode plates, a plurality of negative electrode plates, and between them. A laminated type in which intervening separators are laminated is known (see Patent Documents 1 and 2, for example).

The electrode body is provided with current collecting tabs electrically connected to the positive terminal and the negative terminal of the secondary battery, respectively. The position of the current collecting tab on the electrode body varies depending on the structure of the electrode body and the like. For example, as described in Patent Document 1, a wound electrode body generally has a structure in which a positive electrode side current collecting tab and a negative electrode side current collecting tab are provided at both ends of the electrode body. Some laminated electrode bodies (hereinafter referred to as "electrode plate group") have a structure in which both positive and negative current collecting tabs are provided at one end of the electrode plate group. When the current collecting tab is provided at one end of the electrode plate assembly in this manner, the space occupied by the current collecting tab can be reduced compared to the wound electrode assembly, and the space occupied by the electrode mixture can be increased. Since it is possible, there is an advantage that the battery capacity can be increased.

JP 2016-62645 A JP 2018-10850 A

When assembling a secondary battery comprising an electrode plate group, first, a positive electrode current collecting tab and a negative electrode current collecting tab provided at one end of the electrode plate group, and a current collecting portion provided on the lid portion of the secondary battery. and are electrically connected. Next, the electrode plate group connected to the lid via the current collecting tab is covered with a film made of an insulator.

Next, the electrode plate group covered with the film is housed in a case. At this time, a pressing force is applied from above the lid portion to push the electrode plate group into the case while generating a frictional force between the electrode plate group and the inner peripheral surface of the case. The electrode plate group is structurally connected to the lid via the current collecting tab, and the electrode plate group is held on the inner peripheral surface of the case. through the body portion except for the current collecting tabs.

However, since the current collecting tabs of the electrode plate group are formed as part of the base material made of metal foil, they are easily deformed by applying a pressing force. As described above, the current collecting tab has the function of electrically connecting the positive electrode plate, the negative electrode plate, and the positive electrode terminal and the negative electrode terminal, and thus deformation is not preferable.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a secondary battery having a group of electrode plates in which current collecting tabs of a positive electrode and a negative electrode are positioned at one end thereof. The object is to suppress deformation.

A secondary battery for solving the above problems is a secondary battery having a plurality of electrode plates each including a rectangular base material having a current collecting tab at one end and an electrode mixture provided on the base material, an electrode plate group in which a plurality of the electrode plates are stacked with the positions of the current collecting tabs aligned for each electrode via a separator; and a lid portion provided with a current collecting portion to which the current collecting tabs are joined. an insulating cover made of an insulating material and covering a part of the electrode plate group; and a case accommodating the electrode group accommodated in the insulating cover together with an electrolyte, wherein the insulating cover comprises the electrode group. Among them, a pair of side surfaces located between a front wall portion and a rear wall portion respectively facing the front surface and the back surface located at the end in the stacking direction, the upper surface where the current collecting tab is located, and the lower surface on the opposite side thereof each having a pair of side wall portions facing each other, the side wall portions protruding upward from the upper surface of the electrode plate group housed in the insulating cover, connected to the lid portion and housed in the insulating cover; It has a contact surface that contacts the lid portion when the electrode plate group is inserted into the case.

An insulating cover for a secondary battery that solves the above problems comprises a rectangular base material having a current collecting tab at one end, and a plurality of electrode plates containing an electrode mixture provided on the base material, the current collecting tab being interposed between separators. A secondary battery comprising: an electrode plate group stacked with tabs aligned; a lid portion provided with a current collecting portion to which the current collecting tabs are joined; and a case accommodating the electrode plate group together with an electrolyte. The insulating cover used includes a front wall portion and a rear wall portion facing the front surface and the rear surface located at the end in the stacking direction of the electrode plate group, and the upper surface where the current collecting tab is located and the opposite side. a pair of side walls facing each other on a pair of side surfaces positioned between the cover and the lower surface; and a contact surface that contacts the lid portion when the electrode plate group housed in the insulating cover is inserted into the case.

According to the above configuration, when the electrode plate group housed in the insulating cover and structurally connected to the lid portion is pushed into the case by applying a pressing force to the lid portion, the contact surface of the side wall portion of the insulating cover. and the lid abut, and the lid is supported by the side wall. Therefore, it is possible to suppress the pressing force applied to the lid portion from being applied to the current collecting tab. Therefore, in the secondary battery including the electrode plate group in which the current collecting tabs of the positive electrode and the negative electrode are positioned at one end, deformation of the current collecting tabs can be suppressed.

In the secondary battery, the shortest distance between the front wall portion and the rear wall portion is such that when the electrode plate group is housed in the insulating cover, the front wall portion and the rear wall portion are the poles. It is preferable that the length in the stacking direction of the electrode plate group or less is set so as to abut on the front surface and the back surface of the plate group.

According to the above configuration, the electrode plate group is held while being sandwiched between the front wall portion and the rear wall portion of the insulating cover. Therefore, it is possible to prevent an increase in the thickness of the electrode plate group due to the restoring force (springback) of the electrode plate group.

In the above secondary battery, it is preferable that the thickness of the side wall portion is greater than the thicknesses of the front wall portion and the rear wall portion.
According to the above configuration, the thickness of the side wall portion of the insulating cover is greater than the thicknesses of the front wall portion and the rear wall portion, so that the strength of the insulating cover can be increased. On the other hand, by thinning the front wall portion and the rear wall portion of the insulating cover, the secondary battery can be made compact in the direction from the front wall portion to the rear wall portion.

In the secondary battery, the shortest distance between the pair of side wall portions is such that a space is provided between the side wall portion and the electrode plate group when the electrode plate group is housed in the insulating cover. It is preferably larger than the width along the direction from one of the side surfaces of the electrode plate group to the other side surface.

According to the above configuration, a space is provided between the electrode plate group accommodated in the insulating cover and the side wall portion of the insulating cover. Therefore, since the laminated surface of the electrode plate group 14 and the side wall portion of the insulating cover do not come into contact with each other, it is possible to prevent the electrode plates constituting the electrode plate group from being displaced or otherwise deformed or deformed. can be done.

At least one of the pair of side wall portions of the secondary battery preferably has a communication hole that communicates between the inside and the outside of the insulating cover.
According to the above configuration, by causing the electrolyte injected into the case to flow through the communication hole, the electrolyte can be filled between the insulating cover and the case. Further, the electrolyte can flow out of the insulating cover or flow into the insulating cover through the communication holes as the electrode plate group expands and contracts due to charging and discharging of the secondary battery.

In the above secondary battery, the insulating cover comprises the current collecting tab and a metal material positioned on the upper surface of the electrode plate group when the electrode plate group to which the lid is connected is housed inside. It is preferable to have the upper wall portion interposed between the lid portion.

According to the above configuration, since the upper wall portion of the insulating cover is interposed between the current collecting tab and the lid portion made of a metal material, it is possible to prevent positive and negative short circuits due to contact between the current collecting tab and the lid portion. .
In the secondary battery, it is preferable that the thickness of the upper wall portion is greater than the thickness of the front wall portion and the rear wall portion facing the front surface and the rear surface of the electrode plate group, respectively.

According to the above configuration, since the thickness of the upper wall portion of the insulating cover is greater than the thicknesses of the front wall portion and the rear wall portion, the strength of the insulating cover can be increased. On the other hand, by thinning the front wall portion and the rear wall portion of the insulating cover, the secondary battery can be made compact in the direction from the front wall portion to the rear wall portion.

In the above secondary battery, the insulating cover preferably has a bottom wall facing the lower surface of the electrode plate group.
According to the above configuration, since the insulating cover has the bottom wall portion, when the case is made of a metal material, it is interposed between the electrode plate group and the case, thereby preventing a short circuit between the case and the electrode plate group. can.

In the above secondary battery, the front surface and the back surface of the insulating cover are opposed to the front surface on the inner peripheral surface of the case in the process and in the state in which the electrode plate group is accommodated in the case. It is preferable that the surface facing the rear surface is in contact with the surface facing the rear surface.

According to the above configuration, since the front and back surfaces of the insulating cover abut against the inner peripheral surface of the case while being housed in the case, the secondary battery can be made compact in the direction from the front surface to the back surface of the insulating cover. can be done. Further, the electrode plate group accommodated in the insulating cover is accommodated in the case while the insulating cover slides on the inner peripheral surface of the case. Therefore, the electrode plate group can be accommodated in the case while being held by the case.

ADVANTAGE OF THE INVENTION According to this invention, deformation|transformation of a current collection tab can be suppressed about the secondary battery provided with the electrode plate group which the current collection tab of a positive electrode and a negative electrode is located in one end part.

The figure which shows the outline of the perspective structure about one Embodiment which actualized the secondary battery. FIG. 3 is a schematic diagram for explaining the structure of the electrode plate group in the embodiment; The perspective view of the electrode plate group connected with the cover part in the same embodiment. The perspective view of the insulation cover in the same embodiment. FIG. 2 is an exploded perspective view of the internal structure of the secondary battery in the embodiment; The figure which expanded a part of insulation cover in the same embodiment. The figure explaining the process of accommodating the battery structure in the same embodiment in a case. FIG. 4 is a cross-sectional view of the secondary battery in the same embodiment in the vicinity of the current collecting portion; The exploded perspective view of the insulating cover in other embodiment. The perspective view of the insulating cover in other embodiment. The perspective view of the insulating cover in other embodiment.

An embodiment of the present invention will be described with reference to FIGS. 1 to 8. FIG. An example in which the secondary battery is embodied as a lithium ion secondary battery will be described below.
As shown in FIG. 1 , secondary battery 11 includes case 12 having an opening and lid 13 that seals the opening of case 12 . The case 12 and the lid portion 13 are made of a metal material. A positive collector 20 including a positive terminal 21 and a negative collector 30 including a negative terminal 31 are provided on the lid 13 . The case 12 accommodates an electrode plate group 14 and an electrolyte. The lid portion 13 is provided with a discharge portion 40 for discharging gas in the battery according to the internal pressure of the battery, and an injection hole 41 for injecting an electrolyte.

As shown in FIG. 2, the electrode plate group 14 is a laminate in which a plurality of positive electrode plates 15 and a plurality of negative electrode plates 16 are alternately laminated with separators 17 interposed therebetween. The positive electrode plate 15 includes a positive electrode substrate 18 and positive electrode mixture layers 19 provided on both sides of the positive electrode substrate 18 . The positive electrode base material 18 is made of a metal foil (or a thin metal plate) and shaped into a rectangular shape. The positive electrode substrate 18 is provided with a positive electrode tab 18A (collecting tab) extending from an end. The positive electrode mixture is not provided on the positive electrode tab 18A. The positive electrode tab 18A is provided at the upper end of the upper end and the lower end corresponding to the long side of the positive electrode substrate 18 . Further, the positive electrode tab 18A is provided at a position shifted by a predetermined distance toward one side (left side in FIG. 2) from the center of the upper end.

Materials constituting the positive electrode substrate 18 include, for example, aluminum and an aluminum alloy. Materials constituting the positive electrode mixture include a lithium-containing composite oxide as a positive electrode active material, a binder, a conductive agent, and the like.

The negative electrode plate 16 includes a negative electrode substrate 23 and negative electrode mixture layers 24 provided on both surfaces of the negative electrode substrate 23 . The negative electrode base material 23 is made of metal foil and shaped into a rectangular shape. The negative electrode base material 23 is provided with a negative electrode tab 23A (collecting tab) extending from an end portion. The negative electrode mixture is not provided on the negative electrode tab 23A. The negative electrode tab 23A is provided at a position shifted by a predetermined distance from the center of the negative electrode substrate 23 in the width direction toward the other side (right side in FIG. 2).

Materials constituting the negative electrode substrate 23 include, for example, copper and nickel. Materials constituting the negative electrode mixture include particles containing a negative electrode active material, a binder, a conductive agent, and the like. The negative electrode active material is a material capable of intercalating and deintercalating lithium, and is, for example, carbon such as graphite, metallic lithium, or a lithium alloy.

The positive electrode plate 15 and the negative electrode plate 16 are stacked with the positions of the positive electrode tab 18A and the negative electrode tab 23A aligned. That is, the positive electrode plate 15 is stacked so that the positive electrode tab 18A is located at the upper end of the positive electrode substrate 18 and at a position shifted to one side from the center position in the width direction. The negative electrode plate 16 is stacked such that the negative electrode tab 23A is located at the upper end of the negative electrode substrate 23 and on the other side from the center position in the width direction. The positive electrode tabs 18A of the plurality of positive electrode plates 15 are bundled together to form a positive electrode tab group. The negative electrode tabs 23A of the plurality of negative electrode plates 16 are bundled together to form a negative electrode tab group. By locating the positive electrode tab group and the negative electrode tab group at the same end portion of the electrode plate group 14 in this way, the positive electrode tabs can be formed more easily than the current collecting tabs are provided at different ends as in the case of the wound electrode body. The space occupied by the group and the negative tab group can be reduced. The electrode plate group 14 does not include the positive electrode tab group and the negative electrode tab group.

The separator 17 is made of an insulating material and has a size approximately equal to that of the positive electrode plate 15 and the negative electrode plate 16 . Separators 17 are arranged in the frontmost layer and the last layer in the stacking direction of the electrode plate group 14 .

FIG. 3 shows a battery assembly 29 in which the lid portion 13 and the electrode plate group 14 are combined. The electrode plate group 14 includes a top surface 14A as an upper end portion where the positive electrode tab group 25 and the negative electrode tab group 26 are located, a lower surface 14B as an end portion located on the opposite side of the upper surface 14A, side surfaces 14C and 14D, a front surface 14E and a rear surface 14F. have The positive electrode tab group 25 and the negative electrode tab group 26 are arranged on the surface (end portion) of the electrode plate group 14 structurally connected to the lid portion 13 on the lid portion 13 side. The positive electrode tab group 25 is electrically connected to the positive electrode terminal 21 of the positive current collecting portion 20 provided on the lid portion 13 . The negative electrode tab group 26 is electrically connected to a negative electrode terminal 31 of a negative current collecting portion 30 provided on the lid portion 13 . The upper surface 14A, the lower surface 14B, the side surfaces 14C, and the side surfaces 14D are laminated surfaces where the end surfaces of the plurality of positive electrode plates 15 and the plurality of negative electrode plates 16 are exposed. The shortest distance from the lower surface 14B to the upper surface 14A is height H1, the shortest distance from the side surface 14C to the side surface 14D is width W1, and the shortest distance from the front surface 14E to the rear surface 14F is depth D1. The electrode plate group 14 is housed in an insulating cover made of an insulating material before being housed in the case 12 .

As shown in FIG. 4 , the insulating cover 50 that accommodates the electrode plate group 14 has a rectangular parallelepiped shape and has an internal space that accommodates the electrode plate group 14 . The insulating cover 50 has a top wall portion 51 , a bottom wall portion 52 , left and right side wall portions 53 , a front wall portion 55 and a rear wall portion 56 .

The upper wall portion 51 is formed in a size slightly smaller than the lid portion 13 or the same size as the lid portion 13 . Through holes 57 are formed at both ends of the upper wall portion 51 in the longitudinal direction. A part of the positive electrode collector 20 is accommodated in one through hole 57 . A part of the negative electrode collector 30 is accommodated in the other through hole 57 . A hole portion 58 is formed between the pair of through holes 57 to accommodate the valve mechanism described above. Recesses 59 are formed between the one through-hole 57 and the hole 58 and between the other through-hole 57 and the hole 58, respectively. One concave portion 59 is interposed between the lid portion 13 and the positive electrode tab group 25 when the electrode plate group 14 is housed in the insulating cover 50 to insulate the positive electrode collector portion 20 from the positive electrode tab group 25 . do. The other concave portion 59 is interposed between the lid portion 13 and the positive electrode tab group 25 when the electrode plate group 14 is accommodated in the insulating cover 50 , and insulates the negative electrode current collecting portion 30 from the negative electrode tab group 26 . do. Furthermore, an injection hole 54 for injecting an electrolyte is formed between the recess 59 and the hole 58 . There may be a plurality of injection holes 54 as shown in the drawing, or there may be one injection hole.

When the electrode plate group 14 is accommodated in the insulating cover 50 , each side wall portion 53 protrudes above the upper surface 14 A of the electrode plate group 14 . In addition, the upper end surface of the left side wall portion 53 and the upper end surface of the right side wall portion 53 are contact points that can come into contact with the lid portion 13 when the battery assembly 29 accommodated in the insulating cover 50 is pushed into the case 12 . It functions as the contact surface 60 .

As shown in FIG. 5, the insulating cover 50 is made up of a first cover member 50A and a second cover member 50B. The first cover member 50A includes a front wall portion 55, a front upper wall portion 61 that is part of the upper wall portion 51, a front bottom wall portion 62 that is part of the bottom wall portion 52, and a portion of the left side wall portion 53. and a front side wall portion 63 that is part of the right side wall portion 53 . The front upper wall portion 61 has a notch portion 67 forming the through hole 57, a notch portion 68 forming the hole portion 58, a front recess portion 69 forming the recess portion 59, and a notch portion 64 forming the injection hole 54. formed.

The second cover member 50</b>B includes a rear wall portion 56 , a rear upper wall portion 71 that is part of the upper wall portion 51 , a rear bottom wall portion 72 that is part of the bottom wall portion 52 , and one portion of each of the side wall portions 53 . and a rear sidewall portion 73 which is a portion. Cutouts 74 , 77 , 78 and a rear concave portion 79 are formed in the rear upper wall portion 71 as in the front upper wall portion 61 . The front upper wall portion 61 and the rear upper wall portion 71 have the same thickness, and the front bottom wall portion 62 and the rear bottom wall portion 72 have the same thickness. Further, the thickness of the front side wall portion 63 and the rear side wall portion 73 are the same.

By combining the first cover member 50A and the second cover member 50B, the cutouts 67 and 77 form a through hole 57 and the cutouts 68 and 78 form a hole 58 . The recess 59 is formed by the front recess 69 and the rear recess 79, and the injection hole 54 is formed by the notches 64 and 74. As shown in FIG.

The height of the inner space 100 of the insulating cover 50 , that is, the height H2 that is the shortest distance from the inner surface of the bottom wall portion 52 to the inner surface of the upper wall portion 51 is greater than the height H1 of the electrode plate group 14 . More specifically, the height H2 of the internal space 100 is equal to or greater than the sum of the height H1 of the electrode plate group and the height of the current collecting tab group (the positive electrode tab group 25 and the negative electrode tab group 26). . Accordingly, even if the electrode plate group 14 is accommodated in the internal space 100, the upper wall portion 51 of the insulating cover 50 and the upper surface 14A of the electrode plate group 14 do not come into contact with each other. Moreover, the upper wall portion 51 of the insulating cover 50 and the positive electrode tab group 25 and the negative electrode tab group 26 may or may not contact each other.

When the electrode plate group 14 is housed in the insulating cover 50, the lid portion 13 abuts against the upper wall portion 51 and the side wall portion 53, and the height position of the electrode plate group 14 is determined. At this time, a space may be provided between the electrode plate group 14 and the bottom wall portion 52 , or the bottom surface of the electrode plate group 14 and the bottom wall portion 52 may be in contact with each other.

Moreover, the height H3 from the bottom surface to the top surface of the insulating cover 50 is equal to or less than the height of the accommodation space of the case 12 formed by sealing the opening of the case 12 with the lid portion 13 . In other words, the insulating cover 50 is formed so that the upper wall portion 51 is located inside the case 12 relative to the lid portion 13 when the insulating cover 50 that accommodates the battery assembly 29 is accommodated in the case 12 .

Also, the width W2 of the internal space 100 is greater than the width W1 of the electrode plate group 14 (W2>W1). Therefore, by accommodating the electrode plate group 14 in the internal space 100 evenly between the left and right sides, the space between the left side wall portion 53 of the insulating cover 50 and the side surface 14C of the electrode plate group 14, and the right side wall portion 53 and the electrode plate group 14 are separated. A space is provided between the side surface 14D of the . The shortest distance (length in the width direction) between the left side wall portion 53 and the side surface 14C of the electrode plate group 14 and the shortest distance (length in the width direction) between the right side wall portion 53 and the side surface 14D of the electrode plate group 14 are It is preferably several millimeters and shorter than the height of the space provided between the upper wall portion 51 and the electrode plate group 14 . Therefore, since the side walls 14C and 14D, which are laminated surfaces, do not come into contact with the side wall portion 53 of the insulating cover 50, it is possible to prevent the electrode plates forming the electrode plate group 14 from being displaced or deformed.

The shortest distance between the front wall portion 55 and the rear wall portion 56 of the insulating cover 50, that is, the depth D2 of the internal space 100 (see FIG. 4) is less than or equal to the depth D1 of the electrode plate group . As a result, when the electrode plate group 14 is housed in the internal space 100 of the insulating cover 50 , the separators 17 located in the foremost and last layers of the electrode plate group 14 come into contact with the front wall portion 55 and the rear wall portion 56 . . Since the insulating cover 50 holds the electrode plate group 14 from the front and rear in this way, it is possible to prevent the electrode plates from collapsing.

When the electrode plate group 14 is accommodated in the insulating cover 50, the first cover member 50A is arranged on the front surface 14E side and the second cover member 50B is arranged on the rear surface 14F side of the electrode plate group 14 to which the lid portion 13 is connected. to place. The electrode plate group 14 is sandwiched between the first cover member 50A and the second cover member 50B. At this time, the first cover member 50A and the second cover member 50B may be fixed to each other. For example, they may be adhered to each other with an adhesive or the like, fixed by laser welding or the like, or fixed by other methods.

By holding the electrode plate group 14 between the first cover member 50</b>A and the second cover member 50</b>B, the upper wall portion 51 of the insulating cover 50 is positioned between the lid portion 13 of the battery assembly 29 and the electrode plate group 14 . intervene in A part of the positive electrode collector 20 is accommodated in one through-hole 57 , and a part of the negative electrode collector 30 is accommodated in the other through-hole 57 . A part of the positive current collector 20 and a part of the negative current collector 30 are accommodated in the concave portion 59 respectively. Also, the front wall portion 55 and the rear wall portion 56 of the insulating cover 50 are in contact with the electrode plate group 14 .

The thicknesses of the front wall portion 55, the rear wall portion 56, the upper wall portion 51, and the side wall portions 53 of the insulating cover 50 will be described with reference to FIG. The thickness of the front wall portion 55 and the thickness of the rear wall portion 56 are the same. Furthermore, the thickness of the pair of side wall portions 53 is the same.

The thickness T2 of the side wall portion 53 is greater than the thickness T1 of the front wall portion 55 and the rear wall portion 56 (T2>T1). Also, the thickness T3 of the upper wall portion 51 is greater than the thickness T1 of the front wall portion 55 and the rear wall portion 56 (T3>T1). Note that the thickness T3 of the upper wall portion 51 is the thickness of the portion excluding the recess 59 . The thickness T2 of the side wall portion 53 and the thickness T3 of the upper wall portion 51 may be the same or different. Also, the thickness of the bottom wall portion 52 is not particularly limited. In addition, when each wall portion is not uniform in thickness, such as partially thin portions are formed in the upper wall portion 51, the side wall portion 53, the front wall portion 55, and the rear wall portion 56, the above thickness T1 to T3 are thicknesses of portions having the largest occupancy ratio in the wall portion among the portions divided by thickness.

As shown in FIG. 7, the depth D3, which is the shortest distance from the front surface 80 to the rear surface 81 of the insulating cover 50, is slightly smaller than the depth D4 of the housing space 90 of the case 12. As shown in FIG. As a result, when the battery assembly 29 housed in the insulating cover 50 is further housed in the housing space 90 of the case 12 , the front surface 80 and rear surface 81 of the insulating cover 50 come into contact with the inner side surface 91 of the case 12 . Also, when inserting the battery assembly 29 housed in the insulating cover 50 into the housing space 90 of the case 12 , a frictional force is generated between the insulating cover 50 and the case 12 . Thereby, the battery assembly 29 is pushed into the case 12 while the insulating cover 50 is held by the case 12 .

When battery assembly 29 accommodated in insulating cover 50 is inserted into accommodation space 90 of case 12 , battery assembly 29 is pushed into case 12 by applying pressure to lid portion 13 . At this time, the lid portion 13 is in contact with the contact surface 60 that is the upper end surface of the side wall portion 53 of the insulating cover 50 and the upper surface of the upper wall portion 51 . For this reason, the pressing force applied to the lid portion 13 is applied to the side wall portion 53 and the upper wall portion 51 of the insulating cover 50 without being transmitted to the electrode plate group 14, and the insulating cover 50 housing the electrode plate group 14 is separated from the case. 12 is press-fitted. Therefore, even if the lid portion 13 is pushed into the case 12, deformation of the positive electrode tab group 25 and the negative electrode tab group 26, which are structurally fragile, can be suppressed. In addition, when the battery assembly 29 housed in the insulating cover 50 is pushed into the case 12, the pressing force is not directly applied to the electrode plate group 14, so that the stacked state of the electrode plate group 14 is prevented from collapsing.

FIG. 8 shows the internal structure of the secondary battery. Battery assembly 29 is housed in insulating cover 50 and case 12 . 8 shows a cross section when only the case 12, the lid portion 13, and the insulating cover 50 are partially cut before the positive current collector 20, and does not show the cross section of the positive current collector 20. FIG. .

The positive electrode tab group 25 of the electrode plate group 14 is electrically connected to the collector terminal 20A of the positive collector portion 20 . The collector terminal 20A is connected to the positive terminal 21 via a crimped terminal 20B inserted through the through hole 57 of the lid portion 13 . An insulating portion 20</b>C made of an insulating material is provided between the positive electrode terminal 21 and the lid portion 13 . A protrusion 13 A provided on the lower surface of the lid portion 13 is accommodated in the recess portion 59 of the insulating cover 50 .

The upper wall portion 51 of the insulating cover 50 is interposed between the positive electrode tab group 25 and the lid portion 13 . Therefore, even when both the positive electrode and negative electrode current collecting tabs are provided at the end of the electrode plate group 14 on the lid portion 13 side, the upper wall portion 51 intervenes between the positive electrode tab group 25 and the lid portion 13 made of metal. It is possible to prevent positive and negative electrode short circuits due to contact with.

Effects of the present embodiment will be described.
(1) The side wall portion 53 of the insulating cover 50 is higher than the height H1 of the electrode plate group 14 accommodated in the insulating cover 50 and protrudes above the upper surface 14A of the electrode plate group 14 . The side wall portion 53 also has a contact surface 60 that contacts the lid portion 13 when the electrode plate group 14 connected to the lid portion 13 and accommodated in the insulating cover 50 is inserted into the case 12 . As a result, when the electrode plate group 14 housed in the insulating cover 50 and structurally connected to the lid portion 13 is pushed into the case 12 by applying a pressing force to the lid portion 13 , the sidewall portion 53 of the insulating cover 50 is pushed into the case 12 . The lid portion 13 is supported by the side wall portion 53 by the contact surface 60 of the lid portion 13 coming into contact with the lid portion 13 . Therefore, it is possible to suppress the pressing force applied to the lid portion 13 from being applied to the positive electrode tab group 25 and the negative electrode tab group 26 . Therefore, deformation of the positive electrode tab group 25 and the negative electrode tab group 26 can be suppressed in the secondary battery including the electrode plate group in which the current collecting tabs of the positive electrode and the negative electrode are positioned at one end.

(2) When the electrode plate group 14 is accommodated in the insulating cover 50, the depth D2, which is the shortest distance between the front wall portion 55 and the rear wall portion 56, is such that the front wall portion 55 and the rear wall portion 56 are extremely close to each other. The depth in the stacking direction of the electrode plate group is set to D1 or less so as to abut on the front and rear surfaces of the plate group 14 . As a result, the electrode plate group 14 is held between the front wall portion 55 and the rear wall portion 56 of the insulating cover 50 , so that the electrode plate group 14 is held between the front wall portion 55 and the rear wall portion 56 of the insulating cover 50 . An increase in the thickness of the plate group 14 can be prevented.

(3) Since the thickness of the side wall portion 53 of the insulating cover 50 is greater than the thicknesses of the front wall portion 55 and the rear wall portion 56, the strength of the insulating cover 50 can be increased. On the other hand, by thinning the front wall portion 55 and the rear wall portion 56 of the insulating cover, the secondary battery 11 can be made compact in the depth direction from the front wall portion 55 to the rear wall portion 56 .

(4) The width W2, which is the shortest distance between the pair of side wall portions 53, is set so that a space is provided between the side wall portions 53 and the electrode plate group 14 when the electrode plate group 14 is accommodated in the insulating cover 50. , is larger than the width W1 of the electrode plate group 14 . Therefore, the side walls 14C and 14D of the electrode plate group 14, which are laminated surfaces, do not come into contact with the side wall portion 53 of the insulating cover 50, so that the electrode plates constituting the electrode plate group 14 are not shifted or deformed. can be suppressed.

(5) The upper wall portion 51 of the insulating cover 50 is interposed between the positive electrode tab group 25 and the negative electrode tab group 26 and the lid portion 13 made of a metal material. It is possible to prevent positive and negative short circuits due to contact with 13 .

(6) Since the thickness T3 of the upper wall portion 51 of the insulating cover 50 is larger than the thickness T1 of the front wall portion 55 and the rear wall portion 56, the strength of the insulating cover 50 can be increased. On the other hand, by thinning the front wall portion 55 and the rear wall portion 56 of the insulating cover 50 , the secondary battery 11 can be made compact in the depth direction from the front wall portion 55 to the rear wall portion 56 .

(7) Since the insulating cover 50 has the bottom wall portion 52, it can be interposed between the electrode plate group 14 and the case 12 made of a metal material to prevent positive and negative short circuits.
(8) Since the front surface 80 and the back surface 81 of the insulating cover 50 are in contact with the inner peripheral surface of the case 12 while being accommodated in the case 12 , in the depth direction from the front surface 80 to the back surface 81 of the insulating cover 50 , the The battery 11 can be made compact. Further, the electrode plate group 14 housed in the insulating cover 50 is housed in the case 12 while the insulating cover 50 slides on the inner peripheral surface of the case 12 . Therefore, the electrode plate group 14 can be accommodated in the case 12 while being held by the case 12 .

This embodiment can be implemented with the following modifications. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
The insulating cover 50 has the upper wall portion 51, the bottom wall portion 52, the side wall portion 53, the front wall portion 55, and the rear wall portion 56, but at least when the lid portion 13 is pushed in, the positive electrode tab group 25 and the negative electrode tab group 26 can be suppressed, and the configuration is not limited to this configuration. Examples of other configurations will be described below.

As shown in FIG. 9, the insulating cover 50 may have a configuration in which the bottom wall portion 52 is omitted and an opening 92 is provided on the lower end side thereof. Even in this mode, when the lid portion 13 is arranged above the electrode plate group 14 in the vertical direction, the lid portion 13 is supported by the upper wall portion 51 of the insulating cover 50, so that the electrode plate group 14 is insulated. It does not come off from the cover 50. Further, according to the above configuration, as the electrode plate group expands and contracts due to charging and discharging of the secondary battery, the electrolyte flows out of the insulating cover through the opening on the lower end side of the insulating cover 50, or flows into the insulating cover. can flow into

As shown in FIG. 10, at least one of the left side wall portion 53 and the right side wall portion 53 of the insulating cover 50 may be provided with a notch portion 85 (communication hole). A plurality of notch portions 85 may be formed in the side wall portion 53 as illustrated, or a single notch portion 85 may be formed. With the electrode plate group 14 to which the insulating cover 50 is attached, the notch portion 85 allows the electrolyte to fill every corner of the case 12 when the electrolyte is injected into the case 12 . . In addition, the electrolyte can flow out of the insulating cover or into the insulating cover through the notch 85 as the electrode plate group expands and contracts due to charging and discharging of the secondary battery.

At least one of the front wall portion 55 and the rear wall portion 56 of the insulating cover 50 may be provided with a notch portion (communication hole). One wall may have one notch, or a plurality of notches may be provided. Moreover, the notch portion may be cut out in a rectangular shape along the longitudinal direction of the front wall portion 55, or may be cut out in a shape other than that.

As shown in FIG. 11, the insulating cover 50 may have a configuration in which the upper wall portion 51 is omitted and an opening 93 is provided at the upper end. Even in this case, short-circuiting of positive and negative electrodes can be suppressed by insulating the upper wall portion 51 from the positive electrode tab group 25 and the negative electrode tab group 26 by providing another member or space.

- The first cover member 50A and the second cover member 50B may each have a structure that structurally couples them. For example, it may have a snap-fit structure in which one is fitted into the other by utilizing the elastic force of resin, or a concave-convex structure.

- The electrode mixture may be positioned on at least one side of the base material, and may be positioned on only one side of the base material.
- In the above embodiment, the case where the positive electrode plate 15, the negative electrode plate 16, and the separator 17 are rectangular is exemplified. However, the positive electrode plate, the negative electrode plate, and the separator are not limited to this, as long as they can constitute the electrode plate of the secondary battery, and may be in other rectangular shapes such as a square shape.

- The shape of the positive electrode tab 18A and the negative electrode tab 23A is appropriately set according to the shape of the non-aqueous battery, and can be changed to other shapes.
- In the above embodiment, the secondary battery has a structure in which one electrode plate group 14 is provided in the case 12 , but a structure in which a plurality of electrode plate groups 14 are provided in the case 12 may be employed. For example, a plurality of electrode plate groups are connected in series within the case 12 .

- In the above embodiment, the case where the secondary battery 11 is a lithium-ion secondary battery has been exemplified. However, the secondary battery is not limited to this, and may be a secondary battery with other non-aqueous electrolyte, or a secondary battery with aqueous electrolyte such as a nickel-hydrogen secondary battery. For example, a nickel-metal hydride secondary battery includes a positive electrode plate comprising a base material made of nickel metal or the like and a positive electrode mixture containing nickel hydroxide or the like, and a negative electrode mixture containing a hydrogen absorbing alloy on the base material made of a metal material. It has an electrode plate group in which a negative electrode plate is laminated with a separator interposed therebetween.

- The secondary battery 11 may be used in vehicles such as electric vehicles, hybrid vehicles, gasoline vehicles, and diesel vehicles, and other moving bodies. Alternatively, it may be fixedly installed.

DESCRIPTION OF SYMBOLS 11... Secondary battery, 12... Case, 13... Cover part, 14... Electrode plate group, 14A... Top surface, 14B... Bottom surface, 14C, 14D... Side surface, 14E... Front surface, 14F... Back surface, 18... Positive electrode as base material Base material 18A... positive electrode tab as current collecting tab 19... positive electrode mixture layer as electrode mixture 20... positive electrode current collecting part as current collecting part 23... negative electrode base material as base material 23A... collection Negative electrode tab as current tab 30 Negative current collector as current collector 50 Insulating cover 55 Front wall portion 56 Rear wall portion 53 Side wall portion 60 Contact surface.

Claims (10)

A secondary battery having a plurality of electrode plates each including a rectangular substrate having a current collecting tab at one end and an electrode mixture provided on the substrate,
an electrode plate group in which a plurality of the electrode plates are stacked with the positions of the current collecting tabs aligned for each electrode with separators interposed therebetween;
a lid portion provided with a current collecting portion to which the current collecting tab is joined;
an insulating cover made of an insulating material and covering a part of the electrode plate group;
a case that houses the electrode plate group housed in the insulating cover together with an electrolyte,
The insulating cover is
In the electrode plate group, the front wall portion and the rear wall portion facing the front surface and the rear surface located at the ends in the stacking direction, respectively, and the upper surface and the opposite lower surface of the electrode plate group where the current collecting tabs are located. a pair of side walls facing each of the pair of side surfaces located therebetween;
The side wall portion protrudes upward from the upper surface of the electrode plate group housed in the insulating cover, and when the electrode plate group connected to the lid portion and housed in the insulating cover is inserted into the case, Having a contact surface that contacts the lid ,
The thickness of the sidewall is greater than the thickness of the front wall and the rear wall.
secondary battery. A secondary battery having a plurality of electrode plates each including a rectangular substrate having a current collecting tab at one end and an electrode mixture provided on the substrate,
an electrode plate group in which a plurality of the electrode plates are stacked with separators interposed therebetween, with the positions of the current collecting tabs aligned for each electrode;
a lid portion provided with a current collecting portion to which the current collecting tab is joined;
an insulating cover made of an insulating material and covering a part of the electrode plate group;
a case that houses the electrode plate group housed in the insulating cover together with an electrolyte,
The insulating cover is
A front wall portion and a rear wall portion respectively facing the front surface and the rear surface located at the ends in the stacking direction of the electrode plate group, and the upper surface and the opposite lower surface of the electrode plate group where the current collecting tabs are located. having a pair of side wall portions respectively facing a pair of side surfaces located therebetween and an upper wall portion ;
The side wall portion protrudes upward from the upper surface of the electrode plate group housed in the insulating cover, and when the electrode plate group connected to the lid portion and housed in the insulating cover is inserted into the case, Having a contact surface that contacts the lid ,
When the electrode plate group to which the lid portion is connected is accommodated inside the insulating cover, the upper wall portion is configured to be positioned on the upper surface of the electrode plate group and the lid made of a metal material. intervene between
secondary battery. The stacking direction of the electrode plate group is such that the shortest distance between the front wall portion and the rear wall portion is such that the front wall portion and the rear wall portion are in contact with the front surface and the back surface of the electrode plate group. 3. The secondary battery according to claim 1 or 2 , wherein the length is equal to or less than the length of . The shortest distance between the pair of side wall portions is set to one side of the electrode plate group so that a space is provided between the side wall portion and the electrode plate group when the electrode plate group is housed in the insulating cover. 4. The secondary battery according to any one of claims 1 to 3, wherein the width is greater than the width along the direction from the side surface of the secondary battery to the other side surface of the secondary battery. The secondary battery according to any one of claims 1 to 4, wherein at least one of the pair of side wall portions has a communication hole that communicates the inside and the outside of the insulating cover. 3 . The secondary battery according to claim 2 , wherein the thickness of the upper wall portion is greater than the thickness of the front wall portion and the rear wall portion facing the front surface and the rear surface of the electrode plate group, respectively. The secondary battery according to any one of claims 1 to 6 , wherein the insulating cover has a bottom wall portion facing the lower surface of the electrode plate group. The front surface and the rear surface of the insulating cover are the inner peripheral surfaces of the case facing the front surface and the rear surface when the electrode plate group is accommodated in the case and in the state of being accommodated in the case. The secondary battery according to any one of claims 1 to 7 , wherein the secondary battery is in contact with the opposing surface. An electrode plate group in which a rectangular base material having a current collecting tab at one end and a plurality of electrode plates containing an electrode mixture provided on the base material are laminated with the current collecting tabs aligned via a separator. an insulating cover for use in a secondary battery comprising: a lid portion provided with a current collecting portion to which the current collecting tab is joined; and a case accommodating the electrode plate group together with an electrolyte,
A front wall portion and a rear wall portion respectively facing the front surface and the back surface located at the ends in the stacking direction of the electrode plate group, and the upper surface and the opposite lower surface of the electrode plate group on which the current collecting tabs are located. and a pair of side wall portions respectively facing a pair of side surfaces located between
The side wall portion protrudes upward from the upper surface of the electrode plate group housed in the insulating cover, and when the electrode plate group connected to the lid portion and housed in the insulating cover is inserted into the case, Having a contact surface that contacts the lid ,
The thickness of the sidewall is greater than the thickness of the front wall and the rear wall.
Insulating cover for secondary battery. An electrode plate group in which a rectangular base material having a current collecting tab at one end and a plurality of electrode plates containing an electrode mixture provided on the base material are laminated with the current collecting tabs aligned via a separator. an insulating cover for use in a secondary battery comprising: a lid portion provided with a current collecting portion to which the current collecting tab is joined; and a case accommodating the electrode plate group together with an electrolyte,
A front wall portion and a rear wall portion respectively facing the front surface and the back surface located at the ends in the stacking direction of the electrode plate group, and the upper surface and the opposite lower surface of the electrode plate group on which the current collecting tabs are located. having a pair of side wall portions respectively opposed to a pair of side surfaces located between and an upper wall portion ;
The side wall portion protrudes upward from the upper surface of the electrode plate group housed in the insulating cover, and when the electrode plate group connected to the lid portion and housed in the insulating cover is inserted into the case, Having a contact surface that contacts the lid ,
When the electrode plate group to which the lid portion is connected is accommodated inside the insulating cover, the upper wall portion is configured to be positioned on the upper surface of the electrode plate group and the lid made of a metal material. intervene between
Insulating cover for secondary battery.

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