Power storage device and method for manufacturing the same

Abstract

To provide a power storage device which can elastically compress an electrode laminate unit of an electrode body in the thickness direction of the electrode body by the power storage device.SOLUTION: A power storage device 1 has a case 10 including: a bottomed angular cylindrical body member 21 forming a second main wall part 12 and four side wall parts 13 to 16; and a rectangular lid member 31 forming a first main wall part 11, the first main wall part 11 and the second main wall part 12 elastically compressing an electrode laminate unit 50e of an electrode body 50. In a graph GF1 of the relation between the compression amount C of the electrode laminate unit 50e and a surface pressure P on the electrode laminate unit 50e, the power storage device 1 has an elastic characteristic in which the inclination of a tangent TL1 at the point (c1, p1) is not larger than the inclination (p1 / c1) of a virtual straight line VL connecting original points (0,0) and (c1,p1) to each other.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a rectangular power storage device in which an electrode body is housed in a rectangular parallelepiped box-shaped case, and a method for manufacturing the power storage device.

Background Art

[0002] Among rectangular batteries in which an electrode body is housed in a rectangular parallelepiped box-shaped case, particularly in batteries mounted on vehicles and used over a long period of time, for reasons such as improving charge-discharge cycle characteristics, the battery is generally externally constrained using a constraint member outside the battery composed of a pair of end plates and a plurality of restraint bands. As a result, the electrode laminate portion of the electrode body housed in the case is pressed in the electrode body thickness direction. As a related prior art, for example, Patent Document 1 can be cited (see FIG. 1 etc. of Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when externally constraining the battery using a constraint member, there are problems such as increased cost, increased size, increased weight, and increased number of parts.

[0005] The present invention has been made in view of such a situation, and provides a power storage device in which the electrode laminate portion of the electrode body is elastically compressed in the electrode body thickness direction by the power storage device itself, and a method for manufacturing the power storage device.

Means for Solving the Problems

[0006] (1) One aspect of the present invention for solving the above problems includes a case and an electrode body housed in the case. The case has a rectangular parallelepiped box shape and includes a rectangular first main wall portion, a rectangular second main wall portion facing the first main wall portion, and four rectangular side wall portions connecting between the first main wall portion and the second main wall portion and extending in the case thickness direction. The electrode body includes an electrode plate and has a rectangular parallelepiped-shaped electrode laminated portion in which the electrode plates are laminated in the electrode body thickness direction. The electrode body thickness direction is parallel to the case thickness direction, and the electrode body is housed in the case in a parallel posture. The case includes a bottomed rectangular tubular body member forming the second main wall portion and the four side wall portions and having a rectangular opening formed by the four side wall portions, and a rectangular lid member forming the first main wall portion and having a lid peripheral portion joined to the opening peripheral edge of the opening of the body member over the entire circumference. The first main wall portion and the second main wall portion of the case elastically compress the electrode laminated portion of the electrode body in the electrode body thickness direction. When the compression amount C of the electrode laminated portion in the state where the electrode body is housed in the case is set to C = c1 and the surface pressure P applied to the electrode laminated portion is set to P = p1, the storage device has an elastic characteristic such that the slope of the tangent line at the point (c1, p1) in a graph showing the relationship between the compression amount C and the surface pressure P with the horizontal axis being the compression amount C and the vertical axis being the surface pressure P is less than or equal to the slope (p1 / c1) of the virtual straight line connecting the origin (0, 0) and (c1, p1).

[0007] In the above-described storage device, the first main wall portion and the second main wall portion of the case elastically compress the electrode laminated portion of the electrode body in the electrode body thickness direction. That is, this storage device is a self-compression type that elastically compresses the electrode laminated portion of the electrode body by the storage device itself. Therefore, when using the storage device, it is not necessary to separately use a restraint member, or external restraint by a simple restraint member is sufficient. Furthermore, in the above-described storage device, since the case is formed by joining a lid member forming the first main wall portion to a body member forming the second main wall portion and the four side wall portions, a self-compression type storage device can be easily manufactured as described later, and an inexpensive storage device can be obtained.

[0008] Incidentally, there is a variation in the thickness of the electrode laminate for each electrode body. Therefore, in a self-compressing type power storage device, the compression amount C of the electrode laminate is different for each power storage device, and the surface pressure P applied to the electrode laminate is also different. If the variation in the surface pressure P applied to the electrode laminate is large, the variation in the performance (such as charge / discharge cycle characteristics) of the power storage device will also become large. On the other hand, the above-mentioned power storage device has an elastic characteristic such that, in a graph showing the relationship between the compression amount C and the surface pressure P of the electrode body, the slope of the tangent line at the point (c1, p1) is less than or equal to the slope (p1 / c1) of the virtual straight line connecting the origin (0, 0) and (c1, p1). That is, at the point (c1, p1), since the ratio (ΔP / ΔC: slope of the tangent line) of the minute change ΔP in the surface pressure P caused by the minute change ΔC in the compression amount C is less than or equal to the slope p1 / c1 of the virtual straight line, in this power storage device, even if there is a variation in the compression amount C for each power storage device, the variation in the surface pressure P applied to the electrode laminate can be reduced. For this reason, the variation in the performance (such as charge / discharge cycle characteristics) of the power storage device can be reduced.

[0009] Examples of the "power storage device" include secondary batteries such as lithium ion secondary batteries, capacitors such as lithium ion capacitors, and all solid state batteries. In the above-mentioned power storage device, an intervening member made of metal or resin, such as a flat plate or a corrugated plate, may be interposed between the first main wall portion of the case and the electrode laminate portion of the electrode body, or between the second main wall portion of the case and the electrode laminate portion of the electrode body.

[0010] (2) Another aspect includes a case and an electrode body housed in the case. The case is in the shape of a rectangular parallelepiped box, having a rectangular first main wall portion, a rectangular second main wall portion facing the first main wall portion, and four rectangular side wall portions connecting between the first main wall portion and the second main wall portion and extending in the case thickness direction. The electrode body includes an electrode plate and has a rectangular parallelepiped-shaped electrode laminate portion in which the electrode plates are laminated in the electrode body thickness direction. The electrode body is housed in the case in a posture where the electrode body thickness direction is parallel to the case thickness direction. a power storage device,The above-described case includes a bottomed rectangular tubular body member forming the second main wall portion and the four side wall portions, and having a rectangular opening formed by the four side wall portions, and a lid member forming the first main wall portion and having a lid peripheral portion joined to the entire periphery of the opening peripheral edge of the opening of the body member. The first main wall portion and the second main wall portion of the case elastically compress the electrode laminate portion of the electrode body in the thickness direction of the electrode body. When the compression amount C of the electrode laminate portion is C = c1 and the surface pressure P applied to the electrode laminate portion is P = p1 in a state where the electrode body is accommodated in the case, in a graph showing the relationship between the compression amount C and the surface pressure P with the horizontal axis being the compression amount C and the vertical axis being the surface pressure P, the slope of the tangent line at the point (c1, p1) is equal to or less than the slope (p1 / c1) of the virtual straight line connecting the origin (0, 0) and (c1, p1). A method for manufacturing a power storage device having such an elastic characteristic, comprising: a housing step of housing the electrode body in the body member; a pressing and compressing step of arranging the lid member on the electrode body housed in the body member and applying an external force to the first main wall portion formed by the lid member and the second main wall portion of the body member to press and compress the electrode laminate portion of the electrode body in the thickness direction of the electrode body; a joining step of joining the lid peripheral portion of the lid member to the entire periphery of the opening peripheral edge of the opening of the body member in a state where the electrode body is pressed and compressed to form the case; and a releasing step of releasing the external force after the joining step.

[0011] In a conventional rectangular battery, the case is constituted by a bottomed rectangular tubular body member forming the first main wall portion, the second main wall portion, and three side wall portions, and a lid member forming one side wall portion. In a battery having such a configuration, it is difficult to manufacture a self-compressing type battery. This is because the gap between the first main wall portion and the second main wall portion of the body member is made narrower than the thickness of the electrode body or, in a battery having the aforementioned intervening member, the combined thickness of the electrode body and the intervening member in order to press and compress the electrode body in the assembled battery, making it difficult to insert the electrode body and the like into the body member.

[0012] In contrast, in the method for manufacturing the above-described power storage device, in the housing step, first, the electrode body is housed in the bottomed rectangular tubular main body member forming the second main wall portion and the four side wall portions, so that the electrode body can be easily housed in the main body member. Then, by performing the above-described pressing and compressing step, joining step, and releasing step, a self-compressing type power storage device in which the electrode stacking portion of the electrode body is elastically compressed by the power storage device itself can be easily manufactured.

[0013] Note that, as a method for joining the lid member to the main body member in the "joining step", for example, joining by welding such as laser welding, joining by caulking, etc. can be mentioned.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a perspective view of a battery (power storage device) 1 according to the present embodiment, FIG. 2 shows an exploded perspective view of the battery 1, and FIG. 3 shows a cross-sectional view of the battery 1. Further, FIG. 4 shows a plan view of the battery 1 as viewed from the inner side CH3 in the thickness direction of the first main wall portion 11 (second main wall portion 12). FIG. 5 shows a perspective view of the electrode body 50. In the following, the case height direction AH, the case width direction BH, the case thickness direction CH, the electrode body axis direction DH, the electrode body width direction EH, and the electrode body thickness direction FH are defined as the directions shown in FIGS. 1 to 5 for explanation. This battery 1 is a rectangular (cuboid-shaped) sealed lithium-ion secondary battery mounted on vehicles such as hybrid cars, plug-in hybrid cars, and electric vehicles.

[0016] The battery 1 includes a case 10, a flat wound electrode body 50 housed in the case 10, a positive electrode terminal 60 and a negative electrode terminal 70 respectively supported by the case 10, and the like. The electrode body 50 is covered with a bag-shaped insulating holder (not shown) made of an insulating film in the case 10. Further, an electrolytic solution 3 is housed in the case 10, a part of which is impregnated in the electrode body 50, and the rest accumulates on the second side wall portion 14 which is the lower wall portion of the case 10.

[0017] Among these, the case 10 is made of metal (aluminum in this embodiment). This case 10 is in the shape of a rectangular parallelepiped box and has a first main wall portion 11, a second main wall portion 12, and four side wall portions 13 to 16 (first side wall portion 13, second side wall portion 14, third side wall portion 15, and fourth side wall portion 16), each of which is rectangular. The first main wall portion 11 and the second main wall portion 12 are larger in area than the side wall portions 13 to 16. The first main wall portion 11 and the second main wall portion 12 face each other, with the first main wall portion 11 on one side CH1 of the case thickness direction CH (the front right side in FIGS. 1 and 2, the upper side in FIG. 3), and the second main wall portion 12 on the other side CH2 of the case thickness direction CH (the back left side in FIGS. 1 and 2, the lower side in FIG. 3).

[0018] On the other hand, the side wall portions 13 to 16 connect between the first main wall portion 11 and the second main wall portion 12 and extend respectively in the case thickness direction CH. The first side wall portion 13 and the second side wall portion 14 face each other, with the first side wall portion 13 on the upper side AH1 of the case height direction AH and the second side wall portion 14 on the lower side AH2 of the case height direction AH. Also, the third side wall portion 15 and the fourth side wall portion 16 face each other, with the third side wall portion 15 on one side BH1 of the case width direction BH and the fourth side wall portion 16 on the other side BH2 of the case width direction BH.

[0019] The first side wall portion 13, which is also the upper wall portion of the case 10, is provided with a safety valve 17 that breaks and opens when the internal pressure of the case 10 exceeds the opening pressure. Also, the first side wall portion 13 is provided with a liquid injection hole 13k that communicates the inside and outside of the case 10, and is hermetically sealed with a disk-shaped sealing member 18 made of aluminum. Furthermore, in the first side wall portion 13, near the end on one side BH1 of the case width direction BH, a positive electrode terminal 60 is fixedly provided. Specifically, the positive electrode terminal 60 is formed by clamping and connecting a plurality of metal members made of aluminum, and is fixedly provided on the first side wall portion 13 in a state of being insulated from the first side wall portion 13 via a resin portion 65 made of a plurality of resin members. This positive electrode terminal 60 is connected and conducts to the positive electrode current collector portion 50c of the electrode body 50 inside the case 10, while extending through the first side wall portion 13 to the outside of the battery.

[0020] Also, near the end of the other side BH2 in the case width direction BH of the first side wall portion 13, a negative electrode terminal 70 is fixedly provided. Specifically, the negative electrode terminal 70 is formed by clamping and connecting a plurality of metal members made of copper, and is fixedly provided on the first side wall portion 13 in a state insulated from the first side wall portion 13 via a resin portion 75 made of a plurality of resin members. This negative electrode terminal 70 is connected and electrically conducted to the negative electrode current collecting portion 50d of the electrode body 50 inside the case 10, while extending through the first side wall portion 13 to the outside of the battery.

[0021] The first main wall portion 11 of the case 10 has a pressing convex portion 11e having a rectangular shape in plan view at the central portion of the first main wall portion 11 excluding the peripheral portion 11s of the first main wall portion 11. The entire pressing convex portion 11e protrudes toward the inner side CH3 in the thickness direction in the case thickness direction CH (toward the electrode stacking portion 50e of the electrode body 50), and presses the electrode stacking portion 50e of the electrode body 50 in the electrode body thickness direction FH by elastic compression by the first main wall portion 11 and the second main wall portion 12 of the case 10. Also, the second main wall portion 12 of the case 10 has a pressing convex portion 12e having a rectangular shape in plan view at the central portion of the second main wall portion 12 excluding the peripheral portion 12s of the second main wall portion. The entire pressing convex portion 12e protrudes toward the inner side CH3 in the thickness direction in the case thickness direction CH (toward the electrode stacking portion 50e of the electrode body 50), and presses the electrode stacking portion 50e of the electrode body 50 in the electrode body thickness direction FH by elastic compression by the first main wall portion 11 and the second main wall portion 12 of the case 10.

[0022] The case 10 is composed of a bottomed rectangular tubular main body member 21 having a rectangular opening 21c and a rectangular lid member 31. Among these, the main body member 21 forms the aforementioned second main wall portion 12 and four side wall portions 13 to 16, and the opening 21c of the main body member 21 is composed of the four side wall portions 13 to 16. On the other hand, the lid member 31 forms the aforementioned first main wall portion 11 and closes the opening 21c of the main body member 21. Specifically, the lid peripheral edge portion 31f of the lid member 31 is joined (welded) to the opening peripheral edge portion 21f of the opening 21c of the main body member 21 over the entire circumference.

[0023] Next, the electrode body 50 will be described (see FIGS. 1 to 3 and FIG. 5). This electrode body 50 is formed by overlapping a strip-shaped positive electrode plate (electrode plate) 51 and a strip-shaped negative electrode plate (electrode plate) 54 with each other via a pair of separators 57 made of a strip-shaped resin porous film, winding them cylindrically around the winding axis DX, and then pressing them flat. That is, the electrode body 50 has a pair of electrode R portions 50r respectively located at both ends in the electrode body width direction EH, and an electrode stacking portion 50e located between them. The electrode R portion 50r is a semi-cylindrical portion where the positive electrode plate 51, the negative electrode plate 54, and the separator 57 overlap while being bent in a semi-cylindrical shape. On the other hand, the electrode stacking portion 50e is a rectangular parallelepiped portion where the positive electrode plate 51, the negative electrode plate 54, and the separator 57 are stacked in a flat plate shape in the electrode body thickness direction FH. Further, the electrode body 50 has a positive electrode current collector portion 50c, which will be described later, at one end DH1 in the electrode body axis direction DH along the winding axis DX, and a negative electrode current collector portion 50d, which will be described later, at the other end DH2 in the electrode body axis direction DH.

[0024] The electrode body 50 is housed in the case 10 in a posture where the electrode body axis direction DH is parallel to the case width direction BH, the electrode body width direction EH is parallel to the case height direction AH, and the electrode body thickness direction FH is parallel to the case thickness direction CH. Further, the electrode body 50 is housed in the case 10 in a state of being compressed in the electrode body thickness direction FH (case thickness direction CH). That is, the battery 1 is a self-compressing type battery, the case 10 is elastically deformed, and the first main wall portion 11 and the second main wall portion 12 of the case 10 elastically compress the electrode stacking portion 50e of the electrode body 50 in the electrode body thickness direction FH.

[0025] The positive electrode plate 51 has a positive electrode current collector foil 52 made of a strip-shaped aluminum foil. On both main surfaces of this positive electrode current collector foil 52, positive electrode active material layers 53 containing positive electrode active material particles capable of occluding and releasing lithium ions are formed in a strip shape. Among the positive electrode plates 51, at one end in the width direction, the positive electrode active material layer 53 does not exist on the positive electrode current collector foil 52, and the positive electrode current collector foil 52 is exposed. The exposed portion of this positive electrode current collector foil 52 protrudes in a spiral shape from the electrode stacking portion 50e to one side DH1 in the electrode body axis direction DH in the electrode body 50, forming the aforementioned positive electrode current collector portion 50c. The positive electrode current collector portion 50c is connected to the positive electrode terminal 60.

[0026] The negative electrode plate 54 has a negative electrode current collector foil 55 made of a strip-shaped copper foil. On both main surfaces of the negative electrode current collector foil 55, negative electrode active material layers 56 each containing negative electrode active material particles capable of occluding and releasing lithium ions are formed in a strip shape. Of the negative electrode plate 54, one end in the width direction has no negative electrode active material layer 56 on the negative electrode current collector foil 55, and the negative electrode current collector foil 55 is exposed. The exposed portion of the negative electrode current collector foil 55 protrudes in a spiral shape from the electrode laminate portion 50e of the electrode body 50 to the other side DH2 in the electrode body axis direction DH, forming the aforementioned negative electrode current collector portion 50d. The negative electrode current collector portion 50d is connected to the negative electrode terminal 70.

[0027] Here, the elastic characteristics of the battery 900 according to the comparative form and the battery 1 according to the present embodiment will be described. First, the battery 900 of the comparative form will be described (see FIG. 11). This battery 900 includes an electrode body 50 similar to that of the embodiment, but the form of the case 910 is different from that of the case 10 of the embodiment. Specifically, among the four side wall portions of the case 910 of the comparative form (the first side wall portion (not shown), the second side wall portion (not shown), the third side wall portion 915, and the fourth side wall portion 916), they are the same as the four side wall portions (the first side wall portion 13, the second side wall portion 14, the third side wall portion 15, and the fourth side wall portion 16) of the case 10 of the embodiment. On the other hand, the first main wall portion 911 of the case 910 of the comparative form does not have a convex portion such as the pressing convex portion 11e of the first embodiment and is flat. Also, the second main wall portion 912 of the case 910 does not have a convex portion such as the pressing convex portion 12e of the first embodiment and is flat. This battery 900 of the comparative form is also a self-compressing type battery, and the case 910 is elastically deformed, and the first main wall portion 911 and the second main wall portion 912 of the case 910 elastically compress the electrode laminate portion 50e of the electrode body 50 in the electrode body thickness direction FH.

[0028] Next, for each of the battery 900 in the comparative form and the battery 1 in the present embodiment, the relationship between the compression amount C of the electrode laminate portion 50e of the electrode body 50 and the surface pressure P applied to the electrode laminate portion 50e was investigated. The results are shown in FIG. 6. In the state where the electrode body 50 is housed in the case 910 or the case 10, that is, in the completed battery 900 or battery 1, let the compression amount C (mm) of the electrode laminate portion 50e of the electrode body 50 be C = c1, and the surface pressure P (MPa) applied to the electrode laminate portion 50e be P = p1.

[0029] There are thickness variations in the electrode laminate portion 50e for each electrode body 50. For this reason, for each battery 900, the compression amount C of the electrode laminate portion 50e is different, and the surface pressure P applied to the electrode laminate portion 50e is also different. Also, for each battery 1, the compression amount C of the electrode laminate portion 50e is different, and the surface pressure P applied to the electrode laminate portion 50e is also different. Note that in both the battery 900 in the comparative form and the battery 1 in the embodiment, the average value of the compression amount c1 is c1 = 1.0 mm, and the average value of the surface pressure p1 is p1 = 7.0 MPa.

[0030] First, in the battery 900 of the comparative form, as shown by the thick broken line graph GF2 in FIG. 6, as the compression amount C of the electrode laminate portion 50e increases, the surface pressure P applied to the electrode laminate portion 50e increases. Specifically, as the compression amount C increases, the increase amount of the surface pressure P becomes larger (the minute change ΔP of the surface pressure P caused by the minute change ΔC of the compression amount C becomes larger). Therefore, in the battery 900 of the comparative form, the slope of the tangent line TL2 at the point (c1, p1) is larger than the slope (p1 / c1) of the virtual straight line VL connecting the origin (0, 0) and (c1, p1). In such a battery 900, when there are variations in the compression amount C of the electrode laminate portion 50e for each battery 900, the variations in the surface pressure P applied to the electrode laminate portion 50e become larger. For this reason, the variations in performance such as the charge-discharge cycle characteristics of the battery 900 also become larger.

[0031] In contrast, in the battery 1 of the present embodiment, as shown by the thick solid line graph GF1 in FIG. 6, as the compression amount C of the electrode laminate 50e increases, the surface pressure P applied to the electrode laminate 50e increases. However, in the present embodiment, unlike the comparative form, as the compression amount C increases, the increase amount of the surface pressure P decreases (the minute change ΔP of the surface pressure P caused by the minute change ΔC of the compression amount C decreases). Therefore, in the battery 1 of the present embodiment, the slope of the tangent line TL1 at the point (c1, p1) is smaller than the slope (p1 / c1) of the aforementioned virtual straight line VL. In such a battery 1, even if there is a variation in the compression amount C of the electrode laminate 50e for each battery 1, the variation in the surface pressure P applied to the electrode laminate 50e becomes smaller. For this reason, the variation in performance such as the charge-discharge cycle characteristics of the battery 1 also becomes smaller.

[0032] As described above, the battery 1 of the present embodiment has an elastic characteristic in the graph GF1 showing the relationship between the compression amount C of the electrode laminate 50e and the surface pressure P, such that the slope of the tangent line TL1 at the point (c1, p1) is equal to or less than the slope (p1 / c1) of the virtual straight line VL connecting the origin (0, 0) and (c1, p1). The elastic characteristic of the battery 1 varies depending on the material and thickness of the case 10, the form and size of the pressing projections 11e and 12e, the form and size of the electrode body 50, etc., but it is difficult to predict the elastic characteristic at the time of designing the battery 1. For this reason, in order to obtain a battery having the elastic characteristic according to the present invention, it is good to actually manufacture a plurality of sample batteries with different designs and investigate the relationship between the compression amount C of the electrode laminate 50e and the surface pressure P.

[0033] As described above, in the battery 1 of the present embodiment, the first main wall portion 11 and the second main wall portion 12 of the case 10 elastically compress the electrode laminate 50e of the electrode body 50 in the electrode body thickness direction FH. That is, this battery 1 is a self-compression type that elastically compresses the electrode laminate 50e of the electrode body 50 by the battery 1 itself. For this reason, when using the battery 1, it is not necessary to separately use a restraining member, or external restraint by a simple restraining member is sufficient. Furthermore, since the battery 1 is formed by joining the lid member 31 forming the first main wall portion 11 to the main body member 21 in which the case 10 forms the second main wall portion 12 and the four side wall portions 13 to 16, as will be described later, a self-compressing type battery 1 can be easily manufactured, and an inexpensive battery 1 can be obtained.

[0034] In addition, the battery 1 has an elastic characteristic such that the slope of the tangent line TL1 at the point (c1, p1) is equal to or less than the slope (p1 / c1) of the virtual straight line in the graph GF1 showing the relationship between the compression amount C and the surface pressure P of the electrode body 50. That is, at the point (c1, p1), since the ratio (ΔP / ΔC: slope of the tangent line) of the minute change ΔP of the surface pressure P caused by the minute change ΔC of the compression amount C is equal to or less than the slope p1 / c1 of the virtual straight line, in this battery 1, even if there is a variation in the compression amount C for each battery 1, the variation in the surface pressure P applied to the electrode laminate portion 50e can be reduced. For this reason, the variation in performance such as the charge / discharge cycle characteristics of the battery 1 can be reduced.

[0035] Next, a method for manufacturing the battery 1 will be described (see FIGS. 7 to 10). In advance, the main body member 21 with the positive electrode terminal 60 and the negative electrode terminal 70 fixed thereto and the lid member 31 are prepared. Further, the strip-shaped positive electrode plate 51, negative electrode plate 54, and pair of separators 57 are wound cylindrically around the winding axis DX and then pressed flat to form the electrode body 50. Further, this electrode body 50 is wrapped with a bag-shaped insulating holder (not shown).

[0036] Then, in the "accommodation step S1" (see FIG. 7), the electrode body 50 wrapped with an insulating holder is accommodated in the main body member 21 to which the positive electrode terminal 60 and the negative electrode terminal 70 are fixed (see FIG. 8). Specifically, the main body member 21 is placed on the flat mounting table 510 of the pressing device 500 in a posture where the entire second main wall portion 12 thereof is in contact with the mounting table 510. Then, the electrode body 50 is accommodated in the main body member 21 in a posture where the electrode body axis direction DH is parallel to the case width direction BH, the electrode body width direction EH is parallel to the case height direction AH, and the electrode body thickness direction FH is parallel to the case thickness direction CH. Then, the positive current collector portion 50c of the electrode body 50 and the positive electrode terminal 60 fixed to the main body member 21 are connected by laser welding. Also, the negative current collector portion 50d of the electrode body 50 and the negative electrode terminal 70 fixed to the main body member 21 are connected by laser welding.

[0037] Next, in the "pressing and compressing step S2" (see FIG. 7), the lid member 31 is disposed on the electrode body 50 accommodated in the main body member 21, and an external force Fa is applied to the first main wall portion 11 formed by the lid member 31 and the second main wall portion 12 of the main body member 21 to press and compress the electrode laminated portion 50e of the electrode body 50 in the electrode body thickness direction FH (see FIG. 9). Specifically, the pressing portion 520 of the pressing device 500 is brought into contact with the first main wall portion 11 formed by the lid member 31, and the lid member 31 and the main body member 21 are sandwiched between the pressing portion 520 and the mounting table 510 to apply an external force Fa to the first main wall portion 11 and the second main wall portion 12. Then, the electrode laminated portion 50e of the electrode body 50 is pressed and compressed in the electrode body thickness direction FH, and the lid peripheral edge portion 31f of the lid member 31 is brought into contact with the opening peripheral edge portion 21f of the opening 21c of the main body member 21 over the entire circumference (see FIG. 10).

[0038] Next, in the "joining step S3" (see FIG. 7), with the electrode body 50 being pressed and compressed by the pressing device 500, the lid peripheral edge portion 31f of the lid member 31 is joined to the opening peripheral edge portion 21f of the main body member 21 over the entire circumference to form the case 10 (see FIG. 10). In the present embodiment, the lid peripheral edge portion 31f and the opening peripheral edge portion 21f are irradiated with laser light LB to perform laser welding, thereby joining the lid peripheral edge portion 31f and the opening peripheral edge portion 21f over the entire circumference.

[0039] Next, in the "release step S4" (see FIG. 7), the aforementioned external force Fa is released. That is, the pressing portion 520 of the pressing device 500 is moved away from the lid member 31 to release the external force Fa. At this time, since the case 10 has already been formed in the joining step S3, the compressed electrode body 50 does not return to its original state (thickness). After releasing the external force Fa, the first main wall portion 11 and the second main wall portion 12 of the case 10 elastically compress the electrode stacking portion 50e of the electrode body 50.

[0040] Next, in the "electrolyte injection and sealing step S5", the electrolyte 3 is injected into the case 10 through the injection hole 13k, and the electrolyte 3 is impregnated into the electrode body 50. Then, the injection hole 13k is covered with a sealing member 18 from the outside, and the sealing member 18 is laser welded to the case 10 to hermetically seal the space between the sealing member 18 and the case 10. Next, in the "first charging and aging step S6", a charging device (not shown) is connected to this battery 1 to perform the first charging of the battery 1. Then, the initially charged battery 1 is allowed to stand for a predetermined time to age the battery 1. Thus, the battery 1 is completed.

[0041] Here, in a conventional rectangular battery, the case 10 is constituted by a bottomed rectangular tubular main body member forming the first main wall portion 11, the second main wall portion 12, and three side wall portions (the second side wall portion 14, the third side wall portion 15, and the fourth side wall portion 16) of the case 10, and a lid member forming the first side wall portion 13. In a battery of such a form, it is difficult to manufacture a self-compression type battery. This is because the gap between the first main wall portion 11 and the second main wall portion 12 of the main body member is made narrower than the thickness of the electrode body 50 in order to press and compress the electrode body 50 in the assembled battery, making it difficult to insert the electrode body 50 into the main body member.

[0042] In contrast, in the method for manufacturing the battery 1 described above, in the accommodation step S1, the electrode body 50 is accommodated in the bottomed rectangular tube-shaped main body member 21 forming the second main wall portion 12 and the four side wall portions 13 to 16. Therefore, the electrode body 50 can be easily accommodated in the main body member 21. Then, by performing the pressing and compressing step S2, the bonding step S3, and the releasing step S4, a self-compressing type battery 1 in which the electrode stacking portion 50e of the electrode body 50 is elastically compressed by the battery 1 itself can be easily manufactured.

[0043] As described above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to the embodiments, and it goes without saying that the present invention can be appropriately modified and applied without departing from the gist thereof. For example, in the embodiment, the flat wound type electrode body 50 is exemplified as the electrode body, but the present invention is not limited thereto. The electrode body may be, for example, a stacked type electrode body in which a plurality of rectangular positive electrode plates (electrode plates) and a plurality of rectangular negative electrode plates (electrode plates) are stacked via rectangular separators.

Explanation of Reference Numerals

[0044] 1 Battery (Power Storage Device) 10 Case 11 First Main Wall Portion 12 Second Main Wall Portion 13 First Side Wall Portion (Upper Wall Portion) 14 Second Side Wall Portion (Lower Wall Portion) 15 Third Side Wall Portion 16 Fourth Side Wall Portion 21 Main Body Member 21c Opening 21f Opening Peripheral Portion 31 Lid Member 31f Lid Peripheral Portion 50 Electrode Body 50e Electrode Stacking Portion 51 Positive Electrode Plate (Electrode Plate) 54 Negative Electrode Plate (Electrode Plate) 57 Separator CH Case Thickness Direction FH Electrode Body Thickness Direction C Compression Amount (of the Electrode Stacking Portion of the Electrode Body) Compression amount of the electrode laminate in the battery Surface pressure P applied to the electrode laminate of the electrode body Surface pressure p1 applied to the electrode laminate in the battery Graph GF1 related to the battery of the embodiment Tangent TL1 related to the battery of the embodiment Virtual straight line VL External force Fa Containing process S1 Pressing and compression process S2 Bonding process S3 Release process S4

Claims

1. A case, and an electrode body housed in the case, and the case is in the shape of a rectangular parallelepiped box and has a rectangular first main wall portion, a rectangular second main wall portion facing the first main wall portion, and four rectangular side wall portions connecting between the first main wall portion and the second main wall portion and extending in the case thickness direction, the electrode body includes an electrode plate and has a rectangular parallelepiped-shaped electrode laminate portion in which the electrode plates are laminated in the electrode body thickness direction, and the electrode body thickness direction is housed in the case in a posture parallel to the case thickness direction, a power storage device, wherein the case has a bottomed rectangular tube-shaped main body member forming the second main wall portion and the four side wall portions and having a rectangular opening formed by the four side wall portions, and a rectangular lid member forming the first main wall portion and having a lid peripheral portion joined to the entire periphery of the opening peripheral edge of the opening of the main body member, the first main wall portion and the second main wall portion of the case elastically compress the electrode laminate portion of the electrode body in the electrode body thickness direction, wherein the power storage device has an elastic characteristic such that, when the compression amount C of the electrode laminate portion in the state where the electrode body is housed in the case is C = c1 and the surface pressure P applied to the electrode laminate portion is P = p1, in a graph showing the relationship between the compression amount C and the surface pressure P with the horizontal axis being the compression amount C and the vertical axis being the surface pressure P, the slope of the tangent line at the point (c1, p1) is equal to or less than the slope (p1 / c1) of the virtual straight line connecting the origin (0, 0) and (c1, p1). Power storage device.

2. A case, and an electrode body housed in the case, and the case is in the shape of a rectangular parallelepiped box and has a rectangular first main wall portion, a rectangular second main wall portion facing the first main wall portion, and four rectangular side wall portions connecting between the first main wall portion and the second main wall portion and extending in the case thickness direction, the electrode body includes an electrode plate and has a rectangular parallelepiped-shaped electrode laminate portion in which the electrode plates are laminated in the electrode body thickness direction, and the electrode body thickness direction is housed in the case in a posture parallel to the case thickness direction, a power storage device, wherein the case has a bottomed rectangular tube-shaped main body member forming the second main wall portion and the four side wall portions and having a rectangular opening formed by the four side wall portions, and a rectangular lid member forming the first main wall portion and having a lid peripheral portion joined to the entire periphery of the opening peripheral edge of the opening of the main body member, The first main wall portion and the second main wall portion of the above case elastically compress the electrode laminate portion of the above electrode body in the thickness direction of the above electrode body, The above storage device is, When the compression amount C of the above electrode laminate portion is set to C = c1 and the surface pressure P applied to the above electrode laminate portion is set to P = p1 in the state where the above electrode body is accommodated in the above case, In a graph showing the relationship between the compression amount C and the surface pressure P, with the horizontal axis being the compression amount C and the vertical axis being the surface pressure P, the slope of the tangent line at the point (c1, p1) has an elastic characteristic such that it is less than or equal to the slope (p1 / c1) of the virtual straight line connecting the origin (0, 0) and (c1, p1), A method for manufacturing a storage device, A housing step of housing the above electrode body in the above body member, A pressing and compressing step of disposing the above lid member on the above electrode body housed in the above body member, applying an external force to the above first main wall portion formed by the above lid member and the above second main wall portion of the above body member, and pressing and compressing the above electrode laminate portion of the above electrode body in the thickness direction of the above electrode body, A joining step of joining the above lid peripheral portion of the above lid member to the above opening peripheral portion of the above opening of the above body member over the entire circumference in the state where the above electrode body is pressed and compressed to form the above case, A releasing step of releasing the above external force after the above joining step, and comprising A method for manufacturing a storage device.

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