JP2018098154A - Power storage element, power storage device and method of manufacturing power storage element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage element capable of sufficiently reducing resistance of a current path, and also to provide a method of manufacturing a power storage device and the power storage element.SOLUTION: A power storage device according to the present invention includes: an electrode body which is formed by laminating a positive electrode plate, a separator, and a negative electrode plate, and has a first side and a second side whose separators are opposite to each other, and in which the positive electrode plate has a first tab protruding from the first side of the separator and a second tab protruding from the second side, and the negative electrode plate has a third tab protruding from the first side of the separator so as not to be overlapped on the first tab in a plan view; and a case in which the electrode body is housed and the first tab and the second tab are electrically connected to each other. A method of manufacturing the power storage device includes the steps of: connecting the first tab to the substrate; surrounding the electrode body with a main body; and connecting the second tab to a bottom plate.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power storage element, a power storage device, and a method for manufacturing a power storage element.

  Japanese Patent Application Laid-Open No. 2013-171784 discloses a prismatic nonaqueous electrolyte secondary battery. In this rectangular nonaqueous electrolyte secondary battery, a plurality of positive electrode current collecting tabs are bent at the upper part of the flat wound electrode body, and at least one positive electrode current collecting tab is provided on each of two long sides of the flat rectangular outer package body. Each tip is sandwiched and welded between the flat rectangular exterior body and the sealing body so as to be positioned.

JP 2013-17184 A

  An electric storage element to be charged / discharged such as a lithium ion secondary battery is required to be able to perform rapid charging and rapid discharging. Recently, in applications such as electric vehicles, there has been an increasing demand for securing a current path inside a storage element that is difficult to melt even if a large current flows due to rapid charging or rapid discharging.

  Based on such a demand, an object of the present invention is to provide a power storage element, a power storage device, and a method for manufacturing a power storage element that can sufficiently reduce the resistance of a current path.

  In the conventional power storage element, a configuration in which the positive electrode tab and the negative electrode tab protrude in the same direction and a configuration in which the positive electrode tab and the negative electrode tab protrude in the opposite direction have been adopted. The inventor has devised a new configuration in which a first tab of a positive electrode tab and a negative electrode tab are provided on one side of the electrode body, and a second tab of the positive electrode tab is provided on the other side of the electrode body.

  In a power storage element according to one embodiment of the present invention, a positive electrode plate, a separator, and a negative electrode plate are stacked, the separator has a first side and a second side facing each other, and the positive plate protrudes from the first side of the separator. An electrode having a first tab and a second tab protruding from the second side, and a third tab protruding from the first side of the separator so that the negative electrode plate does not overlap the first tab in plan view A body and a case in which the electrode body is accommodated and the first tab and the second tab are electrically connected.

  According to another aspect of the present invention, there is provided a method for manufacturing a power storage element, in which a positive electrode plate, a separator, and a negative electrode plate are stacked, the separator has a first side and a second side facing each other, A first tab protruding from the first side and a second tab protruding from the second side; a third protruding from the first side of the separator so that the negative electrode plate does not overlap the first tab in plan view. Using the electrode body having a tab and a case having a cylindrical main body, a lid plate and a bottom plate, mechanically connecting the first tab to the lid plate, and surrounding the electrode body by the body. And mechanically connecting the second tab to the bottom plate.

  The power storage element according to the embodiment of the present invention can sufficiently reduce the resistance of the current path. In addition, the method for manufacturing a power storage element according to an embodiment of the present invention can manufacture a power storage element with sufficiently low current path resistance.

It is a typical front view showing an electrical storage element concerning one embodiment of the present invention. FIG. 2 is a schematic exploded perspective view of the electricity storage device of FIG. 1. It is typical AA sectional view taken on the line of the electrical storage element of FIG. It is a typical partial enlarged view which shows the electrical storage element which concerns on the form different from the electrical storage element of FIG. It is a mimetic diagram showing an electrical storage device concerning one embodiment of the present invention.

  A power storage device according to an embodiment of the present invention includes a positive electrode plate, a separator, and a negative electrode plate that are stacked, the separator having a first side and a second side that face each other, and the positive plate from the first side of the separator. A first tab protruding and a second tab protruding from the second side; and a third tab protruding from the first side of the separator so that the negative electrode plate does not overlap the first tab in plan view. An electrode body and a case that accommodates the electrode body and that is electrically connected to the first tab and the second tab are provided.

  In the storage element, the first tab of the positive electrode plate and the third tab of the negative electrode plate protrude from the first side of the separator, and the second tab of the positive electrode plate protrudes from the second side of the separator. The total cross-sectional area of the positive electrode tab can be expanded by the second tab while securing the cross-sectional areas of the first tab and the third tab. Therefore, the power storage element can sufficiently reduce the resistance of the current path.

  The power storage element may further include a discharge mechanism that is disposed outside the case and is electrically connected to the case and the third tab. By further including a discharge mechanism electrically connected to the case and the third tab, the discharge mechanism rapidly discharges the electrode body when heat is generated inside the storage element in a specific situation that is not normally foreseen. Thus, the storage element can be brought into a safe state. Further, since the positive electrode plate has the second tab in addition to the first tab, the resistance of the current path is low, so that the current path is unlikely to melt. Since the resistance of the current path is low, the discharge mechanism can be operated reliably.

  The case includes a first portion to which the first tab and the third tab are mechanically connected, and a second portion to which the second tab is mechanically connected. It may be provided in one part. According to this configuration, since the first tab, the third tab, and the discharge mechanism are provided in the first portion of the case and arranged close to each other, the current path during the rapid discharge is shortened to reduce the resistance of the current path. be able to. The second tab is mechanically connected to a second part different from the first part of the case. The current path (second current path) from the second tab to the discharge mechanism via the second part of the case is the current path (second current path) from the first tab to the discharge mechanism via the first part of the case. The resistance of the second current path is higher than the resistance of the first current path. When the first current path and the second current path are regarded as resistance elements, the first resistance by the first current path and the second resistance by the second current path are connected in parallel to the positive electrode plate. Since the first resistor has a lower resistance value than the second resistor, a large amount of discharge current from the positive electrode plate flows through the first current path during rapid discharge. However, the discharge current from the positive electrode plate also flows in the second current path. By causing a part of the discharge current to flow through the second current path, the discharge current does not concentrate on the first current path, so that the first tab and the first current path are unlikely to melt. Therefore, more reliable rapid discharge can be performed.

  The average width of the third tab in plan view may be larger than the average width of the first tab. Since the positive electrode plate has a second tab protruding from the second side in addition to the first tab protruding from the first side of the separator, the power storage element has a positive electrode even if the average width of the first tab is relatively small. The resistance of the current path extending from the plate can be made sufficiently low. By making the average width of the first tab relatively small and the average width of the third tab relatively large, the cross-sectional area of the third tab can be sufficiently secured. As a result, the resistance of the current path extending from the negative electrode plate can be suppressed sufficiently low, and the third tab can be prevented from fusing when a large current flows.

  The average thickness of the third tab may be smaller than the average thickness of the first tab. Even when the average thickness of the third tab is smaller than the average thickness of the first tab, the average width of the third tab is made larger than the average width of the first tab, so that the current path extending from the negative electrode plate can be reduced. The resistance can be suppressed sufficiently low, and the third tab can be prevented from fusing when a large current flows.

  A power storage device according to another embodiment of the present invention includes a plurality of the power storage elements and a bus bar that contacts a case of the power storage elements.

  Each of the plurality of power storage elements includes a case that is electrically connected to the positive electrode plate through the first tab and the second tab. Therefore, by bringing the bus bar into contact with the case, the power storage element can be connected to other power storage elements or other power storage elements. Can be connected in series or in parallel with electrical circuits. The power storage device configured in this manner has a high degree of freedom in designing the bus bar. Since the resistance of the current path inside each power storage element is low, the resistance of the current path of the entire power storage device can be sufficiently reduced.

  According to another embodiment of the present invention, there is provided a method for manufacturing a power storage device, wherein a positive electrode plate, a separator, and a negative electrode plate are stacked, the separator has a first side and a second side, and the positive plate is A first tab protruding from the first side and a second tab protruding from the second side; a third protruding from the first side of the separator so that the negative electrode plate does not overlap the first tab in plan view. Using the electrode body having a tab and a case having a cylindrical main body, a lid plate and a bottom plate, mechanically connecting the first tab to the lid plate, and surrounding the electrode body by the body. And mechanically connecting the second tab to the bottom plate.

  According to this method for manufacturing an electric storage element, the first tab and the second tab extending from the positive electrode plate can be smoothly and stably connected to the case, and an electric storage element having a sufficiently low current path resistance can be manufactured. it can.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

[First Embodiment]
A power storage device 1 according to an embodiment of the present invention shown in FIGS. 1 to 3 includes an electrode body 2, a case 3, and a negative electrode terminal 4 exposed on the outer surface of the case 3. The negative electrode terminal 4 is provided in the case 3 via an insulating member (not shown), and is insulated from the case 3 by the insulating member. The case 3 contains an electrolyte together with the electrode body 2. The power storage element 1 is a secondary battery capable of charging and discharging electricity, and is typically a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. In the power storage device 1, the case 3 also serves as a positive electrode terminal, and the positive electrode terminal is not provided in the case 3.

  As shown in FIG. 3, the electrode body 2 has a laminated structure in which a positive electrode plate 5, a separator 6, and a negative electrode plate 7 are laminated. The separator 6 has a first side 6a and a second side 6b facing each other. The positive electrode plate 5 has a first tab 8 protruding from the first side 6 a of the separator 6 and a second tab 9 protruding from the second side 6 b. The negative electrode plate 7 has a third tab 10 that protrudes from the first side 6a of the separator 6 so as not to overlap the first tab 8 in plan view. As shown in FIG. 3, the electrode body 2 may be a laminated type in which a sheet-like (plate-shaped) positive electrode plate 5, a separator 6, and a negative electrode plate 7 are laminated. Alternatively, as shown in FIG. 2, a winding type in which a long belt-like positive electrode plate and negative electrode plate are wound flat via a separator may be used. As shown in FIG. 3, the first side 6a of the separator 6 faces a lid plate 3b described later, and the second side 6b faces a bottom plate 3c described later.

  The positive electrode plate 5 includes a conductive foil-shaped or sheet-shaped positive electrode base material and a positive electrode active material layer 11 laminated on both surfaces of the positive electrode base material.

  As a material of the positive electrode base material, a metal such as aluminum, copper, iron, nickel, or an alloy thereof is used. Among these, aluminum, an aluminum alloy, copper, and a copper alloy are preferable from the balance between high conductivity and cost, and aluminum and an aluminum alloy are more preferable. Examples of the form of the positive electrode substrate include a foil and a vapor deposition film, and the foil is preferable from the viewpoint of cost. That is, the positive electrode base material is preferably an aluminum foil.

  The average thickness of the positive electrode base material can be, for example, 12 μm or more and 15 μm or less.

  The positive electrode active material layer 11 is a layer formed from a so-called mixture containing a positive electrode active material. The mixture may include a conductive agent, a binder, a thickener, a filler, and the like.

Examples of the positive electrode active material include composite oxides represented by Li _x MO _y (M represents at least one transition metal) (Li _x CoO ₂ , Li _x NiO ₂ , Li _x Mn ₂ O ₄ , Li _{x MnO 3, Li x Ni α Co} (1-α) O 2, Li x Ni α Mn β Co (1-α-β) O 2, Li x Ni α Mn (2-α) O 4 , etc.), Li _w A polyanion compound (LiFePO ₄ , LiMnPO ₄ , LiNiPO ₄ , LiCoPO ₄ ) represented by Me _x (XO _y ) _z (Me represents at least one transition metal, and X represents, for example, P, Si, B, V, etc.) Li ₃ V ₂ (PO ₄ ) ₃ , Li ₂ MnSiO ₄ , Li ₂ CoPO ₄ F, etc.). The elements or polyanions in these compounds may be partially substituted with other elements or anion species. In the positive electrode active material layer 11, one of these compounds may be used alone, or two or more thereof may be mixed and used. The crystal structure of the positive electrode active material is preferably a layered structure or a spinel structure.

  As a minimum of content of the positive electrode active material in the positive electrode active material layer 11, 50 mass% is preferable, 70 mass% is more preferable, 80 mass% is further more preferable. On the other hand, as an upper limit of content of a positive electrode active material, 99 mass% is preferable and 94 mass% is more preferable. By making content of a positive electrode active material into the said range, the energy density of an electrical storage element can be raised.

  The conductive agent is not particularly limited as long as it is a conductive material that does not adversely affect battery performance. Examples of such a conductive agent include carbon black such as natural or artificial graphite, furnace black, acetylene black, and ketjen black, metals, and conductive ceramics. Examples of the shape of the conductive agent include powder and fiber.

  As a minimum of content of a conductive agent in cathode active material layer 11, 0.1 mass% is preferred and 0.5 mass% is more preferred. On the other hand, as an upper limit of content of a electrically conductive agent, 10 mass% is preferable and 5 mass% is more preferable. By setting the content of the conductive agent in the above range, the energy density of the power storage element can be increased.

  Examples of the binder include thermoplastic resins such as fluororesin (polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), etc.), polyethylene, polypropylene, polyimide; ethylene-propylene-diene rubber (EPDM), sulfonated EPDM. , Elastomers such as styrene butadiene rubber (SBR) and fluororubber; polysaccharide polymers and the like.

  As a minimum of content of a binder in cathode active material layer 11, 1 mass% is preferred and 2 mass% is more preferred. On the other hand, as an upper limit of content of a binder, 10 mass% is preferable and 5 mass% is more preferable. By setting the content of the binder in the above range, the positive electrode active material can be stably held.

  Examples of the thickener include polysaccharide polymers such as carboxymethylcellulose (CMC) and methylcellulose. When the thickener has a functional group that reacts with lithium, it is preferable to deactivate this functional group in advance by methylation or the like.

  The filler is not particularly limited as long as it does not adversely affect battery performance. Examples of the main component of the filler include polyolefins such as polypropylene and polyethylene, silica, alumina, zeolite, glass, and carbon. The “main component” means a component having the largest mass content.

  The 1st tab 8 is comprised from the positive electrode base material. In other words, the first tab 8 has no positive electrode active material layer 11 laminated on both surfaces of the positive electrode base material. The first tab 8 is formed by laminating a plurality of protruding portions that extend from the stacked positive electrode plates 5 and protrude from the first side 6 a of the separator 6. The first tab 8 is joined to the inner surface of a cover plate 3b of the case 3 to be described later in a state where the first tab 8 is bent in the stacking direction (Y direction in FIG. 2) of the positive electrode plate 5, the separator 6 and the negative electrode plate 7, for example.

  The lower limit of the ratio of the width of the first tab 8 to the width of the cover plate 3b to which the first tab 8 is joined (the length in the direction parallel to the width of the first tab 8) is preferably 0.2, 0 .3 is more preferable. On the other hand, the upper limit of the ratio is preferably 0.5, and more preferably 0.4. When the ratio is within the above range, the width of the third tab 10 can be sufficiently increased while ensuring the width of the first tab 8. Moreover, when the ratio is within the above range, the fusing of the first tab 8 can be sufficiently suppressed.

  The 2nd tab 9 is comprised from the positive electrode base material. In other words, the second tab 9 has no positive electrode active material layer 11 laminated on both surfaces of the positive electrode base material. The second tab 9 is formed by laminating a plurality of protruding portions extending from the stacked positive electrode plates 5 and protruding from the second side 6 b of the separator 6. The second tab 9 is joined to the inner surface of a bottom plate 3c of the case 3 described later, for example, in a state where the second tab 9 is bent in the stacking direction of the positive electrode plate 5, the separator 6 and the negative electrode plate 7.

  The lower limit of the ratio of the width of the second tab 9 to the width of the bottom plate 3c to which the second tab 9 is joined (the length in the direction parallel to the width of the second tab 9) is preferably 0.2. 3 is more preferable. On the other hand, the upper limit of the ratio is preferably 0.9, and more preferably 0.8. When the ratio is within the above range, the width of the second tab 9 can be made sufficiently large, and the resistance of the current path of the electricity storage device 1 can be made sufficiently low. Moreover, when the ratio is within the above range, the fusing of the second tab 9 can be sufficiently suppressed.

  The negative electrode plate 7 has a conductive foil-shaped or sheet-shaped negative electrode base material and a negative electrode active material layer 12 laminated on both surfaces of the negative electrode base material.

  The negative electrode substrate can have the same shape as the above-described positive electrode substrate, but the material is preferably copper or a copper alloy. That is, the negative electrode base material of the negative electrode plate 7 is preferably a copper foil. Examples of the copper foil include a rolled copper foil and an electrolytic copper foil.

  The average thickness of the negative electrode substrate can be, for example, 6 μm or more and 10 μm or less. For example, when an aluminum foil is used as the material for the positive electrode base material and a copper foil is used as the material for the negative electrode base material, the strength of the negative electrode base material is higher than the strength of the positive electrode base material. Therefore, the average thickness of the negative electrode substrate may be smaller than the average thickness of the positive electrode substrate.

  The negative electrode active material layer 12 is a layer formed from a so-called mixture containing a negative electrode active material. The mixture may include a conductive agent, a binder, a thickener, a filler, and the like.

  As the negative electrode active material, a material capable of inserting and extracting lithium ions is preferably used. Specific examples of the negative electrode active material include metals such as lithium and lithium alloys; metal oxides; polyphosphate compounds; carbon materials such as graphite and amorphous carbon (easily graphitizable carbon or non-graphitizable carbon). Can be mentioned.

  Among the negative electrode active materials, Si, Si oxide, Sn, Sn oxide, or a combination thereof is used from the viewpoint of setting the discharge capacity per unit facing area between the positive electrode plate 5 and the negative electrode plate 7 to a suitable range. It is preferable to use Si oxide.

  The 3rd tab 10 is comprised from the negative electrode base material. That is, the third tab 10 does not have the negative electrode active material layer 12 laminated on both surfaces of the negative electrode base material. The third tab 10 is formed by laminating a plurality of protruding portions that extend from the stacked negative electrode plates 7 and protrude from the first side 6 a of the separator 6. The third tab 10 is electrically connected to the negative electrode terminal 4 via a negative electrode current collector (not shown) in a state where the third tab 10 is bent in the stacking direction of the positive electrode plate 5, the separator 6 and the negative electrode plate 7, for example.

  The lower limit of the ratio of the width of the third tab 10 to the width of the cover plate 3b to which the third tab 10 is joined (the length in the direction parallel to the width of the third tab 10) is preferably 0.4, 0 .5 is more preferred. On the other hand, the upper limit of the ratio is preferably 0.8 and more preferably 0.7. When the ratio is within the above range, the resistance of the current path of the electricity storage device 1 can be sufficiently reduced by sufficiently increasing the width of the third tab 10. Moreover, when the ratio is within the above range, the fusing of the third tab 10 can be sufficiently suppressed.

  The average width of the third tab 10 in a plan view (viewed in the Y direction in FIG. 2 and viewed in the stacking direction of the electrode plates in FIG. 3) is preferably larger than the average width of the first tab 8. Since the positive electrode plate 5 includes the second tab 9 protruding from the second side 6b of the separator 6 in addition to the first tab 8 protruding from the first side 6a of the separator 6, the power storage element 1 has an average width of the first tab 8 Even if it is relatively small, the resistance of the current path extending from the positive electrode plate 5 can be made sufficiently low. By making the average width of the first tab 8 relatively small and the average width of the third tab 10 relatively large, the cross-sectional area of the third tab 10 can be sufficiently secured. As a result, the resistance of the current path extending from the negative electrode plate 7 can be kept sufficiently low, and the third tab 10 can be prevented from fusing when a large current flows.

  The lower limit of the ratio of the average width of the third tab 10 to the average width of the first tab 8 in plan view is preferably 1.0, and more preferably 1.5. On the other hand, the upper limit of the ratio is preferably 3.0 and more preferably 2.5. When the ratio is within the above range, the average width of the third tab 10 can be sufficiently increased while preventing the average width of the first tab 8 from becoming too small. While suppressing the resistance of the current path sufficiently low, the fusing of the first tab 8 and the third tab 10 when a large current flows can be sufficiently suppressed.

  When the average width of the third tab 10 in plan view is larger than the average width of the first tab 8, the average thickness of the third tab 10 may be smaller than the average thickness of the first tab 8. In the electricity storage device 1, when the aluminum foil is used as the material of the positive electrode base material and the copper foil is used as the material of the negative electrode base material as described above, the strength of the negative electrode base material is higher than the strength of the positive electrode base material. . Therefore, even if the average thickness of the third tab 10 made of the negative electrode substrate laminate is smaller than the average thickness of the first tab 8 made of the positive electrode substrate laminate, the strength of the third tab 10 is sufficiently high. Can keep. Even in the case where the average thickness of the third tab 10 is thus made smaller than the average thickness of the first tab 8, the power storage device 1 makes the average width of the third tab 10 larger than the average width of the first tab 8. As a result, the resistance of the negative electrode plate 7 can be suppressed sufficiently low, and the fusing of the third tab 10 when a large current flows can be sufficiently suppressed.

  The separator 6 is formed from a porous sheet-like or film-like resin, and is infiltrated with an electrolytic solution. The separator 6 separates the positive electrode plate 5 and the negative electrode plate 7 and holds an electrolytic solution between the positive electrode plate 5 and the negative electrode plate 7.

  Examples of the main component of the separator 6 include polyolefins such as polyethylene (PE), polypropylene (PP), ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, and chlorinated polyethylene. Derivatives, polyolefins such as ethylene-propylene copolymers, and polyesters such as polyethylene terephthalate and copolymerized polyesters can be employed. Among these, as the main component of the separator 6, polyethylene and polypropylene excellent in electrolytic solution resistance, durability, and weldability are preferably used.

As the electrolytic solution enclosed in the case 3, a known electrolytic solution that is usually used for a power storage element can be used. For example, cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), or diethyl A solution in which lithium hexafluorophosphate (LiPF ₆ ) or the like is dissolved in a solvent containing a chain carbonate such as carbonate (DEC), dimethyl carbonate (DMC), or ethyl methyl carbonate (EMC) can be used.

  Case 3 has conductivity. The case 3 accommodates the electrode body 2 and is electrically connected to the first tab 8 and the second tab 9. Examples of the material of the case 3 include metals such as aluminum. The case 3 includes a first portion 13 (the cover plate 3b in this embodiment) to which the first tab 8 and the third tab 10 are mechanically connected, and a second portion 14 to which the second tab 9 is mechanically connected. (In this embodiment, the bottom plate 3c). In the present embodiment, the first tab 8 is directly connected to the first portion 13, and the second tab 9 is directly connected to the second portion 14. On the other hand, the third tab 10 is indirectly connected to the first portion 13 via the negative electrode current collector. Alternatively, the third tab 10 may be directly connected to the negative electrode terminal 4 provided on the cover plate 3b without using the negative electrode current collector.

  The case 3 includes a cylindrical main body 3a, a lid plate 3b that seals an opening on one side of the main body 3a, and a bottom plate 3c that seals an opening on the other side of the main body 3a. The case 3 is integrally configured, for example, by laser welding the main body 3a, the lid plate 3b, and the bottom plate 3c. The main body 3a is typically formed in a rectangular tube shape having a rectangular opening. The cover plate 3b is provided with a negative electrode terminal 4 on one end side in the long side direction. The specific shape of the main body 3a is not limited to the above-described square cylinder shape, and may be, for example, an elliptic cylinder shape. In the case 3, the inner surface of the cover plate 3 b faces the first side 6 a of the separator 6, and the inner surface of the bottom plate 3 c faces the second side 6 c of the separator 6. The first tab 8 is directly connected to the inner surface of the cover plate 3b, and the second tab 9 is directly connected to the inner surface of the bottom plate 3c. In the present invention, the “lid” and the “bottom” are defined for convenience with the central axis direction of the main body as the vertical direction, and do not specify the specific shape and orientation of the electricity storage device according to the present invention.

  Next, an example of a method for manufacturing the electricity storage device 1 will be described. The manufacturing method of the electricity storage element includes mechanically connecting the first tab 8 to the cover plate 3b, surrounding the electrode body 2 with the main body 3a, and mechanically connecting the second tab 9 to the bottom plate 3c. With. In the method for manufacturing the storage element, for example, the first tab 8 is ultrasonically welded to the inner surface of the lid plate 3b, and the outer periphery of the electrode body 2 is moved by the main body 3a in a state where the first tab 8 is joined to the inner surface of the lid plate 3b. After enclosing and ultrasonically welding the second tab 9 to the inner surface of the bottom plate 3c, the lid plate 3b, the main body 3a and the bottom plate 3c are laser welded. The method for manufacturing a power storage element in the present embodiment further includes electrically connecting the third tab 10 to the negative electrode terminal 4 before laser welding the cover plate 3b and the main body 3a. In the method for manufacturing the power storage element, for example, the third tab 10 is electrically connected to the negative electrode terminal 4 by ultrasonically welding the third tab 10 to the negative electrode current collector. In the method for manufacturing the power storage element, the first tab 8 may be mechanically connected to the cover plate 3b after the outer periphery of the electrode body 2 is surrounded by the main body 3a. Before the first tab 8 is mechanically connected to the cover plate 3b, the second tab 9 may be mechanically connected to the bottom plate 3c.

  In the storage element 1, the first tab 8 of the positive electrode plate 5 and the third tab 10 of the negative electrode plate 7 protrude from the first side 6 a of the separator 6, and the second tab 9 of the positive electrode plate 5 is the second side of the separator 6. Since it protrudes from 6b, the total cross-sectional area of a positive electrode tab can be expanded by the 2nd tab 9, ensuring each cross-sectional area of the 1st tab 8 and the 3rd tab 10 in the 1st edge | side 6a. Therefore, the resistance of the current path can be made sufficiently low. Since the positive electrode plate 5 has the second tab 9 in addition to the first tab 8, the current path is unlikely to melt.

  According to the method for manufacturing a power storage element, the power storage element 1 having a sufficiently low current path resistance can be easily and reliably manufactured.

[Second Embodiment]
Next, with reference to FIG. 4, the electrical storage element which concerns on 2nd embodiment is demonstrated. The power storage element has the same configuration as the power storage element 1 of FIGS. 1 to 3 except that it includes a discharge mechanism 22 that is electrically connected to the case and the third tab. Therefore, only the discharge mechanism 22 will be described below.

  The discharge mechanism 22 is provided outside the case 3 shown in FIG. 1, and in detail, is provided in the first portion 13 of the case 3. The specific configuration of the discharge mechanism 22 is not particularly limited as long as the case 3 and the negative electrode terminal 4 can be short-circuited outside the case 3. For example, as shown in FIG. 4, a metal bus bar 23 having one end connected to the negative electrode terminal 4, and a first solder layer laminated from the inner surface of the bus bar 23 to the outer surface of the cover plate 3 b on the other end side of the bus bar 23. 24, a metal foil layer 25 in which nickel foil and aluminum foil are alternately laminated, a resin layer 26 having a plurality of through holes in the thickness direction, and a second solder layer 27. The discharge mechanism 22 is configured such that a current flows through the metal foil layer 25 when rapid discharge is to be performed. In the discharge mechanism 22, the first solder layer 24 and the second solder layer 27 are melted by heat generated by the alloying reaction of nickel and aluminum in the metal foil layer 25, and these solders flow into the through holes of the resin layer 26. The case 3 and the negative terminal 4 are configured to conduct.

  Since the electricity storage device includes the discharge mechanism 22 that is electrically connected to the case 3 and the third tab 10, when the inside of the electricity storage device generates heat in a specific situation that is not normally used, the positive electrode plate 5 and the negative electrode plate 7 can be short-circuited outside the case 3, and heat generation in the case 3 can be suppressed.

  Since the discharge mechanism 22 is provided in the first portion 13 of the case 3, the power storage element reaches the negative terminal 4 from the first tab of the positive electrode plate through the case 3 and the discharge mechanism 22 during rapid discharge. The resistance of the current path can be lowered by shortening the current path. Therefore, more rapid and reliable discharge can be performed.

[Third embodiment]
Next, a power storage device 31 including a plurality of power storage elements 1 will be described with reference to FIG. The power storage device 31 includes a plurality of power storage elements 1 and a bus bar 32 that contacts the case 3 of the plurality of power storage elements 1. In addition, the power storage device 31 includes a sheet-like heat transfer member 33 that contacts the case 3 of the plurality of power storage elements 1 and a cooling member 34 that is stacked on the surface of the heat transfer member 33 opposite to the surface that contacts the case 3. Prepare. The power storage device 31 is an assembled battery in which a plurality of power storage elements 1 are electrically connected by a bus bar 3.

  The plurality of power storage elements 1 are arranged side by side with the outer surface of the main body 3a of the case 3 (in this embodiment, the side surface connecting the short side of the lid plate and the short side of the bottom plate) in contact with the heat transfer member 33. ing. In the plurality of power storage elements 1, the negative electrode terminals 4 face the same direction (direction perpendicular to the paper surface in FIG. 5). The plurality of power storage elements 1 are arranged side by side in the direction in which the heat transfer member 33 extends so that the negative electrodes 4 are staggered vertically. The plurality of power storage elements 1 may be arranged with a gap therebetween or in contact with each other (insulation between the cases is ensured).

  The bus bar 32 that connects the plurality of power storage elements 1 in series and / or in parallel has conductivity and is typically made of metal. The bus bar 32 connects the cover plate 3 b of one adjacent power storage element 1 to the negative electrode terminal 4 of the other power storage element 1. The bus bars 32 connect adjacent power storage elements 1 alternately up and down.

  The heat transfer member 33 has flexibility and insulation. The heat transfer member 33 is composed mainly of a material having higher thermal conductivity than air. Examples of the main component of the heat transfer member 33 include polyamides such as 66 nylon, synthetic resins such as acrylic resin, silicone resin, polyester, and polyolefin. Moreover, as heat conductivity of the heat-transfer member 33, it can be 0.2 W / m * K or more and 5.0 W / m * k or less, for example. The average thickness of the heat transfer member 33 can be, for example, 0.5 mm or more and 10 mm or less.

  The cooling member 34 may be a plate-like member or may have a flow passage through which a refrigerant flows. The cooling member 34 may have an inflow port that communicates with the flow passage and introduces the refrigerant, and an exhaust port that communicates with the flow passage and discharges the refrigerant. The cooling member 34 may be configured to be able to cool the plurality of power storage elements 1 by allowing the refrigerant continuously introduced from the inflow port to pass through the flow path. Examples of the refrigerant include liquids such as water, organic solvents, and oils.

  In the power storage device 31, each power storage element 1 has a first tab 8, a second tab 9, and a third tab 10 as in the first embodiment. The first tab 8, the third tab 10, and the lid The total contact area with the plate 3b and the contact area between the bottom plate 3c and the second tab 9 can be sufficiently increased. Therefore, the resistance of the current path in the case 3 of each power storage element 1 can be sufficiently reduced, and the central axis direction of the main body 3a of the case 3 (the direction orthogonal to the cover plate 3b; the direction perpendicular to the paper surface in FIG. 5). Heat transfer is promoted. For this reason, the power storage device 31 can enhance the cooling effect by the cooling member 34, and thus can promote the extension of the life of the power storage device 31.

[Other Embodiments]
The said embodiment does not limit the structure of this invention. Therefore, in the above-described embodiment, the components of each part of the above-described embodiment can be omitted, replaced, or added based on the description and common general knowledge of the present specification, and they are all interpreted as belonging to the scope of the present invention. Should. For example, in the storage element, it is preferable that the first tab and the second tab are directly connected to the case in order to reduce the resistance, but the first tab and the second tab are connected to the case via the positive electrode current collector. May be.

  The power storage element does not necessarily have to have a first portion where the first tab and the third tab are mechanically connected and a second portion where the second tab is mechanically connected. As for an electrical storage element, the 1st part may be provided in places other than the cover plate of a case, and the 2nd part may be provided in places other than the bottom plate of a case. The first part and the second part may not be clearly divided, for example, the opposing side walls of the case body may be the first part and the second part, or in any two opposing walls of the case These regions may be the first portion and the second portion.

  In the power storage device, each of the plurality of power storage elements may have the above-described discharge mechanism.

  The power storage device according to the present invention can be widely used as a power source for various devices, and is particularly preferably used for an electric vehicle or the like.

DESCRIPTION OF SYMBOLS 1 Power storage element 2 Electrode body 3 Case 3a Main body 3b Cover plate 3c Bottom plate 4 Negative electrode terminal 5 Positive electrode plate 6 Separator 6a First side 6b Second side 7 Negative electrode plate 8 First tab 9 Second tab 10 Third tab 11 Positive electrode active material Layer 12 Negative electrode active material layer 13 First portion 14 Second portion 22 Discharge mechanism 23 Bus bar 24 First solder layer 25 Metal foil layer 26 Resin layer 27 Second solder layer 31 Power storage device 32 Bus bar 33 Heat transfer member 34 Cooling member

Claims (7)

A positive electrode plate, a separator, and a negative electrode plate are stacked, the separator has first and second sides facing each other, and the positive electrode plate protrudes from the first tab and the second side protruding from the first side of the separator. An electrode body having a third tab protruding from the first side of the separator so that the negative electrode plate does not overlap the first tab in plan view,
A power storage device comprising: a case for housing the electrode body and electrically connecting the first tab and the second tab.   The electricity storage device according to claim 1, further comprising a discharge mechanism disposed outside the case and electrically connected to the case and the third tab.   The case includes a first portion to which the first tab and the third tab are mechanically connected, and a second portion to which the second tab is mechanically connected. The electric storage element according to claim 2, which is provided in one part.   The electrical storage element according to claim 1, wherein the average width of the third tab in plan view is larger than the average width of the first tab.   The electrical storage element according to claim 4, wherein an average thickness of the third tab is smaller than an average thickness of the first tab.   A power storage device comprising: the plurality of power storage elements according to any one of claims 1 to 5; and a bus bar that contacts a case of the power storage elements. A positive electrode plate, a separator, and a negative electrode plate are stacked, the separator has first and second sides facing each other, and the positive electrode plate protrudes from a first tab and a second side that protrude from the first side of the separator. An electrode body having a second tab and having a third tab protruding from the first side of the separator so that the negative electrode plate does not overlap the first tab in plan view;
Using a case with a cylindrical main body, a lid plate and a bottom plate,
Mechanically connecting the first tab to the lid plate;
Surrounding the electrode body with the body;
Mechanically connecting the second tab to the bottom plate.

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