JP2014110209A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device capable of surely performing short-circuiting, and also capable of securing capacity.SOLUTION: A secondary battery 100 comprises a case 10, an electrode assembly 5 accommodated in the case 10, a first conductive plate 14 disposed between the case 10 and the electrode assembly 5, a second conductive plate 16 disposed between the case and the first conductive plate 14, and an insulation member 18 disposed between the first conductive plate 14 and the second conductive plate 16. The first conductive plate 14 is electrically connected to one of a cathode and an anode, and the second conductive plate 16 is connected to the other of the cathode and the anode, an electric resistance value of one of the first conductive plate 14 and the second conductive plate 16 being twice or less the electric resistance value of the other conductive plate.

Description

  The present invention relates to a power storage device.

  A secondary battery having a positive electrode plate and a negative electrode plate (a pair of conductive plates) on which an active material is not formed and an insulator disposed between a pair of conductive plates is known as an outermost layer of an electrode assembly. (For example, refer to Patent Document 1). In this secondary battery, the tensile strength of the insulator is smaller than the tensile strength of the separator disposed between the positive electrode active material and the negative electrode active material. Thereby, in this secondary battery, when a force is applied from the outside, the insulator is broken before the separator and the pair of conductive plates are short-circuited.

JP 2008-277201 A

  By the way, when a pair of conductive plates are short-circuited, if the difference in calorific value between the two conductive plates is large, one of the conductive plates may be burned out (melted). In this case, there is a possibility that a short circuit does not occur reliably between the pair of conductive plates. Therefore, in order to prevent the conductive plate from being burned out, increasing the thickness of the conductive plate is considered as one of the countermeasures. However, if the conductive plate is increased in thickness, the case size is determined. The electrode assembly must be small. In this case, the capacity of the power storage device is inevitably reduced.

  An object of this invention is to provide the electrical storage apparatus which can perform a short circuit reliably and can ensure capacity | capacitance.

  A power storage device according to the present invention includes a case, an electrode assembly housed in the case, a first conductive plate disposed between the case and the electrode assembly, and between the case and the first conductive plate. And an insulating member disposed between the first conductive plate and the second conductive plate. The electrode assembly includes a positive electrode, a negative electrode, and a positive electrode and a negative electrode. The first conductive plate is electrically connected to one of the positive electrode and the negative electrode, the second conductive plate is electrically connected to the other of the positive electrode and the negative electrode, The electric resistance value of one of the first conductive plate and the second conductive plate is not more than twice the electric resistance value of the other conductive plate.

  In this power storage device, the electrical resistance value of one of the first conductive plate and the second conductive plate is not more than twice the electrical resistance value of the other conductive plate. Therefore, in the power storage device, the ratio of the electrical resistance values between the first conductive plate and the second conductive plate is 2 or less. The ratio of the electrical resistance values is equal to the calorific value ratio between the first conductive plate and the second conductive plate. Therefore, in the power storage device, the heat generation amount can be leveled by setting the heat generation amount ratio between the first conductive plate and the second conductive plate to 2 or less. Therefore, the first and second conductive plates can be reliably short-circuited. In the power storage device, the first and second conductive plates satisfy the condition that the electric resistance value of one of the first conductive plate and the second conductive plate is less than twice the electric resistance value of the other conductive plate. By setting the thickness of the two conductive plates, the first conductive plate and the second conductive plate that can prevent the first conductive plate and the second conductive plate from being burned out when the first conductive plate and the second conductive plate are short-circuited. The thickness of the conductive plate can be set to a minimum thickness. As a result, in the power storage device, short-circuiting can be performed reliably and capacity can be secured.

  In one embodiment, the first conductive plate is electrically connected to the negative electrode and is made of copper or a copper alloy, and the second conductive plate is electrically connected to the positive electrode and is made of aluminum or an aluminum alloy. It is preferable that the ratio of the electrical resistance value of the first conductive plate / second conductive plate is 0.5 to 2.0. In the power storage device, the ratio of the electric resistance values (first conductive plate: second conductive plate = 1.0: 0.5 to 1.0: 2.0) is set as described above, whereby the first and second electric resistance values are set. It is possible to satisfactorily level the heat generation amount of the conductive plate.

  In one embodiment, the ratio of the thickness of the first conductive plate / second conductive plate is preferably 0.3 to 1.2. In the power storage device, the ratio of the thickness of the first conductive plate / second conductive plate (first conductive plate: second conductive plate = 1.0: 0.3 to 1.0: 1.2) is thus set. Thus, the thickness of the first conductive plate and the second conductive plate that can prevent the first conductive plate and the second conductive plate from being burned out can be favorably set to the minimum thickness.

  In one embodiment, the power storage device may be a secondary battery.

  According to the present invention, a short circuit can be reliably performed and a capacity can be secured.

It is sectional drawing which shows typically the electrical storage apparatus which concerns on one Embodiment. It is sectional drawing along the II-II line of FIG. It is a figure which expands and shows a part of FIG. It is a graph which shows the relationship between electrical resistance value ratio and thickness ratio.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted.

  FIG. 1 is a cross-sectional view schematically showing a power storage device according to one embodiment. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1 and 2 is a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery.

  The secondary battery 100 includes a case 10 and an electrode assembly 20 accommodated in the case 10. The case 10 may be made of a metal such as aluminum or a metal alloy containing aluminum. The electrode assembly 20 includes a positive electrode 30, a negative electrode 40, and a separator 50 disposed between the positive electrode 30 and the negative electrode 40. The positive electrode 30 and the negative electrode 40 are, for example, in sheet form. The separator 50 is, for example, a bag shape, but may be a sheet shape. For example, the positive electrode 30 is accommodated in the bag-shaped separator 50. A plurality of positive electrodes 30 and a plurality of negative electrodes 40 may be alternately stacked via separators 50. The case 10 can be filled with the electrolytic solution 60. Examples of the electrolytic solution 60 include an organic solvent-based or non-aqueous electrolytic solution.

  The positive electrode 30 can include a metal foil 30b and a positive electrode active material layer 30c provided on both surfaces of the metal foil 30b. The metal foil 30b is, for example, an aluminum foil. The positive electrode active material layer 30c may include a positive electrode active material and a binder. Examples of the positive electrode active material include composite oxide, metallic lithium, and sulfur. The composite oxide includes at least one of manganese, nickel, cobalt, and aluminum and lithium.

  The positive electrode 30 may have a tab 30a formed at the edge. The tab 30a does not carry a positive electrode active material. The positive electrode 30 can be connected to the conductive member 32 via the tab 30a. The conductive member 32 can be connected to the positive terminal 34. The positive electrode terminal 34 may be attached to the case 10 via an insulating ring 36.

  The negative electrode 40 can include a metal foil 40b and a negative electrode active material layer 40c provided on both surfaces of the metal foil 40b. The metal foil 40b is, for example, a copper foil or a copper alloy foil. The negative electrode active material layer 40c may include a negative electrode active material and a binder. Examples of the negative electrode active material include carbon such as graphite, highly oriented graphite, mesocarbon microbeads, hard carbon, and soft carbon, alkali metals such as lithium and sodium, metal compounds, SiOx (0.5 ≦ x ≦ 1.5 ) And the like, and boron-added carbon.

  The negative electrode 40 may have a tab 40a formed at the edge. The tab 40a does not carry a negative electrode active material. The negative electrode 40 can be connected to the conductive member 42 via the tab 40a. The conductive member 42 can be connected to the negative terminal 44. The negative electrode terminal 44 may be attached to the case 10 via the insulating ring 46.

  Examples of the separator 50 include a porous film made of a polyolefin resin such as polyethylene (PE) and polypropylene (PP), a woven fabric or a non-woven fabric made of polypropylene, polyethylene terephthalate (PET), methylcellulose, and the like.

  The first conductive plate 14 is disposed between the case 10 and the electrode assembly 20. The first conductive plate 14 is formed by laminating a plurality of metal foils 14a to 14c, for example, but may be a single plate member. The first conductive plate 14 is not provided with an active material layer. The thickness of the first conductive plate 14 may be thicker than the thickness of the metal foil 40 b of the negative electrode 40.

  A second conductive plate 16 is disposed between the case 10 and the first conductive plate 14. The second conductive plate 16 is formed by, for example, laminating a plurality of metal foils 16a to 16c, but may be a single plate member. The second conductive plate 16 is not provided with an active material layer. The thickness of the second conductive plate 16 may be thicker than the thickness of the metal foil 30b of the positive electrode 30.

  An insulating member 18 is disposed between the first conductive plate 14 and the second conductive plate 16. The insulating member 18 may be an insulating sheet or an insulating layer. As the insulating member 18, for example, a resin sheet, a resin layer, or a separator 50 may be used.

  The first conductive plate 14 is electrically connected to one of the positive electrode 30 and the negative electrode 40. The second conductive plate 16 is electrically connected to the other of the positive electrode 30 and the negative electrode 40. In the present embodiment, the first conductive plate 14 is electrically connected to the negative electrode 40, and the second conductive plate 16 is electrically connected to the positive electrode 30. In this case, for example, the first conductive plate 14 is made of copper or a copper alloy, and the second conductive plate 16 is made of aluminum or an aluminum alloy.

  The first conductive plate 14 may have a tab 14d formed on the edge. The tab 14 d can be connected to the tab 40 a of the negative electrode 40. The thickness of the tab 14d may be smaller than the thickness of other portions of the first conductive plate 14. The tab 14d can be arranged to overlap the tab 40a. The second conductive plate 16 may have a tab 16d formed on the edge. The tab 16 d can be connected to the tab 30 a of the positive electrode 30. The thickness of the tab 16d may be smaller than the thickness of other portions of the second conductive plate 16. The tab 16d can be arranged to overlap the tab 30a.

  In the secondary battery 100, the electrical resistance value on the energization path of one of the first conductive plate 14 and the second conductive plate 16 is not more than twice the electrical resistance value on the energization path of the other conductive plate. Set to In the present embodiment, as described above, the first conductive plate 14 is electrically connected to the negative electrode 40, the second conductive plate 16 is electrically connected to the positive electrode 30, and the first conductive plate 14 is made of copper, or The second conductive plate 16 is made of aluminum or an aluminum alloy. Under this condition, the ratio of the electrical resistance value of the first conductive plate 14 / second conductive plate 16 is set to 0.5 to 2.0 (first conductive plate 14: second conductive plate 16 = 1.0). : 0.5 to 1.0 to 2.0). More preferably, the ratio of the electrical resistance values of the first conductive plate 14 / second conductive plate 16 is set to about 1.0. The “electric resistance value on the energization path” means an electric resistance value between any two points having the same distance on the main surfaces of the first conductive plate and the second conductive plate.

  FIG. 3 is an enlarged view of a part of FIG. In FIG. 3, the first conductive plate 14 and the second conductive plate 16 are shown as a single plate member. The thickness ratio (T1 / T2) of the first conductive plate 14 / second conductive plate 16 is set to 0.3 to 1.2 (first conductive plate 14: second conductive plate 16 = 1.0: 0. .3-1.0-1.2). More preferably, the thickness ratio (T1 / T2) of the first conductive plate 14 / second conductive plate 16 is about 0.6 (first conductive plate 14: second conductive plate 16≈1.0: 1.5). Set to

  As described above, in the secondary battery 100 of this embodiment, the ratio of the electrical resistance values of the first conductive plate 14 / second conductive plate 16 is set to 0.5 to 2.0. The ratio of the electrical resistance values of the first conductive plate 14 / second conductive plate 16 is equal to the heat value ratio of the first conductive plate 14 / second conductive plate 16. Therefore, in the secondary battery 100, the first conductive plate 14 and the second conductive plate 16 are set by setting the ratio of the electrical resistance value of the first conductive plate 14 / second conductive plate 16 to 0.5 to 2.0. It is possible to level the heat generation amount.

  Thereby, in the secondary battery 100, when the 1st conductive plate 14 and the 2nd conductive plate 16 short-circuit, it can prevent that the 1st conductive plate 14 or the 2nd conductive plate 16 burns out. In the secondary battery 100, the first conductive plate 14 or the first conductive plate 14 or 16 is set by setting the thicknesses of the first and second conductive plates 14 and 16 so that the ratio of the electrical resistance values satisfies 0.5 to 2.0. The thickness of the first conductive plate 14 and the second conductive plate 16 can be set to a minimum thickness that can prevent the two conductive plates 16 from being burned out. As a result, in the secondary battery 100, the short circuit can be reliably performed and the capacity can be secured.

The effects of the secondary battery 100 will be described in more detail with reference to FIG. FIG. 4 is a diagram showing the relationship between the electrical resistance value ratio and the thickness ratio. In FIG. 4, the vertical axis represents the electrical resistance value ratio and the combined resistance value, and the horizontal axis represents the thickness ratio. In the graph shown in FIG. 4, the resistivity of the first conductive plate 14 is 1.68 × 10 ⁻⁸ [Ω · m], and the resistivity of the second conductive plate 16 is 2.65 × 10 ⁻⁸ [Ω · m]. It is said. The thickness ratio (T1 / T2) is calculated when the thickness of the second conductive plate 16 is set to “1” and the total thickness of the first conductive plate 14 and the second conductive plate 16 is set to “0.5”. doing.

  As shown in FIG. 4, by setting the ratio of the electrical resistance values of the first conductive plate 14 / second conductive plate 16 to 0.5 to 2.0, particularly about 1.0, the first conductive plate 14 / The calorific value ratio of the second conductive plate 16 can be about 1.0, that is, the calorific values of the first conductive plate 14 and the second conductive plate 16 can be made equal. Thereby, in the secondary battery 100, it is possible to prevent the first conductive plate 14 or the second conductive plate 16 from being burned out (melted).

  When the ratio of the electrical resistance values of the first conductive plate 14 / second conductive plate 16 is about 1.0, the thickness ratio (T1 / T2) between the first conductive plate 14 and the second conductive plate 16 is 0.6. Degree. Thereby, in the secondary battery 100, the thickness of the 1st conductive plate 14 and the 2nd conductive plate 16 is set by setting the thickness of the 1st and 2nd conductive plates 14 and 16 so that thickness ratio may satisfy about 0.6. The minimum thickness can be set. Therefore, in the secondary battery 100, the thickness of the first and second conductive plates 14 and 16 disposed in the case 10 can be reduced, so that capacity can be secured in the electrode assembly 20.

  As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to the said embodiment.

  For example, the first conductive plate 14 may be electrically connected to the positive electrode 30 and the second conductive plate 16 may be electrically connected to the negative electrode 40. In this case, it is preferable that the first conductive plate 14 is made of aluminum and the second conductive plate 16 is made of copper.

  A wound electrode assembly may be used instead of the stacked electrode assembly 20. The wound-type electrode assembly is manufactured by winding a belt-like positive electrode, a belt-like separator 50, and a belt-like negative electrode 40 around an axis in a stacked state.

  As the power storage device, in addition to the secondary battery 100, for example, an electric double layer capacitor or the like can be given.

  For example, a power storage device such as the secondary battery 100 may be mounted on the vehicle. Examples of the vehicle include an electric vehicle, a hybrid vehicle, a plug-in hybrid vehicle, a hybrid railway vehicle, an electric wheelchair, an electrically assisted bicycle, and an electric motorcycle.

  DESCRIPTION OF SYMBOLS 10 ... Case, 14 ... 1st electrically conductive plate, 16 ... 2nd electrically conductive plate, 18 ... Insulating member, 20 ... Electrode assembly, 30 ... Positive electrode, 40 ... Negative electrode, 50 ... Separator, 100 ... Secondary battery.

Claims (4)

Case and
An electrode assembly housed in the case;
A first conductive plate disposed between the case and the electrode assembly;
A second conductive plate disposed between the case and the first conductive plate;
An insulating member disposed between the first conductive plate and the second conductive plate;
With
The electrode assembly includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode,
The first conductive plate is electrically connected to one of the positive electrode and the negative electrode;
The second conductive plate is electrically connected to the other of the positive electrode and the negative electrode;
The electrical storage device, wherein an electrical resistance value of one of the first conductive plate and the second conductive plate is not more than twice an electrical resistance value of the other conductive plate. The first conductive plate is electrically connected to the negative electrode and made of copper or a copper alloy,
The second conductive plate is electrically connected to the positive electrode and made of aluminum or an aluminum alloy,
The power storage device according to claim 1, wherein a ratio of an electric resistance value of the first conductive plate / the second conductive plate is 0.5 to 2.0.   The power storage device according to claim 2, wherein a ratio of the thickness of the first conductive plate / the second conductive plate is 0.3 to 1.2.   The electrical storage apparatus as described in any one of Claims 1-3 which is a secondary battery.

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