JP2018137068A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery capable of suppressing deterioration due to temperature rise. A secondary battery is a secondary battery including a metal case, a core that can be housed in the case, and an electrolyte solution filled in the case housing the core, and the core is a separator. A core body in which positive electrodes and negative electrodes are alternately laminated to each other, and a resin layer that surrounds the core body and electrically insulates the core body and the case, and at least one of the resin layer and the separator is , Is characterized by having diamond particles therein. [Selection diagram]

Description

  The present disclosure relates to a secondary battery.

Patent Document 1 discloses a secondary battery including a core having a structure in which a positive electrode and a negative electrode are alternately stacked with a separator having a first side and a second side opposite to the outer periphery. Yes.
The positive electrode of the secondary battery includes a positive electrode current collector having a positive electrode lead extending beyond the first side of the separator, and a positive electrode that covers both surfaces of the positive electrode current collector in a range inside the outer peripheral edge of the separator. And an insulating part formed on both surfaces of the positive electrode lead at a position away from the edge of the positive electrode active material.
The negative electrode of the secondary battery has a negative electrode current collector having a negative electrode lead extending beyond the second side of the separator, and wider than the range where the positive electrode active material is formed inside the outer peripheral edge of the separator A negative electrode active material covering both sides of the negative electrode current collector in the range.
In addition, the insulating part of the positive electrode of the secondary battery includes a first insulating layer that covers the positive electrode lead that does not allow the electrolyte to permeate, and a second insulating layer that covers the first insulating layer that has a gap through which the electrolyte passes. An insulating layer.

Japanese Patent Laid-Open No. 2015-60787

  By the way, the secondary battery generates heat due to the flow of electricity and the temperature rises, but the secondary battery deteriorates at a temperature higher than room temperature, and the degree of deterioration increases as the temperature increases.

  In view of the above-described circumstances, at least one embodiment of the present invention aims to provide a secondary battery that can suppress deterioration due to an increase in temperature.

  (1) A secondary battery according to at least one embodiment of the present invention includes a metal case, a core that can be stored in the case, and an electrolytic solution that is filled in the case in which the core is stored. The core is a secondary battery, wherein the core surrounds the core body, in which positive and negative electrodes are alternately stacked with a separator interposed therebetween, and electrically connects the core body and the case. An insulating resin layer, and at least one of the resin layer or the separator contains diamond particles.

  According to the configuration of (1) above, the heat generated by the flow of electricity is conducted through the diamond particles and released to the outside of the case (heat radiation). Diamond particles are excellent in thermal conductivity and insulation, and also have resistance to electrolytes. Therefore, the temperature rise of the secondary battery is efficiently suppressed, and the deterioration of the secondary battery due to the temperature rise of the secondary battery is suppressed. be able to.

(2) In some embodiments, in the configuration of the above (1), the diamond particles are present in the resin layer and exposed to the front and back surfaces of the resin layer, and one of the particles is formed on the core body. While abutting, the other abuts the case.
According to the configuration of (2) above, the diamond particles are inherent in the resin layer and exposed on the front and back surfaces of the resin layer, one of which contacts the core body and the other contacts the case. Therefore, the heat generated in the core body by the flow of electricity is transferred from the core body to the case through one diamond particle that contacts the core body and the other contacts the case, and is released to the outside of the case. (Heat dissipation). Thereby, the temperature rise of a core main body can be suppressed efficiently and the deterioration by the temperature rise of a secondary battery can be suppressed.

(3) In some embodiments, in the configuration of (1) or (2), the resin layer is formed of an insulating tape.
According to the configuration of (3) above, since the resin layer is made of the insulating tape, it can be stored in the case after the core body is surrounded by the insulating tape.

(4) In some embodiments, in the configuration of (1) or (2), the resin layer is formed of an insulating sheet.
According to the configuration of (4) above, since the resin layer is formed of the insulating sheet, the core main body can be surrounded by the insulating sheet after the core main body is stored in the case.

(5) In some embodiments, in any one of the configurations (1) to (4), the diamond particles are present in the separator and exposed to the front and back surfaces of the separator, One contacts the positive electrode and the other contacts the negative electrode.
According to the configuration of the above (5), the diamond particles are present in the separator and exposed to the front and back surfaces of the separator, one of which contacts the positive electrode and the other contacts the negative electrode. Accordingly, the heat generated in the positive electrode or the negative electrode due to the flow of electricity is thermally conducted through the diamond in which one contacts the positive electrode and the other contacts the negative electrode, and is released to the outside of the case (heat dissipation). Thereby, the temperature rise of a positive electrode or a negative electrode is suppressed efficiently, and degradation by the temperature rise of a secondary battery can be suppressed. In addition, since the diamond particles have excellent insulating properties and electrolyte resistance, the positive electrode and the negative electrode are isolated and insulated, so that even when the separator is melted, a short circuit can be avoided.

(6) In some embodiments, in any one of the above configurations (1) to (5), a heat radiating portion capable of releasing heat is further provided outside the case.
According to the configuration of (6) above, since the heat radiating portion capable of releasing heat is provided outside the case, the heat generated inside the case is released by the heat radiating portion (heat radiating). Thereby, the temperature rise of the secondary battery is efficiently suppressed, and deterioration of the secondary battery due to the temperature rise of the secondary battery can be suppressed.

  According to at least one embodiment of the present invention, the secondary battery can suppress deterioration due to an increase in temperature.

It is a perspective view which shows roughly the structure of the lithium ion secondary battery which concerns on embodiment of this invention. FIG. 2 is a plan sectional view schematically showing a configuration of the lithium ion secondary battery shown in FIG. 1. FIG. 3 is a plan sectional view schematically showing a configuration of a resin layer shown in FIG. 2. FIG. 3 is a perspective view schematically showing a configuration of a core body shown in FIG. 2. FIG. 5 is a cross-sectional view schematically illustrating a configuration of a core body illustrated in FIG. 4. It is the expanded sectional view which expanded the insulating part periphery of the positive electrode shown in FIG.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.
Here, the lithium ion secondary battery 1 will be described as an example of the secondary battery, but the present invention is not limited to the lithium ion secondary battery 1.

As shown in FIG. 1, the lithium ion secondary battery 1 includes a case 2, a core 5 that can be stored in the case 2, an electrolyte solution (not shown) filled in the case 2 in which the core 5 is stored, Is provided.
The case 2 is a metal rectangular container, and a lid 3 is attached to an opening 21 provided on the upper surface. The case 2 may be a cylindrical type other than the rectangular container as shown in FIG. The positive electrode terminal 101 and the negative electrode terminal 102 are each attached through the lid 3.

As shown in FIG. 1, the case 2 includes a heat radiating portion 22 that can release heat to the outside of the case 2. The heat radiating part 22 is made of, for example, a material having excellent thermal conductivity. Examples of the material having excellent conductivity include a synthetic resin containing diamond particles.
For example, in a battery pack (not shown) or a battery module (not shown) that houses a plurality of lithium ion secondary batteries 1, the heat radiating unit 22 is a heat conducting member (heat radiating member) installed in the battery pack or battery module. ).
If it does in this way, the heat generated inside case 2 will be emitted in heat dissipation part 22 (heat dissipation). Thereby, the temperature rise of the lithium ion secondary battery 1 is efficiently suppressed, and deterioration of the lithium ion secondary battery 1 due to the temperature rise of the lithium ion secondary battery 1 can be suppressed.

As shown in FIG. 2, the core 5 includes a core body 10 and a resin layer 15.
As shown in FIG. 5, the core body 10 is configured such that the positive electrodes 11 and the negative electrodes 12 are alternately stacked with the separators 13 interposed therebetween.
As shown in FIG. 4, the core main body 10 is a wound type in which a strip-like long separator 13 is sandwiched therebetween and a long positive electrode 11 and a negative electrode 12 are wound around each other.

  As shown in FIG. 6, the separator 13 has a first side 131 and a second side 132 located on the opposite side in the longitudinal direction of the band. The separator 13 is made of, for example, a polyolefin microporous film such as polyethylene or polypropylene, and flows and holds the electrolyte in the pores.

  As shown in FIGS. 5 and 6, the separator 13 contains diamond particles 16. The diamond particles 16 are exposed on the front and back surfaces of the separator 13, and one is in contact with the positive electrode 11 and the other is in contact with the negative electrode 12.

  In this way, the heat generated in the positive electrode 11 or the negative electrode 12 due to the flow of electricity is thermally conducted through the diamond particles 16 one of which contacts the positive electrode 11 and the other contacts the negative electrode 12, It is discharged outside the case 2 (heat dissipation). Thereby, the temperature rise of the positive electrode 11 or the negative electrode 12 is efficiently suppressed, and deterioration due to the temperature rise of the lithium ion secondary battery 1 can be suppressed. Further, since the diamond particles 16 are excellent in insulation and have an electrolyte solution resistance, the positive electrode 11 and the negative electrode 12 are isolated and insulated, so that even when the separator 13 is melted, a short circuit can be avoided.

  As shown in FIG. 5, the positive electrode 11 includes a positive electrode current collector 111, a positive electrode active material 112, and an insulating portion 14. The positive electrode current collector 111 includes a positive electrode lead 113 extending from the first side 131 of the separator 13. In this embodiment, the positive electrode current collector 111 is an aluminum foil. The positive electrode active material 112 is formed so as to cover both surfaces of the positive electrode current collector 111 in the range inside the outer peripheral edge 13 </ b> A of the separator 13. The positive electrode active material 112 is formed by dissolving powder of an electrode material with a solvent to form a slurry, which is uniformly coated on both sides of the positive electrode current collector 111 and dried. As an example of the positive electrode active material 112, lithium manganate is employed.

  As shown in FIGS. 5 and 6, the insulating portion 14 is formed on both surfaces of the positive electrode lead 113 at a position away from the edge 112 </ b> A of the positive electrode active material 112. In the present embodiment, the insulating portion 14 is formed in parallel to the edge 112A of the positive electrode active material 112, as shown in FIG. The insulating part 14 is applied in the form of a slurry in the same manner as the positive electrode active material 112. Since the insulating part 14 is formed away from the positive electrode active material 112, it may be applied simultaneously with the positive electrode active material 112, or may be applied before or after the positive electrode active material 112.

  The negative electrode 12 includes a negative electrode current collector 121 and a negative electrode active material 122. The negative electrode current collector 121 includes a negative electrode lead 123 extending from the second side 132 of the separator 13. In this embodiment, the negative electrode current collector 121 is a copper foil. The negative electrode active material 122 is formed so as to cover both surfaces of the negative electrode current collector 121 in a range inside the outer peripheral edge 13A of the separator 13 and in a range wider than the range where the positive electrode active material 112 is formed. The negative electrode active material 122 is applied as a slurry in the same manner as the positive electrode active material 112. As an example of the negative electrode active material 122, graphite is employed.

  Further, as shown in FIGS. 5 and 6, the insulating portion 14 has a two-layer structure including a first insulating layer 141 and a second insulating layer 142. The first insulating layer 141 is a solid member that does not allow the electrolytic solution to pass therethrough and covers the positive electrode lead 113. The first insulating layer 141 is formed of a synthetic resin material that does not react with the electrolyte, such as polyolefin, aramid, carboxymethylcellulose (CMC), or the like, preferably the same material as the separator 13 or a material having higher heat resistance than the separator. The The thickness T41 of the first insulating layer 141 is thinner than the thickness T1 of the positive electrode active material 112.

  The second insulating layer 142 is a member having a gap through which the electrolytic solution passes, and is formed so as to cover the first insulating layer 141. Any material that forms a coating film as the material of the second insulating layer 142 may be a polyolefin-based organic material such as polyethylene or polypropylene, or a ceramic-based inorganic material.

  An example of a ceramic-based inorganic material is an oxide of a metal having a large ionization tendency that does not cause a chemical reaction with the aluminum foil that is the material of the positive electrode current collector 111 of the positive electrode 11, and also has a chemical reaction with the electrolytic solution. A material that does not occur, specifically, alumina or silica is preferable. By adopting a ceramic inorganic material as the second insulating layer 142, the polyolefin resin material employed as the first insulating layer 141 in which the lithium ion secondary battery 1 is thermally runaway and is in close contact with the positive electrode current collector The second insulating layer 142 can maintain the insulating function between the positive electrode 11 and the negative electrode 12 even when the material melts.

  The insulating portion 14 is formed in a range from the inside of the range where the negative electrode active material 122 is formed to at least a position beyond the edge 122A of the negative electrode active material 122. In this embodiment, as shown in FIGS. 5 and 6, the insulating portion 14 is formed in a range from the inside of the range where the negative electrode active material 122 is formed to a position exceeding at least the outer peripheral edge 13 </ b> A of the separator 13. . That is, the end portion 14 </ b> A of the insulating portion 14 facing the inside of the core body 10 is located inside the range where the negative electrode active material 122 is formed, and the end portion of the insulating portion 14 facing the outside of the core body 10. 14B is located outside the outer peripheral edge 13A of the separator 13. The thickness T4 of the insulating portion 14 in the stacking direction of the positive electrode 11 and the negative electrode 12 is uniform from the inner end portion 14A to the outer end portion 14B, and is the same as the thickness T1 of the positive electrode active material 112. The thickness T41 of the first insulating layer 141 is thinner than the thickness T42 of the second insulating layer 142.

  By forming the insulating portion 14 in this way, the outer peripheral edge 13A of the separator 13 is held between the insulating portion 14 and the end portion 12A of the negative electrode 12. In particular, in the case of the lithium ion secondary battery 1 of the present embodiment in which the insulating portion 14 is formed to a position beyond the outer peripheral edge 13A of the separator as shown in FIG. 6, the direction along the positive electrode current collector 111 with respect to the stacking direction. Therefore, even when dendrite grows in the gap of the second insulating layer 142, the dendrite does not reach the positive electrode active material 112 beyond the insulating portion 14.

  As shown in FIG. 2, the resin layer 15 surrounds the core body 10 and electrically insulates the core body 10 and the case 2. As shown in FIG. 3, the resin layer 15 contains diamond particles 17. The diamond particles 17 are exposed on the front and back surfaces of the resin layer 15, and one of them contacts the core body 10 and the other contacts the case 2.

  In this way, the heat generated in the core body 10 due to the flow of electricity is transferred from the core body 10 to the case 2 via the diamond particles 17, one of which contacts the core body 10 and the other contacts the case 2. To the outside of the case 2 (heat radiation). Thereby, the temperature rise of the core main body 10 is efficiently suppressed, and deterioration due to the temperature rise of the lithium ion secondary battery 1 can be suppressed.

The resin layer 15 is composed of an insulating tape 151, for example.
In this way, the core body 10 can be stored in the case 2 after being surrounded by the insulating tape 151.

The resin layer 15 is composed of an insulating sheet 152, for example.
In this way, the core body 10 can be surrounded by the insulating sheet 152 after the core body 10 is stored in the case 2.

  According to the lithium ion secondary battery 1 configured as described above, the heat generated by the flow of electricity is conducted through the diamond particles 16 and 17 and released to the outside of the case 2 (heat dissipation). ). Since the diamond particles 16 and 17 are excellent in thermal conductivity and insulation, and also have electrolyte resistance, the temperature rise of the lithium ion secondary battery 1 is effectively suppressed, and the temperature rise of the lithium ion secondary battery 1 is achieved. It is possible to suppress deterioration of the lithium ion secondary battery 1 due to the above.

The present invention is not limited to the above-described embodiments, and includes forms obtained by modifying the above-described embodiments and forms obtained by appropriately combining these forms.
For example, a lithium ion battery having a laminated core in which a separator is inserted and a positive electrode and a negative electrode are stacked, a positive electrode lead extends from a first side of the separator, and a negative electrode lead extends from a second side of the separator. It can also be used in secondary batteries. As described above, even when the lithium-ion secondary battery having the laminated core is employed, the same effects as those of the lithium-ion secondary battery having the wound core can be obtained.

DESCRIPTION OF SYMBOLS 1 Lithium ion secondary battery 2 Case 21 Opening part 22 Heat radiation part 3 Cover 5 Core 10 Core main body 101 Positive electrode terminal 102 Negative electrode terminal 11 Positive electrode 111 Positive electrode collector 112 Positive electrode active material 112A, 122A Edge 113 Positive electrode lead 12 Negative electrode 12A End 121 negative electrode current collector 122 negative electrode active material 123 negative electrode lead 13 separator 13A outer peripheral edge 131 first side 132 second side 14 insulating part 14A, 14B end part 141 first insulating layer 142 second insulating layer 15 resin layer 16, 17 Diamond particles

Claims (6)

A secondary battery comprising a metal case, a core that can be stored in the case, and an electrolyte solution that is filled in the case in which the core is stored,
The core is
A core body in which positive and negative electrodes are alternately stacked with a separator in between;
A resin layer that surrounds the core body and electrically insulates the core body and the case;
Including
At least one of the resin layer or the separator contains diamond particles.   The diamond particles are present in the resin layer and exposed on the front and back surfaces of the resin layer, one of which contacts the core body and the other contacts the case. 2. The secondary battery according to 1.   The secondary battery according to claim 1, wherein the resin layer is made of an insulating tape.   The secondary battery according to claim 1, wherein the resin layer is formed of an insulating sheet.   5. The diamond particles are present in the separator, exposed to the front and back surfaces of the separator, and one of the diamond particles contacts the positive electrode and the other contacts the negative electrode. The secondary battery as described in any one of.   The secondary battery according to claim 1, further comprising a heat dissipating part capable of releasing heat to the outside of the case.

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