Secondary battery, battery pack, electric vehicle, electric tool and electronic device

Patent metadata

Field	Value
Publication number	US-2020058941-A1
Application number	US-201916535589-A
Country	US
Kind code	A1
Filing date	Aug 8, 2019
Priority date	Feb 9, 2017
Publication date	Feb 20, 2020
Grant date	—

Abstract

A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution, and the negative electrode includes a first negative electrode active substance, a second negative electrode active substance, and a negative electrode binder. The first negative electrode active substance includes a central portion containing a material containing silicon as a constituent element, and a covering portion provided on a surface of the central portion and containing a salt compound and a conductive substance. The salt compound contains at least one of polyacrylate and carboxymethylcellulose salt, and the conductive substance contains at least one of a carbon material and a metal material. The second negative electrode active substance contains a material containing carbon as a constituent element. The negative electrode binder contains at least one type of polyvinylidene fluoride, polyimide, and aramid.

First claim

1 . A secondary battery comprising:
a positive electrode; a negative electrode; and an electrolytic solution, wherein the negative electrode includes a first negative electrode active substance, a second negative electrode active substance, and a negative electrode binder, wherein the first negative electrode active substance includes a central portion containing a material containing silicon (Si) as a constituent element, and a covering portion provided on a surface of the central portion and containing a salt compound and a conductive substance, wherein the salt compound contains at least one of polyacrylate and carboxymethylcellulose salt, wherein the conductive substance contains at least one of a carbon material and a metal material, wherein the second negative electrode active substance contains a material containing carbon (C) as a constituent element, and wherein the negative electrode binder contains at least one type of polyvinylidene fluoride, polyimide, and aramid.

2 . The secondary battery according to claim 1 , wherein the negative electrode includes a plurality of first negative electrode active substances, and further includes composite grain formed by bringing the plurality of first negative electrode active substances into close contact with each other.

3 . The secondary battery according to claim 2 , wherein a specific surface area of the composite grain is 0.1 m 2 /g or more and 10 m 2 /g or less.

4 . The secondary battery according to claim 1 ,
wherein the polyacrylate contains at least one type of lithium polyacrylate, sodium polyacrylate, and potassium polyacrylate, and wherein the carboxymethylcellulose salt contains at least one type of lithium carboxymethylcellulose, sodium carboxymethylcellulose, and potassium carboxymethylcellulose.

5 . The secondary battery according to claim 1 , wherein a ratio W1 of a weight of the salt compound contained in the covering portion to a weight of the central portion is 0.1% by weight or more and less than 20% by weight.

6 . The secondary battery according to claim 1 , wherein the carbon material includes at least one type of carbon nanotubes, carbon nanofibers, carbon black, and acetylene black.

7 . The secondary battery according to claim 6 , wherein an average tube diameter of the carbon nanotubes is 1 nm or more and 300 nm or less.

8 . The secondary battery according to claim 6 , wherein a ratio W2 of a weight of the carbon material contained in the covering portion as the conductive substance to a weight of the central portion is 0.1% by weight or more and less than 15% by weight.

9 . The secondary battery according to claim 1 , wherein the carbon material contains single-walled carbon nanotubes.

10 . The secondary battery according to claim 9 , wherein an average tube diameter of the single-walled carbon nanotube is 0.1 nm or more and 5 nm or less.

11 . The secondary battery according to claim 9 , wherein a ratio W2 of a weight of the carbon material contained in the covering portion as the conductive substance to a weight of the central portion is 0.001% by weight or more and less than 1% by weight.

12 . The secondary battery according to claim 1 ,
wherein the carbon material contains a fibrous carbon material, wherein an average fiber diameter of the fibrous carbon material is 0.1 nm or more and 50 nm or less, wherein the negative electrode includes a plurality of first negative electrode active substances, wherein the plurality of first negative electrode active substances are connected to each other via a plurality of connection portions which extend between the plurality of first negative electrode active substances to form a three-dimensional network structure, and wherein each of the plurality of connection portions extends between the plurality of first negative electrode active substances, and includes a fiber portion containing the fibrous carbon material, and a protective portion provided on a surface of the fiber portion and containing the salt compound.

13 . The secondary battery according to claim 12 , wherein the fibrous carbon material contains at least one type of carbon nanotubes, carbon nanofibers, and single-walled carbon nanotubes.

14 . The secondary battery according to claim 12 ,
wherein a ratio W1 of a weight of the salt compound contained in the covering portion to a weight of the central portion and a ratio W2 of a weight of the fibrous carbon material contained in the covering portion as the conductive substance to the weight of the central portion satisfy W1/W2≤200, and wherein a cross-sectional area S1 of the connection portion in an extending direction of the connection portion and a cross-sectional area S2 of the protective portion in the extending direction of the connection portion satisfy S2/S1≥0.5.

15 . The secondary battery according to claim 1 , wherein the metal material contains at least one type of tin (Sn), aluminum (Al), germanium (Ge), copper (Cu), and nickel (Ni).

16 . The secondary battery according to claim 15 , wherein a ratio W3 of a weight of the metal material contained in the covering portion as the conductive substance to a weight of the central portion is 0.1% by weight or more and 10% by weight or less.

17 . A battery pack comprising:
a secondary battery; a control unit that controls an operation of the secondary battery; and a switch unit that switches the operation of the secondary battery in accordance with an instruction of the control unit, wherein the secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution, wherein the negative electrode includes a first negative electrode active substance, a second negative electrode active substance, and a negative electrode binder, wherein the first negative electrode active substance includes a central portion containing a material containing silicon as a constituent element, and a covering portion provided on a surface of the central portion and containing a salt compound and a conductive substance, wherein the salt compound contains at least one of polyacrylate and carboxymethylcellulose salt, wherein the conductive substance contains at least one of a carbon material and a metal material, wherein the second negative electrode active substance contains a material containing carbon as a constituent element, and wherein the negative electrode binder contains at least one type of polyvinylidene fluoride, polyimide, and aramid.

18 . A electric vehicle comprising:
a secondary battery; a conversion unit that converts power supplied from the secondary battery into a driving force; a driving unit that performs driving operation in accordance with the driving force; and a control unit that controls an operation of the secondary battery, wherein the secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution, wherein the negative electrode includes a first negative electrode active substance, a second negative electrode active substance, and a negative electrode binder, wherein the first negative electrode active substance includes a central portion containing a material containing silicon as a constituent element, and a covering portion provided on a surface of the central portion and containing a salt compound and a conductive substance, wherein the salt compound contains at least one of polyacrylate and carboxymethylcellulose salt, wherein the conductive substance contains at least one of a carbon material and a metal material, wherein the second ne

Assignees

• Murata Manufacturing Co

Inventors

• Hayashi Naoki
• Ikeda Yasuhiro

Classifications

• H01M2220/20

  Batteries in motive systems, e.g. vehicle, ship, plane · CPC title

• H01M4/386

  Silicon or alloys based on silicon · CPC title

• H01M4/625 Primary

  Carbon or graphite · CPC title

• H01M4/366 Primary

  as layered products · CPC title

• H01M2004/021

  Physical characteristics, e.g. porosity, surface area · CPC title