Electrode for power storage device and method for producing same

Patent metadata

Field	Value
Publication number	US-2020365899-A1
Application number	US-201816643364-A
Country	US
Kind code	A1
Filing date	Aug 14, 2018
Priority date	Aug 31, 2017
Publication date	Nov 19, 2020
Grant date	—

Abstract

An object of the present invention is to provide a lithium ion secondary battery having a high energy density and improved cycle characteristics. The present invention is related to an electrode for a power storage device comprising a negative electrode mixture layer comprising: (a) a negative electrode active material ( 42 - 2 ) comprising 1% or more of a material comprising Si as a constituent element; (b) a first polymer ( 42 - 1 ) coating the negative electrode active material and comprising vinylidene fluoride as a monomer unit; and (c) a negative electrode binder ( 42 - 3 ) comprising a second polymer that has a molecular weight of 80,000 or more and comprises at least one monomer unit selected from the group consisting of acrylic acid, acrylate salt, methacrylic acid, and methacrylate salt.

First claim

1 . An electrode for a power storage device comprising a negative electrode mixture layer comprising:
(a) a negative electrode active material comprising 1% or more of a material comprising Si as a constituent element; (b) a first polymer coating the negative electrode active material and comprising vinylidene fluoride as a monomer unit; and (c) a negative electrode binder comprising a second polymer that has a molecular weight of 80,000 or more and comprises at least one monomer unit selected from the group consisting of acrylic acid, acrylate salt, methacrylic acid and methacrylate salt.

2 . The electrode for a power storage device according to claim 1 , wherein the second polymer is a polymer having a molecular weight of 400,000 or more.

3 . The electrode for a power storage device according to claim 1 , wherein the second polymer is a copolymer comprising sodium acrylate as a monomer unit.

4 . The electrode for a power storage device according to claim 3 , wherein the second polymer is a copolymer comprising sodium acrylate and aromatic vinyl as monomer units.

5 . A method for producing an electrode for a power storage device comprising:
applying a slurry on an electrode, wherein the slurry is obtained by mixing: (a) a negative electrode active material comprising 1% or more of a material comprising Si as a constituent element; (b) a first polymer coating the negative electrode active material and comprising vinylidene fluoride as a monomer unit; and (c) a negative electrode binder comprising a second polymer that has a molecular weight of 80,000 or more and comprises at least one monomer unit selected from the group consisting of acrylic acid, acrylate salt, methacrylic acid, and methacrylate salt; and then performing heat treatment at a temperature of 250° C. or higher.

6 . The method for producing an electrode for a power storage device according to claim 5 , wherein the heat treatment is performed at a temperature of 300° C. or higher.

7 . The method for producing an electrode for a power storage device according to claim 5 , wherein the heat treatment is performed at a temperature of 350° C. or higher.

8 . The electrode for a power storage device according to claim 1 , wherein the material comprising Si as a constituent element is a Si oxide represented as SiO x (0<x≤2).

Assignees

• Nec Corp

Inventors

• Tamai Suguru
• Ishikawa Hitoshi

Classifications

• H01M4/366

  as layered products · CPC title

• H01M4/623

  fluorinated polymers · CPC title

• H01M4/386

  Silicon or alloys based on silicon · CPC title

• H01M10/0525 Primary

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M2220/20

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