Electric storage device

Patent metadata

Field	Value
Publication number	US-9455091-B2
Application number	US-201414497781-A
Country	US
Kind code	B2
Filing date	Sep 26, 2014
Priority date	Sep 30, 2013
Publication date	Sep 27, 2016
Grant date	Sep 27, 2016

Abstract

An electric storage device having a positive electrode, a negative electrode, a separator located between the positive electrode and the negative electrode, and a nonaqueous electrolyte. The positive electrode has a positive substrate layer, a positive composite layer containing a positive active material, and an undercoat layer located between the positive substrate layer and the positive composite layer. A density of the positive composite layer is 2.1 g/cm 3 or more and 2.7 g/cm 3 or less. The positive electrode has the rate of increase in sheet resistance after a solvent immersion test of 30% or less. The undercoat layer contains a binder selected from the group consisting of chitosan derivatives, cellulose derivatives and acrylic acid derivatives.

First claim

What is claimed is:

1. An electric storage device having a positive electrode, a negative electrode, a separator located between the positive electrode and the negative electrode, and a nonaqueous electrolyte,
wherein the positive electrode has a positive substrate layer,
a positive composite layer containing a positive active material and an undercoat layer located between the positive substrate layer and the positive composite layer,
a density of the positive composite layer is 2.1 g/cm 3 or more and 2.7 g/cm 3 or less,
the positive electrode has a rate of increase in sheet resistance after a solvent immersion test of 30% or less, and
the undercoat layer contains a binder selected from the group consisting of chitosan derivatives, cellulose derivatives and acrylic acid derivatives;
wherein the positive active material has a compound represented by Li a Ni b M1 c M2 d W x Nb y Zr z O 2 , (in the formula, a, b, c, d, x, y, and z satisfy the 0≦a≦1.2, 0≦b≦1, 0≦c≦0.5, 0≦d≦0.5, 0≦x≦0.1, 0≦y≦0.1, 0≦z≦0.1, b+c+d=1, and M1 and M2 are respectively at least one element selected from the group consisting of Mn, Ti, Cr, Fe, Co, Cu, Zn, Al, Ge, Sn and Mg).

2. The electric storage device according to claim 1 , wherein
a density of the positive composite layer is 2.2 g/cm 3 or more and 2.6 g/cm 3 or less.

3. The electric storage device according to claim 1 , wherein
the positive electrode has the rate of increase in sheet resistance after a solvent immersion test of −50% or more.

4. The electric storage device according to claim 1 , wherein
the undercoat layer has a thickness of 0.1 μm or more and 3.0 μm or less.

5. The electric storage device according to claim 4 , wherein
the undercoat layer has a thickness of 0.2 μm or more and 2.0 μm or less.

6. The electric storage device according to claim 1 , the undercoat layer further including a conductive agent, wherein
a mass of the binder is two or more times and three or less times larger than a mass of the conductive agent.

7. The electric storage device according to claim 1 , wherein
the negative electrode contains hardly-graphitizable carbon as a negative active material.

Assignees

• Gs Yuasa Int Ltd

Inventors

• Miyazaki Akihiko
• Mori Sumio
• Kako Tomonori
• Nakai Kenta

Classifications

• H01G9/0425

  specially adapted for cathode · CPC title

• H01M2004/021

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

• H01M10/0525

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

• H01M4/667

  in the form of layers, e.g. coatings · CPC title

• H01G9/042 Primary

  characterised by the material (H01G11/22 takes precedence) · CPC title