Lithium ion secondary battery having positive electrode that comprises thermal run-away suppressing layer on positive electrode active material layer

Patent metadata

Field	Value
Publication number	US-9812702-B2
Application number	US-201414912971-A
Country	US
Kind code	B2
Filing date	Jul 17, 2014
Priority date	Aug 22, 2013
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

To provide a lithium ion secondary battery capable of suppressing thermal run-away when internal short circuiting occurs. The lithium ion secondary battery includes: a positive electrode including a current collector, a positive electrode active material layer that is formed on the current collector and that contains a lithium-containing complex oxide having a layered rock salt structure and being represented by general formula: Li a Ni b Co c Mn d D e O f (0.2≦a≦1; b+c+d+e=1; 0≦e<1; D is at least one element selected from Li, Fe, Cr, Cu, Zn, Ca, Mg, S, Si, Na, K, and Al; 1.7≦f≦2.1), and a thermal run-away suppressing layer formed on the positive electrode active material layer and containing a lithium transition metal silicate; and a negative electrode including a negative electrode active material. A ratio of the mass of the lithium-containing complex oxide with respect to the mass of the lithium transition metal silicate in the positive electrode is not lower than 1.5.

First claim

The invention claimed is:

1. A lithium ion secondary battery comprising:
a positive electrode including a current collector, a positive electrode active material layer that is formed on the current collector and that contains a positive electrode active material having a layered rock salt structure and being represented by a compositional formula: Li a Ni b Co c Mn d D e O f (0.2≦a≦1; b+c+d+e=1; 1/3≦b<1; 20/100≦c<1; 0≦e<1; D is at least one element selected from Li, Fe, Cr, Cu, Zn, Ca, Mg, S, Si, Na, K, and Al; 1.7≦f≦2.1), and a thermal run-away suppressing layer that is formed on the positive electrode active material layer and that contains a lithium transition metal silicate and a binding agent in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the lithium transition metal silicate; and
a negative electrode including a negative electrode active material, wherein
a ratio of a mass of the lithium-containing complex oxide with respect to a mass of the lithium transition metal silicate in the positive electrode is not lower than 1.5.

2. The lithium ion secondary battery according to claim 1 , wherein a total amount of lithium in the thermal run-away suppressing layer is less than an amount corresponding to an irreversible capacity of the negative electrode active material.

3. The lithium ion secondary battery according to claim 1 , wherein the lithium transition metal silicate is represented by Li 2 MSiO 4 (M is one or more elements selected from transition elements).

4. The lithium ion secondary battery according to claim 1 , wherein the negative electrode active material includes Si.

5. The lithium ion secondary battery according to claim 1 , wherein the thickness of the thermal run-away suppressing layer is within a range of 1 to 20 μm.

Assignees

• Toyota Jidoshokki Kk
• Nat Inst Advanced Ind Science & Tech

Inventors

• IKEUCHI Yuta
• Kojima Toshikatsu
• Sakai Tetsuo
• Eguchi Tatsuya
• Aikiyo Hitoshi
• Kojima Akira

Classifications

• H01M4/525

  of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy · CPC title

• H01M4/366

  as layered products · CPC title

• H01M4/505

  of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy · CPC title

• H01M4/131 Primary

  Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx · CPC title

• H01M4/386

  Silicon or alloys based on silicon · CPC title