Nonaqueous electrolyte secondary battery

Patent metadata

Field	Value
Publication number	US-11302954-B2
Application number	US-201816113093-A
Country	US
Kind code	B2
Filing date	Aug 27, 2018
Priority date	Sep 11, 2017
Publication date	Apr 12, 2022
Grant date	Apr 12, 2022

Abstract

Provided is a nonaqueous electrolyte secondary battery with excellent low-temperature performance. The nonaqueous electrolyte secondary battery disclosed herein includes a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and a nonaqueous electrolytic solution. The positive electrode includes a positive electrode active material layer. The positive electrode active material layer includes, as a positive electrode active material, a lithium transition metal composite oxide including at least lithium, nickel, manganese, cobalt, and tungsten. The nonaqueous electrolytic solution includes lithium fluorosulfonate and LiPF6. The concentration of LiPF6 in the nonaqueous electrolytic solution is 1.11 mol/L or more. The viscosity of the nonaqueous electrolytic solution at 25° C. is 3.1 cP or more. The separator includes a resin layer and an inorganic layer formed on a surface of the resin layer that faces the positive electrode. Where a porosity of the inorganic layer is denoted by α, a porosity of the resin layer is denoted by β, and a porosity of the positive electrode active material layer is denoted by γ, relationships of 0.6≤(β/α)≤0.9 and 0.6≤(γ/α)≤0.9 are fulfilled.

First claim

What is claimed is:

1. A nonaqueous electrolyte secondary battery comprising:
a positive electrode;
a negative electrode;
a separator interposed between the positive electrode and the negative electrode; and
a nonaqueous electrolytic solution, wherein
the positive electrode includes a positive electrode active material layer,
the positive electrode active material layer includes, as a positive electrode active material, a lithium transition metal composite oxide including at least lithium, nickel, manganese, cobalt, and tungsten,
the nonaqueous electrolytic solution includes lithium fluorosulfonate and LiPF 6 ,
a concentration of LiPF 6 in the nonaqueous electrolytic solution is 1.11 mol/L or more,
a viscosity of the nonaqueous electrolytic solution at 25° C. is 3.1 cP to 4.0 cp,
the separator includes a resin layer and an inorganic layer formed on a surface of the resin layer that faces the positive electrode, and
where a porosity of the inorganic layer is denoted by α, a porosity of the resin layer is denoted by β, and a porosity of the positive electrode active material layer is denoted by γ, relationships of 0.6≤(β/α)≤0.9 and 0.6≤(γ/α)≤0.9 are fulfilled;
a relationship of (γ/β)≥1.0 is further fulfilled;
a content of nickel with respect to a total content of nickel, manganese, and cobalt in the lithium transition metal composite oxide is 34 mol % or more; and
the inorganic layer of the separator includes aluminum oxide.

2. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the resin layer of the separator includes polypropylene and polyethylene.

Assignees

• Toyota Motor Co Ltd

Inventors

• Nakayama Tetsuri

Classifications

• H01M50/451

  comprising layers of only organic material and layers containing inorganic material · CPC title

• H01M50/417

  Polyolefins · CPC title

• H01M50/434

  Ceramics · CPC title

• H01M50/491

  Porosity · CPC title

• H01M4/48 Primary

  of inorganic oxides or hydroxides · CPC title