Cathode active material, cathode and nonaqueous secondary battery

Patent metadata

Field	Value
Publication number	US-9419280-B2
Application number	US-201414575194-A
Country	US
Kind code	B2
Filing date	Dec 18, 2014
Priority date	May 22, 2009
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

A cathode active material of the present invention is a cathode active material having a composition represented by General Formula (1) below,

LiFe 1−x M x P 1−y Si y O 4   (1),
where: an average valence of Fe is +2 or more; M is an element having a valence of +2 or more and is at least one type of element selected from the group consisting of Zr, Sn, Y, and Al; the valence of M is different from the average valence of Fe; 0<x≦0.5; and y=x×({valence of M}−2)+(1−x)×({average valence of Fe}−2). This provides a cathode active material that not only excels in terms of safety and cost but also can provide a long-life battery.

First claim

What is claimed is:

1. A nonaqueous secondary battery, comprising:
a cathode including a cathode active material;
an anode;
an electrolyte; and
a separator,
the cathode active material consisting of a composition represented by General Formula (1) below,
LiFe 1−x M x P 1−y Si y O 4   (1)

where:
Fe takes on a valence of +2 or +3;
M has a valence of +3 or +4, and M is at least one type of element selected from the group consisting of Zr, Sn, Y, and Al;
the valence of M is different from average valence of Fe;
0<x≦0.5; and
0<y≦1.0,
the cathode active material having, in a case where the nonaqueous secondary battery has a voltage of 3.9 V or higher, a composition represented by General Formula (2) below,
Li x Fe 1−x M x P 1−y Si y O 4   (2).

2. The nonaqueous secondary battery according to claim 1 ,
wherein:
the electrolyte is an electrolyte selected from the group consisting of an organic electrolyte, a gel electrolyte, a polymer solid electrolyte, an inorganic solid electrolyte, and a molten salt.

3. The nonaqueous secondary battery according to claim 1 ,
wherein:
the cathode active material is provided with a carbon film.

4. The nonaqueous secondary battery according to claim 1 , further comprising:
a battery armor made of a metal.

5. The nonaqueous secondary battery according to claim 1 ,
wherein:
the nonaqueous secondary battery is a layered cuboidal battery.

6. A method for producing a nonaqueous secondary battery, the nonaqueous secondary battery including:
a cathode including a cathode active material;
an anode;
an electrolyte; and
a separator,
the cathode active material consisting of a composition represented by General Formula (1) below,
LiFe 1−x M x P 1−y Si y O 4   (1)

where:
Fe takes on a valence of +2 or +3;
M has a valence of +3 or +4, and M is at least one type of element selected from the group consisting of Zr, Sn, Y, and Al;
the valence of M is different from average valence of Fe;
0<x≦0.5; and
0<y≦1.0,
the method comprising the steps of:
forming a layered product or wound product including the cathode, the anode, and the separator; and
heating the layered product or wound product in a decompressed chamber.

7. The method according to claim 6 , further comprising the steps of:
inserting the layered product or wound product into a battery container; and
sealing the nonaqueous secondary battery by fitting a lid in an opening of the battery container and laser-welding the lid to the opening.

8. The method according to claim 6 , further comprising the steps of:
forming an electrode by applying, to a current collector, a slurry obtained by mixing the cathode active material, a conductive material, a binder, and an organic solvent; and
pressing the electrode by passing the electrode through a space between two metal rollers for the electrode to have an intended thickness,
the space between the two metal rollers having been adjusted to a size 0.858 to 0.867 time as large as the intended thickness.

Assignees

• Sharp Kk

Inventors

• Ohira Koji
• Nishijima Motoaki
• Sueki Toshitsugu
• Esaki Shogo
• Tanaka Isao
• Koyama Yukinori
• Tanaka Katsuhisa
• Fujita Koji
• Murai Shunsuke

Classifications

• H01M4/625

  Carbon or graphite · CPC title

• C01B33/20

  Silicates (persilicates C01B15/14 {; containing aluminium C01B33/26}) · CPC title

• H01M2004/028

  Positive electrodes · CPC title

• Y02P20/133

  Renewable energy sources, e.g. sunlight · CPC title

• H01M4/5825 Primary

  Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines · CPC title