Copper-containing silicon material, method for producing same, negative electrode active material, and secondary battery

Patent metadata

Field	Value
Publication number	US-2017200949-A1
Application number	US-201515314421-A
Country	US
Kind code	A1
Filing date	May 26, 2015
Priority date	May 29, 2014
Publication date	Jul 13, 2017
Grant date	—

Abstract

A negative electrode active material having improved electron conductivity is provided.
A reaction between an acid and a copper-containing calcium silicide represented by CaCu x Si y is caused, and a heat treatment is performed in a non-oxidizing atmosphere on the reaction product,
to obtain a copper-containing silicon material. The copper-containing silicon material contains Si and copper in an amorphous phase, and fine copper silicide is uniformly deposited within the amorphous phase. Thus, electron conductivity improves. Therefore, a secondary battery in which the negative electrode active material is used as a negative electrode has improved rate characteristics and also has an increased charge/discharge capacity.

First claim

1 . A method for producing a copper-containing silicon material, the method comprising:
a first step of preparing a calcium source, a copper source, and a silicon source, preparing a molten metal by mixing and melting the calcium source, the copper source, and the silicon source such that calcium (Ca), copper (Cu), and silicon (Si) have a predetermined ratio as an atom ratio, and cooling the molten metal, to form a copper-containing calcium silicide having a composition of Ca, Cu, and Si represented by a formula CaCu x Si y (x and y satisfy 0.1≦x≦0.7, 1.33≦y≦2.1, and 1.8≦x+y≦2.2); a second step of causing a reaction between the copper-containing calcium silicide and an acid that extracts calcium (Ca) from the copper-containing calcium silicide, to form a silicon precursor; and a third step of performing a heat treatment in a non-oxidizing atmosphere on the silicon precursor.

2 . The method for producing the copper-containing silicon material according to claim 1 , wherein the calcium source, the copper source, and the silicon source are metal calcium, metal copper, and metal silicon, respectively.

3 . The method for producing the copper-containing silicon material according to claim 1 , wherein a heat treatment temperature in the third step is 350° C. to 950° C.

4 . The method for producing the copper-containing silicon material according to claim 1 , wherein the copper-containing calcium silicide has a crystal structure that belongs to P6/mmm space group.

5 . A copper-containing silicon material obtained by the method according to claim 1 .

6 . The copper-containing silicon material according to claim 5 , wherein the copper-containing silicon material contains 1 to 50 mass % of copper (Cu).

7 . The copper-containing silicon material according to claim 5 , wherein the copper-containing silicon material contains an amorphous phase and copper silicide deposited within the amorphous phase.

8 . The copper-containing silicon material according to claim 7 , wherein the amorphous phase contains silicon and copper.

9 . A negative electrode active material formed from the copper-containing silicon material according to claim 5 .

10 . A secondary battery comprising a negative electrode containing the negative electrode active material according to claim 9 .

11 . (canceled)

Assignees

• Toyota Jidoshokki Kk

Inventors

• Harata Masanori
• Mohri Takashi

Classifications

• H01G11/86

  specially adapted for electrodes (carbonisation or activation of carbon for the manufacture of electrodes H01G11/34) · CPC title

• H01M4/386 Primary

  Silicon or alloys based on silicon · CPC title

• H01G11/50

  specially adapted for lithium-ion capacitors, e.g. for lithium-doping or for intercalation · CPC title

• H01M10/0525

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

• C01B33/06

  Metal silicides (alloys C22) · CPC title