Non-stoichiometric titanium compound-carbon composite, method for producing same, negative electrode active material and lithium ion secondary battery

Patent metadata

Field	Value
Publication number	US-2016164083-A1
Application number	US-201514963896-A
Country	US
Kind code	A1
Filing date	Dec 9, 2015
Priority date	Jun 14, 2013
Publication date	Jun 9, 2016
Grant date	—

Abstract

A composite material including a carbon-containing material and a non-stoichiometric titanium compound shown by a chemical formula of Li 4+x Ti 5−x O 12 , where x is in a range of 0<x<0.30, the composite material including at least one composite particle that has a core portion including the non-stoichiometric titanium compound and a mixed layer formed on a surface of the core portion, the mixed layer including non-stoichiometric titanium compound and carbon, and having an atomic ratio of titanium and carbon in a range of Ti/C=1/50 or more.

First claim

What is claimed is:

1 . A non-stoichiometric titanium compound-carbon composite material shown by a chemical formula of Li 4+x Ti 5−x O 12 , where x is in a range of 0<x<0.30, comprising:
at least one composite particle that has a core portion comprising the non-stoichiometric titanium compound and a mixed layer formed on a surface of the core portion, the mixed layer including non-stoichiometric titanium compound and carbon, and having an atomic ratio of titanium and carbon in a range of Ti/C=1/50 or more.

2 . The non-stoichiometric titanium compound-carbon composite material according to claim 1 , wherein the mixed layer exists over the entire surface of the composite particle.

3 . The non-stoichiometric titanium compound-carbon composite material according to claim 1 , wherein the mixed layer is formed with a thickness of 100 nm or less.

4 . The non-stoichiometric titanium compound-carbon composite material according to claim 1 , wherein a specific surface area thereof determined by BET method is 20 to 100 m 2 g −1 .

5 . The non-stoichiometric titanium compound-carbon composite material according to claim 1 , wherein the composite particle has an average particle diameter in 20 μm or less.

6 . A method for producing the non-stoichiometric titanium compound-carbon composite material shown by a chemical formula of Li 4+x Ti 5−x O 12 (where x is in a range of 0<x<0.30) according to claim 1 , at least comprising:
performing dissolution of a hydrophilic polymer, a lithium salt, and a titanium alkoxide in an aqueous solvent by adding these components in the solvent and dissolving these components while dispersing the components by agitation; performing formation of a precursor material by spray-drying a solution obtained by the dissolution; and performing firing of the precursor material under a reduced atmosphere or inert atmosphere at a temperature of not lower than 600° C. and not higher than 900° C.

7 . The method of claim 6 , further comprising preliminary firing the precursor material under a reduced atmosphere or an inert atmosphere at a temperature of not lower than 300° C. and lower than 600° C. before the firing.

8 . The method of claim 6 , wherein a polyvinyl alcohol is used as the hydrophilic polymer.

9 . A negative electrode active material comprising the non-stoichiometric titanium compound-carbon composite material according to claim 1 .

10 . A lithium ion secondary battery comprising a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolyte, wherein the negative electrode comprises the negative electrode active material according to claim 9 .

Assignees

• Kuraray Co
• Nat University Iwate Univ Inc

Inventors

• Wakui Takashi
• Fujiwara Naoki
• Shimazumi Yuhi
• Yamamoto Yoshio
• Ui Koichi
• Kadoma Yoshihiro

Classifications

• H01M10/0525

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

• H01M2220/30

  Batteries in portable systems, e.g. mobile phone, laptop · CPC title

• H01M4/485

  of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy (H01M4/505, H01M4/525 take precedence) · CPC title

• H01M4/587

  for inserting or intercalating light metals · CPC title

• H01M4/366 Primary

  as layered products · CPC title