Lithium titanate, electrode active material and electricity storage device each comprising the same

Patent metadata

Field	Value
Publication number	US-9452940-B2
Application number	US-201514812125-A
Country	US
Kind code	B2
Filing date	Jul 29, 2015
Priority date	May 26, 2009
Publication date	Sep 27, 2016
Grant date	Sep 27, 2016

Abstract

Disclosed is lithium titanate having excellent rate properties and useful for electricity storage devices, which is produced by preparing lithium titanate secondary particles that are aggregates of lithium titanate primary particles and forming at least macro-pores on the surfaces of the secondary particles. The lithium titanate can be produced by a process which comprises drying and granulating a slurry comprising crystalline titan oxide, a titanic acid compound and a lithium compound and firing the granulated product to thereby produce lithium titanate secondary particles, wherein (1) the crystalline titan oxide to be used comprises at least two types of crystalline titan oxide particles having different average particle diameters from each other, and/or (2) the crystalline titan oxide is used in an amount at least four-fold larger than that of the titanic acid compound in terms of TiO 2 content by weight. The lithium titanate can achieve a satisfactory level of charge-discharge capacity for practical uses when used in a electricity storage device without requiring the use of a carbon-containing substance, such as carbon black, acethylene black or Ketjen black, as an electrically conductive material in combination, in spite of a fact that lithium titanate has an electrically insulating properties by nature.

First claim

The invention claimed is:

1. A process for producing a lithium titanate, comprising the steps of: drying and granulating a slurry comprising a crystalline titanium oxide, a titanic acid compound, and a lithium compound; and firing a resultant product to obtain a lithium titanate secondary particle, wherein ( 1 ) the crystalline titanium oxide comprises at least two crystalline titanium oxide particles having different average particle sizes wherein the crystalline titanium oxide particles having the smallest average particle size and other crystalline titanium oxide particles have an average particle size 1.3 or more times larger than that of the crystalline titanium oxide particles having the smallest average particle size are used.

2. The process for producing the lithium titanate according to claim 1 , further comprising a step to make a carbon containing lithium titanate secondary particle.

3. The process for producing the lithium titanate according to claim 2 , wherein:(A) the slurry comprising the crystalline titanium oxide, the titanic acid compound, and the lithium compound is granulated with drying, and a resultant product is fired, followed by firing an obtained fired product again in the presence of a carbon-containing substance; or (B) the slurry comprises the crystalline titanium oxide, the titanic acid compound, the lithium compound, and a carbon-containing substance is granulated with drying, and a resultant product is fired.

4. The process for producing the lithium titanate according to claim 1 , further comprising a step to make the lithium titanate secondary particle contain an additional metal element other than lithium and titanium.

5. The process for producing the lithium titanate according to claim 4 , wherein: (A) the compound of the different metal element is added to the slurry comprising the crystalline titanium oxide, the titanic acid compound, and the lithium compound; or (B) the slurry comprises the crystalline titanium oxide containing the different metal element, the titanic acid compound, and the lithium compound, and the slurry is dried and granulated, and then the resultant product is fired.

6. The process for producing the lithium titanate according to claim 1 , further comprising a step to make the lithium titanate secondary particle contain an additional metal element selected from the group consisting of magnesium, aluminum and zirconium.

7. The process for producing the lithium titanate according to claim 1 , wherein an amount of the crystalline titanium oxide to be used is more than 4 times larger than that of the titanic acid compound in a weight ratio in terms of TiO2.

Assignees

• Ishihara Sangyo Kaisha

Inventors

• Moriyama Nariaki
• Honma Masatoshi
• Takeshima Kazuyoshi
• Okuda Yusuke
• Nagahashi Naoya

Classifications

• C01G23/005 Primary

  Alkali titanates · CPC title

• H01M4/131

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

• C01P2006/40

  Electric properties · CPC title

• H01M4/62

  Selection of inactive substances as ingredients for active masses, e.g. binders, fillers · CPC title

• H01M4/485 Primary

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