Titanium-niobium composite oxide-based electrode active material and lithium secondary battery using the same

Patent metadata

Field	Value
Publication number	US-2015243979-A1
Application number	US-201514627682-A
Country	US
Kind code	A1
Filing date	Feb 20, 2015
Priority date	Feb 24, 2014
Publication date	Aug 27, 2015
Grant date	—

Abstract

An electrode active material comprising in major proportions a monoclinic titanium-niobium composite oxide represented by the formula TiNb x O (2+5x/2) , wherein X is from 1.90 or more to less than 2.00.

First claim

What is claimed is:

1 . An electrode active material comprising in major proportions a monoclinic titanium-niobium composite oxide represented by the formula TiNb x O (2+5x/2) , wherein X is from 1.90 or more to less than 2.00.

2 . The electrode active material of claim 1 , wherein the titanium-niobium composite oxide has a crystallite size of 85 nm or more as determined from a full-width at half maximum of a (−110) X-ray diffraction line.

3 . The electrode active material of claim 1 , wherein the titanium-niobium composite oxide has a coating with 1.0 to 5.0 wt. % of carbon and a specific resistance (powder) of 1.0×10 4 Ω·cm or less.

4 . The electrode active material of claim 1 , wherein secondary particles present in the form of a spherical or massive aggregate of primary particles of the titanium-niobium composite oxide have an average secondary particle size of 1 to 50 μm.

5 . The electrode active material of claim 1 , wherein a lithium secondary battery prepared using Li metal as a counter electrode has a discharge capacity of 280 mAh/g or more at 1st cycle in a charge and discharge test conducted at 54 mA per gram of the active material and has a discharge capacity retention rate of 90% or more after the 100th cycle relative to that at the 5th cycle.

6 . A battery electrode comprising an electrode active material comprising in major proportions a monoclinic titanium-niobium composite oxide represented by the formula TiNb x O (2+5x/2) , wherein X is from 1.90 or more to less than 2.00 as a cathode or anode active material.

7 . A lithium secondary battery comprising a battery electrode comprising an electrode active material comprising in major proportions a monoclinic titanium-niobium composite oxide represented by the formula TiNb x O (2+5x/2) , wherein X is from 1.90 or more to less than 2.00 as a cathode or anode active material.

8 . The lithium secondary battery of claim 7 , when Li metal is used as a counter electrode, having a discharge capacity of 280 mAh/g or more at 1st cycle in a charge and discharge test conducted at 54 mA per gram of the active material and having a discharge capacity retention rate of 90% or more after the 100th cycle relative to that at the 5th cycle.

9 . A method for producing the electrode active material comprising in major proportions a monoclinic titanium-niobium composite oxide represented by the formula TiNb x O (2+5x/2) , wherein X is from 1.90 or more to less than 2.00, the method comprising:
mixing a titanium source material and a niobium source material in a Nb/Ti molar ratio of from 1.90 or more to less than 2.00 to prepare a source material mixture; and firing the source material mixture at 1000 to 1300° C. under an oxidizing atmosphere to prepare a fired product.

10 . The method of claim 9 , further comprising:
a carbon source addition step of mixing the fired product and an organic material to prepare a mixture; and a carbon coating formation step of heating the mixture to 650 to 800° C. under a non-oxidizing atmosphere to decompose and carbonize the organic material to form a carbon coating on a surface of the titanium-niobium composite oxide particles.

Assignees

• Titan Kogyo Kk
• Toshiba Kk

Inventors

• Nakahara Kiyoshi
• Seki Toshimasa
• Ishioka Hidenori
• Mino Wataru
• Harada Yasuhiro
• Takami Norio
• Inagaki Hiroki

Classifications

• C01P2006/40

  Electric properties · CPC title

• H01M4/625

  Carbon or graphite · CPC title

• H01M10/052

  Li-accumulators · CPC title

• H01M4/0471

  involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis · CPC title

• H01M4/0402

  Methods of deposition of the material · CPC title