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

Patent metadata

Field	Value
Publication number	US-9806339-B2
Application number	US-201514627682-A
Country	US
Kind code	B2
Filing date	Feb 20, 2015
Priority date	Feb 24, 2014
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

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 urn or more as determined from a full-width at half maximum of a (−110) X-ray diffraction line, 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, and wherein the titanium-niobium composite oxide forms secondary particles present in the form of a spherical or massive aggregate of primary particles of the titanium-niobium composite oxide and the secondary particles have an average secondary particle size of 1 to 50 μm.

3. The electrode active material of claim 2 , wherein the titanium-niobium composite oxide has a coating with 1.5 to 3.6 wt. % of carbon.

4. The electrode active material of claim 2 , 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.

5. The electrode active material of claim 1 , wherein said electrode active material further comprises a conducting agent and a binder, wherein the weight ratio between the titanium-niobium composite oxide particles, the conducting agent, and the binder is 90:5:5 to 70:15:15.

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 ,
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, 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,
wherein the titanium-niobium composite oxide forms secondary particles present in the form of a spherical or massive aggregate of primary particles of the titanium-niobium composite oxide and the secondary particles have an average secondary particle size of 1 to 50 μm, and
wherein the battery comprises Li metal as a counter electrode, and 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.

9. The lithium secondary battery of claim 7 , wherein said electrode active material further comprises a conducting agent and a binder, wherein the weight ratio between the titanium-niobium composite oxide particles, the conducting agent, and the binder is 90:5:5 to 70:15:15.

10. A method for producing 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, 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.

11. The method of claim 10 , 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

• H01M10/052

  Li-accumulators · CPC title

• C01P2004/61

  Micrometer sized, i.e. from 1-100 micrometer · CPC title

• C01G33/006

  Compounds containing niobium, with or without oxygen or hydrogen, and containing two or more other elements · CPC title

• H01M4/623

  fluorinated polymers · CPC title

• C01P2002/60

  Compounds characterised by their crystallite size · CPC title