Composite active material for lithium secondary batteries and method for producing same

Patent metadata

Field	Value
Publication number	US-2016197345-A1
Application number	US-201414911826-A
Country	US
Kind code	A1
Filing date	Aug 12, 2014
Priority date	Aug 14, 2013
Publication date	Jul 7, 2016
Grant date	—

Abstract

Provided is a production method for a composite active material for lithium secondary batteries which enables production of an electrode material in which volume expansion is suppressed even after repeated charging and discharging, and enables production of a lithium secondary battery exhibiting excellent cycle characteristics. A composite active material for lithium secondary batteries is produced using a mixing step of mixing graphite having a specific surface area of not less than 30 m 2 /g, silicon monoxide, and a carbon precursor to obtain a mixture; a conglobation step of performing conglobation treatment on the mixture and obtaining a spherical mixture; and a heating step of heat-treating the spherical mixture and producing a substantially spherical composite active material for lithium secondary batteries.

First claim

1 . A composite active material for lithium secondary batteries comprising:
a composite containing silicon and silicon dioxide; and a graphite component; an area ratio of the graphite component exposed on a surface observed by scanning electron microscope at acceleration voltage of not greater than 10 kV being not less than 95%.

2 . The composite active material for lithium secondary batteries according to claim 1 , wherein an average particle size of the silicon is from 1 to 100 nm.

3 . The composite active material for lithium secondary batteries according to claim 1 , wherein an average particle size of the composite is from 50 to 1000 nm.

4 . A production method for the composite active material for lithium secondary batteries described in claim 1 , comprising:
a mixing step of mixing graphite having a specific surface area of not less than 30 m 2 /g, silicon monoxide, and a carbon precursor to obtain a mixture; a conglobation step of performing conglobation treatment on the mixture and obtaining a spherical mixture; and a heating step of heat-treating the spherical mixture and producing a substantially spherical composite active material for lithium secondary batteries.

5 . The production method for a composite active material for lithium secondary batteries according to claim 4 , wherein an average particle size of the silicon monoxide is not greater than 1 μm.

6 . The production method for a composite active material for lithium secondary batteries according to claim 4 , wherein
the carbon precursor is at least one type selected from the group consisting of polymer compounds, coal-based pitch, petroleum-based pitch, mesophase pitch, coke, low-molecular-weight oil, and derivatives thereof.

7 . The production method for a composite active material for lithium secondary batteries according to claim 4 , wherein the graphite is expanded graphite.

8 . A lithium secondary battery comprising the composite active material for lithium secondary batteries described in claim 1 .

Assignees

• Tosoh Corp

Inventors

• Tamaki Ryo

Classifications

• H01M4/366

  as layered products · CPC title

• H01M4/13

  Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof · CPC title

• H01M4/587 Primary

  for inserting or intercalating light metals · CPC title

• H01M2004/027

  Negative electrodes · CPC title

• H01M4/0471

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