Negative electrode active material for lithium secondary battery, method of preparing the same, and lithium secondary battery including the same

Patent metadata

Field	Value
Publication number	US-2017222222-A1
Application number	US-201515515398-A
Country	US
Kind code	A1
Filing date	Oct 1, 2015
Priority date	Oct 2, 2014
Publication date	Aug 3, 2017
Grant date	—

Abstract

The present invention relates to a negative electrode active material for a lithium secondary battery, a method of preparing the same, and a lithium secondary battery including the negative electrode active material, wherein since the negative electrode active material includes a surface-treated silicon nanoparticle and the surface-treated silicon nanoparticle includes a silicon nanoparticle and a surface treatment layer which is disposed on a surface of the silicon nanoparticle and includes crystalline SiO 2 , the negative electrode active material may exhibit significantly improved initial efficiency characteristics as well as excellent lifetime and capacity characteristics when used in a battery.

First claim

1 . A negative electrode active material for a lithium secondary battery, comprising:
a surface-treated silicon nanoparticle, wherein the surface-treated silicon nanoparticle comprises a silicon nanoparticle and a surface treatment layer which is disposed on a surface of the silicon nanoparticle and includes crystalline SiO 2 .

2 . The negative electrode active material for a lithium secondary battery of claim 1 ,
wherein the crystalline SiO 2 is included in an amount of 2 wt % to 15 wt % based on a total weight of the surface-treated silicon nanoparticle.

3 . The negative electrode active material for a lithium secondary battery of claim 1 ,
wherein the silicon nanoparticle has an average particle diameter (D 50 ) of 150 nm or less.

4 . The negative electrode active material for a lithium secondary battery of claim 1 ,
wherein the surface treatment layer has a thickness of 1 nm to 20 nm.

5 . The negative electrode active material for a lithium secondary battery of claim 1 , further comprising a carbon-based negative electrode active material.

6 . The negative electrode active material for a lithium secondary battery of claim 5 ,
wherein the carbon-based negative electrode active material is included in an amount of 10 wt % to 90 wt % based on a total weight of the negative electrode active material.

7 . The negative electrode active material for a lithium secondary battery of claim 1 , further comprising a coating layer including a carbon-based negative electrode active material on the surface treatment layer.

8 . The negative electrode active material for a lithium secondary battery of claim 1 , further comprising a carbon-based negative electrode active material,
wherein the surface-treated silicon nanoparticle is disposed on a surface of the carbon-based negative electrode active material.

9 . A method of preparing a negative electrode active material for a lithium secondary battery, the method comprising preparing surface-treated silicon nanoparticles in which a surface treatment layer including crystalline SiO 2 is formed on surfaces of silicon nanoparticles by mixing silicon nanoparticles including amorphous SiO 2 on surfaces thereof with an alkali metal compound and performing a heat treatment to convert the amorphous SiO 2 into the crystalline SiO 2 .

10 . The method of claim 9 ,
wherein the silicon nanoparticles including amorphous SiO 2 on surfaces thereof are prepared by dispersing silicon nanoparticles in an alcohol-based solvent and grinding the silicon nanoparticles.

11 . The method of claim 9 ,
wherein the silicon nanoparticles including amorphous SiO 2 on surfaces thereof have an average particle diameter of 150 nm or less.

12 . The method of claim 9 ,
wherein the alkali metal compound comprises at least one selected from the group consisting of LiOH, NaOH, KOH, Be(OH) 2 , Mg(OH) 2 , Ca(OH) 2 , and a hydrate thereof.

13 . The method of claim 9 ,
wherein the alkali metal compound is used in an amount of 1 part by weight to 10 parts by weight based on 100 parts by weight of the silicon nanoparticles including amorphous SiO 2 on surfaces thereof.

14 . The method of claim 9 ,
wherein the heat treatment is performed in a temperature range of 500° C. to 1,000° C. in an inert atmosphere.

15 . The method of claim 9 , further comprising forming a coating layer including a carbon-based negative electrode active material on the surface treatment layer of the surface-treated silicon nanoparticles; or mixing with a carbon-based negative electrode active material to form a coating layer including the surface-treated silicon nanoparticles on a surface of the carbon-based negative electrode active material, after the preparing of the surface-treated silicon nanoparticles.

16 . A negative electrode for a lithium secondary battery comprising the negative electrode active material of claim 1 .

17 . A lithium secondary battery comprising the negative electrode of claim 16 .

18 . A battery module comprising the lithium secondary battery of claim 17 as a unit cell.

19 . A battery pack comprising the battery module of claim 18 .

20 . The battery pack of claim 19 ,
wherein the battery pack is used as a power source of a medium and large sized device.

21 . (canceled)

Assignees

• Lg Chemical Ltd

Inventors

• Lee Yong Ju
• Choi Seung Youn
• Jo Rae Hwan
• Kim Eun Kyung
• Kim Hyun Chul
• Choi Jung Hyun

Classifications

• H01M4/364

  as mixtures · CPC title

• H01M4/386 Primary

  Silicon or alloys based on silicon · CPC title

• H01M4/366

  as layered products · CPC title

• H01M10/0525

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

• H01M4/0471

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