Negative active material for lithium secondary battery and method for preparating same

• US 20070190413A1
• Filed: 07/29/2004
• Published: 08/16/2007
• Est. Priority Date: 07/29/2003
• Status: Active Grant

• Current Assignee: LG Energy Solution Limited (LG Corporation)
• Original Assignee: Kangwon National University Industry Cooperation Foundation, LG Chem Limited (LG Corporation)
• Inventors: Lee, Sung-Man, Lee, Heon, Hong, Moon
• Granted Patent: US 7,906,236 B2
• Time in Patent Office: Days
• US Class Current: 429/218.1
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 4/02 Electrodes composed of, or comprising, active material
• CPC Class Codes: H01M 4/0471 involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
• CPC Class Codes: H01M 4/049 Manufacturing of an active layer by chemical means
• CPC Class Codes: H01M 4/13 Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• CPC Class Codes: H01M 4/131 Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• CPC Class Codes: H01M 4/133 Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 4/134 Electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/139 Processes of manufacture
• CPC Class Codes: H01M 4/1395 of electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/366 as layered products
• CPC Class Codes: H01M 4/386 Silicon or alloys based on silicon
• CPC Class Codes: H01M 4/48 of inorganic oxides or hydroxides
• CPC Class Codes: H01M 4/485 of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy H01M4/505, H01M4/525 take precedence
• CPC Class Codes: H01M 4/625 Carbon or graphite
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Provided are an anode active material for a lithium secondary battery having high reversible capacity and excellent charge/discharge efficiency, comprising a complex composed of ultra-fine Si phase particles and an oxide surrounding the ultra-fine Si phase particles, and a carbon material; and a method for preparing the same. The present invention also provides a method for preparing an anode active material for a lithium secondary battery comprising producing a complex composed of ultra-fine Si particles and an oxide surrounding the ultra-fine Si particles by mixing a silicon oxide and a material having an absolute value of oxide formation enthalpy (ΔH_for) greater than that of the silicon oxide and negative oxide formation enthalpy by a mechanochemical process or subjecting them to a thermochemical reaction to reduce the silicon oxide; and mixing the Si phase-containing oxide complex and carbon material.

Claims

1. An anode active material for a lithium secondary battery comprising a complex composed of ultra-fine Si phase particles and an oxide surrounding the Si phase particles, and a carbon material.

2. The anode active material according to claim 1, wherein the oxide comprises a material selected from the group consisting of Al, Ti, Zr, Nb, Cr, Fe, Li, Mn, Ni, Co, Sn, V, In, Y, Ge, Ta, Mg, Ca, Mo, Sb, P, B, N and mixtures of two or more thereof.

3. The anode active material according to claim 1, wherein the anode active material is surface-modified by coating it with a low crystalline or amorphous carbon material.

4. An anode active material for a lithium secondary battery comprising a complex composed of Si phase particles and an oxide surrounding the Si phase particles.

5. A method for preparing an anode active material for a lithium secondary battery comprising:

producing a complex composed of ultra-fine Si particles and an oxide surrounding the ultra-fine Si particles by mixing a silicon oxide and a material having an absolute value of oxide formation enthalpy (Δ

H_for) greater than that of the silicon oxide and also a negative oxide formation enthalpy by a mechanochemical process or subjecting them to a thermochemical reaction to reduce the silicon oxide; and

mixing the complex and carbon material.

6. The method according to claim 5, wherein the material having an absolute value of oxide formation enthalpy (Δ

H_for) greater than that of the silicon oxide and also a negative oxide formation enthalpy comprises material selected from the group consisting of Al, Ti, Zr, Nb, Cr, Fe, Li, Mn, Ni, Co, Sn, V, In, Y, Ge, Ta, Mg, Ca, Mo, Sb, P, B, Li₃N and mixtures of two or more thereof.

7. The method according to claim 5, further comprising:

ball milling the Si phase-containing oxide complex and carbon material to form a composite material.

8. The method according to claim 5, further comprising:

forming a composite material of the Si phase-containing oxide complex and carbon material; and

coating the composite material with a low crystalline or amorphous carbon material.

9. The method according to claim 5, further comprising:

adding a lithium compound selected from the group consisting of Li₂O, Li₂O₂, LiNO₃, Li₂S and mixtures of two or more thereof, in the first step.

10. A method for preparing an anode active material for a lithium secondary battery comprising:

a process of producing a complex composed of ultra-fine Si particles and an oxide surrounding the ultra-fine Si particles by mixing a silicon oxide and a material having an absolute value of oxide formation enthalpy (Δ

H_for) greater than that of the silicon oxide and also a negative oxide formation enthalpy by a mechanochemical process or subjecting them to a thermochemical reaction to reduce the silicon oxide.