Surface-treatment method of cathode active material and cathode active material formed therefrom

• US 9,776,879 B2
• Filed: 10/10/2013
• Issued: 10/03/2017
• Est. Priority Date: 05/03/2011
• Status: Active Grant

• Current Assignee: LG Energy Solution Limited (LG Corporation)
• Original Assignee: LG Chem Limited (LG Corporation)
• Inventors: Kang, Sung-Joong, Park, Hong-Kyu, Jin, Joo-Hong, Lee, Dae-Jin
• Primary Examiner(s): RUDDOCK, ULA CORINNA
• Assistant Examiner(s): Passa, Gregory
• Application Number:
  US14/050,990
• Publication Number:
  US 20140050656A1
• Time in Patent Office: 1,454 Days
• CPC Class Codes: C01D 15/02 Oxides; 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 4/505 of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
• CPC Class Codes: H01M 4/525 of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• CPC Class Codes: H01M 4/5825 Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The present invention provides a method for treating the particle surface of a cathode active material for a lithium secondary battery, the method comprising (a) preparing a cathode active material having a lithium compound; (b) generating a plasma from a gas comprising at least one of a fluorine-containing gas and a phosphorus-containing gas as a part of a reactive gas; and (c) removing lithium impurities present on the particle surface of the cathode active material with the plasma. In accordance with the present invention, the amount of the lithium impurities present on the particle surface of the cathode active material can be reduced to suppress a side reaction of the lithium impurities and an electrolyte.

Claims

1. A method for treating particle surface of a cathode active material for a lithium secondary battery, the method comprising:

(a) preparing a cathode active material comprising a lithium compound;

(b) generating a plasma from gases comprising at least one of a fluorine-containing gas and a phosphorus-containing gas as a part of a reactive gas; and

(c) removing lithium impurities present on particle surface of the cathode active material with the plasma,

wherein the reactive gas comprises SF₆,

wherein the gases further comprise a carrier gas comprising an inert gas, and

wherein the lithium impurities comprise at least one of LiOH and Li₂CO₃.

2. The method for treating particle surface of a cathode active material according to claim 1, wherein the lithium compound is selected from the group consisting of LiCoO₂, LiNiO₂, LiMn₂O₄, LiFePO₄, LiFe_1-xMn_xPO₄, LiNi_1-x-yMn_xCo_yO₂ (0≦

x<

1, 0≦

y<

1) and LiNi_1-x-y-zCo_xM1_yM2_zO₂ (wherein, M1 and M2 are each independently selected from the group consisting of Al, Ni, Co, Fe, Mn, V, Cr, Ti, W, Ta, Ma and Mo; and

x, y and z are each independently an atomic fraction of oxide-forming elements, in which 0≦

x<

1, 0≦

y<

1, and 0≦

z<

1).

3. The method for treating particle surface of a cathode active material according to claim 1, wherein the reactive gas further comprises at least one selected from hydrogen, oxygen, hydrocarbon and a compound containing halogen family elements.

4. The method for treating particle surface of a cathode active material according to claim 1, wherein the phosphorus-containing gas comprises at least one selected from PH₃, P(CH₃)₃ and PF₃.

5. The method for treating particle surface of a cathode active material according to claim 3, wherein the hydrocarbon is CH₄.

6. The method for treating particle surface of a cathode active material according to claim 1, wherein the inert gas is at least one selected from nitrogen, argon, helium and neon.

7. The method for treating particle surface of a cathode active material according to claim 1, wherein the reactive gas further comprises CH₄, and the inert gas is N₂.

8. The method for treating particle surface of a cathode active material according to claim 1, wherein the step (b) is conducted by using a capacitively-coupled plasma (CCP) generator, an inductively-coupled plasma (ICP) generator, a direct current (DC) plasma generator or a dielectric barrier discharge (DBD) plasma generator.

9. The method for treating particle surface of a cathode active material according to claim 1, wherein the step (c) comprises modifying at least part of the lithium impurities to LiF.

10. The method for treating particle surface of a cathode active material according to claim 9, wherein the step (c) further comprises sputtering at least part of the lithium impurities with the accelerated ions of the plasma.