Electrode composite material, method for making the same, and lithium ion battery using the same

1. A method for preparing an electrode composite material, the method comprising:

providing an aluminum nitrate solution containing aluminum ions, wherein the aluminum nitrate solution comprises an organic solvent and an aluminum nitrate dissolved in the solvent;

introducing a plurality of electrode active material particles into the aluminum nitrate solution;

coating surfaces of the electrode active material particles with the aluminum ions by mixing the plurality of electrode active material particles with the aluminum nitrate solution to form a mixture;

adding a phosphate solution into the mixture to react with the aluminum ions and form an aluminum phosphate layer on the surfaces of the electrode active material particles; and

heat treating the electrode active material particles with the aluminum phosphate layer formed on the surfaces thereof.

2. The method of claim 1 , further comprising controlling a volumetric ratio of the aluminum nitrate solution and the electrode active material particles to make the mixture pasty.

3. The method of claim 2 , wherein the volumetric ratio of the aluminum nitrate solution and the electrode active material particles is in a range from about 1:10 to about 1:40.

4. The method of claim 1 , wherein the organic solvent is selected from the group consisting of ethanol, acetone, chloroform, diethyl ether, dichloromethane, ethylidene chloride, and combinations thereof.

5. The method of claim 1 , wherein a diameter of the plurality of electrode active material particles is smaller than 20 microns.

6. The method of claim 1 , wherein a mass percentage of the aluminum phosphate layer in the electrode composite material is in a range from about 0.1% to about 3%.

7. The method of claim 1 , wherein the phosphate solution comprises a liquid phase solvent and a phosphate dissolved in the solvent.

8. The method of claim 7 , wherein the phosphate is selected from the group consisting of monoammonium phosphate, diammonium phosphate, ammonium phosphate, phosphoric acid, and combinations thereof.

9. The method of claim 1 , wherein the aluminum phosphate layer is formed on the surfaces of the plurality of electrode active material particles in situ.

10. The method of claim 1 , wherein the heat treating temperature is in a range from about 400° C. to about 800° C.

11. The method of claim 1 , wherein a heat treating time period is in a range from about 0.5 hours to about 2 hours.

12. A method for preparing an electrode composite material, the method comprising:

providing an aluminum nitrate solution containing aluminum ions, wherein the aluminum nitrate solution comprises an organic solvent and an aluminum nitrate dissolved in the solvent;

introducing a plurality of electrode active material particles into the aluminum nitrate solution;

coating surfaces of the electrode active material particles with the aluminum ions by mixing the plurality of electrode active material particles with the aluminum nitrate solution to form a mixture, a material of the plurality of electrode active material particles being a lithium cobalt oxide;

controlling an amount of the electrode active material particles introduced to the aluminum nitrate solution according to an amount of the aluminum ions in the aluminum nitrate solution, such that the amount of the aluminum ions is just sufficient to coat all the surfaces of the electrode active material particles;

adding a phosphate solution into the mixture to react with the aluminum ions and form an aluminum phosphate layer on the surfaces of the electrode active material particles; and

heat treating the electrode active material particles with the aluminum phosphate layer formed on the surfaces thereof.

13. The method of claim 12 , wherein the lithium cobalt oxide is represented by a chemical formula of Li x Co 1−y L y O 2 , wherein 0.1≦x<1.1 and 0≦y<1, L represents at least one of the chemical elements of alkali metal elements, alkaline-earth metal elements, Group-13 elements, Group-14 elements, transition metal elements, and rare-earth elements.

14. A method for preparing an electrode composite material, the method comprising:

providing an aluminum nitrate solution containing aluminum ions, wherein the aluminum nitrate solution comprises an organic solvent and an aluminum nitrate dissolved in the solvent;

introducing a plurality of electrode active material particles into the aluminum nitrate solution;

coating surfaces of the electrode active material particles with the aluminum ions by mixing the plurality of electrode active material particles with the aluminum nitrate solution to form a mixture, a material of the plurality of electrode active material particles being a lithium titanate;

adding a phosphate solution into the mixture to react with the aluminum ions and form an aluminum phosphate layer on the surfaces of the electrode active material particles; and

heat treating the electrode active material particles with the aluminum phosphate layer formed on the surfaces thereof.

15. The method of claim 14 , wherein the lithium titanate is represented by a chemical formula of Li 4 Ti 5 O 12 , Li (4−g) A g Ti 5 O 12 , or Li 4 A h Ti (5−h) O 12 , wherein 0<g≦0.33 and 0<h≦0.5, and A represents at least one of the chemical elements of alkali metal elements, alkaline-earth metal elements, Group-13 elements, Group-14 elements, transition metal elements, and rare-earth elements.

16. The method of claim 1 , wherein the phosphate solution comprises a liquid phase solvent and (NH 4 ) 3 PO 4 dissolved in the solvent.