Cathode material structure and method for preparing the same

1. A cathode material structure, comprising:

a material body, having a particle size of 0.1-50 μm; and

a composite film, coated on a surface of the material body and having a porous structure and electrical conductivity,

wherein

the composite film comprises at least one hyper-branched oligomer/polymer, and at least one nanometer conductive material mixed in the at least one hyper-branched oligomer/polymer, and

above a safety trigger temperature, a free volume of the at least one hyper-branched oligomer/polymer decreases with an increase in temperature.

2. The cathode material structure of claim 1 , wherein the nanometer conductive material is selected from the group consisting of carbonaceous materials, inorganic conductive materials, organic conductive materials, and combinations thereof.

3. The cathode material structure of claim 2 , wherein a group of the carbonaceous materials consists of carbon black, graphite, acetylene black, and combinations thereof.

4. The cathode material structure of claim 2 , wherein a group the inorganic conductive materials consists of nickel powder, aluminum powder, titanium powder, stainless steel powder, and combinations thereof.

5. The cathode material structure of claim 2 , wherein a group of the organic conductive materials consists of organic conductive polymers.

6. The cathode material structure of claim 1 , wherein the hyper-branched oligomer/polymer contains nitrogen atoms in a skeleton thereof.

7. The cathode material structure of claim 6 , wherein the hyper-branched oligomer/polymer is formed in a process comprising polymerizing a diketone compound and at least one compound that is selected from the group consisting of amine compounds, amide compounds, imide compounds and maleimide compounds.

8. The cathode material structure of claim 7 , wherein the diketone compound is selected from the group consisting of barbituric acid, derivatives of barbituric acid, acetylacetone, derivatives of acetylacetone, and combinations thereof.

9. The cathode material structure of claim 1 , wherein the material body comprises at least one material selected from the group consisting of Li-M-O series materials and Li—N—X—O series materials, M is selected from the group consisting of Ni, Co, Mn, Mg, Ti, Al, Sn, Cr, V and Mo, N is selected from the group consisting of Fe, Ni, Co, Mn, V and Mo, and X is selected from the group consisting of P and Si.

10. The cathode material structure of claim 1 , wherein the composite film also functions as a binder.

11. The cathode material structure of claim 1 , wherein a thickness of the composite film ranges from 1 nm to 10 μm.

12. A method for preparing a cathode material structure, comprising:

providing a material body having a particle size of 0.1-50 μm; and

coating, on a surface of the material body, a composite film that has a porous structure and electrical conductivity,

wherein

the composite film comprises at least one hyper-branched oligomer/polymer, and at least one nanometer conductive material mixed in the at least one hyper-branched oligomer/polymer, and

above a safety trigger temperature, a free volume of the at least one hyper-branched oligomer/polymer decreases with an increase in temperature.

13. The method of claim 12 , wherein coating the composite film on the surface of the material body comprises: immersing the material body in a solution that contains the hyper-branched oligomer/polymer and the nanometer conductive material.

14. The method of claim 12 , wherein coating the composite film on the surface of the material body comprises:

immersing the material body in a solution that contains the nanometer conductive material and a precursor of the hyper-branched oligomer/polymer; and

reacting the precursor to form the hyper-branched oligomer/polymer and in-situ coat the surface of the material body with the hyper-branched oligomer/polymer together with the nanometer conductive material.

15. The method of claim 12 , wherein coating the composite film on the surface of the material body comprises:

immersing the material body in a solution that contains the nanometer conductive material and monomers for forming the hyper-branched oligomer/polymer; and

polymerizing the monomers to form the hyper-branched oligomer/polymer and in-situ coat the surface of the material body with the hyper-branched oligomer/polymer together with the nanometer conductive material.

16. The method of claim 12 , wherein the nanometer conductive material is selected from the group consisting of carbonaceous materials, inorganic conductive materials, organic conductive materials, and combinations thereof.

17. A cathode material structure, comprising:

a material body, having a particle size of 0.1-50 μm; and

a composite film, coated on a surface of the material body and having a porous structure and electrical conductivity,

wherein

the composite film comprises at least one hyper-branched oligomer/polymer, and at least one nanometer conductive material mixed in the at least one hyper-branched oligomer/polymer,

above a safety trigger temperature, a free volume of the at least one hyper-branched oligomer/polymer decreases with an increase in temperature, and

the composite film is coated on the surface of the material body by steps comprising:

immersing the material body in a solution that contains the nanometer conductive material and monomers for forming the hyper-branched oligomer/polymer, while the material body is not mixed with a binder; and

polymerizing the monomers to form the hyper-branched oligomer/polymer and in-situ coat the surface of the material body with the hyper-branched oligomer/polymer together with the nanometer conductive material.

18. A method for preparing a cathode material structure, comprising:

providing a material body having a particle size of 0.1-50 μm; and

coating, on a surface of the material body, a composite film that has a porous structure and electrical conductivity,

wherein

the composite film comprises at least one hyper-branched oligomer/polymer, and at least one nanometer conductive material mixed in the at least one hyper-branched oligomer/polymer,

above a safety trigger temperature, a free volume of the at least one hyper-branched oligomer/polymer decreases with an increase in temperature, and

coating the composite film on the surface of the material body comprises:

immersing the material body in a solution that contains the nanometer conductive material and monomers for forming the hyper-branched oligomer/polymer, while the material body is not mixed with a binder; and

polymerizing the monomers to form the hyper-branched oligomer/polymer and in-situ coat the surface of the material body with the hyper-branched oligomer/polymer together with the nanometer conductive material.