COMPOSITE MATERIAL AND METHOD FOR PREPARING THE SAME, AS WELL AS ELECTRODE, SECONDARY BATTERY, AND ELECTRICAL APPARATUS THEREOF

1 . A composite material, comprising

a negative electrode active material;

a dielectric material particle; and

a binder;

wherein, at least a part of a surface of the dielectric material particle is covered with a coupling agent that bridges the dielectric material particle and the binder.

2 . The composite material according to claim 1 , wherein the binder binds the dielectric material particles onto the negative electrode active material.

3 . The composite material according to claim 1 , wherein the dielectric material particle has a relative dielectric constant of 80 to 200.

4 . The composite material according to claim 1 , wherein the dielectric material is selected from one or more of the following: barium titanate, lead titanate, lithium niobate, lead zirconate titanate, lead metaniobate and lead barium lithium niobate.

5 . The composite material according to claim 1 , wherein the binder is an organic binder.

6 . The composite material according to claim 1 , wherein the binder is selected from one or more of the following: polyacrylic acid (PAA), styrene butadiene rubber (SBR), polyamide-imide (PAI), polyvinyl alcohol (PVA), polyethyleneimine (PEI), a polyimide binder (PI), and polytert-butyl acrylate-triethoxyvinylsilane (TBATEVS).

7 . The composite material according to claim 1 , wherein the coupling agent is selected from one or more of the following: a silane coupling agent and a titanate coupling agent.

8 . The composite material according to claim 1 , wherein the coupling agent is selected from one or more of a silane coupling agent KH590, a silane coupling agent KH550, a silane coupling agent KH560, a silane coupling agent KH570, a silane coupling agent KH792, a silane coupling agent DL602, a silane coupling agent DL171, a chelated type 100 titanate coupling agent, and a chelated type 200 titanate coupling agent.

9 . The composite material according to claim 1 , which has one or more of the following properties

(1) the coupling agent is linked to the dielectric material through a first terminal functional group, and the first terminal functional group comprises —O—; and

(2) the coupling agent is linked to the binder through a second terminal functional group, and the second terminal functional group comprises —S—.

10 . The composite material according to claim 1 , which has one or more of the following properties

(1) the coupling agent is linked to the dielectric material through a first terminal functional group, and the first terminal functional group comprises —Si—O—; and

(2) the coupling agent is linked to the binder through a second terminal functional group, and the second terminal functional group comprises —C—S—.

11 . The composite material according to claim 1 , wherein the binder has a number average molecular weight of 1 million to 2 million.

12 . The composite material according to claim 1 , wherein the dielectric material particle has one or more of the following properties:

(1) the dielectric material particle is a zero-dimensional particle;

(2) the dielectric material particle is a tetragonal barium titanate particle;

(3) the dielectric material particle has a median particle diameter by volume of 50 nm-200 nm;

(4) the negative electrode active material has a median particle diameter by volume of 4-10 μm; and

(5) a ratio of median particle diameter by volume of the negative electrode active material to the dielectric material particle is 200:1-20:1.

13 . The composite material according to claim 1 , wherein a mass ratio of the dielectric material to the binder is 0.1:100-1:100.

14 . A method for preparing a composite material, wherein the definition of the composite material is as described in claim 1 ;

the preparation method comprising:

(1) subjecting a dielectric material particle to hydroxylation treatment to obtain a hydroxylated dielectric material particle;

(2) grafting a coupling agent on the hydroxylated dielectric material particle to obtain a dielectric material particle grafted with the coupling agent;

(3) linking the coupling agent grafted on the dielectric material particle to a binder through a condensation reaction; and

(4) mixing the product from the previous step with a negative electrode active material.

15 . The method according to claim 14 , wherein in the step (3), the coupling agent on the dielectric material particle contains a mercapto end group, the binder contains an alkenyl end group, and the coupling agent is linked to the binder via a mercapto-alkenyl click chemical reaction.

16 . The method according to claim 15 , wherein the mercapto-alkenyl click chemical reaction is conducted under the action of a photoinitiator and ultraviolet light.

17 . An electrode, comprising the composite material according to claim 1 .

18 . A secondary battery, comprising the electrode according to claim 17 .

19 . An electrical apparatus, comprising the secondary battery according to claim 18 .