Modified graphite and preparation method thereof, secondary battery, battery module, battery pack, and electrical device

1 . A type of modified graphite, wherein the modified graphite comprises a graphite moiety and a binder moiety covalently linked to the graphite moiety, wherein the binder moiety possesses a structure expressed as Formula (IV´):

wherein,

R 1 to R 6 each are independently selected from hydrogen, halogen, cyano, hydroxyl, amino, substituent-free or substituent-containing C 1 to C 6 alkyl, substituent-free or substituent-containing C 1 to C 6 alkoxyl, substituent-free or substituent-containing C 2 to C 6 alkenyl, or substituent-free or substituent-containing C 6 to C 20 aryl, wherein substituents in the substituent-containing alkyl, alkoxyl, alkenyl, and aryl each are at least one selected from C 1 to C 3 alkyl, hydroxyl, amino, amido, cyano, carboxyl, or halogen;

R 7 to R 9 each are independently selected from hydrogen, hydroxyl, amino, substituent-free or substituent-containing C 1 to C 6 alkyl, substituent-free or substituent-containing C 1 to C 6 alkoxyl, substituent-free or substituent-containing C 1 to C 6 alkylamino, substituent-free or substituent-containing C 2 to C 6 alkenyl, or substituent-free or substituent-containing C 6 to C 20 aryl, wherein substituents in the substituent-containing alkyl, alkoxyl, alkylamino, alkenyl, and aryl each are at least one selected from hydroxyl, carboxyl, amino, amido, or halogen;

R 10 represents linear or branched C 1 to C 12 alkyl;

R 11 represents halogen or cyano;

Z is selected from linear or branched C 1 to C 5 alkylthio;

L represents linear or branched C 1 to C 12 alkylidene;

R 13a represents #—COO—*, #—CH 2 O—*, or #—NH—*, and # represents a position linked to L, and * represents a position linked to the graphite moiety; and

a ratio of m to n is 1 to 100.

2 . The modified graphite according to claim 1 , wherein m is an integer ranging from 500 to 15,000, and n is an integer ranging from 500 to 15,000.

3 . The modified graphite according to claim 1 , wherein a number-average molecular weight of the binder moiety of Formula (IV´) is 30,000 to 3,000,000.

4 . The modified graphite according to claim 1 , wherein structural units

in the binder moiety are copolymerized in a random, blocked, and/or alternating manner, and optionally, in a blocked manner.

5 . The modified graphite according to claim 1 , wherein the binder moiety is selected from the following structures:

wherein * represents a position at which the binder moiety is covalently linked to the graphite moiety.

6 . The modified graphite according to claim 1 , wherein a mass ratio between the graphite moiety and the binder moiety is 85: 12 to 96.5: 0.5.

7 . The modified graphite according to claim 6 , wherein a mass ratio between the graphite moiety and the binder moiety is 90: 7 to 96: 1.

8 . A negative electrode plate, wherein the negative electrode plate comprises a negative current collector and a negative material layer disposed on at least one surface of the negative current collector, and the negative material layer comprises the modified graphite according to claim 1 .

9 . A secondary battery, wherein the secondary battery further comprises the negative electrode plate according to claim 8 .

10 . A battery module, comprising the secondary battery according to claim 9 .

11 . A battery pack, comprising at least one of the secondary battery according to claim 9 .

12 . An electrical device, comprising at least one of the secondary battery according to claim 9 .

13 . A preparation method of modified graphite, comprising:

leaving a binder compound to react with graphite in a solvent in the presence of a catalyst, wherein

the binder compound possesses a structure expressed as Formula (IV):

wherein,

R 1 to R 6 each are independently selected from hydrogen, halogen, cyano, hydroxyl, amino, substituent-free or substituent-containing C 1 to C 6 alkyl, substituent-free or substituent-containing C 1 to C 6 alkoxyl, substituent-free or substituent-containing C 2 to C 6 alkenyl, or substituent-free or substituent-containing C 6 to C 20 aryl, wherein substituents in the substituent-containing alkyl, alkoxyl, alkenyl, and aryl each are at least one selected from C 1 to C 3 alkyl, hydroxyl, amino, amido, cyano, carboxyl, or halogen;

R 7 to R 9 each are independently selected from hydrogen, hydroxyl, amino, substituent-free or substituent-containing C 1 to C 6 alkyl, substituent-free or substituent-containing C 1 to C 6 alkoxyl, substituent-free or substituent-containing C 1 to C 6 alkylamino, substituent-free or substituent-containing C 2 to C 6 alkenyl, or substituent-free or substituent-containing C 6 to C 20 aryl, wherein substituents in the substituent-containing alkyl, alkoxyl, alkylamino, alkenyl, and aryl each are at least one selected from hydroxyl, carboxyl, amino, amido, or halogen;

R 10 represents linear or branched C 1 to C 12 alkyl;

R 11 represents halogen or cyano;

Z is selected from linear or branched C 1 to Cs alkylthio;

L represents linear or branched C 1 to C 12 alkylidene;

R 13 represents carboxyl, hydroxymethyl, or amino; and

a ratio of m to n is 1 to 100.

14 . The preparation method according to claim 13 , wherein, in the binder compound, m is an integer ranging from 500 to 15,000, and n is an integer ranging from 500 to 15,000.

15 . The preparation method according to claim 13 , wherein a number-average molecular weight of the binder compound is 30,000 to 3,000,000.

16 . The preparation method according to claim 13 , wherein structural units

in the binder compound are copolymerized in a random, blocked, and/or alternating manne.

17 . The preparation method according to claim 13 , wherein the binder compound is at least one selected from:

.

18 . The preparation method according to claim 13 , wherein a pH value of the reaction is 4 to 7.

19 . The preparation method according to claim 13 , wherein a mass ratio between the graphite and the binder compound is 85: 12 to 96.5: 0.5.

20 . The preparation method according to claim 13 , wherein the reaction occurs at 20° C. to 40° C.