MODIFIED GRAPHITE AND PREPARATION METHOD THEREOF, CARBON-COATED NEGATIVE ACTIVE MATERIAL AND PREPARATION METHOD THEREOF, NEGATIVE ELECTRODE PLATE, SECONDARY BATTERY, BATTERY MODULE, BATTERY PACK, AND ELECTRICAL DEVICE
Provided are a modified graphite and a preparation method thereof, a carbon-coated negative active material and a preparation method thereof, a negative electrode plate, a secondary battery, a battery module, a battery pack, and an electrical device. The preparation method of a modified graphite includes the following steps: (S 10 ) providing a graphite substrate; and (S 20 ) heat-treating the graphite substrate in a micro-oxidizing atmosphere to obtain the modified graphite, where the micro-oxidizing atmosphere includes a reactive gas, and the reactive gas is one or more selected from CO 2 , O 2 , and O 3 . The preparation method of a carbon-coated negative active material includes the following steps: (S 100 ) providing a negative active material substrate; and (S 200 ) heat-treating the negative active material substrate and a carbonaceous precursor in a micro-oxidizing atmosphere to obtain the carbon-coated negative active material, where the micro-oxidizing atmosphere includes a reactive gas.
1 . A preparation method of a modified graphite, comprising the following steps:
providing a graphite substrate; and
heat-treating the graphite substrate in a micro-oxidizing atmosphere to obtain the modified graphite, wherein
the micro-oxidizing atmosphere comprises a reactive gas, and the reactive gas is one or more selected from CO 2 , O 2 , and O 3 .
2 . The method according to claim 1 , wherein
the heat treatment is performed at a temperature of 600° C. to 1400° C., and optionally 1000° C. to 1200° C.; and/or
the heat treatment lasts for a period of 0.5 to 2 hours.
3 . The method according to claim 1 , wherein
a volume fraction V 1 of CO 2 in the micro-oxidizing atmosphere is less than or equal to 100%, and optionally, 50%≤V 1 ≤100%;
a volume fraction V 2 of O 2 in the micro-oxidizing atmosphere is less than or equal to 21%, and optionally, 0.05%≤V 2 ≤10%; and/or
a volume fraction V 3 of O 3 in the micro-oxidizing atmosphere is less than or equal to 21%, and optionally, 0.05%≤V 3 ≤10%.
4 . The method according to claim 3 , wherein V 2 +V 3 ≤20%.
5 . The method according to claim 1 , wherein the micro-oxidizing atmosphere further comprises a non-reactive gas.
6 . The method according to claim 1 , wherein the micro-oxidizing atmosphere is an air atmosphere.
7 . The method according to claim 1 , wherein the micro-oxidizing atmosphere is a CO 2 atmosphere.
8 . A modified graphite prepared by using the method according to claim 1 .
9 . A preparation method of a carbon-coated negative active material, comprising the following steps:
providing a negative active material substrate; and
heat-treating the negative active material substrate and a carbonaceous precursor in a micro-oxidizing atmosphere to obtain the carbon-coated negative active material, wherein
the micro-oxidizing atmosphere comprises a reactive gas, and the reactive gas is one or more selected from CO 2 , O 2 , and O 3 .
10 . The method according to claim 9 , wherein
the heat treatment is performed at a temperature of 600° C. to 1400° C., and optionally 1000° C. to 1200° C.; and/or
the heat treatment lasts for a period of 0.5 to 2 hours.
11 . The method according to claim 9 , wherein
the negative active material substrate comprises one or more of artificial graphite, natural graphite, simple-substance silicon, oxide of silicon, a silicon-nitrogen composite, a silicon alloy, simple-substance tin, oxide of tin, or a tin alloy, and optionally, the negative active material substrate is one or more selected from artificial graphite and natural graphite; and/or
the carbonaceous precursor comprises one or more of pitch, a biomass material, a polymer, or resin.
12 . The method according to claim 9 , wherein a mass ratio between the carbonaceous precursor and the negative active material substrate is less than or equal to 1/10.
13 . The method according to claim 9 , wherein
a volume fraction V 1 of CO 2 in the micro-oxidizing atmosphere is less than or equal to 100%;
a volume fraction V 2 of O 2 in the micro-oxidizing atmosphere is less than or equal to 21%; and/or
a volume fraction V 3 of O 3 in the micro-oxidizing atmosphere is less than or equal to 21%.
14 . The method according to claim 13 , wherein V 2 +V 3 ≤20%.
15 . The method according to claim 9 , wherein the micro-oxidizing atmosphere further comprises a non-reactive gas.
16 . The method according to claim 9 , wherein the micro-oxidizing atmosphere is an air atmosphere.
17 . The method according to claim 9 , wherein the micro-oxidizing atmosphere is a CO 2 atmosphere.
18 . A carbon-coated negative active material prepared by using the method according to claim 9 .