NEGATIVE ACTIVE MATERIAL, METHOD FOR PREPARING SAME, SECONDARY BATTERY CONTAINING SAME, AND ELECTRICAL DEVICE
Provided are a negative active material, a method for preparing same, a secondary battery containing same, and an electrical device. The negative active material includes a natural graphite substrate of a porous structure and a functional material distributed in pores of the natural graphite substrate, and the functional material includes amorphous carbon and a titanium-containing compound. The negative active material provided in this application exhibits excellent kinetic performance, and the secondary battery provided herein exhibits excellent fast-charging performance and cycle performance.
1 . A negative active material, comprising a natural graphite substrate of a porous structure and a functional material distributed in pores of the natural graphite substrate, wherein the functional material comprises amorphous carbon and a titanium-containing compound.
2 . The negative active material according to claim 1 , wherein the titanium-containing compound comprises one or more of a titanium-containing oxide or a titanate salt;
optionally, a chemical formula of the titanium-containing oxide is expressed as TiO x , wherein 0<x≤2.
3 . The negative active material according to claim 1 , wherein a morphology of the titanium-containing compound is one or more of a sphere, a spheroid, a polyhedron, or a nanorod.
4 . The negative active material according to claim 1 , wherein a mass percent of the functional material in the negative active material is less than or equal to 10%.
5 . The negative active material according to claim 1 , wherein a mass ratio between the amorphous carbon and the titanium-containing compound is (1 to 9):1.
6 . The negative active material according to claim 1 , wherein the porous structure of the natural graphite substrate comprises mesopores, and a volume percent of the mesopores is greater than or equal to 60%, and optionally, the volume percent of the mesopores is greater than or equal to 70%.
7 . The negative active material according to claim 1 , wherein
the porous structure of the natural graphite substrate comprises micropores, and optionally, a volume percent of the micropores is less than or equal to 20%; and/or
the porous structure of the natural graphite substrate comprises macropores.
8 . The negative active material according to claim 1 , wherein a porosity of the negative active material is greater than or equal to 70%.
9 . The negative active material according to claim 1 , wherein the negative active material further comprises at least one of element N or element S.
10 . The negative active material according to claim 1 , wherein Dv 50 of the negative active material is 5 μm to 30 μm, and optionally 17 μm to 25 μm; and/or
a span (Dv 90 −Dv 10 )/Dv 50 of the negative active material is 0.5 to 2.0; and/or
a specific surface area of the negative active material is 2.0 m 2 /g to 20 m 2 /g; and/or
a tapped density of the negative active material is 0.6 g/cm 3 to 1.3 g/cm 3 .
11 . The negative active material according to claim 1 , wherein a gram capacity of the negative active material is greater than or equal to 360 mAh/g.
12 . A method for preparing the negative active material according to claim 1 , wherein the method comprises the following steps:
S1: performing, by using a pore-forming agent, pore-forming treatment on natural graphite raw pellets to obtain a porous natural graphite precursor;
S2: mixing a carbon precursor with a titanium-containing precursor to obtain a functional material precursor; and
S3: mixing the porous natural graphite precursor obtained in step S1 with the functional material precursor obtained in step S2 to obtain a mixture, and heat-treating the mixture under an inert atmosphere to obtain the negative active material, wherein
the negative active material comprises a natural graphite substrate of a porous structure and a functional material distributed in pores of the natural graphite substrate, and the functional material comprises amorphous carbon and a titanium-containing compound.
13 . The preparation method according to claim 12 , wherein the pore-forming agent in step S1 is selected from salt pore-forming agents.
14 . The preparation method according to claim 12 , wherein a mass ratio between the natural graphite raw pellets and the pore-forming agent in step S1 is 1:(1 to 50).
15 . The preparation method according to claim 12 , wherein a temperature of the pore-forming treatment in step S1 is less than or equal to 1100° C.; and/or
a heating rate of the pore-forming treatment is 2° C./min to 5° C./min; and/or
a temperature holding time of the pore-forming treatment is 0.5 to 48 hours.
16 . The preparation method according to claim 12 , wherein a mass ratio between the carbon precursor and the titanium-containing precursor in step S2 is (1 to 160):(1 to 8).
17 . The preparation method according to claim 12 , wherein a mass ratio between the porous natural graphite precursor and the functional material precursor in step S3 is (3 to 9):(1 to 7).
18 . The preparation method according to claim 12 , wherein a temperature of a heat treatment in step S3 is 500° C. to 1500° C.; and/or
a heating rate of the heat treatment is 2° C./min to 10° C./min; and/or
a temperature holding time of the heat treatment is 0.5 to 48 hours.
19 . A secondary battery, comprising the negative active material according to claim 1 .
20 . An electrical device, comprising the secondary battery according to claim 19 .