SILICON-BASED MATERIAL, PREPARATION METHOD THEREOF, AND SECONDARY BATTERY, BATTERY MODULE, BATTERY PACK, AND APPARATUS ASSOCIATED THEREWITH
This application provides a silicon-based material, a preparation method thereof, and a secondary battery, a battery module, a battery pack, and an apparatus associated therewith. The silicon-based material includes a core structure and a coating layer provided on at least partial surface of the core structure, where the core structure includes both a silicon phase and a lithium metasilicate phase, and a particle size P of the lithium metasilicate phase is ≥30 nm. The silicon-based material of this application can not only increase energy density of a secondary battery with the silicon phase, but also improve structural stability and chemical stability of the silicon-based material, so that the secondary battery can deliver satisfactory and balanced cycling performance and first-cycle coulombic efficiency in overall.
1 . A silicon-based material, comprising a core structure and a coating layer provided on at least partial surface of the core structure, wherein the core structure comprises both a silicon phase and a lithium metasilicate phase, and a particle size P of the lithium metasilicate phase is ≥30 nm.
2 . The silicon-based material according to claim 1 , wherein 30≤P≤500 nm.
3 . The silicon-based material according to claim 1 , wherein a particle size Q of the silicon phase is ≥10 nm.
4 . The silicon-based material according to claim 1 , wherein the silicon-based material satisfies:
0.5≤Q/P≤5.
5 . The silicon-based material according to claim 1 , wherein in the silicon-based material, a molar ratio m of element silicon to element lithium satisfies 1≤m≤5.
6 . The silicon-based material according to claim 1 , wherein a median particle size by volume D v 50 of the silicon-based material is ≤10 μm.
7 . The silicon-based material according to claim 1 , wherein a specific surface area of the silicon-based material is 0.5 m 2 /g-3 m 2 /g.
8 . The silicon-based material according to claim 1 , wherein
a powder tap density of the silicon-based material is 0.6 g/cm 3 -1.2 g/cm 3 , or,
a powder press density of the silicon-based material is 1.0 g/cm 3 -1.5 g/cm 3 .
9 . The silicon-based material according to claim 1 , wherein the lithium metasilicate phase comprises at least one of Li 2 Si 2 O 5 , Li 2 SiO 3 , and Li 4 SiO 4 .
10 . The silicon-based material according to claim 1 , wherein the coating layer is made of at least one of carbon-based material, organic polymer, metal, and metal oxide.
11 . The silicon-based material according to claim 1 , wherein a thickness of the coating layer is ≤30 nm.
12 . A preparation method of a silicon-based material, comprising the following steps:
(1) adding silicon monoxide, metallic lithium, and a complexing agent into an ether solvent and performing filtration, and performing heat treatment on a solid-phase system resulting from the filtration to obtain primary precursor particles;
(2) adding the primary precursor particles into a solvent mixture of ethanol and water and performing filtration to obtain secondary precursor particles; and
(3) performing coating treatment on the secondary precursor particles to obtain a silicon-based material;
where the silicon-based material includes a core structure and a coating layer provided on at least partial surface of the core structure, where the core structure includes both a silicon phase and a lithium metasilicate phase, and a particle size P of the lithium metasilicate phase is ≥30 nm.
13 . The preparation method according to claim 12 , wherein in step (1), a mass ratio of the silicon monoxide to the metallic lithium is 1:(0.03-0.16).
14 . The preparation method according to claim 12 , wherein in step (1), a heat treatment temperature is ≥600° C.
15 . The preparation method according to claim 12 , wherein in step (1), a heat treatment time is ≥0.5 h.
16 . The preparation method according to claim 12 , wherein in step (2), the primary precursor particles are stirred for at least 12 h in the solvent mixture and filtration is performed to obtain the secondary precursor particles; and optionally, the primary precursor particles are stirred for 12 h-24 h in the solvent mixture.
17 . The preparation method according to claim 12 , wherein in step (3), a coating treatment temperature is ≤800° C.; or, a heat treatment time is ≤6 h.
18 . The preparation method according to claim 12 , wherein a mass ratio of the primary precursor particles to the ethanol/water solution is 0.01-0.1.
19 . A secondary battery, comprising the silicon-based material according to claim 1 .
20 . A battery module, comprising the secondary battery according to claim 19 .
21 . A battery pack, comprising the battery module according to claim 20 .