Negative electrode active material and preparation method thereof
This application provides a negative electrode active material and a preparation method thereof. The negative electrode active material may be self-embedded graphite composed of graphite A and graphite B, where the surface of the graphite A may have a tenon structure, the surface of the graphite B may have a mortise structure, the tenon structure of the graphite A and the mortise structure of the graphite B may be mutually embedded, and a hydrogen bond may be formed between the tenon structure of the graphite A and the mortise structure of the graphite B.
1 . A negative electrode active material, wherein
the negative electrode active material is self-embedded graphite composed of graphite A and graphite B;
a surface of the graphite A has a tenon structure, and a surface of the graphite B has a mortise structure; and
the tenon structure of the graphite A and the mortise structure of the graphite B are mutually embedded, and a hydrogen bond is formed between the tenon structure of the graphite A and the mortise structure of the graphite B.
2 . The negative electrode active material according to claim 1 , wherein
the tenon structure of the graphite A is formed by an oxygen-containing metal salt, and a contact angle between the graphite A and a blank electrolyte is less than or equal to 20°; and
the blank electrolyte is formed by dissolving lithium hexafluorophosphate at a concentration of 1 mol/L in a solvent that is formed by mixing ethylene carbonate and dimethyl carbonate at a mass ratio of 1:1.
3 . The negative electrode active material according to claim 2 , wherein
the surface of the mortise structure of the graphite B has a hydroxyl group, and a contact angle between the graphite B and the blank electrolyte is less than or equal to 15°.
4 . The negative electrode active material according to claim 2 , wherein
the oxygen-containing metal salt is an oxygen-containing lithium metal salt or an oxygen-containing sodium metal salt, and is selected from at least one of lithium metaaluminate, lithium metazincate, sodium metaaluminate, or sodium metazincate.
5 . The negative electrode active material according to claim 1 , wherein
a contact angle between the self-embedded graphite and a blank electrolyte is less than or equal to 15°; and
the blank electrolyte is formed by dissolving lithium hexafluorophosphate at the concentration of 1 mol/L in the solvent that is formed by mixing ethylene carbonate and dimethyl carbonate at the mass ratio of 1:1.
6 . A preparation method of negative electrode active material, comprising the following steps:
(1) adding a first graphite matrix into a polar solvent, then adding a raw material for preparing an oxygen-containing metal salt to make an amount of the oxygen-containing metal salt coating a surface of the first graphite matrix be 1-5 wt % of a weight of the first graphite matrix, followed by stirring, evaporation, and drying, and then calcining the resulting mixture in a nitrogen atmosphere at a temperature of 500-1200° C. for 8-24 hours to obtain graphite A having a tenon structure;
(2) adding a second graphite matrix into an alkaline solution having a pH greater than or equal to 13, stirring at a constant temperature of 60-100° C. for 8-36 hours, and after filtering, cleaning, and drying the resulting product to obtain graphite B having a mortise structure; and
(3) mixing the graphite A and the graphite B to obtain a negative electrode active material.
7 . The preparation method according to claim 6 , wherein
the first graphite matrix and the second graphite matrix are different from each other.
8 . The preparation method according to claim 6 , wherein
the first graphite matrix and the second graphite matrix are the same or different artificial graphite.
9 . The preparation method according to claim 6 , wherein
the raw material for preparing the oxygen-containing metal salt comprises:
(1) any one of lithium nitrate, sodium nitrate, and potassium nitrate; and
(2) at least one of aluminum nitrate, zinc nitrate, or ferric nitrate.
10 . The preparation method according to claim 6 , wherein
D v 50 of the first graphite matrix and the second graphite matrix each satisfy the following condition:
3.0 μm≤ D v 50≤15.0 μm.
11 . The preparation method according to claim 6 , wherein
D v 50, D v 90, and D v 10 of the first graphite matrix and the second graphite matrix each satisfy the following condition:
1.0≤( D+ 90− D v 50)/ D v 50≤2.0.
12 . The preparation method according to claim 6 , wherein
length-diameter ratios D L /D W of the first graphite matrix and the second graphite matrix each satisfy the following condition:
1.0≤ D L /D w ≤2.5.
13 . The preparation method according to claim 6 , wherein
the oxygen-containing metal salt is an oxygen-containing lithium metal salt or an oxygen-containing sodium metal salt, and is selected from at least one of lithium metaaluminate, lithium metazincate, sodium metaaluminate, or sodium metazincate.
14 . The preparation method according to claim 6 , wherein
in step (1), the contact angle between the obtained graphite A and a blank electrolyte is less than or equal to 20°;
in step (2), the contact angle between the obtained graphite B and the blank electrolyte is less than or equal to 15°; and
the blank electrolyte is formed by dissolving lithium hexafluorophosphate at a concentration of 1 mol/L in a solvent that is formed by mixing ethylene carbonate and dimethyl carbonate at a mass ratio of 1:1.
15 . The preparation method according to claim 6 , wherein
the obtained negative electrode active material is self-embedded graphite composed of the graphite A and the graphite B, the tenon structure of the graphite A and the mortise structure of the graphite B are mutually embedded, and a hydrogen bond is formed between the tenon structure of the graphite A and the mortise structure of the graphite B.
16 . The preparation method according to claim 15 , wherein
a contact angle between the self-embedded graphite and a blank electrolyte is less than or equal to 15°; and
the blank electrolyte is formed by dissolving lithium hexafluorophosphate at the concentration of 1 mol/L in the solvent that is formed by mixing ethylene carbonate and dimethyl carbonate at the mass ratio of 1:1.
17 . A negative electrode plate, wherein
the negative electrode plate comprises a negative electrode active material layer, and the negative electrode active material layer comprises the negative electrode active material according to claim 1 .
18 . The negative electrode plate according to claim 17 , wherein
the negative electrode active material layer further comprises a binder, and relative to a weight of the negative electrode active material layer, a proportion of the binder is more than 1.3 wt % and less than 2.0 wt %.
19 . A secondary battery, wherein the secondary battery comprises the negative electrode plate according to claim 17 .
20 . An electric apparatus, wherein the electric apparatus comprises the secondary battery according to claim 19 .