CN-121983522-A - Negative electrode material, preparation method thereof, negative electrode sheet and secondary battery

CN121983522ACN 121983522 ACN121983522 ACN 121983522ACN-121983522-A

Abstract

The invention provides a negative electrode material, a preparation method thereof, a negative electrode sheet and a secondary battery. The negative electrode material comprises Si element, O element, M1 element and M2 element, wherein the M1 element contains Ca and/or Ba, the M2 element is one or more of metal elements with electronegativity of <1.8, the negative electrode material is subjected to particle size classification to obtain a negative electrode material A and a negative electrode material B, and when the ratio of the particle size D 50 (A) of the negative electrode material A to the particle size D 50 (B) of the negative electrode material B is more than or equal to 2, the mass content of the M1 element and the mass content of the M2 element accord with a certain relational expression. The negative electrode material is applied to the secondary battery, so that the capacity and the cycle performance of the battery can be remarkably improved, the expansion of the material can be effectively inhibited, and the safety of the battery is improved.

Inventors

Liang tengyu
PANG CHUNLEI
HE PENG
GUO SONGTAO
QU LIJUAN

Assignees

贝特瑞新材料集团股份有限公司

Dates

Publication Date: 20260505
Application Date: 20241031

Claims (10)

1. A negative electrode material, characterized in that the negative electrode material contains an Si element, an O element, an M1 element and an M2 element, wherein the M1 element contains Ca and/or Ba, and the M2 element is selected from one or more of metal elements having electronegativity < 1.8; Carrying out particle size classification on the anode material to obtain an anode material A and an anode material B, wherein when the ratio of the particle size D 50 (A) of the anode material A to the particle size D 50 (B) of the anode material B is more than or equal to 2, the mass content of M1 element and the mass content of M2 element are in accordance with the formulas I and II: m1 mass content (A)/M1 mass content (B) is less than or equal to 0.8, formula I M2 mass content (A)/M2 mass content (B) of 0.8-1.25, formula II Wherein, the mass content (A) of M1 represents the mass content of M1 element in the anode material A, the mass content (B) of M1 element in the anode material B, the mass content (A) of M2 element in the anode material A, and the mass content (B) of M2 element in the anode material B; The method for testing the mass content of the M1 element or the M2 element comprises the steps of burning 1g of the anode material A or the anode material B to constant weight at 750-1000 ℃ in an oxygen-containing atmosphere, dissolving 100mL of mixed acid consisting of concentrated HF, concentrated HCl and concentrated HNO 3 in a volume ratio of 1:3:1 until the solution does not generate bubbles, repeatedly adding one time of mixed acid until the solution is still bubble-free, carrying out solid-liquid separation to obtain a digestion solution of the anode material, and testing the mass content of the metal M1 element or the metal M2 element in the digestion solution by adopting an electric coupling plasma atomic emission spectrum.
2. The anode material according to claim 1, wherein the anode material satisfies at least one of the following characteristics: (1) The mass content of M1 element in the anode material is less than or equal to 200ppm; (2) The mass content of M2 element in the anode material is 50000 ppm-200000 ppm; (3) The M2 element is at least one selected from Mg, li, K, na, al, la, zn, ti and Mn; (3) The mass content of oxygen in the anode material is 10% -35%; (4) The specific surface area of the anode material is less than or equal to 20m 2 /g; (5) The pH value of the negative electrode material is 8-10; (6) The mass content (A) of M1 is less than or equal to 200ppm, and the mass content (B) of M1 is less than or equal to 200ppm; (7) The mass content (A) of M2 is 50000 ppm-200000 ppm, and the mass content (B) of M2 is 50000 ppm-200000 ppm; (8) When the ratio of the particle diameter D 50 (A) of the anode material A to the D 50 (B) of the anode material B is more than or equal to 2, the value of the mass content (A)/the mass content (B) of M1 is less than or equal to 0.6; (9) When the ratio of the particle diameter D 50 (A) of the anode material A to the D 50 (B) of the anode material B is 2 or more, the mass content (A) of M2/the mass content (B) of M2 is 0.9 or less or 1.1 or less.
3. The anode material according to claim 1, wherein the anode material satisfies at least one of the following characteristics: (1) The particle size D 50 of the anode material is 1-20 mu m; (2) Each pair of increasing intervals and decreasing intervals which are connected end to end in the particle size-volume distribution curve is called a peak, the particle size distribution curve of the anode material consists of two peaks, the peaks with smaller particle size are marked as peak 1, the peaks with larger particle size are marked as peak 2, and the integral area of the peak 2 is 12-48 times of the integral area of the peak 1; (3) Each pair of increasing intervals and decreasing intervals which are connected end to end in the particle size-volume distribution curve is called a peak, the particle size distribution curve of the anode material consists of two peaks, the peaks with smaller particle sizes are marked as peak 1, the peaks with larger particle sizes are marked as peak 2, the particle size corresponding to the peak 1 is 0.1-1 mu m, and the particle size corresponding to the peak 2 is 2-20 mu m; (4) The volume of particles with the particle diameter of less than 1 mu m in the anode material accounts for 5% or less of the total volume of the anode material, and the volume of particles with the particle diameter of more than 10 mu m in the anode material accounts for 25% or less of the total volume of the anode material; (5) The particle size of the anode material meets the following condition D 50 <0.5(D 10 +D 90 ; (6) The particle size of the negative electrode material satisfies D 50 <0.5 (dmin+Dmax); (7) The XRD diffraction pattern of the anode material contains silicate characteristic peaks of M2 element, and the peak height of the strongest peak is lower than that of Si characteristic peaks at 28.6 degrees.
4. A negative electrode material according to any one of claims 1 to 3, wherein the means of particle size classification comprises air classification.
5. A negative electrode material according to any one of claims 1 to 3, characterized in that the negative electrode material satisfies at least one of the following characteristics: (1) The surface of the negative electrode material is provided with a carbon coating layer; (2) The surface of the anode material is provided with a carbon coating layer, and the mass of the carbon coating layer accounts for 1% -40% of the mass of the anode material.
6. A method for producing a negative electrode material, comprising: Decompressing metal M1 and metal M2 and a silicon oxygen raw material in different containers, heating to a first temperature, enabling the metal M1, the metal M2 and the silicon oxygen raw material to evaporate to form steam, introducing the steam into a common cooling area for cooling to form a first intermediate product, wherein the metal M1 contains Ca and/or Ba, and the M2 is selected from one or more of metals with electronegativity of < 1.8; Heating the first intermediate product to 550-650 ℃ under a reduced pressure state, preserving heat for 12-24 h, then filling inert gas, heating to a third temperature, preserving heat for a period of time at the third temperature, and then cooling for at least 12h to obtain a second intermediate product; and carrying out post-treatment on the second intermediate product to obtain the anode material.
7. The method of manufacture of claim 6, wherein the method of manufacture meets at least one of the following characteristics: (1) The M2 element is at least one selected from Mg, li, K, na, al, la, zn, ti and Mn; (2) The first temperature is greater than or equal to 1500 ℃; (3) The third temperature is 1000-1100 ℃, and the heat preservation time at the third temperature is 12-24 hours; (4) The silicon oxygen raw material comprises a combination of Si and SiO 2 or SiOx, wherein x is more than 0 and less than or equal to 2.
8. The method of manufacture of claim 6, wherein the method of manufacture meets at least one of the following characteristics: (1) The post-treatment comprises a crushing treatment and a carbon coating treatment; (2) The post-treatment comprises a crushing treatment and a carbon coating treatment, wherein the crushing treatment comprises the steps of crushing the second intermediate product until the D 50 of the material particles is smaller than 10 mu m; (3) The post-treatment comprises a crushing treatment and a carbon coating treatment, wherein the carbon coating treatment comprises at least one of solid-phase carbon coating, liquid-phase carbon coating and gas-phase carbon coating; (4) The post-treatment comprises crushing treatment and carbon coating treatment, wherein the carbon coating treatment comprises the steps of crushing the second intermediate product, introducing hydrocarbon gas, and depositing at high temperature to obtain a negative electrode material; (5) The post-treatment comprises crushing treatment and carbon coating treatment, wherein the carbon coating treatment comprises the steps of crushing the second intermediate product, introducing hydrocarbon gas, and depositing at a high temperature to obtain a negative electrode material, wherein the deposition temperature is 800-1100 ℃ and the deposition time is 2-20 hours; (6) The post-treatment comprises crushing treatment and carbon coating treatment, wherein the carbon coating treatment comprises crushing the second intermediate product, introducing hydrocarbon gas, and depositing at high temperature to obtain the anode material, wherein the hydrocarbon gas comprises one or more of methane, ethane, propane, ethylene, propylene, acetylene and propyne.
9. A negative electrode sheet comprising the negative electrode material according to any one of claims 1 to 5 or a negative electrode material produced by the production method according to any one of claims 6 to 8.
10. A secondary battery comprising the negative electrode sheet according to claim 9.

Description

Negative electrode material, preparation method thereof, negative electrode sheet and secondary battery Technical Field The invention relates to the technical field of battery anode materials, in particular to an anode material, a preparation method thereof, an anode sheet and a secondary battery. Background With the increasing development of the fields of electric automobiles, 3C numbers, electric tools and the like, the demand for lithium battery materials is increasing. Graphite is a current commonly used lithium ion battery cathode material, and the increase of capacity requirements of the lithium ion battery material cannot be met due to the theoretical capacity of 372 mAh/g. Si becomes a new product of the next generation lithium battery cathode material because of its theoretical capacity up to 4200 mAh/g. Si, however, is easily pulverized during the cycle due to its 300% expansion rate, and is limited in practical use. SiO x (0 < x≤2) can make up the defect of Si due to the structure that Si is dispersed in the SiO 4 skeleton. However, when SiO x is intercalated with lithium for the first time, since O in SiO x is combined with Li in the electrolyte to form an SEI film and irreversible Li 4SiO4 and Li 2 O, a larger irreversible capacity is caused, so that the first coulomb efficiency is lower. Disclosure of Invention The invention mainly aims to provide a negative electrode material, a preparation method thereof, a negative electrode plate and a secondary battery, so as to solve the problem of poor cycle performance of the negative electrode material in the prior art. In order to achieve the above object, according to one aspect of the present invention, there is provided a negative electrode material comprising Si element, O element, M1 element and M2 element, wherein M1 comprises Ca and/or Ba, and M2 element is selected from one or more of metal elements having electronegativity <1.8, the negative electrode material is subjected to particle size classification to obtain a negative electrode material A and a negative electrode material B, and when a ratio of a particle diameter D 50 (A) of the negative electrode material A to a particle diameter D 50 (B) of the negative electrode material B is 2 or more, a mass content of the M1 element and a mass content of the M2 element conform to formula I and formula II: M1 mass content (A)/M1 mass content (B) is less than or equal to 0.8, formula I M2 mass content (A)/M2 mass content (B) of 0.8-1.25, formula II Wherein, the mass content (A) of M1 represents the mass content of M1 element in the anode material A, the mass content (B) of M1 element in the anode material B, the mass content (A) of M2 element in the anode material A, and the mass content (B) of M2 element in the anode material B; The method for testing the mass content of the M1 element or the M2 element comprises the steps of burning 1g of the anode material A or the anode material B to constant weight at 750-1000 ℃ under the oxygen-containing atmosphere, dissolving 100mL of mixed acid consisting of concentrated HF, concentrated HCl and concentrated HNO 3 in a volume ratio of 1:3:1 until the solution does not generate bubbles, repeatedly adding one time of mixed acid until the solution is still bubble-free, carrying out solid-liquid separation to obtain a digestion solution of the anode material, and testing the mass content of the metal M1 element or the metal M2 element in the digestion solution by adopting an electric coupling plasma atomic emission spectrum. Further, the anode material satisfies at least one of the following characteristics: (1) The mass content of M1 element in the anode material is less than or equal to 200ppm; (2) The mass content of M2 element in the anode material is 50000 ppm-200000 ppm; (3) M2 is at least one selected from Mg, li, K, na, al, la, zn, ti and Mn; (3) The mass content of oxygen element in the anode material is 10% -35%; (4) The specific surface area of the anode material is less than or equal to 20m 2/g; (5) The pH value of the anode material is 8-10; (6) The mass content (A) of M1 is less than or equal to 200ppm, and the mass content (B) of M1 is less than or equal to 200ppm; (7) The mass content (A) of M2 is 50000 ppm-200000 ppm, and the mass content (B) of M2 is 50000 ppm-200000 ppm; (8) When the ratio of the particle diameter D 50 (a) of the anode material a to D 50 (B) of the anode material B is 2 or more, the value of the mass content (a)/mass content (B) of M1 is 0.6 or less; (9) When the ratio of the particle diameter D 50 (A) of the anode material A to the D 50 (B) of the anode material B is 2 or more, the mass content (A) of M2/the mass content (B) of M2 is 0.9 or less or 1.1 or less. Further, the anode material satisfies at least one of the following characteristics: (1) The particle diameter D 50 of the anode material is 1-20 mu m; (2) Each pair of increasing intervals and decreasing intervals which are connected end to end in the particle siz