CN-122025575-A - Graphite negative electrode material, negative electrode plate, lithium ion battery and preparation method of lithium ion battery

CN122025575ACN 122025575 ACN122025575 ACN 122025575ACN-122025575-A

Abstract

The invention belongs to the technical field of battery materials, and particularly relates to a high-power long-cycle graphite negative electrode material, a negative electrode plate, a lithium ion battery and a preparation method thereof. The invention relates to the technical field of graphite cathode materials of lithium ion batteries. The graphite cathode material comprises a graphite inner core and a shell coating the graphite inner core, wherein the shell is an amorphous carbon layer doped with a fast ion conductor. The graphite core is artificial graphite particles subjected to sphericizing treatment. The fast ion conductor doped amorphous carbon layer is formed by mixing and heating a fast ion conductor and a carbon source with the graphite core and forming on the surface of the graphite core. The negative electrode plate prepared by using the graphite negative electrode material has rich porosity, and shows excellent power performance, high-temperature performance and cycle stability on a lithium ion battery.

Inventors

WU YONGKANG
LIU CHAOHUI
LI YUANYUAN
QIAN ZHENYANG
WU JIPENG

Assignees

合肥国轩高科动力能源有限公司

Dates

Publication Date: 20260512
Application Date: 20260113

Claims (10)

1. A graphite anode material is characterized by comprising a graphite inner core and an outer shell coating the graphite inner core, wherein the outer shell is an amorphous carbon layer doped with a fast ion conductor.
2. The graphite anode material according to claim 1, wherein the raw material of the graphite core is selected from one or more of needle coke secondary particles, petroleum coke secondary particles or medium sulfur coke secondary particles; the aggregate particle size of the raw material of the graphite core is 7.5-10 mu m.
3. The graphite anode material of claim 1, wherein said fast ion conductor doped amorphous carbon layer is formed on the surface of said graphite core by mixing and carbonizing a fast ion conductor and a carbon source with said graphite core.
4. The graphite anode material according to claim 3, wherein the graphite anode material satisfies at least one of the following conditions (1) to (2): (1) The fast ion conductor is selected from one or more of lithium aluminum titanium phosphate, lithium lanthanum zirconium oxide, lithium lanthanum titanate and derivatives thereof; (2) The carbon source is selected from one or more of asphalt oil, resin oil, rubber and derivatives thereof.
5. A method of preparing a graphite anode material, the method comprising the steps of: S1, sequentially carrying out graphitization treatment, carbonization treatment and sphericization treatment on raw materials of a graphite core to obtain sphericized artificial graphite particles; S2, mixing and carbonizing the spherical artificial graphite particles, the fast ion conductor and a carbon source to obtain the artificial graphite particles coated with the fast ion conductor doped amorphous carbon layer; and S3, sieving the artificial graphite particles coated by the fast ion conductor doped amorphous carbon layer to obtain the graphite anode material.
6. The method of claim 5, wherein the method satisfies at least one of the following conditions (3) - (16): (3) The graphitization treatment temperature in the step S1 is 2600-3400 ℃; (4) The graphitization treatment time in the step S1 is 20-40h; (5) The carbonization treatment temperature in the step S1 is 900-1400 ℃; (6) The carbonization treatment time in the step S1 is 1-8 hours; (7) The rotational speed of the air flow mill classifying wheel for the sphericizing treatment in the step S1 is 2000-12000rpm; (8) The pressure of the air flow for the sphericizing treatment in the step S1 is 0.6-1.0MPa; (9) The granularity of the feed material subjected to the sphericizing treatment in the step S1 is less than or equal to 200 meshes; (10) The rotating speed of the mixing in the step S2 is 20-400r/min; (11) The mixing time in the step S2 is 10-120min; (12) The carbonization temperature in the step S2 is 600-1200 ℃; (13) The carbonization time in the step S2 is 1-8h; (14) The fast ion conductor is selected from one or more of lithium aluminum titanium phosphate, lithium lanthanum zirconium oxide, lithium lanthanum titanate and derivatives thereof; (15) The carbon source is selected from one or more of asphalt oil, resin oil, rubber and derivatives thereof; (16) The mass ratio of the fast ion conductor to the carbon source is 1-10:20-100, the sphericity value is 0.7-0.95, the OI value is 1-4, the K value is 0.5-1.5 and the tortuosity is 10-40.
7. The negative electrode plate is characterized by comprising a current collector and a negative electrode material layer coated on the surface of the current collector; the negative electrode material layer comprises the graphite negative electrode material according to any one of claims 1 to 4 or the graphite negative electrode material prepared by the method according to claim 5 or 6.
8. A method of making the negative electrode tab of claim 7, comprising the steps of: mixing the negative electrode material according to any one of claims 1 to 4, a conductive agent, a thickener, and a binder to obtain a slurry; Coating the slurry on a current collector, and drying to obtain a negative electrode plate; The conductive agent is one or more selected from ketjen black, acetylene black and Super P; the thickener is selected from one or more of sodium carboxymethyl cellulose, hydroxyethyl cellulose, sodium polyacrylate and polyacrylic acid; the binder is selected from one or more of styrene-butadiene rubber, nitrile rubber, polyvinylidene fluoride and polytetrafluoroethylene.
9. Use of a graphite negative electrode material according to any one of claims 1 to 4 or a graphite negative electrode material prepared by a method according to claim 5 or 6 or a negative electrode sheet according to claim 7 in a battery.
10. A battery is characterized by comprising a negative electrode plate, a positive electrode plate, a diaphragm and electrolyte, wherein the negative electrode plate is the negative electrode plate of claim 7.

Description

Graphite negative electrode material, negative electrode plate, lithium ion battery and preparation method of lithium ion battery Technical Field The invention belongs to the technical field of battery materials, and particularly relates to a graphite negative electrode material, a negative electrode plate, a lithium ion battery and a preparation method of the graphite negative electrode material. Background In the process of high-power charge and discharge, the traditional graphite anode material has the defects of low lithium ion transmission rate (10 -12~10-11cm2/s magnitude), low pole piece porosity and high tortuosity, so that the power performance of the battery is limited, and meanwhile, in the long-term circulation process, the capacity attenuation and the impedance increase of the battery are easily caused due to factors such as volume change of graphite particles, thickening of SEI films and the like, so that the circulation performance is reduced. The mainstream technology in the industry is to coat amorphous carbon on the surface of graphite, but the improvement on the quick charge performance is limited, and the high temperature performance of the graphite can be obviously reduced. Disclosure of Invention According to a first aspect of the application, a graphite anode material is provided, the graphite anode material comprises a graphite inner core and a shell coating the graphite inner core, and the shell is an amorphous carbon layer doped with a fast ion conductor. According to the application, through constructing a fast ion conductive channel and cooperatively regulating and controlling the morphology and structure of the artificial graphite negative electrode material, the graphite negative electrode material with optimized surface components and low lithium ion diffusion energy barrier, a negative electrode plate with high porosity and low tortuosity, and a high-power, high thermal stability and long-cycle lithium ion battery are designed. The raw materials of the artificial graphite particles are selected from one or more of needle coke secondary particles, petroleum coke secondary particles or medium sulfur coke secondary particles; The aggregate particle size of the artificial graphite particles is 7.5-10 mu m. By selecting graphite with low aggregate particle size, the migration distance of lithium ions in graphite particles is short, and the quick-charging performance is improved. In some embodiments, the fast ion conductor doped amorphous carbon layer is formed on the surface of the graphite core by mixing and carbonizing a fast ion conductor and a carbon source with the graphite core. By mixing and heating the fast ion conductor, the carbon source and the graphite core, the fast ion conductor doped amorphous carbon layer is formed on the surface of the graphite, so that a composite interface with high lithium ion conductivity and electronic conductivity is constructed, the lithium ion diffusion energy barrier is effectively reduced, the mechanical strength of the surface of the graphite is improved, the SEI film component is optimized, and the fast charging performance, the high temperature performance and the cycling stability of the material are improved. In some embodiments, the graphite anode material satisfies at least one of the following conditions (1) - (2): (1) The fast ion conductor is selected from one or more of lithium phosphate, lithium aluminum titanium phosphate, lithium lanthanum zirconium oxide, lithium lanthanum titanate and derivatives thereof; (2) The carbon source is selected from one or more of asphalt oil, resin oil, rubber and derivatives thereof. The application performs strong shaping on the traditional artificial graphite particles to improve sphericity and reduce OI value, the improvement of sphericity is beneficial to improving bulk density and fluidity of materials, and reducing transmission path (tortuosity) of lithium ions in an electrode, thereby improving lithium ion transmission rate, and the low OI value indicates that the graphite has higher isotropy and lithium ion intercalation active site density, and is beneficial to high-current density charge and discharge performance. In a second aspect of the present application, there is provided a method for preparing the graphite anode material, the method comprising the steps of: s1, sequentially carrying out graphitization treatment, carbonization treatment and sphericization treatment on raw materials of a graphite core to obtain sphericized artificial graphite particles; S2, mixing and carbonizing the spherical artificial graphite particles, the fast ion conductor and a carbon source to obtain the artificial graphite particles coated with the fast ion conductor doped amorphous carbon layer; and S3, sieving the artificial graphite particles coated by the fast ion conductor doped amorphous carbon layer to obtain the graphite anode material. According to the application, firstly, the geometry of gr