Search

EP-4738455-A1 - NEGATIVE ELECTRODE MATERIAL, NEGATIVE ELECTRODE SHEET, ELECTROCHEMICAL APPARATUS, AND ELECTRIC DEVICE

EP4738455A1EP 4738455 A1EP4738455 A1EP 4738455A1EP-4738455-A1

Abstract

A negative electrode material, a negative electrode plate, an electrochemical apparatus, and an electric device are provided. The negative electrode material includes a core and a shell layer. The core is porous carbon with pores; where a silicon material is present on wall surfaces of the pores. The shell layer is a carbon material, and the shell layer encapsulates the core surface, sealing the pores. In the negative electrode material, the porous carbon and the carbon material of the shell layer have a disordered structure, resulting in less lithium storage. The pores serve as the primary region for lithium storage, with the silicon material present on the wall surfaces of the pores. The silicon material, as a lithiophilic substance, can induce lithium to enter the pores of the core from the external shell layer of the negative electrode material, enabling deposition position to be controlled during lithium metal deposition, reducing non-uniform lithium metal deposition, and thereby facilitating an improvement in the specific capacity and cycling performance of lithium-ion batteries.

Inventors

  • TAN, Fujin
  • Yi, Zheng
  • ZHENG, Zigui
  • XIE, YUANSEN

Assignees

  • Ningde Amperex Technology Limited

Dates

Publication Date
20260506
Application Date
20240626

Claims (12)

  1. A negative electrode material, wherein the negative electrode material comprises a core and a shell layer; the core is porous carbon with pores; a silicon material is present on wall surfaces of the pores; and the shell layer is a carbon material.
  2. The negative electrode material according to claim 1, wherein a mass percentage of the silicon material accounts for 0.01% to 20% of a total mass of the negative electrode material.
  3. The negative electrode material according to claim 1, wherein a mass percentage of the silicon material accounts for 0.01% to 4% of a total mass of the negative electrode material.
  4. The negative electrode material according to claim 1, wherein an area ratio of the silicon material to the porous carbon is 0.01 to 0.3.
  5. The negative electrode material according to claim 1, wherein an area ratio of the pores to the porous carbon is 0.3 to 3.
  6. The negative electrode material according to any one of claims 1 to 5, wherein the silicon material comprises at least one of elemental silicon or silicon carbide.
  7. The negative electrode material according to any one of claims 1 to 6, wherein a thickness of the silicon material is 0.5 nm to 4 nm, and/or a thickness of the shell layer is 2 nm to 20 nm.
  8. The negative electrode material according to any one of claims 1 to 7, wherein the core satisfies at least one of the following characteristics: (a) a specific surface area of the porous carbon is 500 m 2 /g to 3000 m 2 /g; (b) an average pore diameter of the porous carbon is 1 nm to 30 nm; (c) a pore volume of the porous carbon is 0.1 cm 3 /g to 1.5 cm 3 /g; (d) a D V 50 of the porous carbon is 1 µm to 20 µm; (e) a d002 of the porous carbon is 0.38 nm to 0.41 nm; or (f) a pore diameter of the porous carbon is 2 nm to 40 nm.
  9. The negative electrode material according to any one of claims 1 to 8, wherein the negative electrode material satisfies the following characteristics: (g) a pore diameter of the negative electrode material is 3 nm to 30 nm; (h) a pore volume of the negative electrode material is 0.005 cm 3 /g to 0.06 cm 3 /g; (i) an average pore diameter of the negative electrode material is 0.01 nm to 5 nm; and (j) a D V 50 of the negative electrode material is 1 µm to 20 µm.
  10. A negative electrode plate, wherein the negative electrode plate comprises the negative electrode material according to any one of claims 1 to 9.
  11. An electrochemical apparatus, wherein the electrochemical apparatus comprises the negative electrode plate according to claim 10.
  12. An electric device, wherein the electric device comprises the electrochemical apparatus according to claim 11.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to Chinese Patent Application No. 202310791499.1, filed on June 29, 2023 and entitled "NEGATIVE ELECTRODE MATERIAL, NEGATIVE ELECTRODE PLATE, ELECTROCHEMICAL APPARATUS, AND ELECTRIC DEVICE," which is incorporated herein by reference in its entirety. TECHNICAL FIELD The present application relates to a negative electrode material, a negative electrode plate, an electrochemical apparatus, and an electric device. BACKGROUND Since the commercialization of lithium-ion batteries by Sony Corporation of Japan in 1991, lithium-ion batteries have been widely used in fields such as mobile phones, compact cameras, handheld computers, and notebook computers due to their advantages such as high energy density, high operating voltage, good load characteristics, and fast charging speed. However, as the demand for battery energy and power performance in downstream applications continues to grow, the capacity of current commercial lithium-ion batteries has become insufficient. SUMMARY Currently, commercial lithium-ion battery negative electrodes primarily use graphite-based materials. Based on the lithium storage mechanism of LiC6 between graphite layers, their theoretical specific capacity is only 372 mAh/g, with limited room for improvement, and lithium diffusion between graphite layers also restricts their rate performance. Therefore, in the research and preparation of new high-capacity, long-cycle lithium-ion batteries, the negative electrode material is key to the further development of lithium-ion battery technology. To increase the capacity of lithium-ion batteries, existing technologies construct a porous carbon framework in the anode electrode plate. During battery discharging, lithium metal is stripped from the anode and intercalated into the cathode material, with the porous carbon framework maintaining its shape. During battery charging, lithium metal is stripped from the cathode and deposited onto the anode electrode plate. The porous carbon framework may also disperse current, reduce local current density, thereby suppressing lithium dendrite formation, increasing lithium deposition density, and achieving the purpose of improving lithium-ion battery performance. However, due to the high binding energy between the porous carbon framework and lithium, the deposition position during lithium metal deposition is uncontrollable, leading to non-uniform lithium metal deposition, which causes significant volume changes and rapid capacity decay in the anode electrode plate during cycling. Based on the above considerations, an objective of the present application is to provide a negative electrode material, a negative electrode plate, an electrochemical apparatus, and an electric device. Embodiments of the present application are implemented as follows. According to a first aspect, an embodiment of the present application provides a negative electrode material, where the negative electrode material includes a core and a shell layer; the core is porous carbon with pores;a silicon material is present on wall surfaces of the pores; andthe shell layer is a carbon material, and the shell layer encapsulates the core surface, sealing the pores. In the above negative electrode material, the porous carbon and the carbon material of the shell layer have a disordered structure, resulting in less lithium storage. The pores serve as the primary region for lithium storage, with the silicon material present on the wall surfaces of the pores. The silicon material, as a lithiophilic substance, can induce lithium to enter the pores of the core from the external shell layer of the negative electrode material, enabling deposition position to be controlled during lithium metal deposition, reducing non-uniform lithium metal deposition, and thereby helping improve the specific capacity and cycling performance of lithium-ion batteries. Further, in the above negative electrode material, the shell layer encapsulates the core surface, sealing the pores and transforming the pores into closed pores, preventing external electrolyte from entering the internal pores, thereby allowing lithium to enter the pores after desolvation. Further, the silicon material is present on the wall surfaces of the pores, and while the pores store metallic lithium, some space may be reserved to buffer volume expansion caused by lithium metal, thereby improving cycling performance. In some optional embodiments, a thickness of the silicon material is 0.5 nm to 4 nm. In the above technical solution, setting the thickness of the silicon material within the above range helps more lithium to pass through the shell layer into the pores while suppressing lithium precipitation on the surface of the negative electrode material, thereby achieving a higher specific capacity. In some optional embodiments, a mass percentage of the silicon material accounts for 0.01% to 20% of a total mass of the negative electrode