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CN-122025608-A - Silicon-carbon material, preparation method thereof, negative plate and battery

CN122025608ACN 122025608 ACN122025608 ACN 122025608ACN-122025608-A

Abstract

The invention provides a silicon-carbon material, a preparation method thereof, a negative plate and a battery. The silicon-carbon material comprises a silicon-carbon matrix and silicon particles attached to at least part of the surface and/or at least part of the pores of the carbon skeleton, wherein the carbon skeleton comprises carbon atoms, electron-deficient heteroatoms and oxygen atoms, the electron-deficient heteroatoms comprise doping-state heteroatoms and interface-state heteroatoms, the doping-state heteroatoms replace at least part of carbon lattice sites, and the interface-state heteroatoms are bonded with the carbon atoms and the oxygen atoms. The silicon-carbon material is used for the battery, and can synchronously improve the cycle stability and the rate capability of the battery, the first coulombic efficiency and the battery capacity.

Inventors

  • ZHENG YA
  • WANG GENQING
  • DENG QIJIU

Assignees

  • 宁波容百新能源科技股份有限公司

Dates

Publication Date
20260512
Application Date
20260330

Claims (12)

  1. 1. A silicon-carbon material comprising a silicon-carbon matrix comprising a carbon skeleton, silicon particles attached to at least a portion of the surface and/or at least a portion of the pores of the carbon skeleton; Wherein the carbon skeleton comprises carbon atoms, electron-deficient hetero atoms and oxygen atoms; The electron-deficient hetero atoms comprise doped hetero atoms and interface hetero atoms, wherein the doped hetero atoms replace at least part of carbon lattice sites, and the interface hetero atoms are bonded with carbon atoms and oxygen atoms.
  2. 2. The silicon-carbon material as claimed in claim 1, wherein the pores of the carbon skeleton have an average pore diameter of 1 to 4nm.
  3. 3. The silicon-carbon material according to claim 1 or 2, wherein the mass percentage of the electron-deficient hetero atoms is 0.1% -5% based on the carbon skeleton; and/or, based on the electron-deficient heteroatom, the doped heteroatom is 20-50% by mass and the interface heteroatom is 50-80% by mass; and/or the electron-deficient heteroatom includes at least one of a boron atom, an aluminum atom, a gallium atom, an indium atom, and a thallium atom.
  4. 4. A silicon-carbon material as claimed in any one of claims 1 to 3 wherein the sphericity of the silicon-carbon material is greater than or equal to 0.85; And/or the specific surface area of the carbon skeleton is 1600-2200 m 2 /g, and the pore volume is more than or equal to 0.7cm 3 /g; And/or the compressive strength of the silicon carbon material is greater than 500Gpa.
  5. 5. The silicon-carbon material as recited in any one of claims 1 to 4, further comprising a carbon coating layer coating at least part of the surface of the carbon skeleton and the surface of the silicon particles; the thickness of the carbon coating layer is 1 nm-15 nm; and/or, the Dv50 of the silicon particles is 1nm to 30nm; And/or at least part of the silicon particles comprises a plurality of silicon grains, the silicon grains having a size <1nm.
  6. 6. The silicon-carbon material according to claim 5, wherein the mass percentage of the silicon particles is 40% -60% based on the sum of the mass of the carbon coating layer, the carbon skeleton and the silicon particles.
  7. 7. The silicon-carbon material as claimed in claim 6, wherein the specific surface area of the silicon-carbon material is 1m 2 /g~10m 2 /g.
  8. 8. A method for producing the silicon carbon material as defined in any one of claims 1 to 7, comprising the steps of: 1) Carrying out hydrothermal reaction on a first reaction system comprising a carbon source and an electron-deficient heteroatom source, and separating to obtain a first precursor; 2) Performing pore-forming treatment on the first precursor by using an activation system comprising carbon dioxide and/or water vapor to obtain a carbon skeleton; 3) Enabling a second reaction system comprising the carbon skeleton and a silicon source to perform deposition reaction to obtain a silicon-carbon material; wherein the carbon source and/or the electron-deficient heteroatom source comprises an oxygen atom.
  9. 9. The method according to claim 8, wherein the mass ratio of the carbon source to the electron-deficient heteroatom source is 3:1 to 1:3; And/or the temperature of the hydrothermal reaction is 150-250 ℃ and the time is 5-20 hours; And/or the temperature of the pore-forming treatment is 800-1200 ℃ and the time is 1-5 h; And/or the temperature of the deposition reaction is 450-550 ℃, the time is 1-10 h, and the flow is 5-20L/h.
  10. 10. The production method according to claim 8 or 9, characterized by further comprising subjecting the silicon-carbon material to a carbon coating treatment; the carbon coating treatment comprises a first coating treatment and a second coating treatment; wherein the flow rate of the first coating treatment is 1-10L/h, the temperature is 550-750 ℃ and the time is 1-10h; and/or the flow rate of the second coating treatment is 1-10L/h, the temperature is 550-750 ℃ and the time is 1-10h.
  11. 11. A negative electrode sheet comprising a negative electrode active layer, wherein the negative electrode active layer comprises the silicon-carbon material according to any one of claims 1 to 7 or the silicon-carbon material produced by the production method according to any one of claims 8 to 10.
  12. 12. A battery comprising the negative electrode sheet according to claim 11.

Description

Silicon-carbon material, preparation method thereof, negative plate and battery Technical Field The invention relates to the field of secondary batteries, in particular to a silicon-carbon material and a preparation method thereof, a negative plate and a battery. Background Batteries are widely regarded as one of the mainstream energy storage devices in society. The cathode material is used as a key component of the battery, and has direct influence on the performance of the battery. The theoretical capacity of graphite materials as traditional negative electrode materials is low, and the development requirements of the current electric automobile or intelligent power grid cannot be met, so that the negative electrode materials with higher capacity are needed to realize batteries with higher energy density. Silicon is the anode material with the highest known capacity at present, the theoretical specific capacity of the anode material is up to 4200mAh/g, and the anode material is one of the best anode materials for developing high-energy-density batteries at present. However, the silicon anode material can generate huge volume change in the charge and discharge process, and the change can cause material structure damage and particle pulverization, thereby causing rapid attenuation of electrode capacity and electrode failure. The silicon material and the carbon material are compounded to prepare the silicon-carbon material, so that the advantages of the silicon material and the carbon material can be fused. However, the existing silicon-carbon material cannot well balance the relationship among the cycle stability, the rate capability, the battery capacity and the first coulombic efficiency, so that a novel silicon-carbon material needs to be explored, and the cycle stability, the rate capability, the first coulombic efficiency and the battery capacity of the battery are synchronously improved. Disclosure of Invention The invention provides a silicon-carbon material which can synchronously improve the cycle stability, the multiplying power performance, the first coulombic efficiency and the battery capacity of a battery after being used for the battery. The invention provides a preparation method of a silicon-carbon material, which can synchronously improve the cycle stability, the multiplying power performance, the first coulombic efficiency and the battery capacity of a battery after the silicon-carbon material prepared by the preparation method is used for the battery. The invention provides a negative plate which comprises the negative material and is used for synchronously improving the cycle stability, the multiplying power performance, the first coulombic efficiency and the battery capacity of a battery after the battery is used. The invention provides a battery, which comprises the negative plate and has excellent cycle stability, rate capability, first coulombic efficiency and capacity. In one aspect, the invention provides a silicon-carbon material comprising a silicon-carbon matrix comprising a carbon skeleton, silicon particles attached to at least a portion of the surface and/or at least a portion of the pores of the carbon skeleton; Wherein the carbon skeleton comprises carbon atoms, electron-deficient hetero atoms and oxygen atoms; The electron-deficient hetero atoms comprise doped hetero atoms and interface hetero atoms, wherein the doped hetero atoms replace at least part of carbon lattice sites, and the interface hetero atoms are bonded with carbon atoms and oxygen atoms. A silicon carbon material as described above, wherein the pores of the carbon skeleton have an average pore diameter of 1 to 4nm. The silicon carbon material is characterized in that the mass percentage of the electron-deficient hetero atoms is 0.1% -5% based on the carbon skeleton; and/or, based on the electron-deficient heteroatom, the doped heteroatom is 20-50% by mass and the interface heteroatom is 50-80% by mass; and/or the electron-deficient heteroatom includes at least one of a boron atom, an aluminum atom, a gallium atom, an indium atom, and a thallium atom. The sphericity of the silicon-carbon material is more than or equal to 0.85; And/or the specific surface area of the carbon skeleton is 1600-2200 m 2/g, and the pore volume is more than or equal to 0.7cm 3/g; And/or the compressive strength of the silicon carbon material is greater than 500Gpa. The silicon-carbon material as described above, further comprising a carbon coating layer coated on at least part of the surface of the carbon skeleton and the surface of the silicon particles; the thickness of the carbon coating layer is 1 nm-15 nm; and/or, the Dv50 of the silicon particles is 1nm to 30nm; And/or at least part of the silicon particles comprises a plurality of silicon grains, the silicon grains having a size <1nm. According to the silicon-carbon material, the mass percentage of the silicon particles is 40% -60% based on the sum of the mass of the carbon