Search

EP-4156335-B1 - PRE-LITHIATED SILICON NEGATIVE ELECTRODE MATERIAL, SILICON NEGATIVE ELECTRODE PLATE, METHOD FOR PREPARING SAME, AND LITHIUM-ION BATTERY

EP4156335B1EP 4156335 B1EP4156335 B1EP 4156335B1EP-4156335-B1

Inventors

  • GUO, Panlong
  • LI, Suli
  • CHEN, WEIPING
  • CHU, LIN

Dates

Publication Date
20260506
Application Date
20211203

Claims (13)

  1. A pre-lithiated silicon negative electrode material, characterized by , comprising a silicon negative electrode material and a lithium-containing polymer compounded with the silicon negative electrode material, wherein the lithium-containing polymer comprises a polymer shown in the following formula 1: wherein x ranges from 1 to 12, and R1 is: wherein y ranges from 1 to 4; or
  2. The pre-lithiated silicon negative electrode material according to claim 1, characterized in that n in the compound of formula 1 generally ranges from 20 to 10000.
  3. The pre-lithiated silicon negative electrode material according to claim 1 or 2, characterized in that content of the lithium-containing polymer in the pre-lithiated silicon negative electrode material ranges from 0.1 wt% to 20 wt%.
  4. The pre-lithiated silicon negative electrode material according to any one of claims 1 to 3, characterized in that the pre-lithiated silicon negative electrode material is prepared according to a preparation process comprising the following steps: placing the silicon negative electrode material in a solution containing a lithium-containing polymer, and then removing a solvent to obtain the pre-lithiated silicon negative electrode material.
  5. The pre-lithiated silicon negative electrode material according to any one of claims 1 to 4, characterized in that the silicon negative electrode material comprises silicon monoxide or pure silicon.
  6. A method for preparing the pre-lithiated silicon negative electrode material according to any one of claims 1 to 5, characterized in that the silicon negative electrode material is placed in a solution containing a lithium-containing polymer, and then a solvent is removed to obtain the pre-lithiated silicon negative electrode material.
  7. A method for preparing the pre-lithiated silicon negative electrode material according to claim 6, characterized in that the solvent is removed by using a decompression rotary evaporation method to obtain the pre-lithiated silicon negative electrode material.
  8. The preparation method according to claim 6 or 7, characterized in that a mass concentration of the lithium-containing polymer in the solution ranges from 0.1 wt% to 50 wt%.
  9. A pre-lithiated silicon negative electrode plate, characterized by comprising: a negative electrode current collector and a functional layer coated on the negative electrode current collector, wherein a raw material of the functional layer comprises the pre-lithiated silicon negative electrode material according to any one of claims 1 to 5, a conductive agent, and a binder.
  10. The pre-lithiated silicon negative electrode plate according to claim 9, characterized in that content of the pre-lithiated silicon negative electrode material in the raw material of the functional layer ranges from 60 wt% to 90 wt%, and/or content of the conductive agent ranges from 5 wt% to 30 wt%, and/or content of the binder ranges from 5 wt% to 30 wt%.
  11. The pre-lithiated silicon negative electrode plate according to claim 9 or 10, characterized in that in a silicon negative electrode active material including the pre-lithiated silicon negative electrode material and a another negative electrode material, content of the pre-lithiated silicon negative electrode material may range from 3 wt% to 100 wt%.
  12. The method for preparing the pre-lithiated silicon negative electrode plate according to any one of claims 9 to 11, characterized by comprising: coating the negative electrode current collector with slurry containing the raw material of the functional layer to form the functional layer, so as to obtain the pre-lithiated silicon negative electrode plate.
  13. A lithium-ion battery, characterized by being formed by using the pre-lithiated silicon negative electrode plate according to any one of claims 9 to 11.

Description

TECHNICAL FIELD The present disclosure belongs to the field of lithium-ion batteries, and specifically, relates to a pre-lithiated silicon negative electrode material, a silicon negative electrode plate, a method for preparing the same, and a lithium-ion battery. BACKGROUND Lithium-ion batteries have developed rapidly due to their advantages such as high energy densities, long cycle life, and environmental friendliness, and are widely applied to electronic products and electric vehicles. Negative electrode materials of a lithium-ion battery mainly include materials such as alloys, carbon-based materials, Li4Ti5O12, and transition metal compounds, of which a carbon-based graphite negative electrode material is most commonly used. However, this material has a relatively low specific capacity (372 mAh/g) and a relatively large irreversible capacity loss. Consequently, it is difficult for lithium-ion batteries to meet requirements for usage performance, and it is difficult to make breakthroughs in development. Silicon has a relatively high specific capacity (4200 mAh/g) and is rich in resources. Silicon is expected to replace graphite as one of the most promising negative electrode materials for batteries (refer to the literature of Nanoscale, 2016, 8(1): 74-103), and has become a current research hotspot. However, silicon has a relatively large volume expansion (300%) and huge capacity fading during delithiation/intercalation, which directly leads to instability of a solid electrolyte interphase film (SEI film). A stable SEI film is a key factor in prolonging a battery cycle life. In addition, formation and destruction of the SEI film during charging/discharging of a lithium-ion battery continuously consume lithium ions, resulting in low initial Coulombic efficiency and short cycle life of the lithium-ion battery (refer to the literature of Journal of the American Chemical Society, 2016, 138(25):7918-7931). US 2017/294648 A1 teaches the anode of a lithium secondary battery, wherein the anode active material particles comprise at least one of Si, Ge, Sn and A1 and a coating which is at least partly polymeric. In view of the foregoing problems, the most effective method at present is: using a pre-lithiation technology to add a small amount of a lithium source before a formal charge/discharge cycle of an electrode to balance lithium excessively consumed in a reaction, and compensate for cathode lithium consumed during side reaction and SEI film formation processes, so as to increase initial Coulombic efficiency, prolong the battery cycle life, alleviate volume expansion to a specific extent, and improve comprehensive performance, such as stability, of the lithium-ion battery (refer to the literature of Advanced Energy Materials, 2017, 7(17):1602607). At present, most commonly used pre-lithiation methods include pre-lithiation with lithium powder or a metal lithium strip, electrochemical pre-lithiation, mechanical pre-lithiation, and the like. However, these methods commonly have disadvantages such as poor safety and complex operations. Therefore, research and development of a novel, efficient, and safe pre-lithiated material and method to improve performance, such as circularity and stability, of a lithium-ion battery are a still important issue faced by persons skilled in the art. SUMMARY In view of the foregoing technical problems existing in conventional technologies, the present disclosure provides a pre-lithiated silicon negative electrode material, and the material is used as an active material of a silicon negative electrode, which can achieve efficient and safe pre-lithiation of the silicon negative electrode, to improve cycle performance of the silicon negative electrode and increase initial charge/discharge efficiency of a battery, and meanwhile, to improve comprehensive performance, such as circularity and stability, of a lithium-ion battery. The present disclosure further provides a silicon negative electrode plate, which is formed by using the foregoing pre-lithiated silicon negative electrode material, to form a stable film on a surface of the negative electrode, and reduce excessively fast thickening of an SEI film caused by a side reaction of the silicon negative electrode plate during a cycle process, and meanwhile, to alleviate volume expansion of a silicon negative electrode. This helps to form a stable solid electrolyte interphase and prolong cycle life of a battery. The present disclosure further provides a method for preparing the foregoing pre-lithiated silicon negative electrode material and silicon negative electrode plate, so that the foregoing pre-lithiated silicon negative electrode material and silicon negative electrode plate can be prepared. The method is simple, safe, and efficient. The present disclosure further provides a lithium-ion battery, which has qualities such as high initial Coulombic efficiency and battery capacity retention. According to one aspect of the present disclo