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CN-122025588-A - Integrated silicon-based lithium ion battery negative electrode material and preparation method thereof

CN122025588ACN 122025588 ACN122025588 ACN 122025588ACN-122025588-A

Abstract

The invention relates to the technical field of electrochemical energy storage materials, and particularly discloses an integrated silicon-based lithium ion battery anode material and a preparation method thereof. The anode material is formed by partially etching monocrystalline silicon pieces, the monocrystalline silicon interlayer is formed by unetched monocrystalline silicon, the nano porous silicon layer is formed by etched nano porous silicon, and the monocrystalline silicon interlayer and the nano porous silicon layer form an integrated homobody with a continuous crystal structure. The invention has the advantages of obviously improving electrochemical performance, cycle stability, manufacturing process, energy density, reliability and the like through the combination of structural innovation and material intrinsic advantages.

Inventors

  • RONG GUOGUANG
  • YIN YANAN

Assignees

  • 北京兴炎科技有限公司

Dates

Publication Date
20260512
Application Date
20260210

Claims (10)

  1. 1. The integrated silicon-based lithium ion battery cathode material is characterized by comprising a monocrystalline silicon interlayer and nano porous silicon layers positioned on two opposite surfaces of the monocrystalline silicon interlayer; the negative electrode material is formed by partially etching monocrystalline silicon pieces, the monocrystalline silicon interlayer is formed by unetched monocrystalline silicon, and the nano porous silicon layer is formed by etched nano porous silicon.
  2. 2. The integrated silicon-based lithium ion battery anode material of claim 1, wherein the monocrystalline silicon interlayer and the nanoporous silicon layer are formed by partial etching of the same monocrystalline silicon piece.
  3. 3. The integrated silicon-based lithium ion battery anode material according to claim 1, wherein the monocrystalline silicon piece is an n + type monocrystalline silicon piece or a p + type monocrystalline silicon piece, the resistivity is 0.005 Ω -cm to 0.02 Ω -cm, and the thickness is 25 μm to 200 μm.
  4. 4. The integrated silicon-based lithium ion battery anode material according to claim 1, wherein the thickness of the nano porous silicon layer is 10-50 μm, the porosity is 30-80%, and the thickness of the single crystal silicon interlayer is 50-130 μm.
  5. 5. The integrated silicon-based lithium ion battery anode material of claim 1, wherein the surface of the nanoporous silicon layer further comprises a passivation layer, the passivation layer being at least one of a natural oxide layer, a thermal oxide layer, and an atomic layer deposition coating.
  6. 6. The integrated silicon-based lithium ion battery anode material according to claim 5, wherein the passivation layer has a thickness of 2 nm-5 nm.
  7. 7. A method for preparing the integrated silicon-based lithium ion battery anode material according to any one of claims 1-6, which is characterized by comprising the following steps: pretreating a monocrystalline silicon wafer; Etching the two sides of the pretreated monocrystalline silicon piece, and forming nano porous silicon layers on the two surface areas of the monocrystalline silicon piece; and (3) by controlling etching time, reserving an unetched monocrystalline silicon interlayer in the middle area of the monocrystalline silicon wafer, and obtaining the anode material.
  8. 8. The method for preparing the negative electrode material of the integrated silicon-based lithium ion battery according to claim 7, wherein the etching adopts electrochemical anodic oxidation etching or metal-assisted chemical etching.
  9. 9. The method for preparing the integrated silicon-based lithium ion battery anode material according to claim 8, wherein the etching time is 12.5 minutes to 62.5 minutes when electrochemical anodic oxidation etching is adopted.
  10. 10. A lithium ion battery characterized by comprising the integrated silicon-based lithium ion battery anode material according to any one of claims 1 to 6.

Description

Integrated silicon-based lithium ion battery negative electrode material and preparation method thereof Technical Field The invention relates to the technical field of electrochemical energy storage materials, in particular to an integrated silicon-based lithium ion battery anode material and a preparation method thereof. Background With the rapid development of electric vehicles and portable electronic devices, there is an increasing demand for lithium ion batteries with high energy density, long cycle life, and low cost. The theoretical specific capacity of the traditional graphite cathode is only 372mAh/g, which is close to the performance limit, and the requirements of the next-generation battery are difficult to meet. Silicon (Si) is considered to be one of the most potential negative electrode materials to replace graphite because of its theoretical specific capacity of up to 4200 mAh/g. However, silicon undergoes more than 300% volume expansion during charge and discharge, resulting in pulverization of materials, cracking of electrode structures, and initiation of repeated cracking and regeneration of Solid Electrolyte Interfaces (SEI), resulting in rapid capacity decay. The main stream solution at present comprises nano silicon particles, a porous silicon structure, a silicon-carbon composite material, a core-shell structure and the like, but the problems of high cost and high energy consumption exist in the methods that most of the methods are powder materials, the powder materials are coated on a copper foil current collector through a binder, extra interface resistance is introduced, the active materials are unstable in contact with the current collector and easy to fall off in a circulating process, the preparation process is complex, the steps of slurry stirring, coating, drying, rolling, slitting and the like are involved, and the problem of electrochemical mismatch exists in a heterogeneous interface (such as Si/Cu) to influence the electron transmission efficiency. Therefore, development of a novel silicon-based negative electrode structure is needed, which can not only relieve volume expansion, but also eliminate interface impedance in the traditional electrode, simplify the manufacturing process and reduce the production cost. Disclosure of Invention In order to solve the technical problems, the invention provides an integrated silicon-based lithium ion battery anode material and a preparation method thereof. The method is characterized in that a nano porous silicon layer is constructed on two sides of a monocrystalline silicon wafer, and an intermediate unetched monocrystalline silicon interlayer is reserved as a full-silicon negative electrode of a self-supporting current collector. In order to achieve the above object, the present invention provides the following technical solutions: In a first aspect, the invention provides an integrated silicon-based lithium ion battery anode material, which comprises a monocrystalline silicon interlayer and a nano porous silicon layer positioned on two opposite surfaces of the monocrystalline silicon interlayer; The negative electrode material is formed by partially etching monocrystalline silicon pieces, the monocrystalline silicon interlayer is formed by unetched monocrystalline silicon, the nano porous silicon layer is formed by etched nano porous silicon, and the monocrystalline silicon interlayer and the nano porous silicon layer form an integrated homogeneous body with a continuous crystal structure. Optionally, the monocrystalline silicon interlayer and the nano-porous silicon layer are formed by partially etching the same monocrystalline silicon piece. Optionally, the monocrystalline silicon piece is an n + type monocrystalline silicon piece or a p + type monocrystalline silicon piece, the resistivity is 0.005 Ω & cm-0.02 Ω & cm, and the thickness is 25 μm-200 μm. Optionally, the thickness of the nano porous silicon layer is 10-50 μm, the porosity is 30-80%, the pore diameter is 20-120 nm, and the thickness of the monocrystalline silicon interlayer is 50-130 μm. Optionally, the surface of the nano-porous silicon layer further comprises a passivation layer, wherein the passivation layer is at least one of a natural oxide layer, a thermal oxide layer and an atomic layer deposition coating layer. Optionally, the passivation layer has a thickness of 2nm to 5nm. In a second aspect, the invention also provides a preparation method of the integrated silicon-based lithium ion battery anode material, which comprises the following steps: pretreating a monocrystalline silicon wafer; Etching the two sides of the pretreated monocrystalline silicon piece, and forming nano porous silicon layers on the two surface areas of the monocrystalline silicon piece; and (3) by controlling etching time, reserving an unetched monocrystalline silicon interlayer in the middle area of the monocrystalline silicon wafer, and obtaining the anode material. Alternatively, the