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CN-121983515-A - Composite negative electrode, preparation method thereof and solid-state lithium metal battery

CN121983515ACN 121983515 ACN121983515 ACN 121983515ACN-121983515-A

Abstract

The invention provides a composite negative electrode, a preparation method thereof and a solid-state lithium metal battery, and particularly relates to the technical field of lithium batteries. The composite anode comprises a porous polymer substrate, wherein a first functional layer and a second functional layer are oppositely arranged on two sides of the porous polymer substrate, a lithium metal layer is further arranged on the outer side of the first functional layer in the direction away from the porous polymer substrate, the first functional layer is made of magnesium halide and a lithium-containing compound, and the second functional layer has an interface wetting function. The invention totally abandons the metal current collector, uses the functionalized substrate as both a carrier and a current collector, greatly reduces the ratio of inactive components, and effectively enhances the cycle life, the coulomb efficiency and the mass/volume energy density while improving the dynamic performance of an interface.

Inventors

  • YAN JINGKUN
  • Weng Zihang
  • BU SHAONING
  • WU JUNWEI
  • WENG WEIJIA

Assignees

  • 江苏英联复合集流体有限公司

Dates

Publication Date
20260505
Application Date
20260228

Claims (11)

  1. 1. The composite anode is characterized by comprising a porous polymer substrate, wherein a first functional layer and a second functional layer are oppositely arranged on two sides of the porous polymer substrate, and a lithium metal layer is arranged on the outer side of the first functional layer in the direction away from the porous polymer substrate; The material of the first functional layer comprises magnesium halide and a lithium-containing compound, and the second functional layer has an interface wetting function.
  2. 2. The composite anode according to claim 1, wherein the lithium-containing compound comprises at least one of Li 2 O、Li 2 C 2 O 4 、Li 3 N; And/or, the magnesium halide comprises MgF 2 ; and/or the material of the second functional layer comprises TiO 2 .
  3. 3. The composite anode according to claim 1, further comprising an alumina layer, wherein the alumina layer is independently disposed between the porous polymer substrate and the first functional layer, and between the porous polymer substrate and the second functional layer.
  4. 4. The composite anode according to claim 3, wherein at least one of the following conditions is satisfied: (1) The thickness of the porous polymer substrate is 10-19 mu m; (2) The thickness of the aluminum oxide layer is 1-3 mu m; (3) The thickness of the first functional layer is 50-500 nm, preferably 80-150 nm; (4) The thickness of the second functional layer is 20-200 nm, preferably 50-100 nm; (5) The thickness of the lithium metal layer is 1-50 mu m.
  5. 5. The composite negative electrode according to any one of claims 1 to 4, wherein the atomic percentage of Mg to Li in MgF 2 and Li 2 O is (30 to 50): (70 to 50); and/or the porous polymer substrate is made of PP, PE or PI.
  6. 6. A method for preparing a composite anode according to any one of claims 1 to 5, wherein a first functional layer and a second functional layer are formed on a porous polymer substrate with aluminum oxide on both sides by vapor deposition, and finally metal lithium is evaporated on the first functional layer in a vacuum manner to obtain the composite anode; wherein the vapor deposition includes chemical vapor deposition and physical vapor deposition.
  7. 7. The method of claim 6, wherein the sputtering power is 150-250 w for 5-50 min during the deposition of the first functional layer; and/or in the process of depositing the second functional layer, the sputtering power is 100-200W, and the time is 4-40 min.
  8. 8. The method according to claim 6, wherein the vacuum evaporation process is performed at 500-650 ℃ for 4-20 min.
  9. 9. The method according to any one of claims 6 to 8, further comprising a process of cleaning the porous polymer substrate coated with alumina on both sides thereof before sputtering starts; And/or the cleaning mode is plasma cleaning; And/or the plasma cleaning uses a mixed gas of argon and oxygen; And/or, in the mixed gas, the volume ratio of argon to oxygen is (3-6): 1; and/or the power of the plasma cleaning is 40-80W, and the time is 30-90 s.
  10. 10. The solid lithium metal battery is characterized by comprising a positive electrode, a solid electrolyte layer and a composite negative electrode which are sequentially laminated; The composite negative electrode is prepared by the preparation method of any one of claims 1-5 or 6-9, and the second functional layer is arranged in a direction of approaching the solid electrolyte layer and the first functional layer is away from the solid electrolyte layer.
  11. 11. An electrical device comprising the solid state lithium metal battery of claim 10.

Description

Composite negative electrode, preparation method thereof and solid-state lithium metal battery Technical Field The invention relates to the technical field of lithium batteries, in particular to a composite negative electrode, a preparation method thereof and a solid-state lithium metal battery. Background Solid-state batteries are widely regarded as the core development direction for the next generation of electrochemical energy storage technology. Compared with the traditional liquid lithium ion battery, the solid electrolyte is adopted to replace inflammable and volatile organic liquid electrolyte, and has the remarkable advantages in the aspects of safety, energy density, structural integration level and the like, on one hand, the solid electrolyte has high mechanical modulus and intrinsic electronic insulation, can effectively inhibit penetration growth of lithium dendrites, can block an electronic conduction path, fundamentally reduces internal short circuit risks, on the other hand, the solid electrolyte does not need to be provided with a traditional porous diaphragm and liquid infiltration system, can realize more compact cell structural design, and accordingly improves energy density of the battery under the same volume or mass constraint, and meets urgent requirements of long-endurance electric vehicles and large-scale energy storage power stations on high specific energy, high safety and long service life power supply systems. However, since lithium metal undergoes a drastic volume change during charge and discharge, and the rigid solid electrolyte inside the battery is difficult to dynamically adapt to the deformation, the solid-solid interface contact of the lithium metal anode/solid electrolyte is continuously deteriorated during the cycle, and the industrialization of the solid battery still faces a key interface bottleneck. In view of this, the present invention has been made. Disclosure of Invention In the prior art, in order to alleviate the solid-solid interface contact problem of the lithium metal negative electrode/solid electrolyte, an artificial interface layer is generally introduced at the lithium metal negative electrode side, but the scheme focuses on a single functional dimension, and is difficult to cooperatively consider multiple indexes such as high ion conductivity, excellent mechanical modulus, electrochemical/chemical stability, interface wettability, process compatibility and the like. More importantly, the current mainstream structure still depends on traditional metal current collectors such as copper foil or nickel foil to bear lithium metal, and the current mainstream structure has no ion conduction capability and high mass/volume ratio, so that the further improvement of the mass energy density and the volume energy density of the full battery is severely restricted. The invention aims to provide a composite negative electrode, a preparation method thereof and a solid-state lithium metal battery, and aims to solve the problem of solid-solid interface contact of the lithium metal negative electrode/solid electrolyte. In order to achieve the above object of the present invention, the following technical solutions are specifically adopted: the first aspect of the invention provides a composite anode, which comprises a porous polymer substrate, wherein a first functional layer and a second functional layer are oppositely arranged on two sides of the porous polymer substrate, a lithium metal layer is arranged on the outer side of the first functional layer in the direction away from the porous polymer substrate, the material of the first functional layer comprises magnesium halide and a lithium-containing compound, and the second functional layer has an interface wetting function. Further, the lithium-containing compound includes at least one of Li 2O、Li2C2O4、Li3 N. And/or, the magnesium halide comprises MgF 2. And/or the material of the second functional layer comprises TiO 2. Further, the composite anode further comprises an alumina layer, and the alumina layer is independently arranged between the porous polymer substrate and the first functional layer and between the porous polymer substrate and the second functional layer. Further, the composite anode satisfies at least one of the following conditions: (1) The thickness of the porous polymer substrate is 10-19 mu m; (2) The thickness of the aluminum oxide layer is 1-3 mu m; (3) The thickness of the first functional layer is 50-500 nm, preferably 80-150 nm; (4) The thickness of the second functional layer is 20-200 nm, preferably 50-100 nm; (5) The thickness of the lithium metal layer is 1-50 mu m. Further, in MgF 2 and Li 2 O, the atomic percentage of Mg and Li is (30-50): (70-50). And/or the porous polymer substrate is made of PP, PE or PI. The second aspect of the invention provides a preparation method of the composite anode, wherein a first functional layer and a second functional layer are formed on a porous pol