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CN-122025646-A - Sodium-philic modified current collector, preparation method thereof and negative-electrode-free sodium metal battery

CN122025646ACN 122025646 ACN122025646 ACN 122025646ACN-122025646-A

Abstract

The invention relates to the technical field of sodium metal batteries, in particular to a sodium-philic modified current collector, a preparation method thereof and a negative-electrode-free sodium metal battery using the modified current collector. The modified current collector is formed by constructing a layer of coating which is formed by taking graphene as an active component and aluminum dihydrogen phosphate as an inorganic binder on the surface of a conductive substrate. The aluminum dihydrogen phosphate is subjected to in-situ dehydration condensation in the electrode drying process to form a high-modulus three-dimensional inorganic cross-linked network, so that on one hand, the high-modulus three-dimensional inorganic cross-linked network is combined with graphene to generate a strong interface, and on the other hand, the coating is endowed with extremely high rigidity. The coating can obviously reduce nucleation overpotential of sodium deposition, guide uniform deposition of sodium, and effectively inhibit volume change and sodium dendrite growth in the circulation process. Research shows that the modified current collector can improve the first coulombic efficiency and the cycle life of the non-negative sodium metal battery.

Inventors

  • WANG HAIYAN
  • ZHU XIAOXIAO
  • ZHANG RUI
  • WANG PEIYU
  • QIU TIAN
  • SU YUEJIN

Assignees

  • 衢州东峰新材料集团股份有限公司

Dates

Publication Date
20260512
Application Date
20260207

Claims (10)

  1. 1. The sodium-philic modified current collector is characterized by comprising a conductive substrate and a modified coating arranged on the surface of the conductive substrate, wherein the modified coating comprises graphene and aluminum dihydrogen phosphate.
  2. 2. The sodium-philic modified current collector of claim 1, wherein graphene is an active functional component of a sodium-philic matrix in the modified coating, aluminum dihydrogen phosphate is an adhesive, and the mass ratio of the graphene to the aluminum dihydrogen phosphate in the modified coating is (80-95) to (5-20).
  3. 3. The sodium-philic modified current collector of claim 1, wherein the dry film thickness of the modified coating is 1-40 μm.
  4. 4. The sodium-philic modified current collector of claim 1, wherein the modified coating is loaded on the conductive substrate at a rate of 0.1-1 mg/cm 2 .
  5. 5. A sodium-philic modified current collector as in any of claims 1-4, wherein the conductive substrate is a planar foil or a three-dimensional porous material and is made of at least one of copper, aluminum, and titanium.
  6. 6. A method for preparing a sodium-philic modified current collector as defined in any one of claims 1 to 5, comprising the steps of mixing graphene powder and aluminum dihydrogen phosphate powder according to a certain mass ratio, adding deionized water, stirring uniformly to obtain coating slurry, coating the coating slurry on the surface of a conductive substrate, controlling the coating wet thickness to be 15-80 mu m, and drying and rolling the conductive substrate coated with the coating slurry to obtain the sodium-philic modified current collector.
  7. 7. The method for preparing the sodium-philic modified current collector as claimed in claim 6, wherein when the graphene powder and the aluminum dihydrogen phosphate powder are mixed and added into deionized water for stirring, a magnetic stirrer with an ultrasonic dispersion function is used for stirring for 6-8 hours, and during stirring, ultrasonic dispersion is performed for 30-60 minutes by using 300-500W power until uniform and particle-free stable slurry is formed, so that the coating slurry is obtained.
  8. 8. The method for preparing a sodium-philic modified current collector as claimed in claim 6, wherein the solid content of the coating slurry is kept at 5-15%.
  9. 9. The method for preparing the sodium-philic modified current collector as claimed in claim 6, wherein when the conductive substrate coated with the coating slurry is dried, the conductive substrate is placed in a vacuum drying oven at 60-80 ℃ to be dried for 6-12 hours, so that the water content of the modified coating after drying is ensured to be less than or equal to 0.5%.
  10. 10. A non-negative sodium metal battery comprises a positive electrode, a diaphragm and a negative electrode current collector which are sequentially compounded, and is characterized in that the negative electrode current collector adopts the sodium-philic modified current collector as set forth in any one of claims 1-5.

Description

Sodium-philic modified current collector, preparation method thereof and negative-electrode-free sodium metal battery Technical Field The invention relates to the technical field of sodium metal batteries, in particular to a sodium-philic modified current collector, a preparation method thereof and a negative-electrode-free sodium metal battery using the modified current collector. Background In the global energy transformation context, high energy density and low cost energy storage technologies are becoming industry core demands. The negative electrode-free sodium metal battery omits the traditional sodium metal negative electrode, only keeps the current collector as a sodium deposition substrate, not only greatly improves the energy density and reduces the production cost, but also solves the problems of high reactivity, uncontrolled volume expansion and the like of the traditional sodium metal battery. However, the technology has the core bottleneck that the negative electrode current collector (such as copper foil) has insufficient sodium affinity, and the combination of an active component and the current collector depends on a traditional binder, so that dendrite growth, dead sodium accumulation, solid Electrolyte Interface (SEI) film rupture and recombination easily occur during sodium deposition, the problems of low coulomb efficiency, short cycle life and the like are caused, the commercialization process is severely restricted, and therefore, the breakthrough of the performance bottleneck through the modification of the current collector is needed. The surface modification of the current collector is a key path for solving the problems, and the prior art forms various functional coating schemes, but the schemes or emphasis on improving the sodium affinity or focusing on the basic combination of the coating, but multi-performance coordination is not realized, so that the comprehensive requirements of the sodium affinity, the binding force and the mechanical stability are difficult to be simultaneously met. For example, chinese patent publication No. CN120600829a discloses a current collector of a non-negative sodium ion battery and application thereof, a non-negative sodium ion battery, the concrete current collector comprises a substrate and a coating layer, the coating layer is composed of porous nitrogen-doped carbon particles loaded with fluorine-containing sodium salt and a metal catalyst, and the surface of the coating layer is coated with a polymer, chinese patent publication No. CN119447322a discloses a modified current collector of a non-negative sodium ion battery and preparation method and application thereof, the concrete preparation method is adding transition metal salt in the preparation process of polypyrrole to regulate nitrogen doping type in polypyrrole-derived nitrogen-doped nano carbon particles, for example, chinese patent publication No. CN118919734A discloses a negative current collector of a non-negative sodium metal battery, preparation method and application thereof, the concrete current collector comprises a substrate and a coating material arranged on the surface of the substrate, the coating material is a composite material of graphite, a carbon nanotube and a binder, and chinese patent publication No. CN114843524A discloses a modified current collector and a modified current collector comprising the concrete modified current collector of the modified current collector and the concrete sodium-doped current collector embedded with sodium metal is coated on the surface of the substrate. In the prior art, the fixation of active components is mostly dependent on traditional binders such as sodium carboxymethyl cellulose, polyvinylidene fluoride and the like, meanwhile, the active components are relatively single in selection, and the binders have common inherent defects, for example, sodium carboxymethyl cellulose is easy to cause uneven dispersion of the active components, the compatibility of the polyvinylidene fluoride, the active components and a conductive substrate is insufficient to promote agglomeration, the two have the problems of weak binding force and lack of elastic buffering, and the two cannot adapt to volume change in the sodium deposition/stripping process, and the sodium affinity and conductivity difference of different active components are obvious and directly influence the performance of a battery. Therefore, developing a current collector coating that can simultaneously provide excellent sodium affinity, strong binding force, and high mechanical stability to improve the problems of low initial coulombic efficiency, short cycle life, etc. of a battery is a key to promoting the practical use of a negative-electrode-free sodium metal battery. Disclosure of Invention Aiming at the problems faced by the existing negative electrode current collector of the non-negative electrode sodium metal battery, the primary aim of the invention is to provide a modifie