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CN-122025661-A - Composite coating modified current collector for magnesium secondary battery and preparation method

CN122025661ACN 122025661 ACN122025661 ACN 122025661ACN-122025661-A

Abstract

The invention discloses a composite coating modified current collector for a magnesium secondary battery and a preparation method thereof, wherein a copper foil is used as a matrix, the surface of the matrix is coated with a composite coating, the composite coating comprises, by mass, 70-90 parts of magnesium boron compounds, 5-20 parts of polyphosphazene nanofibers and 5-10 parts of polyvinylidene fluoride, the current collector is prepared by firstly preparing the magnesium boron compounds through high-temperature high-pressure pressing, then adding the magnesium boron compounds, the polyphosphazene nanofibers and the polyvinylidene fluoride into a polyvinylpyrrolidone solvent, mixing, dispersing and stirring the magnesium boron compounds, the polyphosphazene nanofibers and the polyvinylidene fluoride into uniform slurry, and then coating the obtained slurry on the surface of a copper foil substrate, and drying the copper foil substrate.

Inventors

  • PENG QIUMING
  • ZOU GUODONG
  • WANG JINMING
  • SUN YONG

Assignees

  • 燕山大学

Dates

Publication Date
20260512
Application Date
20260327

Claims (7)

  1. 1. The composite coating modified current collector for the magnesium secondary battery is characterized in that the current collector takes copper foil as a substrate, the surface of the substrate is coated with a composite coating, and the composite coating comprises, by mass, 70-90 parts of magnesium boron compounds, 5-20 parts of polyphosphazene nanofibers and 5-10 parts of polyvinylidene fluoride.
  2. 2. The composite coating modified current collector for magnesium secondary battery according to claim 1, wherein the magnesium boron compound is one of MgB 2 、MgB 4 or MgB 12 .
  3. 3. The method for preparing a composite coating modified current collector for a magnesium secondary battery according to claim 1 or 2, wherein the steps are sequentially performed in the following order: s1, preparing magnesium boron compound powder, namely mixing magnesium powder and boron powder according to stoichiometric ratio, placing the mixture in a hexahedral press for high-temperature and high-pressure treatment, and cooling the mixture to room temperature after the reaction is finished to obtain a block product; S2, preparing composite slurry, namely uniformly mixing magnesium boron compound powder, polyphosphazene nanofiber and polyvinylidene fluoride, dispersing the mixed material in a polyvinylpyrrolidone organic solvent, and stirring to obtain composite slurry; s3, preparing the composite coating modified current collector for the magnesium secondary battery, namely uniformly coating the composite slurry obtained in the step S2 on the surface of the copper foil in a scraper coating mode, and drying in a vacuum oven to obtain the composite coating modified current collector for the magnesium secondary battery.
  4. 4. The method for preparing a composite coating modified current collector for a magnesium secondary battery according to claim 3, wherein in the step S1, the temperature is 500-1000 ℃ during the high-temperature high-pressure treatment, the pressure is 1-5 GPa, and the heat preservation time is 30 min.
  5. 5. The method for preparing a composite coating modified current collector for a magnesium secondary battery according to claim 3, wherein in the step S2, the stirring speed is 1000-1500 rpm, and the time is 10-30 min.
  6. 6. The method for preparing a composite coating modified current collector for a magnesium secondary battery according to claim 3, wherein in the step S3, the thickness of the composite coating on the surface of the copper foil is 10-100 μm.
  7. 7. The method for preparing a composite coating modified current collector for a magnesium secondary battery according to claim 3, wherein in the step S3, the temperature at the time of drying is 80 ℃ and the time is 12 h.

Description

Composite coating modified current collector for magnesium secondary battery and preparation method Technical Field The invention belongs to the field of preparation of current collector materials, and relates to a composite coating modified current collector for a magnesium secondary battery and a preparation method thereof. Background With the continuous increase of the global demand for high-energy-density energy storage systems and sustainable utilization of resources, research on new secondary battery systems is receiving a great deal of attention. Magnesium metal secondary batteries are considered as one of the new generation energy storage systems with important development potential after lithium ion batteries because of the advantages of higher volume specific capacity (about 3833 mAh cm -3), lower reduction potential (-2.37 vvs. She), good safety performance, rich magnesium resource reserves, low cost and the like of magnesium metal. However, the magnesium metal secondary battery is still in an early stage of development at present, and practical application and industrial development thereof are limited by various key technical problems. The problem that the deposition behavior of the magnesium metal anode is difficult to effectively regulate and control in the charge and discharge process is one of the core problems for limiting the performance improvement of the magnesium metal anode. In the electrochemical deposition process, magnesium ions often show non-uniform nucleation and non-uniform growth phenomena on the surface of a current collector, so that the magnesium deposition morphology is rough or locally agglomerated, which not only can cause fluctuation of the effective reaction area of the surface of an electrode and increase polarization and interface impedance, but also can cause local current density concentration, further aggravate the non-uniform deposition phenomena, thereby causing capacity attenuation and coulomb efficiency reduction in the battery cycle process. In addition, magnesium metal has higher chemical activity in most traditional electrolyte systems, and is easy to generate side reaction with electrolyte solvents or electrolyte anions, so that a compact passivation film is formed on the surface of the electrode. Unlike the solid electrolyte interface film (SEI) common in lithium ion batteries, the passivation film generally exhibits electronic insulation and poor conductivity to Mg 2+, thereby severely impeding the reversible deposition and dissolution process of magnesium ions, resulting in an increase in electrode interface charge transfer resistance, slow deposition/stripping reaction kinetics, and ultimately, significant limitations in battery cycling stability and rate capability. In response to the above problems, researchers have recently proposed improving magnesium deposition behavior by modulating the electrode structure or interface. Among them, the functional modification of the surface of the current collector is considered as an effective strategy which has a simple structure, low cost and easy realization of large-scale application. The method generally adjusts the local electric field distribution of the electrode surface and the transmission path of magnesium ions by constructing a functional layer with specific physicochemical properties, such as a conductive framework layer, an ion transmission layer or a magnesium-philic interface layer on the surface of a current collector, so as to reduce the nucleation overpotential of magnesium deposition and promote uniform nucleation and deposition of magnesium ions on the electrode surface, for example, the document Advanced Functional Materials, 2025, 36:e 15655 modifies the copper current collector through CuTU compound to improve the magnesium metal deposition behavior and the battery cycle stability, and the Cu + -thiourea compound can provide active sites to promote desolvation of the Mg 2+ and reduce the nucleation barrier, but the method involves multi-step coordination reaction, has complex process and high ligand cost and is difficult to produce in a large scale. Document Nano Letters, 2022, 22:6808-6815 reports a method for depositing magnesium-philic gold nanoparticles on the surface of a copper foil, wherein an Au-Cu composite interface is constructed on the surface of the copper foil, and the gold nanoparticles are used for regulating an electric field and providing nucleation sites, so that the magnesium deposition uniformity and coulomb efficiency are improved. However, the system uses noble metals, the nano particles are complicated to prepare, the cost is high, and the large-scale application is limited. Chinese patent application No. CN120033313a discloses a magnesium metal battery based on conductive composite current collector and its electric device, a negative electrode active layer is arranged on the surface of the current collector, but large-size solid phase particles in the coating are