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CN-122025606-A - Coated magnesium ion battery positive electrode material and preparation method thereof

CN122025606ACN 122025606 ACN122025606 ACN 122025606ACN-122025606-A

Abstract

The invention discloses a coated magnesium ion battery positive electrode material and a preparation method thereof, wherein the chemical composition expression is A@Mg 1‑ x M x B 4 , wherein x represents an atomic molar ratio, x is more than or equal to 0.1 and less than or equal to 0.2, A is one of Mo 6 S 8 、MoS 2 、MgMn 2 O 4 、MnO 2 、V 2 O 5 、CuS、Cu 2 Se、TiS 2 、TiSe 2 、Mg 0.5 FePO 4 、MgFeSiO 4 , M is one of Al, ti, zn, ni, mn, nb, ga, zr, V, cr, the material is of a core-shell structure and is obtained through instantaneous Joule heat, ball milling and heat treatment, a coating layer of the positive electrode material can inhibit structural collapse and side reaction of the positive electrode material in a circulating process, and can promote ion/electron transmission and reduce impedance, and a magnesium ion battery assembled by the material has higher discharge specific capacity and better circulating stability and multiplying power performance.

Inventors

  • PENG QIUMING
  • ZOU GUODONG
  • WANG JINMING
  • SUN YONG
  • WANG JIREN
  • LI JINYU

Assignees

  • 燕山大学

Dates

Publication Date
20260512
Application Date
20260327

Claims (8)

  1. 1. A coated magnesium ion battery positive electrode material is characterized in that the chemical composition expression of the coated magnesium ion battery positive electrode material is A@Mg 1-x M x B 4 , wherein x represents an atomic molar ratio, x is more than or equal to 0.1 and less than or equal to 0.2, A is one of Mo 6 S 8 、MoS 2 、MgMn 2 O 4 、MnO 2 、V 2 O 5 、CuS、Cu 2 Se、TiS 2 、TiSe 2 、Mg 0.5 FePO 4 、MgFeSiO 4 , and M is one of Al, ti, zn, ni, mn, nb, ga, zr, V, cr.
  2. 2. The coated magnesium ion battery positive electrode material according to claim 1, wherein the coated magnesium ion battery positive electrode material is of a core-shell structure, A is an inner core, mg 1-x M x B 4 is a shell layer coated on the surface of the inner core, and the thickness of the shell layer is 20-50 nm.
  3. 3. The method for preparing the coated magnesium ion battery positive electrode material according to claim 1 or 2, wherein the steps are sequentially performed in the following order: S1, weighing magnesium powder, metal M powder and amorphous boron powder according to a stoichiometric ratio, and fully grinding to obtain mixed powder; S2, pressing the mixed powder obtained in the step S1 into a compact cylinder under the pressure of 5 MPa, placing the compact cylinder between two electrodes of a Joule thermal reaction device, applying pulse current in vacuum, generating instantaneous high temperature by utilizing the self resistance of the mixed powder, and reacting to synthesize metal doped MgB 4 powder; And S3, ball-milling and mixing the metal doped MgB 4 powder obtained in the step S2 with the powder A, and performing heat treatment on the mixed powder in an inert atmosphere to obtain the coated magnesium ion battery anode material.
  4. 4. The method for preparing a coated magnesium ion battery positive electrode material according to claim 3, wherein in the step S2, the current density of the pulse current is 10-1000A/mm 2 , the pulse width is 10 ms-10S, the temperature is 1100-1450 ℃, the heat preservation time is 1-10S, and the instantaneous heating rate and the cooling rate in the Joule heating process are both greater than 10 4 K/S.
  5. 5. The method for preparing a coated magnesium ion battery positive electrode material according to claim 3, wherein in the step S3, the molar ratio of the metal doped MgB 4 powder to the a powder is (1.05-1.1): 1.
  6. 6. The method for preparing a coated magnesium ion battery positive electrode material according to claim 3, wherein in the step S3, the ball-to-material ratio during ball milling is (10-20): 1, the time is 2-6 h, and the rotating speed is 300-400 r/min.
  7. 7. The method for preparing a coated magnesium ion battery positive electrode material according to claim 3, wherein in the step S3, the heat treatment process is performed by heating from room temperature to 300-800 ℃ at a rate of 5 ℃ per minute, maintaining the temperature at 1-10 h, cooling to 200 ℃ at a rate of 2 ℃ per minute, and cooling to room temperature with a furnace.
  8. 8. The method for preparing a coated magnesium ion battery positive electrode material according to any one of claims 3 to 7, wherein the magnesium metal full battery assembled by the magnesium ion battery positive electrode material prepared by the method has a specific discharge capacity retention rate of more than or equal to 90% after 500 cycles of circulation under a current density of 100 mA/g.

Description

Coated magnesium ion battery positive electrode material and preparation method thereof Technical Field The invention belongs to the technical field of magnesium secondary battery anode materials, and relates to a coated magnesium ion battery anode material and a preparation method thereof. Background Magnesium ion batteries are considered as powerful candidates for next generation high energy density energy storage systems beyond lithium battery technology due to their higher volumetric specific capacity, higher safety, and abundant reserves in the crust. However, the development of this system has long been limited by the lack of high performance cathode materials. Currently, the anode materials widely studied, such as transition metal sulfide anode materials (Mo 6S8 and the like) and layered transition metal sulfide anode materials (MoS 2 and the like) are spinel-structured metal oxide anode materials (such as MgMn 2O4 and the like), and generally face serious challenges in the repeated deintercalation process of magnesium ions. Magnesium ions have a relatively high charge density, resulting in a high diffusion barrier in the lattice and slow kinetics, while many materials undergo irreversible phase changes, structural collapse or severe volume expansion during cycling, leading to rapid capacity fade and limited cycle life. In addition, side reactions (e.g., dissolution of transition metal ions, oxidative decomposition of the electrolyte) between the surface of the positive electrode material and the electrolyte can continue to deteriorate the electrode/electrolyte interface, further increasing the impedance and consuming active species. Surface cladding is a key strategy to solve the interface and bulk stability problems described above. The ideal coating should play multiple roles of physical barrier, fast ion conductor and structural reinforcement simultaneously. MgB 4, a metal boride, is considered a promising candidate for cladding layers due to its good chemical/electrochemical stability, certain magnesium ion storage potential and compatibility with magnesium. However, mgB 4 synthesized by the conventional method has obvious limitations, for example, document "ADVANCED ENGINEERING MATERIALS 2020,22,1900750" discloses a method for preparing MgB 4 by a high-temperature solid phase method. The method takes high-purity metal magnesium powder and amorphous boron powder as raw materials, uses a single-shaft press to press the powder into a block body with the diameter of 20 mm and the thickness of 7 mm, then wraps the block body in titanium foil and carries out 2 h sintering in a tube furnace at 1050 ℃. Finally, to remove MgO, the MgB 4 pellets were thoroughly ground to a powder and immersed in a solution of HNO 3 (1M) for 60: 60 min. Although MgB 4 is successfully prepared in the literature, the method has high energy consumption and long period, and is easy to cause overgrowth of crystal grains and reduction of specific surface area in a high-temperature process, and the microscopic morphology, defect type and concentration of a product are difficult to accurately regulate. These factors make MgB 4 obtained by a high temperature solid phase method, which is often poor in intrinsic electron conductivity and magnesium ion mobility, may introduce additional interfacial resistance as a coating layer, limiting the rate capability of the battery. Document "ACS APPLIED Nano Materials 2021,4,12779-12787" discloses a method for preparing MgB 4 MXene nanoplatelets using MAX phase, and researches on its structure, chemical properties, optical properties, thermal stability, etc., the MgB 4 nanoplatelets prepared by this method have many exposed terminal metal sites on its surface, excellent metal layer conductivity. However, the crystal structure has many defects, the structure is unstable, the doping efficiency is low, the coating effect is poor, and the crystal structure cannot be applied to the anode material. Chinese patent application publication No. CN119764427a discloses a NiSe 2 @ CuSe having a heterostructure synthesized by a hydrothermal reaction and applied to a magnesium battery. The positive electrode material prepared by the method has higher charge-discharge specific capacity and longer cycle performance. However, the magnesium ion battery is only a two-phase composite structure, is not a compact core-shell cladding system, has the defects of large volume expansion, easy pulverization of the structure, incapability of inhibiting selenide shuttle effect, weak interface combination and insufficient electron/ion transmission dynamics, can not realize structural reinforcement and transmission optimization through doping and a rigid framework, and is difficult to meet the practical requirements of long cycle and high multiplying power of a high-performance magnesium ion battery. Chinese patent application publication No. CN120581550a discloses a molybdenum-magnesium co-doped Li 2MoO4 coated high-nickel