Alumina has good thermal stability, physical properties and chemical stability, and is widely used in semiconductor materials, fire-resistant fields, ceramic fields and LED fields. In recent years, with the increasing safety requirements for lithium-ion batteries, high-purity alumina is widely used in flame retardant membranes, coated cathode materials and solid electrolyte materials, and has played an important role in the field of lithium batteries.

  Application in positive electrode materials

  In the research of cathode materials for lithium-ion batteries, an important way to improve the performance of materials is to coat the surface of electrode materials. The purpose is to reduce the contact between the acidic substance of the electrolyte and the electrode material, reduce the corrosion of the electrode by hydrofluoric acid, and reduce the acid-base side reaction, which is of great help to improve the structural stability of the positive electrode material.

  At present, Al2O3 is one of the most studied oxide coating materials, which is widely used because of its abundant reserves, cheap price, and can significantly improve the structural stability, electrochemical performance and safety of positive electrode materials.

   The application of alumina in diaphragm

Polypropylene PP, polyethylene PE and their derivatives are conventional materials for lithium-ion battery diaphragms, which are risky to use under high temperature conditions. After coating, the surface of the film has a uniform pore structure, and the mechanical strength of the film is obviously improved. Moreover, the ceramic particle size is small, the specific surface area of the ceramic coating is high, and the pores are many. The coating can absorb more electrolyte (absorption rate increased from 187% to 300%), helping to improve the electrical performance of the battery.

   Application in negative electrode

Alumina powder can be coated not only on the diaphragm, but also on the negative electrode surface. The results show that the alumina coating on the anode has no adverse effect on the high current discharge performance of the battery. In the process of multiple cycles, the morphology and particle size of alumina coating particles remain basically stable, the coating has no obvious effect on the crystal structure of graphite, and the deembedding behavior of lithium ions in graphite has no obvious change.

  Applications in solid electrolytes

Unlike the liquid electrolyte, the solid electrolyte material has high hardness, has a certain mechanical strength, and has an important inhibitory effect on the growth of lithium dendrites. Lithium metal can be used as an electrode in the solid state battery, so the energy density of the battery can be greatly improved