The improvement of energy density is the focus of research in the field of lithium-ion batteries, and the cathode material is the key to determine the energy density of lithium-ion batteries. Lithium nickel manganese oxide material is a high-voltage cathode material with high energy density and good rate performance; however, its own high operating voltage will significantly accelerate the side reactions on the surface of the electrode material and seriously damage the structural stability of the electrode material And long cycle performance limits its application in high specific energy power batteries.
With the support of the National Natural Science Foundation of China and the Pilot Project of the Chinese Academy of Sciences, Cao Anmin ’s research group of the Key Laboratory of Molecular Nanostructures and Nanotechnology, Institute of Chemistry, Chinese Academy of Sciences carried out a series of work on the control and stability improvement of electrode materials based on multi-level tables Interface structure design (J. Am. Chem. Soc. 2018, 140, 7127; J. Am. Chem. Soc. 2018, 140, 9070), surface lattice control (Chem 2018, 4, 1685-1695; ACS Appl. Mater. Interfaces 2018, 10, 22896) and other methods to effectively control the interface activity of the surface of the material, and obtain a significant improvement in the stability of the electrode material and the long-cycle performance of the device.
Recently, the related research team proposed a mechanism for improving the stability of the electrode material based on the limited phase transformation of the surface nano-precision: Based on the controlled surface high-temperature solid phase reaction, the introduction of zinc ions promotes the surface spinel structure of lithium nickel manganate It is transformed into a composite configuration of rock-like salt phase and lamellar phase, and the two phases are precisely controlled to improve the structural stability of the material without sacrificing the electrochemical activity of the material. This special surface phase state regulation mechanism can overcome the damage of the conventional surface inert coating method to charge transport, and provides a new method for obtaining key electrode materials with high capacity and high stability based on the regulation of the surface chemical characteristics of the electrode material itself. Means and mechanisms, related work was published in the Journal of the American Chemical Society (J. Am. Chem. Soc. 2019, 141, 4900-4907).
Zn2 + promotes a phase change on the surface of the spinel structure: the solid phase reaction is precisely controlled to obtain the surface two-phase region where layered and rock-like salts coexist, and the stability of the electrode material is improved based on the optimization of the phase structure and composition
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