702535 polymer battery.Progress in research on high-performance lithium-ion battery electrode materials

　　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 determining 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 side reactions on the surface of the electrode material and seriously damage the structural stability of the electrode material. The stability and long cycle performance limit its application in high specific energy power batteries. With the support of the National Natural Science Foundation of China and the Chinese Academy of Sciences' pilot projects, the Cao Anmin research group of the Key Laboratory of Molecular Nanostructure and Nanotechnology has carried out a series of work on the structure control and stability improvement of electrode materials. Based on the multi-level surface interface structure design ( J.Am.Chem.Soc.2018,140,7127; J.Am.Chem.Soc.2018,140,9070), surface lattice regulation (Chem2018,4,1685-1695; ACSAppl.Mater.Interfaces2018,10, 22896) and other methods, the effective control of the interfacial activity of the material surface has been achieved, and the stability of the electrode material and the long cycle performance of the device have been significantly improved. Recently, a related research team proposed a mechanism to improve the stability of electrode materials based on limited phase change with surface nanometer precision: based on a controllable surface high-temperature solid-state reaction, zinc ions are introduced to promote the surface spinel structure of lithium nickel manganate. It transforms into a composite configuration of a rock-salt-like phase and a layered phase, and accurately controls the proportion of the two phases, improving the structural stability of the material without sacrificing the electrochemical activity of the material. This special surface phase control mechanism can overcome the damage to charge transmission caused by conventional surface inert coating methods, and provides a new way to obtain key electrode materials with high capacity and high stability based on the control of the surface chemical properties of the electrode material itself. Means and mechanisms, related work was published in "Journal of the American Chemical Society" (J.Am.Chem.Soc.2019,141,4900-4907). Zn2+ promotes phase change on the surface of the spinel structure: precise control of the solid-phase reaction, obtaining a surface two-phase region where layered and rock-salt-like coexist, and improving the stability of electrode materials based on the optimization of phase structure and composition.

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