Pan Feng group of Shenzhen Graduate School of Peking University and Guo Yuguo group of Institute of chemistry of Chinese Academy of Sciences designed and synthesized high performance sodium battery materials with "inorganic benzene like ring" functional structural elements

Lithium ion batteries have been successfully and widely used in mobile phones, computers and electric vehicles The large-scale application of electric vehicle power battery and energy storage battery needs raw materials with rich resources and low cost The reserves of sodium are more abundant than lithium on the earth, so the cost is lower Therefore, the development of high capacity and high stability sodium ion battery is the forefront of current energy technology research and development With its superior ionic conductivity, high specific capacity and cheaper raw material cost, sodium layered oxide cathode materials are becoming a powerful alternative to lithium-ion cathode materials However, due to the large radius of sodium ions, the layered intercalation materials are prone to irreversible phase transition due to the relative sliding of the transition metal layer during the electrochemical cycle, resulting in the poor cycle stability of this kind of positive materials Pan Feng research group of new materials College of Shenzhen Graduate School of Peking University and Guo Yuguo research group of Institute of chemistry of Chinese Academy of Sciences jointly designed and synthesized a new type of sodium ion battery cathode material Nani 2 / 3Sb 1 / 3O2 with super high stability based on transition metal d-orbital to form "inorganic benzene like ring" functional structural elements The result is "an ordered Ni 6" -Ring superstructure enables a highly stable medium oxide method "was published in advanced materials (DOI: 10.1002 / ADMA 201903483) Pan Feng's team of new materials Institute found that the structure of this kind of sodium battery material with high stability was composed of a kind of hexagonal structural elements The hexagonal structure is centered on one SBO 6 octahedron, surrounded by six NiO 6 octahedrons, and six Ni ions arranged in a hexagonal structure centered on sb ions Through structural chemistry and quantum chemistry calculation, the researchers found that 90 degree super exchange formed by ni-o-ni structure was connected in the crystal structure, forming a "inorganic benzene like aromatic" structure composed of transition metal d-orbit, which provided extra stability for this Na battery material In addition, the phase transition structure of the battery during the charging and discharging process has also been accurately found, which provides a theoretical basis for the phase transition and stability of such materials It is no accident to find and design this kind of material Previously, Professor Pan Feng's team took the lead in the study of lithium nickel manganate (lini 0.5mn 0.5o2) materials and proposed that there are "inorganic benzene like aromatic" structural elements in the layered materials of lithium batteries (J mater Chem A, 2018, 6, 9893-9898) Based on the spin electron exchange and electron localization / delocalization model of transition metals, it is found that the delocalization groups formed by the direct exchange of six manganese ions through Mn 4 + have "inorganic benzene like" aromaticity These studies provide the basis of structural chemistry for the further design and development of high-performance energy storage and power battery materials The two research results were conducted by Pan Feng and completed by Weng Guiyi and Hu Zongxiang, doctoral students respectively This series of work has been strongly supported by national key research and development plan of material genetic engineering, Key Laboratory of Guangdong Province, Shenzhen Science and Technology Innovation Committee and other projects.