Synthesis And Electrochemical Properties Of Concentration Gradient Nickel-Manganese Compounds

LiMO₂?M=Ni,Mn,Co?have been considered as one of the most promising cathode materials due to their high specific capacity and high operating voltage.In this work,LiMnO₂?M=Ni,Mn,Co?cathode materials were synthesized by co-precipitation method.The crystal structure,morphology and electrochemical properties of the as-synthesized materials were studied by XRD,SEM,EDS,galvanostatic charge-discharge testing,EIS and CV.The diffraction peaks for cobalt-free/low Ni-Mn compounds were indexed to the hexagonal ?-NaFeO₂ layered structure?R-3m space group?.The clear spit between the adjacent peaks of?006?/?102?and?018?/?110?suggests the formation of a highly order hexagonal layered structure of the sample.The hexagonal layered structure could suppress interaction between the cathode and the electrolyte and enhance Li⁺ diffusion.Therefore,the electrodes have excellent Li⁺ electrical conductivity and the charge transfer resistance Rct,leading to the increase of the capacity and capability.The results show that change the molar ratio of reactants,the speed of doping and burning can stabilize material structure,improve their electrochemical performance.