Abstract:

To effectively suppress Jahn-Teller effect of spinel lithium manganate and improve the problem of rapid capacity decay during high-rate charge discharge cycles，the LiNi_0.05Mn_1.95O₄ samples were successfully prepared by using a molten salt combustion method and different calcination temperatures.The experiment results demonstrated that the crystal structure of LiMn₂O₄ did not change under Ni-doping and different calcination temperatures.With the rise of calcination temperature，the crystallinity and particle size of the samples were increased continuously.Besides，the particle sizes were gradually increased from nanoscales to submicron scales.The optimal calcination temperature of 650 ℃ delivered excellent electrochemical performance.The initial discharge specific capacity at 5C and the capacity retention rate after 500 cycles were 100.8 mA·h/g and 80.0%，respectively.At a higher rate of 10C，the capacity of 500 cycles only attenuated by 7.5%.The dynamic performance test results indicated that it had a large lithium-ion diffusion coefficient of 3.26×10^-16 cm²/s and a smaller apparent activation energy of 25.67 kJ/mol.Ni doping and different calcination temperatures inhibited the Jahn-Teller effect of LiMn₂O₄ materials，thereby promoted the rate performance and cycle life of LiMn₂O₄ materials.

Key words: spinel LiMn₂O₄, Ni-doping, molten-salt combustion method, Jahn-Teller effect, calcination temperature