结晶度对尖晶石LiMn_2O_4循环性能的影响

Effect of degree of crystallization on the cycle performance of spinel LiMn_2O_4

采用不同的降温速率(1℃/h、20℃/h)和淬火,制备了尖晶石LiMn2O4正极材料,并研究了它们的结晶度及电化学性能。制备的样品的结晶度随着降温速率的增大而降低。结晶度低的样品,首次充放电效率高,在循环过程中充放电效率的稳定性好。淬火得到的样品的放电比容量较高,0.2C放电时为128.92 mAh/g,1.0C放电时为86.36 mAh/g;1℃/h降温、20℃/h降温和淬火得到的样品以1.0C放电,20次循环的容量保持率分别为86%、91%和100%。

Spinel LiMn204 cathode materials were prepared with different cooling rates（ 1 ℃/h,20 ℃/h） and quenching, their degree of crystallization and electrochemical performance were investigated. The degree of crystallization of the samples decreased with the increasing of the cooling rate. The sample witch lower degree of crystallization had high initial charge-discharge efficiency and fine stability of charge-discharge efficiency in the cycle process. The sample obtained by quenching had higher specific discharge capacity, 128.92 mAh/g at 0.2 C discharge and 86.36 mAh/g at 1.0 C discharge. When discharge at 1.0 C, the capacity retention of samples obtained by 1 ℃/h eoohng,20 ℃/h coohng and quenching after 20 cycles was 86% ,91% and 100% ,respectively.