锂离子电池正极材料LiMn_(2-2x)Sm_xSr_xO_4的合成及电化学性能

Synthesis and Electrochemical Performance of LiMn_(2-2x)Sm_xSr_xO_4 Cathode Materials for Lithium-Ion Battery

采用高温固相反应合成了一系列的LiMn2-2x SmxSrxO4正极材料（O≤x≤0．1）；采用X射线衍射仪分析了合成产物的晶体结构；利用充放电试验测定了产物的电化学性能，利用电化学阻抗谱分析了产物的电化学循环机理．结果表明，所合成的LiMn2-2xSmxSrxO4（x=0，0．01，0．02，0．03，0．04，0．05）样品均保持尖晶石相，属于Fd3m空间群．LiMn1.9Sm0.05Sr0.05O4的电化学性能最佳，首次放电容量为96．8mAh／g，在3．0～4．4V区间内50次循环后容量保持率超过96％．与此同时，LiMn2O4和LiMn1.90Sm0.05Sr0.05O4的电极阻抗变化不同，进而影响其电化学性能．

A series of LiMn2-2xSmxSrxO4（0≤x≤0.1） samples were prepared as cathode materi als of lithium-ion battery by using high-temperature solid phase reaction. The crystal structure of the products was analyzed by means of X-ray diffraction. The electrochemical behavior of the products was evaluated by conducting charge-discharge test. Moreover, the electrochemical cyclic mechanism of the synthetic products was analyzed by means of electrochemical impedance spectroscopy. Results show that all the synthesized LiMn2-2x Sin, SrxO4 cathode materials have cubic structure of spinel phase Fd3m. Of various synthetic samples, LiMn1.9Sm0.05Sr0.05O4 had the best electrochemical performance, eg, an initial discharge capacity of 96.8 mAh/g and capacity retention of more than 96% after 50 cycle of charge discharge within 3.0-4.4 V. Besides, LiMn2O4 and LiMn1.90Sm0.05Sr0.05O4 electrodes had different changes of impedance, leading to different effects on the electrochemical performance.