Cr/Al改性制备LiMn2O4正极材料及电化学性能

Preparation and electrochemical properties of Cr/Al modified LiMn2O4 cathode material

摘要:

采用固相燃烧法制备了Cr/Al共掺LiCr_0.02Al_xMn_1.98-xO₄(x=0.03-0.10, LCAMO-x)正极材料。结果表明,Cr/Al改性促进了材料颗粒的晶体发育及(111)、(100)和(110)晶面的生长,其中,优化LCAMO-0.05样品的单晶截角八面体颗粒数量最多、形貌最完整和具有优良电化学性能,在1 C时初始比容量为121.1 mAh.g_-1^,1000次循环后保持率为72.6%。在高倍率15和20 C时,LCAMO-0.05的首次放电比容量分别为89.1和78.1 mAh.g_-1^,循环1500次后保持率分别为71.6%和76.7%。在55 ℃和1 C条件下,LCAMO-0.05样品初始容量为113.6 mAh.g_-1^,250次循环后保持率65.6%,明显高于LiCr_0.02Mn_1.98O₄样品的53.3%。CV和EIS分析表明,LCAMO-0.05样品有较高的Li+离子扩散系数5.85×10_-12 ^cm₂^.s_-1^{和较低的表观活化能}29.09 kJ.mol_-1^。对5 C、循环1000次后电极极片分析表明,LCAMO-0.05材料的晶体结构和截角八面体颗粒形貌基本没有变化,具有优良的结构稳定性。关键词：尖晶石型锰酸锂; Cr/Al共掺杂; 高倍率性能; 正极材料; 功能材料中图分类号：TM912 文献标识码： A 文章编号：1003-5214 (2024) 01-0000-00

Abstract:

Cr/Al co-doped LiCr_0.02Al_xMn_1.98-xO₄(x=0.03-0.10, LCAMO-x) cathode material was prepared by solid-state combustion method. The results show that Cr/Al modification can promote the crystal development of the material particles and the growth of (111), (100) and (110) crystal faces. Among them, the optimized LCAMO-0.05 sample has the largest number of single-crystal truncated octahedral particles, the most complete morphology, and excellent electrochemical performance. The initial specific capacity at 1 C is 121.1 mAh.g^_-1. The retention rate was 72.6% after 1000 cycles. The initial specific discharge capacities of LCAMO-0.05 at high rates of 15 and 20 C are 89.1 and 78.1 mAh.g^_-1, and the retention rate after 1500 cycles is 71.6% and 76.7%, respectively. At 55 ℃ and 1 C, the initial capacity of LCAMO-0.05 sample is 113.6 mAh.g^_-1, after 250 cycles, and the retention rate is 65.6%, which is significantly higher than that of LiCr_0.02Mn_1.98O₄ sample (53.3%). CV and EIS analyses show that LCAMO-0.05 sample has a high lithium-ion diffusion coefficient of 5.85×10_-12 ^cm₂^.s_-1 and a small apparent activation energy of 29.09 kJ.mol^_-1. After 1 000 cycles at 5 C, the electrode plate analysis shows that the crystal structure and truncated octahedral particle morphology of LCAMO-0.05 material are basically unchanged, and it has excellent structural stability.