锂离子电池正极材料LiNi_0.5Mn_1.5O_4表面包覆CuO的研究

本文首先通过共沉淀法和固相球磨法制备了纳米级的LiNi0.5Mn1.5O4高电压正极材料,然后通过溶胶-凝胶法制备了表面包覆CuO的CuO-LiNi0.5Mn1.5O4复合材料.通过对CuO包覆量为1%,3%和5%的复合材料的电化学性能对比,发现当包覆量为1%时,材料的性能最佳.在1 C下,材料的放电比容量高达126.1 mA h g?1,循环100次后容量保持率在99.5%.CuO包覆在纳米LiNi0.5Mn1.5O4材料表面,阻止电解液与活性颗粒的直接接触,削弱了电解液与LiNi0.5Mn1.5O4的相互作用,进而在一定程度上减缓了电解液的分解;CuO的包覆同时还缓解了电解液中HF对材料的攻击,阻止了锰的溶解和由此带来的结构改变,进而提高了材料的循环稳定性.

CuO-modified LiNi0.5Mn1.5O4 cathode materials for lithium ion batteries

The CuO-coated LiNi0.5Mn1.5O4 has been synthesized to be used as a cathode material for lithium ion batteries via a sol-gel method. The coating of CuO on the material does not have significant effect on the basic spinel structure of LNMO, but effectively reduces the interaction between electrolyte and LNMO, and prevent further the dissolution of manganese. The results show that LNMO with 1% CuO coating has the better electrochemical performance, for example, its discharge specific capacity at a rate of 0.2, 0.5, 1, 2, 5 and 10 C is 123.1, 122.8, 127.8, 125.9, 120 and 113.9 mA h g-1 , respectively, and its capacity retention at 1 C cycle is up to 99.5% after 100 cycles. Even cycling at 5C rate, the cell with 1% CuO-LNMO cathode can has 99.4% of capacity retention after 200 cycles, indicating that it is a promising cathode material for lithium ion batteries.