纳米中空球状高电位LiNi0.5Mn1.5O4的制备及其电化学性能

Preparation and electrochemical performance of hollow nanosphere of LiNi0.5Mn1.5O4

以NiCl2·6 H2O和MnCl2·4 H2O为原料,采用溶剂热法可制备出Ni0.5Mn1.5(CO3)2前驱体,将前驱体进行空烧和锂化可成功制备出具有高电位的LiNi0.5Mn1.5O4正极材料。分别从磁力搅拌混合的搅拌速率与时间,以及空烧、锂化工艺的影响因素出发,探讨了不同条件下合成前驱体Ni0.5 Mn1.5(CO3)2、中间产物Ni3Mn7Ox及终产物LiNi0.5Mn1.5O4的结构与形貌。对得到的正极材料LiNi0.5Mn1.5O4进行电化学性能测试,结果表明:添加非离子活性剂PVP后,慢速下磁力搅拌时间4 h,控制反应温度200℃,反应时间30 min时得到的前驱体结构均匀,并通过空气中500℃处理(1℃/min),800℃条件下在LiOH∶Li2NO3=1∶2 (摩尔比)中锂化5 h,以0.5℃/min降温速率得到的正极材料LiNi0.5Mn1.5O4具有最优的电化学性能。在0.1 C条件下放电比容量可达到150 mAh/g以上,且倍率性能和循环稳定性好。

Based on the raw materials ofNiCl2·6 H2 O and MnCl2·4 H2 O, the hollow nanosphere of LiNi0.5 Mn1.5 O4 is easily synthesized through oxidation and lithiation of the precursor Ni0.5 Mn1.5(CO3)2, which prepared by solvothermal method. In this paper, the structures and morphologies of Ni0.5 Mn1.5(CO3)2, Ni3 Mn7Ox and the final LiNi0.5 Mn1.5 O4 are influenced by magnetic stirring rate and time, as well as the technologies of oxidation and lithiation. As a result,controlling the magnetic stirring with a low rate for 4 h at 200 ℃(reaction time: 30 min), the precursor structure and morphology distribute uniformly after nonionic surfactant of PVP doped. Optimizing the oxidation(500℃ and heating rate of 1 ℃ in air) and lithiation(soaking and stiring in LiOH/Li2 NO3;calcining at 800 oC for 5 h and cooling with 0.5 ℃/min) methods, the final hollow nanospheres of LiNi0.5 Mn1.5 O4 are achieved, and show ultrahigh electrochemical performance. The discharge capacity can keep 150 mAh/g at 0.1 C. Meanwhile, at 20 C, it also show high capacity means high rate capacity and the cyclic stability has competitive advantage at 0.1 C for 100 cycles.