Li-Ni共掺尖晶石型LiMn2O4单晶多面体材料的制备及电化学性能

采用无焰燃烧法在500℃反应3 h，然后分别在600、650、700和750℃二次焙烧6 h制备了尖晶石型Li_1.02Ni_0.05Mn_1.93O₄正极材料。结果表明，不同焙烧温度制备的Li-Ni共掺材料没有改变LiMn₂O₄的立方尖晶石结构，且随着焙烧温度的升高，颗粒尺寸变大，结晶性提高。二次焙烧温度为700℃的Li_1.02Ni_0.05Mn_1.93O₄单晶多面体晶粒正极材料具有{111}、{110}和{100}面，且电化学性能较优，在1 C倍率下初始放电比容量为108.2 mA·h·g?1，循环500次后的容量保持率为76.8%；在5 C下首次放电比容量可达到99.0 mA·h·g?1，1000次循环后，仍能维持72.1%的容量保持率；在10 C下仍显示出71.3 mA·h·g?1的首次放电比容量及经500次循环后86.4%的容量保持率。并且其具有较大的Li+扩散系数和较小的表观活化能。Li-Ni共掺LiMn₂O₄单晶多面体材料能够有效抑制Jahn-Teller效应，减小Mn的溶解及增加Li+扩散通道，使材料的晶体结构稳定，提高倍率性能和循环性能。 

Preparation and electrochemical properties of Li-Ni co-doping spinel LiMn2O4 single crystal polyhedron material

Spinel Li_1.02Ni_0.05Mn_1.93O₄ cathode material was synthesized via a flameless combustion method at 500℃ for 3 h followed by calcination at 600、650、700 and 750℃ for 6 h, respectively. The results show that Li-Ni co-doping material at different calcination temperatures does not change the cubic spinel structure of LiMn₂O₄. With the increase of calcination temperature, the particle size increases and the crystallinity is enhanced. At the secondary calcination temperature of 700℃, the cathode material of Li_1.02Ni_0.05Mn_1.93O₄ single crystal polyhedron possess {111}, {110} and {100} surfaces. It exhibits an excellent electrochemical performance. The Li_1.02Ni_0.05Mn_1.93O₄ cathode material shows the first-discharge specific capacity of 108.2 mA·h·g?1 and maintains the capacity retention of 76.8% after 500 cycles at 1 C. Moreover, it displays an initial discharge capacity of 99.0 and 71.3 mA·h·g?1, while provides a capacity retention rate of 72.1 and 86.4% after 1000 cycles at 5 C and 500 cycles at 10 C, respectively. The optimized electrode has a large Li+ diffusion coefficient and low apparent activation energy. The Li-Ni co-doping material of LiMn₂O₄ single crystal polyhedron can inhibit the Jahn-Teller effect effectively and alleviate Mn dissolution as well as increase Li+ ions expressing channels. Hence, the crystal structure of material is stabilized, the rate and cycle performance are enhanced.