Mg^(2+)掺杂对锰酸锂正极材料电化学性能的影响

Effect of Mg^(2+)Doping on Electrochemical Properties of LiMn_(2)O_(4) Cathode Materials

尖晶石型LiMn_(2)O_(4)正极材料的电压平台高、原料来源丰富、生产成本低廉,但由于Jahn-Teller效应导致晶格畸变和Mn^(3+)歧化分解导致过渡金属锰的溶解严重影响电池的循环性能。本文探究了不同Mg^(2+)掺杂量对LiMn_(2)O_(4)正极材料电化学性能的影响。采用高温固相法制备了LiMg_((x))Mn_((2-x))O_(4)(x=0,0.01,0.03,0.05)样品,并对其组织结构和电化学性能进行分析。结果表明,所有样品均为立方尖晶石结构,呈截断八面体形貌。电化学性能测试表明,当x=0.03时,LiMg_(0.03)Mn_(1.97)O_(4)样品在0.2 C下具有较高的放电比容量和最高的首次库伦效率(98.44%),循环稳定性最佳;在0.5 C下循环100圈后仍具有119.3 mAh/g的放电比容量,容量保持率高达92.62%。

The spinel LiMn_(2)O_(4) cathode material has a high voltage platform,abundant raw materials and low production cost.However,the lattice distortion caused by Jahn-Teller effect and the dissolution of transition metal manganese resulted from manganese dissolution disproportionation reaction seriously affect the cycle performance of the battery.In present paper,LiMg_((x))Mn_((2-x))O_4(x=0,0.01,0.03,0.05)samples were prepared successfully by high temperature solid method.The microstructure and electrochemical properties of LiMn_(2)O_(4) cathode materials doped with Mg^(2+)were systematically studied.The results show that all samples share the cubic spinel structure with a truncated octahedra morphology.The electrochemistry tests demonstrates that when x is 0.03,the LiMg_(0.03)Mn_(1.97)O_(4)sample exhibits a higher discharge specific capacity,the highest initial Coulomb efficiency(98.44%),and optimal cycle stability at 0.2 C.And the sample is still of the specific capacity of 119.3 mAh/g after 100 cycles at 0.5 C,with the capacity retention rate as high as 92.62%.