镁离子掺杂锂离子电池硅酸锰锂正极材料

Effect of Mg^(2+) Doping on Structure and Electrochemical Performance of Lithium Magnesium Silicate

以MgAC2为掺杂剂,葡萄糖碳化为碳包覆源,通过溶胶凝胶法制备了含有镁离子的硅酸锰锂正极材料前驱体,在惰性气保护下经高温焙烧得到碳包覆的硅酸锰锂正极材料。对镁离子掺杂对硅酸锰锂物理和电化学性能的影响进行了探讨。交流阻抗和循环伏安测试表明,碳包覆和低含量镁离子掺杂不会破坏硅酸锰锂的材料,并且显著提高了电子传导过程的电导率,同时硅酸锰锂正极材料的循环性能得到提高。0.1C倍率放电测试显示,镁离子掺杂和非掺杂的硅酸锰锂的不可逆比容量分别有289 mA.h/g和248 mA.h/g。经过20次循环,其容量分别保持在155 mA.h/g和122 mA.h/g。与未掺杂的硅酸锰锂相比,镁离子掺杂后,硅酸锰锂的循环稳定性得到极大的提高。

Stoichiometric Mg-doped Li2MnSiO4 cathode material was synthesized by a sol-gels process with magnesium acetate de-hydrate as a dopant and sucrose as carbon-coating materials and subsequent high temperature treatment in an inert atmosphere.The effect of Mg2＋ doping on the physical and electrochemical properties of the as-prepared cathode materials was investigated.AC im-pedance spectra and cycle voltammagram results showed that the carbon coating and low concentration Mg2＋ doping do not destroy the structure of Li2MnSiO4,but enhance the electron conductivity during the electron translation procedure.Moreover,the cycle per-formance was improved.At a discharging rate of 0.1C,the reversible specific capacities of the Mg-doped lithium magnesium silicate and the un-doped Li2MnSiO4 were 289 and 248 mA·h/g,respectively.After 20 cycles,the capacities were 155 and 122 mA·h/g,re-spectively.By Mg ions doping,Li2MnSiO4 exhibited a more stable cycle performance than that of Li2MnSiO4/C cathode material.