氟掺杂型锂锰氧化物的电化学性能研究

Electrochemical Behaviors of Fluorine Doped Lithium Manganese Oxide

以LiNO3、LiF和Mn(AC)2·4H2O为原料,采用柠檬酸配位法,通过控制n(Li)n(Mn)和掺氟量,在750℃下制备尖晶石型系列Li1+xMn2-xO4-yFy电极材料。Li1+xMn2-xO4-yFy的充放电实验表明,随着锂掺入量的增加,材料的首次放电容量迅速降低,但材料的循环稳定性明显提高。Li1.05Mn2O4的放电容量最高(116mAh g),而且稳定性也较好。室温下,5次循环后容量仅衰减1.92%。掺氟明显降低材料在高温条件下的容量损失,但随着氟掺杂量的增加,材料的首次放电容量降低较大。同时掺杂锂和氟的材料比仅掺杂锂的材料具有更好的循环稳定性,Li1.05Mn1.95O3.95F0.05循环稳定后,放电比容量保持在103.5mAh g。Li1.15Mn1.85O3.9F0.1循环4次以后,便没有容量衰减,放电比容量稳定在98.5mAh g,因此,从比容量和循环稳定性两方面考虑,Li1.05Mn1.95O3.95F0.05和Li1.15Mn1.85O3.9F0.1是较好的电极材料。

Using lithium nitrate, lithium fluoride and manganese acetate as raw materials, a series of spinel Li_(1+x)Mn_(2-x)O_(4-y)F_(y) were prepared by citric acid complex method at 750℃. Increasing the amount of doped lithium, the initial discharge capacity of Li_(1+x)Mn_(2-x)O_(4-y)F_(y) decreased quickly, but the stability of the material was improved in the charge-dischargeteef. Li_(1.05)Mn_2O_4 has the best initial discharge capciity of 116 mAh/g, the capacity was reduced by 1.92% after 5 cycles at room temperature. For fluoride-doped material the loss of capacity at high temperature was decreased however, the initial discharge capacity dropped greatly with the mount of doped fluoride. The cycle stability of materials co-doped with lithium and fluoride was better than that of materials only doped with lithium. The discharge capacity of Li_(1.05)Mn_(1.95)O_(3.95)F_(0.05) maintained of 103.5 mAh/g after stable and Li_(1.15)Mn_(1.85)O_(3.9)F_(0.1) at 98.5 mAh/g after 4 cycles. Thus, Li_(1.05)Mn_(1.95)O_(3.95)F_(0.05) and Li_(1.15)Mn_(1.85)O_(3.9)F_(0.1) are better cathode materials in the riew of capacity and stability.