掺杂元素离子半径对LiM_xMn_(2-x)O_4(M=Li,Na,Tl)电化学性能的影响

Comparative study on LiM_xMn_(2-x)O_4(M=Li,Na,Tl) cathode materials for li-ion batteries

以尿素为络合剂,氢氧化锂、醋酸锰等为原料通过水热反应获得颗粒均匀的尖晶石LiMxMn2-xO4(M=Li,Na,Tl)前驱物,然后将前驱物在600℃～700℃间煅烧4h后获得最终产物。实验主要考察了掺杂元素的离子半径和M-O键离解能对产物LiMxMn2-xO4充放电过程中稳定性的影响,以及煅烧温度对材料形貌与结构的影响。结果表明掺杂元素的离子半径与被取代元素的离子半径越接近则掺杂后的材料越稳定,而M-O键离解能的影响则很小。实验发现LiNa0.02Mn1.98O4的综合性能最佳,该样品在室温0.2C倍率的首次放电容量可以达到107mAh.g-1,且不可逆容量衰减小,电池循环20次后容量只衰减了约2.8%。

Using urea as a complexing agent,spinel LiM_xMn_（2-x）O_4（M=Li,Na,T1） ,as homogeneous Li-M- Mn precursors,was prepared with the hydro-thermal reaction of lithium hydroxide, manganese acetate and so on,by a modified solid-state method. These precursors were calcined at various temperatures between 600 ℃-700 ℃ for 4 hours to obtain the final products. The electrochemical properties and other features of the final products were carefully investegated. It was found that the closer ionic radius of the dopant M was to Mn^3＋ ,the more stable LiM_xMn_（2-x）O_4 was.