溶剂热法制备磷酸锰锂的优化研究

Optimization of lithium manganese phosphate preparation via solvothermal method

橄榄石结构的磷酸锰锂(LiMnPO_(4))具有比容量高､热稳定性好和原料来源广泛等特点,与同为橄榄石结构的磷酸铁锂相比具有更高的放电电压。采用溶剂热法制备了高性能的磷酸锰锂正极材料,通过对过程参数进行优化实现材料性能的提升,以柠檬酸为添加剂优化颗粒形貌得到纳米级颗粒,并对碳层包覆进行优化。结果表明,柠檬酸添加量为1 mmol时,椭球状颗粒平均尺寸为42.3 nm;当以蔗糖为碳源且与LiMnPO_(4)质量比为1∶2时得到的碳层包覆颗粒尺寸较小､碳层石墨化程度更高;在最优参数下制备的LiMnPO_(4)材料具有更高的首次放电容量(126.9 mAh/g)及更优的倍率性能。

Lithium manganese phosphate with an olivine structure has the characteristics of high specific capacity,good thermal stability and abundant raw materials resources.It also exhibits a higher discharge voltage than lithium iron phosphate with a same olivine structure.High performance lithium manganese phosphate anode material is prepared via the solvent thermal method,and its performance is improved by optimizing the process parameters.Citric acid is used as an additive to optimize the particle morphology of the lithium manganese phosphate material to obtain nano-sized particles,and the carbon coating is also optimized.It is concluded that the average elliptic particle size is 42.3 nm when the addition of citric acid is 1 mmol.The size of carbon layer coated particle is less and the graphitization degree of carbon layer is higher when sucrose is employed as carbon source and the mass ratio of sucrose to LiMnPO_(4)is 1∶2.LiMnPO_(4)material prepared under the optimal parameters has higher initial discharge capacity(126.9 mAh·g^(-1))and better rate performance.