铌掺杂锰酸锂正极材料制备工艺优化研究

Optimization of Preparation Process for Nb-Doped LiMn₂O₄ Cathode Material

摘要: 以电解二氧化锰为锰源、碳酸锂为锂源、五氧化二铌为掺杂剂，采用高温固相法制备铌掺杂锰酸锂正极材料，系统研究了Li/Mn摩尔比、铌掺杂量及烧结温度等工艺参数对锰酸锂理化性能及电性能的影响。结果表明，适量铌掺杂可有效调控锰酸锂一次颗粒的晶面生长，使其趋于圆润，进而提升压实密度。随着Li/Mn摩尔比、铌掺杂量及烧结温度的升高，锰酸锂的压实密度增大，比表面积降低，但过高的铌掺杂量及烧结温度会导致1C放电容量和循环稳定性下降。通过单因素实验优化得到最佳工艺参数为：Li/Mn摩尔比0.53、Nb/MnO₂质量比0.2%、烧结温度790℃。在此条件下制备的铌掺杂锰酸锂综合性能最优，压实密度达3.12 g/cm³，1C放电比容量为117.6 mAh/g，50次循环容量保持率为95.96%。

Abstract: Using electrolytic manganese dioxide as the manganese source, lithium carbonate as the lithium source, and niobium pentoxide as the dopant, Nb-doped LiMn₂O₄ cathode materials were synthesized via a high-temperature solid-state method. The effects of process parameters such as Li/Mn molar ratio, Nb doping amount, and sintering temperature on the physicochemical and electrical properties of LiMn₂O₄ were systematically investigated. The results indicate that an appropriate amount of Nb doping can effectively regulate the crystal facet growth of primary particles, making them more rounded and thereby enhancing the compaction density. With the increase of Li/Mn molar ratio, Nb doping amount, and sintering temperature, the compaction density of LiMn₂O₄ increased, while the specific surface area decreased. However, excessive Nb doping and sintering temperature led to a decline in the 1C discharge capacity and cycling stability. Through single-factor experimental optimization, the optimal process parameters were determined as follows: Li/Mn molar ratio of 0.53, Nb/MnO₂ mass ratio of 0.2%, sintering temperature of 790˚C. Under these conditions, the prepared Nb-doped LiMn₂O₄ exhibited the best comprehensive performance, with a compaction density of 3.12 g/cm³, a specific discharge capacity of 117.6 mAh/g at 1C, and a capacity retention rate of 95.96% after 50 cycles.