溶剂热反应矿化剂和表面活性剂对LiMn0.8Fe0.2PO4性能的影响

Effect of Mineralizer and Surfactant on Performance of LiMn0.8Fe0.2PO4 Cathode Material by Solvothermal Method

采用溶剂热法制备LiMn0.8Fe0.2PO4正极材料，研究了矿化剂KOH及阳离子表面活性剂双十二烷基二甲基溴化铵（DDAB）对产物形貌以及性能的影响。利用恒流充放电、循环伏安和交流阻抗对其电化学性能进行测试。结果表明：矿化剂KOH和表面活性剂DDAB均有利于减小颗粒粒径，从而使材料电化学性能得到提高。其中加入矿化剂KOH效果明显，所得LiMn0.8Fe0.2PO4材料粒径最小，分散性能最好，有效碳包覆率最高，0．2C倍率下100次循环后容最保持率为94．3％；0．1C倍率下的放电比容量为157．4mA·h／g，5C下仍可以达到99．2mA·h／g，相比于基础材料LiMn0.8Fe0.2PO4的152．3和82．3mA·h／g分别提高了3．3％和20．5％，具有很好的倍率性能和循环稳定性能。

LiMn0.8Fe0.2PO4 cathode materials were synthesized by a solvothermal method. The effects of mineralizer （i.e., KOH） and surfactant （i.e., didodecyldimethylammonium bromide （DDAB）） on the morphologies and electrochemical performances were investigated. The electrochemical performances were evaluated by galvanostatic charge-discharge tests, cyclic voltammetry and AC impedance tests. The results show that the use of either mineralizer KOH or surfactant DDAB can decrease the particle size, thus improving the electrochemical performances of material. The sample with the minimum particle size and the well-dispersive performance obtained using mineralizer KOH has the optimum effective carbon coating ratio and electrochemical performance with good cycle performance and rate performance. The capacity retention of material is 94.3% after 100 cycles at 0.2 C, the capacity is 157.4 and 99.2 rnA.h/g at 0.1 and 5.0 C, respectively, which are better than those of the base material.