表面活性剂对氧化铝修饰富锂锰基正极材料的影响

采用氧化铝修饰改性富锂锰基正极材料,探讨了表面活性剂在修饰改性中的作用。利用扫描电子显微镜、X射线衍射仪、透射电子显微镜和电化学性能测试等方法对材料结构和电化学性能进行分析。实验结果表明,十二烷基三甲基溴化铵(DTAB)能使Al_2O_3纳米颗粒均匀包覆在富锂锰基正极材料表面,有效增强了复合材料结构的稳定性。在600 mA·g~(-1)电流密度下,该复合材料的初始放电容量为186mAh·g~(-1)。经过500次循环后,其可逆放电比容量仍高于132 mAh·g~(-1),初始容量保持率高达71%。此外,电压衰退也被有效抑制,复合材料表现出优异的综合电化学性能。

The Effects of Surfactants on Al2O3-Modified Li-rich Layered Metal Oxide Cathode Materials for Advanced Li-ion Batteries

In this work, a series of Li-rich layered metal oxides (LLMO) as cathode materials for lithium ion batteries were prepared by the coprecipitation method. Various surfactants were introduced into the preparation of Al₂O₃-modified LLMO. The roles of surfactants were systematically investigated to reveal the mechanism of Al₂O₃ modification. The microstructure, morphology and electrochemical performance of the as-prepared samples were studied by the X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), galvanostatic discharge/charge measurement, cycling stability, rate capability and electrochemical impedance spectroscopies. The experimental results showed that Al₂O₃ nanoparticles were uniformly dispersed on the surface of LLMO by using N, N, N-trimethyl-1-dodecanaminium bromide (DTAB) as the surfactant. Al₂O₃-modified LLMO used DTAB as surfactant delivered the initial discharge capacity of 186 mAh·g^-1 at the current density of 600 mA·g^-1. After 500 cycles, the reversible discharge capacity was 132 mAh·g^-1 with a satisfactory capacity retention of 71%. Moreover, the voltage fade of LLMO was greatly suppressed after Al₂O₃ modification, which exhibited superior electrochemical performances.