甲基三甲氧基硅烷对Li/NCM811电池性能提升的影响

Impact of methyltrimethoxysilane addition on electrochemical performance improvement of Li/NCM811 battery

LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)是一种高镍锂电池的正极材料,比容量高,但在应用中存在阳离子混排、表面结构不稳定等问题。采用金属锂片为负极,1 mol/L LiPF_(6)-EC∶DEC(体积比为1∶1)为电解液,研究了甲基三甲氧基硅烷(MTMS)作电解液添加剂对Li/NCM811电池电化学性能及正极表面性质的影响。研究发现,在电解液中加入质量分数4%的MTMS,0.5 C的电流下充放电循环100圈后,电池容量保持率增加131.95%。电化学测试及反应前后电极表面性质表征结果表明,MTMS添加剂有助于NCM811表面形成稳定致密的CEI膜,抑制电解液分解,有效保护了活性位点的化学稳定性,抑制了电极材料不可逆相变的进行。

LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)is a cathode material with a high specific capacity for high nickel lithium battery,but exists a few problems in the application,such as cationic mixing and surface structure instability.The impact of methyl trimethoxy-silane(MTMS)as an electrolyte additive on the electrochemical performance and cathode surface properties of Li/NCM811 battery are examined through using a lithium metal sheet as negative electrode and 1M LiPF_(6)-EC∶DEC(1∶1)as electrolyte.It is found through study that the capacity retention rate of battery increases by 131.95%after adding 4 wt.%MTMS into the electrolyte,and charging and discharging 100 cycles at 0.5 C current.It is verified through electrochemical testing,and the characterization of electrode surface properties before and after the reaction that MTMS additive agent is beneficial to form the stable and dense CEI film on the surface of NCM811 and can inhibit the decomposition of the electrolyte,which protects the chemical stability of the active sites and inhibits the irreversible phase transition of electrode material.