聚丙烯腈在锂金属电池电解质中的应用

Application of Polyacrylonitrile in the Electrolytes of Lithium Metal Battery

随着便携式电子设备、电动汽车和智能电网等快速发展,人们对高能量密度锂金属电池的关注日益增多。锂金属表面不均匀的剥落或沉积会导致锂枝晶生长,锂枝晶容易刺穿隔膜,存在引发电池短路的风险,而且高反应活性的锂金属会与电解液不断反应被消耗,生成不稳定的固体电解质界面(SEI)膜,造成不可逆的容量损失,因此兼顾高能量密度与高安全性是锂金属电池发展应用中亟需解决的关键科学问题。具有强吸电子基团(C≡N)的聚丙烯腈(PAN)聚合物与碳酸酯溶剂中C=O的相互作用能形成更稳定的SEI膜,PAN作为锂负极涂层还能抑制锂枝晶的生长;另外,PAN具有较低的最低未占据分子轨道、较高的电化学稳定性和较宽的电化学窗口,能作为锂金属电池的聚合物电解质,并匹配高电压正极,兼具高能量密度和高安全性,故PAN聚合物在锂金属电池的电解质中有着很大的应用潜力。本文从电解质的不同状态(液态、凝胶、固态)介绍了PAN聚合物在液态电解质中作为隔膜、锂负极保护层以及在凝胶电解质、固态电解质的最新研究成果,并对PAN聚合物在锂金属电池电解质中的发展趋势进行展望。

With the rapid development of portable electronic devices,electric vehicles,and smart grids,there is an increasing interest in high-energy-density lithium metal batteries.Uneven Li stripping or deposition on the surface of lithium metal will lead to the growth of lithium dendrites,which can easily pierce the separator and cause the short circuit in the battery.Moreover,the highly reactive lithium metal will continue to react with the electrolyte,resulting in an unstable solid electrolyte.interfacial(SEI)film and irreversible capacity loss.Taking high-energy-density and high safety into account is a key scientific problem that needs to be solved urgently in the development and application of lithium metal batteries.The interaction of strong electron withdrawing group(C≡N)in polyacrylonitrile(PAN)polymer and C=O in carbonate solvent can form a more stable SEI film.As a lithium anode coating,PAN can also inhibit the growth of lithium dendrites.In addition,due to the low lowest unoccupied molecular orbital,high electrochemical stability and wide electrochemical window,PAN can be regard as polymer electrolytes for lithium metal batteries,and matched with a high-voltage cathode to achieve both high energy density and safety.Thus,PAN polymer has significant potential application in electrolytes for lithium metal batteries.This review mainly starts from the different states of electrolytes(liquid,gel,and solid state).Recent research development of PAN polymer as separators and lithium anode protective layers in liquid electrolytes,as well as its application in gel electrolytes and solid-state electrolytes are presented.Finally,the review prospects the development trend of PAN polymer in lithium metal battery electrolytes.