全固态锂离子电池中金属锂负极界面优化改性研究

以共聚物PEDOT-co-PEG作为锂金属阳极的表面改性层,采用磷酸铁锂复合阳极和“石榴石型”物质以及聚合氧乙烷聚合物组成的固体电解质制备了全固态锂离子电池。采用SEM分析了锂金属充电-放电反复操作后的形态学改变;采用电化学组抗谱试验研究了改性后的锂金属以及复合固体电解质接触面的稳定性并对全固态锂离子电池的充电-放电性能和界面稳定性进行了研究。结果表明,未改性的锂金属在固态电池充电-放电过程中会生成锂枝晶,从而导致全固态锂离子电池的高电流密度容量快速衰变;“石榴石型”物质以及聚合氧乙烷聚合物组成的固体电解质与改性后的金属锂具有良好的接触面,从而扼制锂枝晶的形成,提高全固态锂离子电池的机械性能;在PEDOT-co-PEG共聚物改性锂金属后,全固态锂离子电池的平稳性显著提高,且容量减弱放缓。

Study on optimization of interface modification of metal lithium anode in all solid state lithium ion battery

All solid state lithium ion batteries are prepared by using copolymer PEDOT-co-PEG as the surface modification layer of lithium metal anode and lithium iron phosphate composite anode,garnet type material and polyoxyethane polymer as solid electrolyte.SEM is used to analyze the morphological changes of lithium metal after repeated charge discharge operation.Electrochemical impedance spectroscopy(EIS)is used to study the contact surface stability of modified lithium metal and composite solid electrolyte,and the charge discharge performance and interface stability of all solid state lithium ion battery are studied.The results show that the high current density capacity of all solid state lithium ion batteries rapidly decays due to the formation of lithium dendrites in the process of charging and discharging.The solid electrolyte composed of"garnet type"substance and polyoxyethane polymer has a good contact surface with the modified lithium metal,which could inhibit the formation of lithium dendrite and improve the mechanical properties of all solid state lithium ion batteries.The stability of all solid state lithium ion batteries is significantly improved and the capacity of all solid state lithium ion batteries is slowed down after the modification of lithium metal by PEDOT-co-PEG copolymer.