摘要
锂硫(Li-S)电池因其高能量密度和低成本,成为下一代能源存储设备的有力候选.然而锂硫电池的商业化应用仍面临诸多挑战,包括多硫化物穿梭效应、硫的缓慢氧化还原反应动力学以及锂枝晶的不可控生长.本文提出了一种新型电解液添加剂联五氟苯碲(C_(6)F_(5))_(2)Te,在硫正极中通过与多硫化锂(LiPSs)发生相互作用,加速多硫化锂的转换.在锂负极,联五氟苯碲参与生成稳定的有机-无机混合固态电解质界面(SEI),从而有效抑制锂枝晶的生长,确保锂的均匀沉积.
Lithium-sulfur(Li-S)batteries are regarded as one of the most promising next-generation energy storage systems due to their high theoretical energy density(~2600 Wh·kg^(-1)),low cost,and the abundance of sulfur.Their high energy potential makes them attractive for applications in electric vehicles and large-scale grid storage.However,their practical deployment is significantly hindered by multiple challenges,including the severe shuttle effect caused by the dissolution and migration of lithium polysulfides(LiPSs),the intrinsi⁃cally sluggish redox kinetics of sulfur species,and the uncontrolled growth of lithium dendrites on the anode.These issues result in rapid capacity fading,poor Coulombic efficiency,and safety concerns,making interfa⁃cial stabilization a key research focus.In this study,we propose bi(s pentafluorophenyl)telluride((C_(6)F_(5))_(2)Te)as a multifunctional electrolyte additive designed to simultaneously address these issues.The molecule was synthesized via a Williamson-type etherification reaction between sodium telluride and pentafluoroiodoben⁃zene,and its chemical structure was confirmed by¹⁹F NMR spectroscopy.Density functional theory(DFT)calculations reveal that the electron-deficient pentafluorophenyl groups on(C_(6)F_(5))_(2)Te facilitate strong interac⁃tions with LiPSs,leading to enhanced conversion kinetics and improved interfacial electron redistribution.A combination of electrochemical characterizations,including galvanostatic cycling,electrochemical impedance spectroscopy(EIS),cyclic voltammetry(CV),and lithium symmetric cell testing,was conducted to assess the additive’s performance.Surface analyses by X-ray photoelectron spectroscopy(XPS)and scanning elec⁃tron microscopy(SEM)were also employed to investigate interfacial evolution.The experimental results demonstrate that(C6F5)2Te promotes the stepwise transformation of LiPSs,effectively mitigating their shuttle effect.Moreover,the additive undergoes preferential reduction on the lithium anode,forming a LiFrich solid electrolyte interphase(SEI)that promotes uniform Li deposition and suppresses dendrite formation.EIS analysis reveals significantly lower interfacial resistance and improved ion transport.With 1 wt%addi⁃tive,the Li-S cell exhibits excellent cycling stability,retaining 49.89%of its capacity after 500 cycles at 0.5 C,far superior to the baseline cell(17.17%).In summary,(C₆F₅)₂Te functions as a bifunctional interfa⁃cial modifier that simultaneously stabilizes both anode and cathode surfaces,accelerates polysulfide conver⁃sion,and enhances long-term battery stability.This work provides a feasible strategy for electrolyte engineer⁃ing in high-performance Li-S batteries and offers new insights into the design of multifunctional molecular ad⁃ditives.
作者
黄秉轩
王琛
张华俊
唐仕海
刘芝孟
何欣
HUANG Bing-Xuan;WANG Chen;ZHANG Hua-Jun;TANG Shi-Hai;LIU Zhi-Meng;HE Xin(School of Chemical Engineering,Sichuan University,Chengdu 610065,China;Sichuan University-Pittsburgh Institute,Chengdu 610211,China)
出处
《四川大学学报(自然科学版)》
北大核心
2025年第6期1456-1462,共7页
Journal of Sichuan University(Natural Science Edition)
基金
四川大学基本科研业务基金(SCU2023HGXY)。
关键词
锂硫电池
联五氟苯碲
添加剂
电化学性能
Lithium-sulfur batteries
(C6F5)2Te
Additives
Electrochemical performanc
