摘要
锂硫电池因其具有出色的能量密度(2600 W·h·kg^(–1))且硫资源分布广泛、易于获取而备受研究人员关注。然而,因其严重的“穿梭效应”制约了其商业化进程。电解质作为锂硫电池中最重要的部分之一,对于锂硫电池容量具有特殊的贡献。聚合物电解质由于其分子链的可设计性,被研究者广泛用来抑制“穿梭效应”,虽然使用聚合物电解质可以在一定程度上抑制“穿梭效应”,但是由于多硫化物在聚合物电解质中特殊的溶解性,使得这种“穿梭效应”无法完全被抑制。本文结合了聚合物电解质在锂硫电池方面的应用,针对解决锂硫电池“穿梭效应”的策略进行了整理归纳,包括物理吸附、化学吸附以及二者协同作用和催化转化,并对未来聚合物电解质的发展方向作出展望,为抑制锂硫电池“穿梭效应”的发展提供一定的参考。
Lithium-sulfur(Li-S)batteries,characterized by an ultrahigh theoretical energy density of 2600 W·h·kg^(–1),have emerged as promising candidates to replace conventional lithium-ion batteries.The abundance and low-cost accessibility of sulfur resources further reinforce their potential for scalable applications.Within the critical components of Li-S batteries,electrolyte research has drawn substantial attention,particularly polymer electrolytes due to their merits of low-cost fabrication,lightweight nature,and tunable structural design.While the introduction of solid polymer electrolytes(SPE)and gel polymer electrolytes(GPE)markedly enhances battery safety by mitigating flammable liquid leakage,persistent dissolution of lithium polysulfides(Li2Sx,4≤x≤8)during cycling remains unresolved.This dissolution phenomenon inevitably triggers the“shuttle effect”,where soluble polysulfides migrate between electrodes,leading to irreversible active material loss and rapid capacity decay.Such challenges position the“shuttle effect”as a pivotal barrier impeding the commercialization of Li-S batteries.Therefore,in-depth exploration of the generation mechanism of the“shuttle effect”is of crucial significance for effectively suppressing this effect through the design and optimization of polymer electrolytes.The working principle of lithium-sulfur batteries is based on the redox reaction between sulfur and lithium,involving a complex“solid-liquid-solid”transformation process.During charging and discharging,the generation and diffusion of soluble lithium polysulfides lead to the“shuttle effect”,which in turn causes self-discharge and capacity decay.Traditional liquid electrolytes are prone to leakage and cannot effectively suppress the shuttle of polysulfides.Therefore,researchers have turned to solid or quasi-solid electrolytes,especially polymer electrolytes.However,the molecular structure of polyethylene oxide(PEO)is similar to that of traditional polyether-based liquid electrolytes,and its ethylene oxide(EO)units have a high Gutmann donor number(DN),showing significant solvation ability.This characteristic enables polysulfides to dissolve in the PEO matrix through complexation,thereby triggering the“shuttle effect”and exacerbating capacity decay.In other polymer electrolytes,the solubility of polysulfides in the polymer electrolyte limits their complete suppression of the“shuttle effect”.To effectively suppress the“shuttle effect”,researchers have proposed various strategies,including the preparation of composite polymer electrolytes by combining polymer matrices with inorganic fillers,ionic liquids,or other functional materials to synergistically enhance the performance of the electrolyte,such as physical adsorption,chemical adsorption,physical-chemical synergy,and catalytic conversion.Physical adsorption mainly restricts the diffusion of polysulfides by constructing physical barriers or utilizing electrostatic interactions.For example,introducing nano-ceramic particles or constructing micro-porous structures in the electrolyte can effectively block the migration of polysulfides.Chemical adsorption fixes polysulfides by introducing functional groups or utilizing Lewis acid-base interactions in the polymer electrolyte.For instance,polymer electrolytes containing ester groups,amino groups,etc.,can form chemical bonds with polysulfides,thereby inhibiting their diffusion.Physical–chemical synergy combines the advantages of physical confinement and chemical adsorption.For example,metal-organic frameworks(MOFs)materials achieve dual restrictions on polysulfides through their micro-porous structures and surface functional groups.The catalytic conversion strategy introduces catalysts to rapidly convert polysulfides into insoluble Li2S,fundamentally suppressing the“shuttle effect”.Summary and Prospects Despite significant advancements in mitigating the“shuttle effect”through polymer electrolyte innovations,lithium-sulfur batteries still face multifaceted challenges that demand interdisciplinary solutions.Fundamental understanding remains incomplete regarding“shuttle effect”mechanisms across diverse polymer matrices,necessitating systematic comparative studies to establish universal theoretical frameworks.While catalytic site integration and functionalized polymer designs have improved polysulfide(LiPS)conversion kinetics,atomic-level manipulation of active sites and precise microstructural control of polymeric networks require further optimization to achieve directional LiPS transformation.Notably,metal-organic frameworks(MOFs),despite their success in sulfur cathodes,remain underexplored in polymer electrolyte systems,where theoretical investigations combining density functional theory calculations and molecular dynamics simulations could elucidate critical interfacial interactions and lithium-ion transport mechanisms.Advanced characterization platforms integrating synchrotron X-ray spectroscopy and cryo-electron microscopy are urgently needed to complement conventional electrochemical techniques like cyclic voltammetry,as current methods cannot directly resolve LiPS dynamic evolution or atomic-scale ion transport phenomena.Concurrently,material optimization must balance enhanced ionic conductivity through molecular engineering against preserved LiPS adsorption/catalytic capabilities,demanding innovative multiscale designs that address hierarchical structure–property relationships and interfacial stability under operational conditions.These interconnected challenges highlight the imperative for coordinated efforts combining computational modeling,advanced characterization,and rational material design to overcome existing barriers in polymer electrolyte development.
作者
雷西萍
张凯忠
赵新晨
肖婉彤
陈悠然
LEI Xiping;ZHANG Kaizhong;ZHAO Xinchen;XIAO Wantong;CHEN Yuran(Institute of Nanomaterials and Technology,School of Materials Science and Engineering,Xi'an University of Architecture and Technology,Xi'an 710055,China)
出处
《硅酸盐学报》
北大核心
2026年第1期297-311,共15页
Journal of The Chinese Ceramic Society
基金
陕西省科技厅重点研发项目(2023-YBGY-500)。
关键词
锂硫电池
聚合物电解质
穿梭效应
多硫化物
催化
lithium-sulfur batteries
polymer electrolyte
shuttle effect
polysulfides
catalysis
