基于高强度磺化聚芳醚的锂硫电池多孔隔膜及其多硫离子穿梭效应抑制研究

Lithium-sulfur batteries as high energy-density energy storage system (theoretical energy density: 2600 Wh/kg) have attracted more and more attention. The separator is a critical component of lithium-sulfur batteries. It provides a physical barrier between the positive and negative electrodes in order to prevent electrical short circuits and also serves as the electrolyte reservoir for the transport of lithium ions during the charging and discharging cycles of a battery. The dissolution and shutting effect of the polysulfide intermediates across the separator results in poor cycle stability, severe lithium anode corrosion and low Coulombic efficiency of lithium-sulfur batteries. To address these issues, considering ion conductivity and electrochemical stability, we propose an ion-selective transporting separator, which will be prepared by acid-base interaction induced method from sulfonated poly(arylene ether)s. By the design of polymer chain structure, controlling preparation, the sulfonic acid groups will be concentrated in the pores of the porous separator. Due to the electrostatic repulsion effect of sulfonate anions to polysulfides anions, polysulfide shuttle effect will be effectively suppressed. On the other hand, with high strength (higher than that of lithium dendrites) and high thermal stability (melting point>300 ℃), the separator from sulfonated poly(arylene ether) can resist the puncture of lithium dendrites and promote the safety performance of battery. By studying the relationships of the morphology structure with lithium ion conductivity, polysulfide shuttle effect, electrochemical stability and mechanical properties of separator, the project will focus on the preparation of separator with high lithium-ion conductivity and good polysulfide barrier property, which will provide a novel approach for promoting the cycle stability and safety of lithium-sulfur batteries.

锂硫电池是新一代高能量密度的锂电池体系，理论能量密度高达2600 Wh/kg。隔膜是锂硫电池的重要组成部分，溶解在电解液中的多硫离子穿过隔膜形成的“多硫离子穿梭效应”是导致锂硫电池容量衰减、循环性能差的主要原因之一。本项目基于高强度耐高温磺化聚芳醚单离子聚合物电解质，利用酸碱相互作用诱导磺酸基高度聚集，形成对多硫负离子具有屏蔽作用的纳微孔结构，制备对多硫离子穿梭效应有抑制作用的锂硫电池隔膜，提高锂硫电池的循环稳定性。此外，磺化聚芳醚隔膜的高强度（高于纯锂的强度）和耐高温（熔点高于300℃）特性，可以抵抗锂枝晶的穿刺，进而提高电池的安全性能。通过研究隔膜微观结构与锂离子传导率、多硫离子穿梭效应、电化学稳定性及力学性能的关系，发展出一种提高锂硫电池循环稳定性和安全性的新方法。

锂硫电池是新一代高能量密度的锂电池体系，理论比能量高达2600 Wh/kg，而隔膜是锂硫电池的重要组成部分，溶解在电解液中的多硫离子穿过隔膜形成的多硫离子的穿梭效应是导致锂硫电池容量衰减、循环性能差的主要原因之一。本项目通过采用功能复合引入静电屏蔽效应来抑制多硫离子效应，设计多孔隔膜的微观结构，实现功能隔膜的可控制备，并利用单离子聚合物来抑制多硫离子穿梭，结合锂硫电池结构设计，实现多级阻硫。同时采用高性能高分子材料，获得具有特殊结构的耐高温高强度的隔膜，可以有效抑制锂枝晶的生长。研究了隔膜微观结构与锂离子传导率、多硫离子穿梭效应、电化学稳定性及力学性能的关系，拓展了提高锂硫电池循环稳定性和安全性的解决途径。