Single-walled carbon nanotubes film supported lithiated PIM-1 ultrathin selective barrier: A multifunctional layer for polypropylene separator to boost performance of Li-S batteries

The commercialization of lithium-sulfur (Li-S) batteries has been restrained mainly by lithium polysulfides (LiPSs) shuttling and sluggish electrochemical reactions. Herein, a functional separator with synergy effect between adsorption and catalysis is proposed to solve the above problems. Specifically, an ultrathin barrier layer of a functionalized intrinsic microporous polymer (Li-AOPIM-1) is coated on SWCNT gutter layer through spin coating and applied to modify the cathode side of commercial polypropylene (PP) separator. In this configuration, the robust SWCNT gutter layer with high conductivity can not only work as a physical barrier to block the macropores of PP separator, but also improve the integral conductivity, resulting in a rapid charge migration and reaction kinetics. The electronegative heteroatoms N and O in Li-AOPIM-1 top layer have strong adsorption capability to LiPSs so that modified separator can restrain the shuttle effect admirably. Moreover, the introduction of lithiated sites further enhance the lithium-ion conductivity. Accordingly, the Li-S batteries implementing this modified separator deliver stable lifespan with only 0.062% capacity fading rate per cycle after 500 cycles at 1 C and superior rate performance of 700.6 mAh g−1 at 3 C. This work will provide a feasible strategy for the practical applications of high-performance Li-S batteries.