Efficient thermal management of lithium-sulfur batteries by highly thermally conductive LBL-assembled composite separators

Abstract

The movement toward lithium-sulfur (Li-S) batteries with high sulfur utilization and low polysulfides (PSs) shuttling has served as a primary motivation for increased research in high energy storage devices for next-generation electric vehicles. Although enormous studies have been made to facilitate the commercial adoption of Li-S batteries, but in actual use, the battery suffers from undesired elevated temperature and temperature gradient, leading to significant limitations for its extensive implementation. Herein, highly thermally conductive composite separators modified by ultralight and double-sided boron nitride nanosheet (BNNS)/poly(acrylic acid) (PAA) composites are fabricated via a facile layer-by-layer (LBL) self-assembly approach. Benefiting from its uniform thermal distribution, in-built high modulus, promising electrolyte affinity, and strong barrier effect, the LBL-assembled composite separator enables Li-S batteries to work stably at elevated temperatures and temperature gradients, giving the batteries excellent PSs shuttle and Li dendrites suppressing capabilities, as well as outstanding cycling stability and rate performance. This work also suggests a new path to construct high-efficiency and high safety battery systems by eliminating elevated temperature and temperature gradient effects with separator engineering.