Biomimetic nacre-like aramid nanofiber-holey MXene composites for lithium-sulfur batteries

Polysulfide shuttle and lithium dendrite formation limit practical applications of lithium-sulfur (Li-S) batteries. To address these issues, we propose a nacre-inspired design of MXene/aramid nanofiber (ANF) separator with “brick-and-mortar” microstructure. The combination of shortened ion transfer distance generated by holes on MXene and enlarged interlayer spacing provided by ANFs creates a hierarchical ion path “highway” that modulates the efficiency of ion transportation while synergistically suppressing the polysulfide shuttles. Furthermore, benefitting from the introduction of ANF, the composite membrane has good mechanical properties and impact tolerance. With simultaneous mitigation of dendrite growth and polysulfide poisoning of anodes, the cells with nacre-inspired separator exhibited excellent rate capability to 5 C and had a possible long cycle life of 3,500+ cycles with capacity decay of 0.013% per cycle to 3 C. This work offers a membrane design strategy inspired by the structure of pearl layers, aiming to resolve materials performance challenges of high-performance energy storage.