MXene@PBA heterostructures via end-group-directed self-assembly strategy for effective inhibition of shuttle effect in lithium–sulfur batteries

Abstract

The commercialization of lithium-sulfur batteries (LSBs) has been hindered by the shuttle effect and slow sluggish conversion kinetics. This study developed MXene and Prussian blue analogue (PBA) heterostructures using an end-group-directed self-assembly strategy. MXene@PBA heterostructures were synthesized through layer-by-layer stacking and in situ growth of Mn-PBA, driven by the electrostatic interactions between Mn2+ and the polar terminal groups of MXene. The dual-metal synergistic adsorption of Mn2+ and Fe3+ within PBA framework significantly enhances both the adsorption capacity and cycling stability of the composite. Furthermore, the in-situ growth of PBA not only reinforces the structural integrity but also increases the number of active sites, mitigates the collapse of the accordion-like layered structure, alleviates volume expansion, and accelerates rapid ion diffusion. Theoretical calculations confirm the composite's superior adsorption capacity for Li polysulfides (LiPSs). As a S host, MXene@PBA facilitates the solid-liquid phase transformation of polysulfides, improving reaction kinetics and delivering exceptional electrochemical performance. MXene@PBA composite exhibited an initial discharge capacity of 1220 mAh g−1 at 0.1 C. Its cycle stability is equally remarkable, with a minimal decay rate of 0.062 % per cycle after 500 cycles at 0.5 C. The construction of these layered heterostructures as S hosts presents an effective strategy to mitigate the shuttle effect and enhance the reaction kinetics of LSBs.