Entropy‐Driven Highly Chaotic MXene‐Based Heterostructures as an Efficient Sulfur Redox Electrocatalysts for Li‐S Battery

Abstract

AbstractBoth the sluggish sulfur redox reaction (SRR) kinetics and lithium polysulfides (LiPSs) shuttle effect limit the practical application of Li‐S batteries. Designing heterostructure sulfur hosts has emerged as an effective way to address these two issues with one material. However, the principles of heterostructures reinforced Li‐S batteries remain inadequately understood. Here, it is demonstrated for the first time that increasing the entropy of heterostructure can promote its SRR catalytic activity and alleviate the LiPSs shuttling. By a simple solution‐based strategy, a highly chaotic MXene‐based heterostructure (HCMH, TiS2/TiN/TiO2/Ti3C2Tx) is fabricated. The smart integration of “high entropy”, heterostructure, and MXene endow the HCMH catalyst with significantly improved performance, demonstrated by a much smaller Tafel slope of 62.9 mV dec−1 and a higher electron transfer number of 7.10, compared with the moderately chaotic MXene‐based heterostructure (MCMH, TiO2/TiN/Ti3C2Tx) and MXene. DFT theoretical calculations reveal that introducing new phases lowers the Gibbs energy barriers of both rate‐limiting Li2S2/Li2S reduction and Li2S decomposition. Upon the addition of only 5 wt.% HCMH to the sulfur cathode, both the reversible capacity and rate capability of Li‐S cells are greatly improved, which further highlights the importance of the high entropy “cocktail effect” in the design of SRR electrocatalysts in the future.