Self-assemble construction of hetero-structured Co(OH)2/MXene aerogel toward Li–S batteries as a self-supported host and bifunctional catalyst

Abstract

The shuttling diffusion of polysulfides is a bottleneck that seriously limits the performance of Li–S batteries. Purposeful construction of sulfur cathodes with reliable trapping ability of polysulfides is the key to overcome such limitation. Herein, a hierarchical porous architecture, i.e., Co(OH)₂ sheets bonded Ti₃C₂T_x MXene aerogel (Co(OH)₂/MXA), is constructed via a facile self-assembled approach and used as an efficient free-standing polysulfides reservoir. The interconnected three-dimensional (3D) porous network with void space and strong interfacial interaction not only enables high sulfur loading but facilitates fast ion and electron transport. Experimental and theoretical results confirm the hetero-framework exhibits outstanding immobilization and conversion ability for polysulfides due to its polar surface and bifunctional catalytic activities toward both formation and decomposition of Li₂S. The optimized Co(OH)₂/MXA cathode delivers excellent rate capability (407 mAh·g^–1 at 5C) with a sulfur loading of 2.7 mg·cm⁻², and ultra-stable cycling performance as an extremely small capacity decay of ~ 0.005% per cycle within 1700 cycles at 1C is achieved with a high sulfur loading of 6.7 mg·cm⁻². More significantly, our design structural/componential methodology here promises the MXene-based aerogel electrodes for Li–S batteries and beyond.

Graphical abstract