Conductive 1T-VS2−MXene heterostructured bidirectional electrocatalyst enabling compact Li-S batteries with high volumetric and areal capacity

A dense high-sulfur-loaded cathode with low porosity is highly desired for achieving high-volumetric-capacity Li-S batteries (LSBs) without sacrificing gravimetric performance. Nevertheless, the heavy shuttling and extremely slow sulfur redox kinetics severely impede its progress. Herein, we develop a dual-conductive 1T-VS2−MXene heterostructured electrocatalyst as a high-efficiency sulfur host, which combines the merits of ultrafast anchoring and catalysis (1T-VS2) with good nucleation and surface diffusion (MXene) for accelerating the bidirectional sulfur redox kinetics, regulating the Li2S nucleation and decomposition, and depressing the polysulfide shuttling. And combining a design of dense sulfur cathode, the highly dense S/1T-VS2−MXene monolith cathode (density: 1.91 g cm−3, conductivity: 76.3 S m−1) achieves a high volumetric capacity of 1571 Ah L−1 (based on the total volume of sulfur cathode) (gravimetric capacity: ∼1430 mAh g−1 based on sulfur) in a routine electrolyte at 0.1 C and a large areal capacity of ∼7.9 mAh cm−2 in an extremely lean electrolyte of 3 μL mgs−1 at 0.05 C. Experimental and theoretical results also clearly reveal the origin of superior performance and the synergistic mechanism of heterostructured catalyst from the perspective of the electronic structure and atomic level. Therefore, this deep work demonstrates the feasibility for the fabrication of LSBs with high volumetric and areal capacities in lean electrolytes by combining the dual-conductive heterostructure electrocatalyst with the dense-structured sulfur cathode.