Constructing a Nickel-Doped Bimetallic Sulfide/Carbon Network Host to Enhance the Electrochemical Performance of Lithium–Sulfur Battery Cathodes

Lithium–sulfur batteries (LSBs) serve as highly competitive alternatives for advanced next-generation energy storage platforms, attributed to their exceptional theoretical energy density and the widely available natural reserves of sulfur. The practical deployment of LSBs, however, remains challenging primarily due to the slow redox conversion of sulfur species and the severe migration of soluble lithium polysulfides (LiPS), known as the shuttle effect. To address these critical challenges, this study proposes a strategy that integrates nickel doping with a conductive/structural network for the development of a nickel-doped bimetallic sulfide. The introduction of nickel enables partial substitution of vanadium sites, which induces lattice distortion and vacancy formation. This structural modification tailors the electronic configuration of Cu3VS4, creating numerous active sites. These sites markedly improve the polysulfide adsorption and catalytic conversion. Concomitantly, a robust three-dimensional porous carbon network is constructed via the interweaving of multiwalled carbon nanotubes (MWCNTs) and cellulose nanofibers (CNFs). This hierarchical architecture not only facilitates rapid electron/ion transport but also accommodates sulfur volume expansion during charge–discharge cycles, which effectively suppresses LiPS shuttling and systematically improves the cathode’s catalytic activity, electrical conductivity, and structural stability. Electrochemical characterizations demonstrate that the assembled LSB delivers a high initial specific capacity of 1246 mAh·g–1 at 0.2C and exhibits excellent cycling stability at 1C, with an extremely low capacity decay rate of merely 0.086% per cycle over 250 cycles. Moreover, stable electrochemical performance is maintained even under a high sulfur loading of 5.1 mg·cm–2. This work provides a design strategy for the structural and catalytic engineering of high-performance LSB cathodes.