MoS2/Mayenite Electride Hybrid as a Cathode Host for Suppressing Polysulfide Shuttling and Promoting Kinetics in Lithium–Sulfur Batteries

Abstract

<p>The commercial viability of emerging lithium−sulfur batteries (LSBs) remains greatly hindered by short lifespans caused by electrically insulating sulfur, lithium polysulfides (Li₂S_<i>n</i>; 1 ≤ n ≤ 8) shuttling, and sluggish sulfur reduction reactions(SRRs). This work proposes the utilization of a hybrid composed of sulfiphilic MoS₂ and mayenite electride (C12A7:e⁻) as a cathode host to address these challenges. Specifically, abundant cement-based C12A7:e⁻ is the most stable inorganic electrode, possessing the ultimate electrical conductivity and low work function. Through density functional theory simulations, the key aspects of the MoS₂/C12A7:e⁻ hybrid including electronic properties, interfacial binding with Li₂S_<i>n</i>, Li+ diffusion, and SRR have been unraveled. Our findings reveal the rational rules for MoS₂ as an efficient cathode host by enhancing its mutual electrical conductivity and surface polarity <i>via</i> MoS₂/C12A7:e⁻. The improved electrical conductivity of MoS₂ is attributed to the electron donation from C12A7:e⁻ to MoS₂, yielding a semiconductor-to-metal transition. The resultant band positions of MoS₂/C12A7:e⁻ are well matched with those of conventional current-collecting materials (<i>i.e.</i>, Cu and Ni), electrochemically enhancing the electronic transport. Theaccepted charge also intensifies MoS₂ surface polarity for attracting polar Li₂S_<i>n</i> by forming stronger bonds with Li₂S_<i>n</i> <i>via</i> ionic Li−Sbonds than electrolytes with Li₂S_<i>n</i>, thereby preventing polysulfide shuttling. Importantly, MoS₂/C12A7:e⁻ not only promotes rapid reaction kinetics by reducing ionic diffusion barriers but also lowers the Gibbs free energies of the SRR for effective S₈-to-Li₂Sconversion. Beyond the reported applications of C12A7:e⁻, this work highlights its functionality as an electrode material to boost the efficiency of LSBs.</p>