MoS 2 /Mayenite Electride Hybrid as a Cathode Host for Suppressing Polysulfide Shuttling and Promoting Kinetics in Lithium-Sulfur Batteries.

The commercial viability of emerging lithium-sulfur batteries (LSBs) remains greatly hindered by short lifespans caused by electrically insulating sulfur, lithium polysulfides (Li 2 S n ; 1 ≤ n ≤ 8) shuttling, and sluggish sulfur reduction reactions (SRRs). This work proposes the utilization of a hybrid composed of sulfiphilic MoS 2 and mayenite electride (C12A7:e - ) as a cathode host to address these challenges. Specifically, abundant cement-based C12A7:e - is the most stable inorganic electride, possessing the ultimate electrical conductivity and low work function. Through density functional theory simulations, the key aspects of the MoS 2 /C12A7:e - hybrid including electronic properties, interfacial binding with Li 2 S n , Li + diffusion, and SRR have been unraveled. Our findings reveal the rational rules for MoS 2 as an efficient cathode host by enhancing its mutual electrical conductivity and surface polarity via MoS 2 /C12A7:e - . The improved electrical conductivity of MoS 2 is attributed to the electron donation from C12A7:e - to MoS 2 , yielding a semiconductor-to-metal transition. The resultant band positions of MoS 2 /C12A7:e - are well matched with those of conventional current-collecting materials ( i.e ., Cu and Ni), electrochemically enhancing the electronic transport. The accepted charge also intensifies MoS 2 surface polarity for attracting polar Li 2 S n by forming stronger bonds with Li 2 S n via ionic Li-S bonds than electrolytes with Li 2 S n , thereby preventing polysulfide shuttling. Importantly, MoS 2 /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 S 8 -to-Li 2 S conversion. Beyond the reported applications of C12A7:e - , this work highlights its functionality as an electrode material to boost the efficiency of LSBs.