Understanding LiI-LiBr Catalyst Activity for Solid State Li2S/S Reactions in an All-Solid-State Lithium Battery

Li||MoS 2 solid-state batteries have higher volumetric energy density and power density than Li||Li 2 S batteries. However, they suffer from energy and power decay due to the formation of lithium sulfide that has low ionic/electronic conductivity and a strong Li–S bond. Herein, we overcome these challenges by incorporating the catalytic LiI-LiBr compound and carbon black into MoS 2 . The comprehensive simulations, characterizations, and electrochemical evaluations demonstrated that LiI-LiBr significantly reduces Li + /S 2– interaction and increases the ionic conductivity of Li 2 S, thus enhancing the reaction kinetics and Li 2 S/S redox reversibility. MoS 2 @LiI-LiBr@C||Li cells with an areal capacity of 0.87 mAh cm –2 provide a reversible capacity of 816.2 mAh g –1 at 200 mA g –1 and maintain 604.8 mAh g –1 (based on the mass of MoS 2 ) for 100 cycles. At a high areal capacity of 2 mAh cm –2, the battery still delivers reversible capacity of 498 mAh g –1 . LiI-LiBr-carbon additive can be broadly applied for all transition-metal sulfide cathodes to enhance the cyclic and rate performance.