La 2 MoO 6 as an Effective Catalyst for the Cathode Reactions of Lithium-Sulfur Batteries.

Lithium-sulfur batteries with high theoretical energy density have emerged as one of the most promising next-generation rechargeable batteries, while their discharge capacity and cycle stability are challenges mainly due to the shuttle effect of polysulfide intermediates. Employing an effective catalyst for the conversion of polysulfides in cathode reactions can promote the reaction kinetics to restrain the shuttle of polysulfides. Here, for the first time, La 2 MoO 6 (LMO) as a catalyst is introduced into sulfur cathodes. To investigate the effect of La 2 MoO 6 , we prepare two different structures of La 2 MoO 6 /carbon nanofiber composites. One is carbon nanofiber-supported crystalline La 2 MoO 6 nanoparticles (LMO@CNFs) and the other is amorphous La 2 MoO 6 nanoparticles embedded in carbon nanofibers (LMO-in-CNFs). For sulfur electrodes with ∼73 wt % sulfur loading, LMO@CNFs/S and LMO-in-CNFs/S deliver initial gravimetric capacities of 1493.4 and 1246.7 mA h g -1 , respectively, at a 0.1C rate, obviously higher than that of the control sample CNFs/S. Moreover, LMO@CNFs/S shows much better rate performance than LMO-in-CNFs/S, indicating strongly that La 2 MoO 6 is a highly effective catalyst to promote kinetic conversion of polysulfides.