The preparation and performances of lithium sulfide (Li2S)-oriented cathode composite via carbothermic reduction.

The high theoretical energy density, high environmental adaptability and safety of lithium sulfide (Li 2 S)-oriented cathodes attract enough attention among lithium-sulfur batteries (LSBs). In this work, the lithium sulfide (Li 2 S)-oriented composite is fabricated via an in-situ carbothermic reduction method, in which lithium sulfate is reduced by CMK3 at an optimized temperature and subsequently the as-prepared Li 2 S is protected via the conformal carbon layer by carbonization of phenol-formaldehyde resin (PF). With the aid of the porous carbon structure of CMK3 and protection of PF-derived conformal carbon layer, the dispersity of Li 2 S and conductivity of cathode are availably enhanced. It has been found that the Li 2 S@CMK3-C prepared at optimum carbothermic reduction temperature of 835 °C has excellent electrochemical performance. The lithium-sulfur battery using Li 2 S@CMK3-C as cathode and metal Li as anode can deliver a high initial discharge capacity of 979 mAh g−1 at 0.1 C, the capacity retention after running at various current density is 94%, and the discharge specific capacity is still 530 mAh g−1 at 2 C after 450 cycles. Therefore, the preparation of CMK3-supported Li 2 S-based cathode material provides a new approach for the development and industrialization of new high-performance Li–S battery. Image 1 • An in-situ carbothermic reduction method is employed. • Lithium sulfide is in-situ formed inside cathode matrix as sulfur source. • The shuttle of polysulfides and activation energy barrier is suppressed. • The as-fabricated batteries deliver elevated electrochemical performance. [ABSTRACT FROM AUTHOR]