Lithium sulfide (Li2S) is one of the most promising cathode materials for the next-generation advanced Li-ion batteries because of its high theoretical capacity (1167 mA h g-1) and large energy density. However, Li2S suffers from poor rate performance and short cycle life due to its insulating nature and polysulfide shuttle during cycling. In this work, we have proposed a facile and scalable strategy for the synthesis of nanosized Li2S particles via a solution-based method. For further application in Li–S batteries, uniform conductive VO2 nanobelts were deposited on the Li2S particles to obtain nano-Li2S@VO2. The average size of the as-prepared nano-Li2S particles is around 100 nm, and covered by VO2 nanobelts with a thickness of 20 nm. These nanoscale Li2S@VO2 particles guarantee a short diffusion distance of lithium ions and the protective layer allows fast electron transport as well as effectively constraining the migration of the soluble polysulfides. As a result, the nano-Li2S@VO2 cathodes show outstanding electrochemical performance with a high initial discharge capacity of 1083.5 mA h g-1 at 0.2 C and 766.3 mA h g-1 after 200 cycles with a low decay of 0.15% per cycle. The enhanced electrochemical performance is due to the unique architecture with enhanced electrical conductivity and better suppression effect for the polysulfide shuttle.
Audience take away:
• Get the latest technology in the synthesize of cathode materials in Li-S battery.
• Lay solid foundation for the deep understanding of VO2 applied in Li-S battery.
• This paper solves the volume expansion of Li-S battery.