Synchronously Consolidating Li, Se, S, and C for Robust Li–SeS Batteries

S-redox
involving solvated polysulfides is accompanied by volumetric
change and structural decay of the S-based cathodes. Here, we propose
a synchronous construction strategy for consolidating Li, Se, S, and
C elements within a composite cathode via a paradigm reaction of 8Li+2Se+CS2 = 2Li4SeS+C. The obtained composite features crystalline
Li4SeS encapsulated in a carbon nanocage (Li4SeS@C), exhibiting ultrahigh electrical conductivity, ultralow activation
barrier, and excellent structural integrity, accordingly enabling
large specific capacity (615 mAh g–1) and high capacity
retention (87.3% after 350 cycles) at 10 A g–1.
TOF-SIMS demonstrates its superior volumetric efficiency to a similar
derivative SeS@C (2Se+CS2 = 2SeS+C), and DFT reveals its
lower activation barrier than Li2S@C and Li2Se@C. This consolidation design significantly improves the electrochemical
performance of S-based cathodes, and the paradigm reaction guarantees
structural diversity and flexibility. Moreover, employing a synchronous
construction mechanism to maximize the synergistic effect between
element consolidation and carbon encapsulation opens up a new approach
for developing robust S or chalcogenide cathodes.