Catalytic Solid‐State Sulfur Conversion Confined in Micropores toward Superhigh Coulombic Efficiency Lithium‐Sulfur Batteries

Abstract Achieving the solid–solid conversion of sulfur is a fundamental solution to eliminating the shuttling of soluble polysulfides and improving the cycling stability of lithium‐sulfur batteries. However, the sluggish solid reaction kinetics seriously challenge the battery performance. In this work, a micropore‐confined catalysis strategy to achieve the smooth solid–solid conversion of sulfur is proposed. It is realized by storing sulfur in a microporous carbon host with narrow pore size and uniformly distributed single‐atom Co catalytic sites. The microporous structure avoids the contact of electrolyte solvents with the inner sulfur, preventing the formation and dissolution of polysulfides and efficiently suppressing sulfur loss during cycling. The introduced single‐atom Co catalytic sites promote the charge transfer to accelerate the solid–solid conversion of sulfur. When coupled with a liquid carbonate electrolyte, the battery exhibits a remarkably high Coulombic efficiency (CE) of ≈99.88% and a minimal capacity decay rate of ≈0.016% per cycle for 1000 cycles at 0.5 C. Even when coupled with the solid‐state electrolyte, the battery still delivers a significantly high capacity of 1100 mAh g −1 and a remarkably high CE of ≈99.83% over 200 cycles. This work reveals a promising solution for developing practical stable Li─S batteries.