Physicochemically Interlocked Sulfur Covalent Triazine Framework for Lithium-Sulfur Batteries with Exceptional Longevity.

An electronically conjugated functional triazine framework is used to synthesize a physicochemically interlocked sulfur cathode that delivers high energy density coupled with exceptional cycle life in lithium-sulfur batteries. Conventional melt-diffusion strategies to impregnate sulfur in the cathode offer poor cycle life due to physical mixing with weak interactions. By contrast, in this approach, sulfur is physicochemically entrapped within a nanoporous and heteroatom doped high surface area covalent triazine framework, resulting in outstanding electrochemical performance (≈89% capacity retention after 1000 cycles, the energy density of ≈2,022 Wh kg-1 sulfur and high-rate capability up to 12 C). The overall structural characteristics and interactions of sulfur with the covalent triazine framework are explored in detail to explain the intriguing properties of the sulfur cathode.