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

Qian, Mengmeng; Wu, Feng; Zhang, Junfan; Li, Yun; Wu, Chongteng; Cao, Duanyun; Wang, Jing; Song, Tinglu et al. · Nano Lett · 2024

basic_science · Level V

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Abstract

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+CS<sub>2</sub> = 2Li<sub>4</sub>SeS+C. The obtained composite features crystalline Li<sub>4</sub>SeS encapsulated in a carbon nanocage (Li<sub>4</sub>SeS@C), exhibiting ultrahigh electrical conductivity, ultralow activation barrier, and excellent structural integrity, accordingly enabling large specific capacity (615 mAh g<sup>-1</sup>) and high capacity retention (87.3% after 350 cycles) at 10 A g<sup>-1</sup>. TOF-SIMS demonstrates its superior volumetric efficiency to a similar derivative SeS@C (2Se+CS<sub>2</sub> = 2SeS+C), and DFT reveals its lower activation barrier than Li<sub>2</sub>S@C and Li<sub>2</sub>Se@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.