Unveiling the autocatalytic growth of Li<sub>2</sub>S crystals at the solid-liquid interface in lithium-sulfur batteries.

Wu, Zhen; Liu, Mingliang; He, Wenfeng; Guo, Tong; Tong, Wei; Kan, Erjun; Ouyang, Xiaoping; Qiao, Fen et al. · Nat Commun · 2024

basic_science · Level V

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Abstract

Electrocatalysts are extensively employed to suppress the shuttling effect in lithium-sulfur (Li-S) batteries. However, it remains challenging to probe the sulfur redox reactions and mechanism at the electrocatalyst/LiPS interface after the active sites are covered by the solid discharge products Li<sub>2</sub>S/Li<sub>2</sub>S<sub>2</sub>. Here, we demonstrate the intrinsic autocatalytic activity of the Li<sub>2</sub>S (100) plane towards lithium polysulfides on single-atom nickel (SANi) electrocatalysts. Guided by theoretical models and experimental data, it is concluded that LiPS dissociates into Li<sub>2</sub>S<sub>2</sub> and short-chain LiPS on the Li<sub>2</sub>S (100) plane. Subsequently, Li<sub>2</sub>S<sub>2</sub> undergoes further lithiation to Li<sub>2</sub>S on the Li<sub>2</sub>S (100) surface, generating a new Li<sub>2</sub>S (100) layer, thus enabling the autocatalytic formation of a new Li<sub>2</sub>S (100) surface. Benefiting from the autocatalytic growth of Li<sub>2</sub>S, the concentration of LiPS in the electrolyte remains at a lower level, enabling Li-S batteries under high loading and low electrolyte conditions to exhibit superior electrochemical performance.