Anode-free lithium–sulfur batteries (AFLSBs) show a surprisingly prolonged cycle life 2-fold higher than anode-free lithium metal batteries. The principal difference is the presence of an intrinsic polysulfide (PS) shuttle between electrodes in AFLSBs. However, the underlying mechanism for the impact of PS redox species on the electrochemical performance of AFLSBs is not clearly understood. Herein, we investigate the role of PS redox species in retrieving inactive lithium for compensating lithium inventory loss using titration gas chromatography, thereby quantifying inactive lithium accumulated after several cycles. Moreover, XPS analysis reveals reduced lithium sulfide (Li₂S/Li₂S₂) species formed through PS redox shuttle refresh inactive solid electrolyte interface (SEI) composition and stabilize the consecutive cycle lithium deposition. Interestingly, synchrotron-based operando transmission X-ray microscopy (TXM) reveals dense and granular electrodeposited lithium morphologies in AFLSBs. Therefore, the interplay between reviving inactive lithium for compensating lithium inventory loss and stabilizing lithium electrodeposition endows high electrochemical performance in AFLSBs.

中文翻译：

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恢复非活性锂并稳定锂沉积以提高无阳极锂硫电池的性能

无阳极锂硫电池 (AFLSB) 的循环寿命令人惊讶地延长，比无阳极锂金属​​电池高 2 倍。主要区别在于 AFLSB 的电极之间存在固有的多硫化物 (PS) 穿梭。然而，PS 氧化还原物质对 AFLSB 电化学性能影响的潜在机制尚不清楚。在此，我们研究了 PS 氧化还原物质在使用滴定气相色谱法回收非活性锂以补偿锂库存损失中的作用，从而量化了几个循环后积累的非活性锂。此外，XPS 分析显示还原的硫化锂 (Li ₂ S/Li ₂ S ₂) 通过 PS 氧化还原穿梭形成的物种刷新非活性固体电解质界面 (SEI) 成分并稳定连续循环锂沉积。有趣的是，基于同步加速器的原位透射 X 射线显微镜 (TXM) 揭示了 AFLSB 中致密和颗粒状的电沉积锂形态。因此，恢复非活性锂以补偿锂库存损失与稳定锂电沉积之间的相互作用赋予了 AFLSB 高电化学性能。