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Challenges from the insulating S and Li2S2/Li2S (Li2S1–2) discharge products are restricting the development of the high‐energy‐density Li–S battery system. The deposition of insulating Li2S1–2 on the surfaces of S based cathodes (e.g., S and Li2S) limits the reaction kinetics, leading to inferior electrochemical performance. In this work, the impact of binders on the deposition of Li2S1–2 on S based cathodes is revealed, along with the interaction between polyvinylidene difluoride and Li2S/polysulfides. This interaction can obstruct the electrochemical reactions near the binder, leading to dense deposition of insulating Li2S1–2 that covers the cathode surface. Without such a binder, localized and uniform Li2S1–2 deposition throughout the whole cathode can be achieved, effectively avoiding surface blockage and significantly improving electrode utilization. A full battery constructed with a binder‐free Li2S cathode delivers a gravimetric and volumetric energy density of 331.0 Wh kg−1 and 281.5 Wh L−1, under ultrahigh Li2S loading (16.2 mgLi2S cm−2) with lean electrolyte (2.0 µL mgLi2S−1), providing a facile but practical approach to the design of next‐generation S‐based batteries. [ABSTRACT FROM AUTHOR]

Elucidating the battery operating mechanism is important for designing better conversion‐type anodes as it determines the strategies used to improve electrochemical performances. Herein, the authors pioneered the electrochemical study of layered Bi2O2Se as anodes for lithium‐ion batteries (LIBs) and potassium‐ion batteries (PIBs). Surprisingly, the Bi2O2Se/graphite composite electrode shows even better cycle stability for PIBs. The electrochemical reaction mechanisms of the Bi2O2Se/graphite electrode for LIBs and PIBs are investigated by potential‐resolved in situ and ex situ X‐ray absorption spectroscopy based at the Bi LIII‐edge and Se K‐edge through characterizing the local atomic structure evolution, valence state change, and charge transfer. New insights are gained regarding the electrochemical process of Se2− anions in Bi2O2Se, where multiple Li–Se intermediates rather than the traditional single‐phase Li2Se are involved in this conversion‐type anode. The advanced understanding of anionic electrochemistry in conversion‐type anodes prompts one to find appropriate ways to suppress side‐reactions and improve the battery performances. [ABSTRACT FROM AUTHOR]