High‐Energy Aqueous Sulfur Battery Chemistry

Aqueous sulfur batteries (ASBs) have garnered ever-increasing interest due to their remarkable safety, high specific capacity, and cost-effectiveness. However, the present understanding of sulfur chemistry in water relies on experience derived from conventional organic electrolyte-based sulfur batteries (OSBs). The absence of a comprehensive review fundamentally distinguishing the sulfur chemistry in aqueous electrolytes from the organic counterparts leads to an insufficient understanding of ASBs, which impedes their advancement. Here, this perspective delves into the intricate aqueous-sulfur-related chemistry, offering a comprehensive analysis of the redox pathways, thermodynamic processes, and kinetic behaviors that are central to the operation of ASBs. All reactions are classified into three categories based on the solubility product constant (K_sp): solid-solid (s-s), solid-liquid (s-l), and liquid-liquid (l-l). Rather than simply compiling recent progress, a critical appraisal of the recent advances in different ASBs is presented, with special emphasis on the challenges and underlying mechanisms of various strategies. Potential interactions and integrated strategies in different ASBs are established. Lastly, this perspective synthesizes current concerns and forward-looking insights for developing next-generation ASBs with improved durability and energy efficiency.