Concentrated Chloride Electrolytes Enable High‐Efficiency, Long‐Cycling, and Dendrite‐Free Aqueous Trivalent Antimony Batteries

Abstract Aqueous trivalent metal batteries are promising energy storage systems, which can leverage unique three‐electron redox reactions to deliver high capacity and high energy. Among them, antimony (Sb) stands out with a high capacity (660 mAh g −1 ), abundant availability, and low cost. However, the severe Sb 3+ hydrolysis reaction drastically hinders the development of aqueous antimony batteries. Herein, we address this issue by employing a concentrated lithium chloride electrolyte, which stabilizes reactive Sb 3+ ions via forming robust antimony‐chloride complexes. This approach effectively mitigates hydrolysis and achieves highly reversible Sb plating behavior, leading to high efficiency (99.7%–99.8%), long lifespan (7300 h, 10 months), and uniform spherical deposition morphology. When paired with a manganese dioxide (MnO 2 ) cathode, the Sb‖MnO 2 battery demonstrates a high capacity of 309 mAh g −1 and exceptional cycling stability of 50 000 cycles (∼70% retention). Additionally, Sb shows promise as a high‐capacity cathode, which can integrate with low‐potential zinc into novel dual‐metal plating batteries with long cycling life (4,000 h). This work not only deepens our fundamental understanding of trivalent Sb 3+ redox chemistry but also opens new opportunities to stabilize hydrolysable and high‐charge‐density cations for multivalent battery applications.