A Long‐Life Aqueous Rechargeable Aluminum‐Ammonium Hybrid Battery

Abstract Aqueous rechargeable batteries (ARBs) offer a low‐cost, high‐safety, and fast‐reacting alternatives for large‐scale energy storage. However, their further practical applications are limited by challenges in achieving satisfactory energy density, long cycling lifetime, and cost‐effectiveness. In this study, an aqueous rechargeable aluminum‐ammonium hybrid battery is reported (AAHB) that utilizes a Prussian blue analogue (K 1.14 Fe III [Fe II (CN) 6 ]·nH 2 O) as an ultra‐stable cathode for reversibly accommodating ammonium ion, paired with aluminum‐ one of the lowest‐cost metals, aside from iron—as the anode. An average working voltage of 1.15 V, remarkable rate capability, and an attractive energy density of 89.3 Wh kg −1 are achieved. Notably, the Prussian blue analogue cathode exhibits almost no attenuation after an ultra‐long cycle life of 100,000 cycles, and the assembled AAHB demonstrates a long cycling lifespan exceeding 10,000 cycles. This work opens a door for exploring high‐performance and low‐cost ARBs for grid‐level energy storage.