A Long-Life Aqueous Rechargeable Aluminum-Ammonium Hybrid Battery

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_1.14Fe^III[Fe^II(CN)₆]·nH₂O) 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.