Bipolar Prussian blue analogues electrodes for symmetric aqueous batteries in diverse scenarios

Among the various energy storage systems, symmetric aqueous batteries (SABs) have attracted increasing attention due to their low cost, high convenience, and intrinsic safety. However, the available bipolar materials for SABs are limited and their practical scenarios remain scarce. Herein, Prussian blue analogues (PBAs) materials with bipolarity are used to construct SABs, by utilizing the two separated redox platforms at cathodes and anodes, respectively. Meanwhile, the phase transition that occurred in the two-charge-transfer process is highly inhibited by dividing the two redox centers into separated charging/discharging processes, leading to a much-improved structural stability of the PBAs electrodes. Consequently, the constructed symmetric cells exhibit an enhanced cyclability with 1500 cycles and the polarity invertible capability which enables longer life and safer operation. Furthermore, various application scenarios have been promoted based on different electrolytes, including fibrous SABs, low-temperature SABs, and seawater SABs. This study reveals a universal strategy of SABs construction using PBAs materials for practical application.