Ammonium-ion batteries with a wide operating temperature window from −40 to 80 ​°C

Ammonium-ion batteries are promising solutions for large-scale energy storage systems owing to their cost-effectiveness, safety, and sustainability. Herein, we propose an aqueous ammonium-ion battery based on an organic poly(1,5-naphthalenediamine) anode and an inorganic Prussian blue cathode in 19 ​M ​(M: mol kg−1) CH3COONH4 electrolyte. Its operation involves a reversible coordination reaction (C=N/C–N– conversion) in the anode and the NH4+ insertion/extraction reaction in the cathode, along with NH4+ acting as the charge carrier in a rocking-chair battery. Benefiting from the fast kinetics and stability of both electrodes, this aqueous ammonium-ion battery shows an excellent rate capability and long cycle stability for 500 cycles. Moreover, an energy density as high as 31.8 ​Wh kg−1 can be achieved, based on the total mass of the cathode and anode. Surprisingly, this aqueous ammonium-ion battery works well over a wide temperature range from −40 to 80 ​°C. This work will provide new opportunities to build wide-temperature aqueous batteries and broaden the horizons for large-scale energy storage systems.