Fig. 7: Scaled-up Zn–Br₂ batteries for practical energy storage applications.

a Schematic of the scaled-up Zn–Br₂ battery structure. b A digital photograph of the assembled battery. c Cycling performance of the scaled-up battery with a capacity of 500 mAh. The battery was charged firstly at 250 mA to 1.95 V and then at 1.95 V to 500 mAh, and finally discharged at 250 mA to 0.5 V. d Discharge curves of the batteries with different connections. The individual battery was charged firstly at 300 mA to 2 V and then at 2 V to 1500 mAh, and finally discharged at 200 mA to designated voltage. e Solar powered battery energy storage system at day and night. The demonstrated system of solar powered energy storage is based on the Zn–Br₂ battery module as the energy storage device (four series-connected Zn–Br₂ batteries with a voltage of ~6 V and a capacity of 1500 mAh), photovoltaic cell panel as power source (rated at 9 W) and an LED display (rated at 10 W) serving as electrical load. The electrochemical measurements of the scale-up Zn–Br₂ batteries were carried out at room temperature (25 °C).