A New Solid-State Zinc–Air Battery for Fast Charge

Rechargeable zinc–air batteries (ZAB) with solid-state electrolyte are a potential power source for flexible electronic devices. However, solid electrolytes for the battery at large currents remain a challenge in bubble removal at the electrode surface and the small contact area of the electrolyte–electrode interface, as well as low conductivity itself. Herein, a three-electrode structure is proposed for the solid-state rechargeable ZAB, where the sodium polyacrylate (PAA-Na) hydrogel serving as the electrolyte exhibits good mechanical properties, excellent water retention ability, and high conductivity (0.19 S cm⁻¹) after being soaked in potassium hydroxide and zinc acetate solution. The zinc electrode of porous structure is sandwiched by the electrolyte on both sides, facilitating ion transport during charge/discharge. MnO₂/C, as the catalyst of the air electrode, is in contact with the hydrogel, increasing the catalyst active area. Nickel mesh is the charging electrode which facilitates the removal of the evolved bubbles. The results demonstrate that rechargeable ZAB with the PAA-Na hydrogel electrolyte can release a maximum power density of 100.7 mW cm⁻² and run for 183 cycles at a current density of 10 mA cm⁻², which can be a strong competitor in the flexible energy-storage field.