Electrolyte additive of sorbitol rendering aqueous zinc-ion batteries with dendrite-free behavior and good anti-freezing ability

Abstract

The benefits from Zn metal anodes and aqueous electrolytes have endowed aqueous zinc-ion batteries with widespread concerns, whereas they are compromised by Zn dendrites, severe side reactions, and poor tolerance to low-temperature environments. Herein, food-grade sorbitol with abundant hydroxyl groups is used as the electrolyte additive, which can interact strongly with both water molecules and Zn electrode, thus tailoring the solvation sheath of hydrated Zn2+ ions, tuning the surface of Zn electrode, improving the wettability with Zn electrode, broadening the working potential of electrolyte, lowering the desolvation activation energy, enhancing the Zn2+ ion transfer number, preventing the corrosion issue, and enhancing the freezing-tolerance ability. According to a series of electrochemical tests as well as in-situ and ex-situ measurements, the addition of 10 % sorbitol into aqueous electrolyte can effectively inhibit dendritic growth and harmful side reactions at the surface of Zn electrode. Hence, the modified electrolyte enables Zn/MnO2 battery to own superior cyclability (89.5 % capacity retention after 1000 cycles) and slow self-discharge rate. Even at a low temperature of − 10 ℃, the battery can still offer good electrochemical performances, while that without sorbitol additive can not work normally. This work offers a facile strategy to realize durable anti-freezing aqueous batteries.