Ethanol as Solvent Additives with Competitive Effect for High-Stable Aqueous Zinc Batteries

Aqueous zinc-ion batteries are emerging as promising sustainable energy-storage devices. However, their cyclic stability is still a great challenge due to the inevitable parasitic reaction and dendrite growth induced by water. Herein, a cosolvent strategy based on competitive effect is proposed to address the aforementioned challenges. Ethanol with a higher Gutmann donor number demonstrates lower polarity and better wettability on the Zn surface compared with water, which endows ethanol with the ability of minimizing water activity by weakening H bonds and preferentially adsorbing on the Zn electrode. The above competitive advantages synergistically contribute to inhibiting the decomposition of free water and dendrite growth. Besides, an organic-inorganic hybrid solid-electrolyte interphase layer is in situ built based on ethanol additives, where organic matrix suppresses water corrosion while inorganic fillers promote fast Zn²⁺ diffusion. Consequently, the electrolyte with ethanol additives boosts a high reversibility of Zn deposition, long-term durability, as well as superior Zn²⁺ diffusibility in both Zn half-cells (Zn||Cu and Zn||Zn batteries) and Zn full cells (Zn||PTCDA and Zn||VO₂ batteries). This work sheds light on a universal strategy to design a high-reversible and dendrite-free Zn anode for stable aqueous batteries.