Multifunctional water-organic hybrid electrolyte for rechargeable zinc ions batteries

Uncontrollable dendrite growth and parasitic reactions are the fundamental obstacles to achieve large-scale application of aqueous Zn-ion batteries. Herein, a new strategy of tuning the electrolyte solvation structure and electrode interface is demonstrated for highly reversible zinc plating/stripping. Acetonitrile (AN) is introduced into Zn(OTf)2 electrolyte as co-solvent, the interaction between Zn2+ and acetonitrile attenuates the Zn2+ solvation and water activity. Concomitantly, theoretical calculations demonstrate that acetonitrile molecules tend to adsorb on the surface of zinc electrode to form an adaptive zinc-electrolyte interface. Such an electrolyte engineering significantly prevents water hydrogen evolution, suppresses vanadium dissolution and modulates Zn deposition behavior. As proof of concept, Zn//Zn symmetric cells with acetonitrile additive exhibit a ultra-long cycling of 2100 h at a high current density of 5 mA cm−2. In particular, the university of the acetonitrile–water co-solvent (AWCS) electrolyte is demonstrated, multiple battery systems (Zn//Al-V-O, Zn//Zn-V-O, Zn//VOOH, and Zn//Mn-V-O) deliver markedly improved cycling stability and rate performance. The mechanism of action of AWCS electrolyte on performance indicators is discussed in detail, which provides a promising insight for energy storage devices.