A Multifunctional Anti-Proton Electrolyte for High-Rate and Super-Stable Aqueous Zn-Vanadium Oxide Battery.

Large volumetric expansion of cathode hosts and sluggish transport kinetics in the cathode-electrolyte interface, as well as dendrite growth and hydrogen evolution at Zn anode side are considered as the system problems that cause the electrochemical failure of aqueous Zn-vanadium oxide battery. In this work, a multifunctional anti-proton electrolyte was proposed to synchronously solve all those issues. Theoretical and experimental studies confirm that PEG 400 additive can regulate the Zn solvation structure and inhibit the ionization of free water molecules of the electrolyte. Then, smaller lattice expansion of vanadium oxide hosts and less associated by-product formation can be realized by using such electrolyte. Besides, such electrolyte is also beneficial to guide the uniform Zn deposition and suppress the side reaction of hydrogen evolution. Owing to the integrated synergetic modification, a high-rate and ultrastable aqueous Zn-VO/C battery can be constructed, which can remain a specific capacity of 222.8 mAh g after 6000 cycles at 5 A g, and 121.8 mAh g even after 18,000 cycles at 20 A g, respectively. Such "all-in-one" solution based on the electrolyte design provides a new strategy for developing high-performance aqueous Zn-ion battery.