Weakly Solvating Effect Spawning Reliable Interfacial Chemistry for Aqueous Zn/Na Hybrid Batteries

Abstract

The insufficient exploration of the interfacial chemistry of Zn anodes and electrolytes in an aqueous environment restricts the application potential of aqueous Zn batteries (AZBs). Herein, a durable anion-derived solid electrolyte interface (SEI) with high ion conduction properties is constructed by designing an aqueous electrolyte with a weakly solvating effect to manipulate the solvation structure of metal ions (Zn²⁺/Na⁺). The constructed SEI significantly restrains the dendrite formation and occurrence of adverse reactions on the surface of the Zn anode, endowing the Zn metal anode with high reversibility of deposition/stripping and ultra-long lifespan over 5000 h with an exceptional cumulative capacity of over 2.5 Ah cm⁻². Significantly, the formation mechanism of the SEI, which is realized by the weakly solvating effect to promote the coordination between anions and metal ions (Zn²⁺/Na⁺), and the composition distribution of anion-derived inorganic-rich SEI, are clarified in detail. Furthermore, benefiting from the synergy of the elaborate SEI and the regulated electrolyte environment, the Zn//Prussian blue analogue (PBA) full battery can operate with a high voltage platform of 2.1 V and deliver 99.3% capacity retention after 5000 cycles.