Single Ion Conductive “Plasticine-Like” Solid Electrolyte Combined with Modulated D-Band Center of Interfacial Zinc Atoms for Highly Reversible Zinc Metal Anode

Abstract

Highly concentrated salts, like 30 m ZnCl₂, can reduce free water molecules in aqueous electrolytes but also increase acidity, causing severe acid-catalyzed corrosion of the Zn anode, current collector, and encapsulation layer. Here, we develop a “plasticine-like” solid electrolyte (PLSE) using mutual solubilization of PAN and (ZnCl4)2-.The weak solvation structure contributes a high Zn2+ ion transfer number of 0.9, much higher than that of 30 m ZnCl2 aqueous electrolyte (0.6). Furthermore, an anti-catalytic indium-rich solid electrolyte interphase (In-rich SEI) is constructed by incorporating trace amounts of InCl3 in PLSE, which boosts Zn2+ ions adsorption by modulating the D-band center. The combination of proton shielding from the “plasticine-like” electrolyte and the anti-catalytic effect of the In-rich SEI expands the stabilized voltage window to 6.8 V (2.8 V for 30 mZnCl2) and significantly suppressed hydrogen generation. As a result, the ZnǀǀZn symmetric cell can continuously cycles for 10,000 h at a current density of 0.5 mA·cm-2 and the ZnǀǀCu symmetric cell achieves over 8,000 cycles with average Coulombic efficiency of >99.4%. Meanwhile, the four-electrons-transfer Zn||I2 batteries delivers a specific capacity of 370 mAh·g-1 at room temperature and 483 mAh·g-1 at 50oC. The battery can operate at a wide temperature range of -50 to 60oC and achieve impressive cyclic stability over 1,200 cycles with 89.28% initial capacity retained. In addition, the ZnǀǀBr2 cell with a higher charge/discharge plateau successfully achieved 3,500 cycles at 1.5 A·g-1 and provided a high specific capacity of 245 mAh·g-1 with 85.31% capacity retention. The PLSE and anti-catalytic interphase provide valuable insights into the design of electrolytes for highly reversible zinc metal anodes.