Lean-water electrolyte to stabilize zinc anode and suppress manganese dissolution of cathode for ampere-hour zinc batteries

Abstract

Rechargeable Zinc battery technologies are regarded as viable candidates for large-scale energy storage due to constitutional safety and inexpensive position. Nevertheless, the strong polarity of H2O molecules initiates the deterioration of both zinc metal anode and cathode. At anode side, radical H2O molecules cause side reactions of zinc corrosion, hydrogen evolution reaction (HER) and dendrite growth. At cathode side, the dissolution of transition metal brings about severe capacity fading of cathodes. Herein, we replace the 90% H2O sheath of Zn2+ solvation with 1,3-propanediol (PDO) molecules to form a lean-water electrolyte, in which the abundant PDO molecules can significantly suppress 99.9% HER and prohibit the Zn dendrite growth, while H2O molecules with a molecular lubrication mechanism enables fast ion transportation. Consequently, at anode side, Zn plating/stripping reversibly processes over 4000 cycles with high average Coulombic efficiency of 99.24% in ZnǀǀCu cell. At cathode side, the decreased water activity and scarce solute-water dissolving surfaces suppress 98.6% dissolution of manganese species. The ZnǀǀMnHCF full cell demonstrates high capacity of 140.7 mAh·g−1 at 0.1 A·g−1 and ultra-long lifespan of 3000 cycles with 85.4% initial capacity retained. More importantly, a 1.4 Ah ZnǀǀMnHCF pouch cell shows excellent lifespan over 150 cycles with charge/discharge run time > 68 days. We expect that this work will promote the practicability of aqueous Zn-ion batteries for grid-scale energy storage.