Boosting Reversibility and Stability of Zn Anodes via Manipulation of Electrolyte Structure and Interface with Addition of Trace Organic Molecules

Abstract

The practical application of aqueous zinc-ion batteries (AZIBs) is significantly limited by poor reversibility and stability of the Zn anode. Here, the first time addition of trace organic gamma butyrolactone (GBL) is reported to a typical ZnSO₄ electrolyte to controllably manipulate the electrolyte structure and interface. Judiciously combined experimental characterization and theoretical computation confirm that the GBL additive weakens the bonding strength between Zn²⁺ ion and solvated H₂O and rearranges the “Zn²⁺−H₂O−SO₄²– GBL” bonding network to reduce water activity and suppress corrosion and side products. The GBL molecules preferentially absorb on the surface of the Zn anode to give a uniform and compact Zn deposition. As a result, the Zn anode is boosted to run over 3105 cycles (6210 h) with average Coulombic efficiency of 99.93% under 1 mA cm−² and 1 mAh cm−², and exhibit stable cycling for 1170 h under harsh testing conditions of 10 mA cm−² and 10 mAh cm−². Additionally, the Zn–MnO₂ full cells using the ZnSO₄–GBL electrolyte exhibit a high capacity of 287 mAh g−¹ at 0.5 A g−¹ and good capacity retention of 87% following 400 cycles. These findings will be of immediate benefit to design low cost AZIBs for clean energy storage.