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

Abstract

AbstractThe 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.