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.

Selection criteria for electrical double layer structure regulators enabling stable Zn metal anodes

“…14,16 One of the optimization strategies is to reduce the H 2 O proportion in solvated Zn(H 2 O) 6 2+ by adding electrolyte additives that have high affinity to Zn 2+ , which can avoid the accumulation of active H 2 O on the EDL structure during the desolvation process. 17–23 However, the enhanced cycling stability comes at the expense of increasing the polarization voltage due to the larger de-solvation penalty. Alternatively, introducing electrolyte additives that have higher adsorption energy on the Zn surface than H 2 O is also capable of altering the EDL structure and thus improving the cycling stability of Zn anodes.…”

Advances in functional organic material-based interfacial engineering on metal anodes for rechargeable secondary batteries

“…Huang et al found that the addition of γ-butyrolactone (GBL) could significantly improve the Zn electroplating/stripping performance. 148 GBL weakened the solvation between Zn 2+ and H 2 O, which rearranged the bonding network between particles and reduced the activity of water, inhibiting the formation of corrosion and byproducts (Fig. 11e).…”

“…(e) Schematic illustration of Zn deposition behaviors in ZnSO 4 and ZnSO 4 -GBL electrolytes. Reproduced with permission 148. Copyright 2022, Wiley-VCH GmbH.…”

Electrolyte Modulation Strategies for High Performance Zinc Batteries

“…Furthermore, they could engage in constructing Zn 2 + solvation sheath and confine the free water molecules, which suppresses waterinduced side reactions and widens water splitting voltage. [68] There are various kinds of organic molecule additives have been used, such as, surfactants [69] (e. g., SDS, TBA 2 SO 4 , SDBS), polymers [70] (e. g., PEO, PAM, PSS), chelating agent [71] (e. g., Na 4 EDTA) and organic solvent (e. g., Et 2 O, EG, DMC, DMSO, NMP, DMF). [29,72] Taking the sodium dodecyl sulfate (SDS) surfactant additive as an example.…”