Manipulating Horizontal Zn Deposition with Indium Salt Additive for Anode-Free Zn Batteries

Anode-free Zn batteries are gaining significant interest due to their reduced weight and simplified production compared to traditional Zn metal batteries. However, challenges such as zinc dendrite formation and parasitic reactions continue to impact their efficiency and cycle life. In this study, we present an effective strategy to form a zincophilic interphase in situ via indium co-deposition during cycling, using InCl3 as an electrolyte additive. We investigated the zinc plating/stripping processes with and without InCl3 using operando electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D). Structural changes from zinc deposition and dissolution were quantified using hydrodynamic spectroscopy (HS) and validated by ex-situ scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Our findings demonstrate that the indium-containing electrolyte additive has triple functions: it induces oriented zinc deposition through pre-nucleation, suppresses hydrogen evolution reaction by forming an indium intermediate layer, and suppresses zinc hydroxide sulfate (ZHS) by consuming OH- with In2O3/InOOH formation. These advantages result in decreased overpotential and higher Coulombic efficiency, enhancing the design of highly reversible anode-free zinc batteries.