Binary Additive in Millimolar Concentration for Long Cycling Life of Zinc-Ion Batteries

The reversibility of stripping and plating of the Zinc anode is one of the major bottlenecks of Zinc-Ion batteries. In this publication, we propose a millimolar concentration additive blend that shall promote homogeneous Zinc plating with suppressed dendrite formation and reduce the influence of water-splitting reactions. We use 5.5 mM sodium dodecyl benzene sulfonate (SDBS). SDBS adsorbs at the Zinc electrode and forms a protection layer that promotes homogenous crystallization. 4.5 mM Ethylenediamine-tetraacetate (EDTA) is meant to hinder water splitting. It reduces the activity of water at the Zinc surface. Both additives together exhibit a synergistic effect, resulting in higher performance compared to cells with either additive alone. We propose a handover of the Zinc ions between the EDTA in solution and the SDBS layer as a reason for this effect. Our Zn//Zn symmetric cell tests ran for 3850 hours and 1925 cycles at 1 mA/cm² and 1 mAh/cm². In the end, Zinc-MnO₂ full cells were tested, showing a capacity retention of 52 % over 400 cycles.