Mechanistic Insights Into Surfactant-Regulated and Carboxylate-Mediated Uniform Zinc Plating

Uniform zinc deposition and dendrite suppression are crucial objectives to enable high-performance aqueous Zn-ion batteries. In this study, a millimolar blend of sodium dodecylbenzenesulfonate (SDBS) and ethylenediaminetetraacetic acid (EDTA) achieves kinetic control over Zn plating in a mildly acidic electrolyte. Collectively, overpotential measurements, distribution of relaxation times analysis, and in situ Raman spectroscopy reveal a persistent coadsorption of SDBS and EDTA on the zinc electrode-slowing down interfacial charge-transfer kinetics and thus maintaining a constant Zn²⁺ surface concentration. This shift from diffusion control to interfacial kinetics fosters homogeneous metal growth and effectively suppresses dendrite formation. Comparative experiments with polyethylene glycol confirm that the surfactant's efficacy derives from its ability to modulate plating kinetics rather than its molecular identity. Screening of trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid, L-histidine, and zinc acetate further uncovers that freely available carboxyl (COO^-) groups, instead of chelation strength, underpin extended cycle life. These mechanistic insights establish a general design principle for zinc metal anode-containing battery systems: synergistic integration of a kinetic surfactant barrier with free COOH moieties to achieve prolonged cycling stability and uniform zinc deposition.