High concentrations of sodium dodecylbenzene sulfonate electrolyte additives improve the performance of aqueous zinc ion batteries

Abstract

In aqueous zinc-ion batteries (AZIBs), traditional electrolytes are unable to fully utilise the potential of the zinc anode due to severe dendrite growth and side reactions on the zinc metal anode. Therefore, this study adds a high concentration of sodium dodecyl benzenesulfonate (SDBS) to the electrolyte to achieve the dual purpose of regulating the zinc deposition process and protecting the zinc substrate. The formation of large micelles induced by SDBS plays a stabilizing role, reduces fluctuations in the electrolyte, and enhances the orderly transfer of Zn²⁺, thereby increasing the amount of ion transfer. Furthermore, SDBS adsorbed on the zinc anode surface improves surface wettability, accelerates the three-dimensional diffusion process and guides Zn²⁺ to form a uniform flaky deposited layer. Additionally, the addition of SDBS effectively replaces the water-rich electric double layer (EDL) on the zinc surface with SDB⁻, significantly mitigating the harmful effects of H₂O on the anode. High-concentration SDBS therefore exhibits excellent performance in symmetrical batteries (over 2000 h at 0.8 mA cm⁻², 0.8 mAh cm⁻²). This study found that with the addition of a high concentration of surfactant, Zn²⁺ has a rapid three-dimensional diffusion process and horizontal deposition behavior, which is instructive for exploring ion transfer in high-concentration electrolyte additives.