Multifunctional additives with dynamic sacrificial S–S bonds for building self-assembled monolayers of Zn-ion batteries with improved stability and longevity

Abstract

Aqueous zinc-ion batteries (AZIBs) possess tremendous potential for large-scale energy storage. Nevertheless, the interfacial stability and cyclic reversibility of Zn anodes are impeded by the unregulated growth of Zn dendrites and active H₂O-induced side reactions. Here, an organic compound bis(2-hydroxyethyl) disulfide (BHED) is proposed as a multifunctional and efficient electrolyte additive, characterized by hydrophilic hydroxyl groups and dynamic sacrificial bonding disulfide bonds. It is discovered that BHED can optimize the Zn²⁺ solvation structure and construct a water-blocking barrier on the Zn anode surface. Besides, BHED undergoes reductive decomposition, promoting the in situ formation of a self-assembled monolayer (SAM) with highly active zincophilic sites on the Zn anode surface. Notably, the unique SAM serves a dual function. It stabilizes the anode/electrolyte interface by trapping active H₂O and guides Zn²⁺ to deposit uniformly and orderly onto the (002) crystal plane. As a result, the Zn‖Zn symmetric cells containing a BHED additive achieve Zn²⁺ uniform plating/stripping exceeding 6300 h at 0.5 mA cm⁻² and 0.5 mA h cm⁻². Furthermore, the Zn‖NH₄V₄O₁₀ full cells maintain a capacity retention rate of 73.9% following 3000 stabilized cycles at 5 A g⁻¹. This work offers novel perspectives for the advancement of stable and long-lasting AZIBs.