Aqueous Zn-ion devices comprising a Zn-metal anode constitute an emerging class of next-generation energy storage devices with the growing demand for renewable energies. Over the past few years, sophisticated strategies have been developed to produce robust electrodes and electrolytes as well as their interface for alleviated Zn dendrite growth and side reactions, yet boosting the electrochemical stability to a commercial level using facile strategies such as an electrolyte additive is still desired. Here, we report scalable electrolyte engineering featuring a hydrophilically tuned nonionic amphiphilic polymer additive to fundamentally suppress water-related side reactions. The polymer additive bearing both hydrophilic and hydrophobic units foster a localized nano-scaled H₂O-poor environment that essentially de-solvates Zn²⁺ from aqueous media. The preferential adsorption of hydrophilic segments on the Zn anode also creates a local hydrophobic layer that synergistically shields the metal from direct aqueous corrosion. Moreover, tuned electrolyte increased anion decomposition on the anode, which further leads to an F-rich and O-deficient interface that promotes the stabilized anode. Consequently, introduction of a trace amphiphilic polymer additive into traditional Zn(OTf)₂ leads to a highly stable anode in symmetric and full batteries, represented by ultralong cycling for over 8800 h (367 days) at 1 mA cm⁻²/1 mA h cm⁻² and 2500 h at 5 mA cm⁻²/5 mA h cm⁻² for Zn–Zn cells with added wide-temperature operation from 50 °C down to −30 °C. The principle of building local hydrophobicity in aqueous ionic electrolyte media using a nonionic amphiphilic polymer contributes new understanding of Zn stabilization that may permit near-future industrialization of aqueous Zn-based energy storage.

The PAM/PVP interphase prevents direct contact of the metal Zn anode with the aqueous electrolyte and uniformizes electric field distribution and ion migration during zinc plating/stripping, suppressing the zinc dendrite growth and side reactions.