Cooperative Anode-Electrolyte Interface Engineering for Wide-Temperature Aqueous Aluminum-Ion Batteries

Aqueous aluminum-ion batteries (AAIBs) are attractive for safe and low-cost energy storage but are fundamentally constrained by the thermodynamic instability of metallic Al in aqueous electrolytes, which induces hydrogen evolution and interfacial corrosion, particularly at sub-zero temperatures. We report a cooperative anode-electrolyte interface (AEI) engineering strategy that simultaneously regulates Al³⁺ solvation chemistry and anode surface crystallography to stabilize Al anodes in aqueous electrolytes. Introducing panthenol into a conventional Al(ClO₄)₃ electrolyte results in the formation of a hydrated eutectic system that reconstructs the hydrogen-bond network and tailors Al³⁺ solvation structures. This electrolyte system is inherently nonflammable and exhibits an expanded electrochemical stability window, along with an ionic conductivity of 2.17 mS cm⁻¹ at −30°C. Meanwhile, trace alloying–directional etching (TADE) generates a nanoporous Al anode enriched with Al(200) facets that suppress proton adsorption and lower the Al nucleation barrier. The regulated solvation sheath induces an anion-rich organic interphase, enabling stable cycling for 300 h at 30°C and −10°C, and operation at −25°C. This work establishes AEI engineering as a general strategy for wide-temperature AAIBs.