| Abstract Scope |
The performance of alkaline aluminum and zinc batteries is limited by corrosion and parasitic hydrogen evolution. Here, a bio-derived apple-based multi-acid fermentate (AMF) is introduced as an electrolyte additive to address both issues. In 4 M KOH, AMF reduces aluminum corrosion current by ~36.5% (2.88→1.83 mA cm⁻2) and suppresses hydrogen evolution. For zinc, corrosion current decreases (0.14→0.10 mA cm⁻2) with a ~64% increase in polarization resistance, indicating improved interfacial stability. Electrochemical impedance spectroscopy confirms enhanced charge-transfer resistance for both metals. 3D profilometry reveals reduced aluminum roughness (Sa: 17.54→6.15 µm), demonstrating mitigation of localized corrosion. Mechanistically, AMF regulates hydroxide access via adsorption without full passivation. This green electrolyte strategy is compatible with additive manufacturing, enabling corrosion-resistant, architected Al and Zn electrodes for advanced alkaline energy storage. |