Potassium Ion-Tuned Electrodeposition of MnO₂ Coating on Pb–Ag Anode Enabling Efficient and Clean Zinc Electrowinning: Film Formation Mechanism and Long-Term Performance

Lead–silver (Pb–Ag) anodes in the zinc electrowinning industry face severe challenges of electrochemical corrosion and sluggish oxygen evolution reaction (OER) kinetics. Precoating a protective MnO2 layer is an effective strategy to enhance their performance. However, conventional MnO2 precoating processes require high temperatures (≥80 °C) and suffer from drawbacks such as poor coverage, loose structure, and insufficient active sites. This study proposes a novel low-temperature MnO2 coating strategy tuned by K+ intercalation, enabling the controllable fabrication of high-performance MnO2 coatings from zinc electrowinning waste electrolytes. The results reveal that introducing an appropriate amount of K+ modulates the redox behavior of Mn2+ and the electrochemical crystallization process, leading to the formation of a uniform MnO2 film on the Pb–Ag anode. The intercalation of K+ into the MnO2 lattice promotes the generation of abundant surface vacancies, which enhance the OER performance. This work presents a scalable solution for low-temperature coating of MnO2 film on Pb–Ag anodes, enabling efficient and clean zinc electrowinning, and opens a new avenue for designing energy-efficient MnO2-based anode materials through additive intercalation tuning.