Study of the phase composition (Zn, ZnO) of anodes recovered from spent alkaline batteries, with respect to their residual voltage

• Recovery of anodes from spent alkaline batteries avoids chemicals reducing energy use. • Residual voltage controls Zn oxidation and ZnO phase formation. • ZnO shows voltage-dependent morphology and photoluminescence. • Raman and PL reveal oxygen defects linked to luminescence of ZnO The development of advanced materials with tailored properties has long been a cornerstone of technological innovation. Increasingly, attention is shifting toward the transformation of end-of-life waste into valuable resources. Spent alkaline batteries, when improperly disposed of as electronic waste (e-waste), pose significant environmental hazards due to their content of toxic metals, which can leach into soil and groundwater. These metals may also undergo physicochemical transformations through interactions with other waste materials. This study investigates the anode recovered from spent alkaline batteries discharged to varying residual voltages. The recovery process involved manual separation, followed by washing with deionized water, filtration, and drying at 50 °C for 48 h prior to characterization. The resulting particles exhibited photoluminescent properties that correlated with the residual voltage of the batteries. Structural analysis revealed the coexistence of Zinc and Zinc Oxide (Zn/ZnO) phases at voltages above 0.78 V, while only ZnO was present below this threshold. The ZnO content was found to depend on the degree of battery depletion, with the residual voltage directly influencing the Zn/ZnO phase ratio.