Vitreous-ceramic coatings produced from recycled alkaline and lithium-ion battery waste via thermal spraying

This study presents a sustainable route for recycling post-consumer alkaline and lithium-ion batteries (LIBs) into functional glass–ceramic coatings through oxy-acetylene thermal spraying. Two glass frit formulations were developed: GF-AA 20%, derived from alkaline battery cathodes rich in manganese, and GF-LIB 5%, obtained from cobalt-rich LIB cathodes, both combined with recycled soda-lime glass. The influence of frit granulometry on coating quality was systematically evaluated using four particle size fractions (−180 + 106 μm, −106 + 75 μm, −75 + 53 μm, and −53 + 38 μm). Characterization by XRF, XRD, FTIR, and SEM-EDS confirmed the effective vitrification of the cathodic materials and the formation of amorphous borosilicate matrices. Minor Mn 2 O 3 crystallization was observed only in GF-AA 20% coatings, indicating partial devitrification. Thermodynamic equilibrium calculations under realistic flame-spray conditions predicted Mn 2 O 3 stabilization during cooling and enhanced alkali volatilization in LIB-derived frits, in agreement with the XRD and SEM–EDS results. The particle-size fraction −53 + 38 μm was identified as optimal, producing thicker, smoother, and more uniform coatings. Cobalt-based frits (GF-LIB 5%) yielded blue-toned coatings with higher porosity, while manganese-based frits (GF-AA 20%) produced denser brown coatings with lower roughness and reduced water absorption. The process demonstrates the technical feasibility of using recycled battery residues as raw materials for glass–ceramic coatings, achieving stable amorphous structures and tunable optical and surface properties. Beyond the materials’ performance, the approach embodies circular-economy principles by converting hazardous electronic residues into value-added products, reducing raw-material consumption and environmental impact. The results open the possibility of scaling this low-energy “dry glazing” technique using existing flame-spray infrastructure, fostering industrial symbiosis among the recycling, glassmaking, and ceramic sectors. Schematic representation of the circular process converting spent batteries and recycled glass into vitreous ceramic coatings through oxy-acetylene flame spraying. • Spent batteries and glass waste are transformed into ceramic coatings by thermal spraying • Manganese and cobalt oxide wastes converted into stable glass matrices with vivid colors • Optimal particle size improved coating uniformity and reduced surface roughness • Alkali-rich frits formed thicker but more porous coatings due to gas volatilization • Circular process links recycling, glassmaking, and ceramics in a low-energy route