Cathode material from spent LiFePO4 electric vehicle batteries reused as a photo-Fenton catalyst and a pseudocapacitor

Abstract This study investigated the reuse of cathode material from spent LiFePO 4 batteries as a heterogeneous photo-Fenton catalyst and pseudocapacitor. Characterization revealed the presence of LiFePO 4 phases, FePO 4 , carbon, and polyvinylidene fluoride. The material exhibited a specific surface area of 24 m 2 g − 1 and a mesoporous structure with particle agglomeration. As a photocatalyst in the photo-Fenton process, the material achieved 96% decolorization of methylene blue under UV-Vis radiation within 30 min over four cycles. Treated solutions contained Fe, Ni, Cu, Co, Mn, and Al ions at concentrations below the regulatory limits established by CONAMA Resolution No. 430/2011. Li is not regulated under this resolution. When applied as a pseudocapacitor, the material achieved up to 500 charge–discharge cycles at a current density of 1 A g − 1 . The specific capacitance was 113 F g − 1 , with 73.98% retention. The energy density was 46.99 Wh kg − 1 , and the power density 850.0 W kg − 1 .