Exploring vitrification with LiCoO₂ cathode-active material and P₂O₅ as glass forming reagent

The search for novel strategies to manage cathode-active materials (CAMs) from lithium-ion batteries (LIBs) is currently an active area of research given their increasing demand in electric mobility. In this work, vitrification (the making of glasses) using lithium cobalt(III) oxide (LiCoO₂) as CAM and phosphorus pentoxide (P₂O₅) as glass former is explored for the first time to provide proof-of-concept. The raw materials were mixed in various proportions and melted in air atmosphere guided by xLiCoO₂-(100 – x)P₂O₅ with x = 20, 25, 30, 35 and 40 mol% formulas. The materials formed were subsequently characterized by X-ray diffraction (XRD), density, Fourier-transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), and optical transmission measurements. The data supported glass formation in the compositional range explored, wherein the densities tended to increase with LiCoO₂ concentration. The FT-IR data suggested that incorporating LiCoO₂ at the expense of P₂O₅ leads to a network depolymerization effect evidenced for instance by the upsurge of the v_as(PO₃²⁻) band of end-of-chain PO₄ tetrahedra. Further, DSC showed that the glass transition temperatures increased steadily while glass stability decreased with increasing LiCoO₂ content. The optical measurements showed overall decreased transmittance ensued in connection with the presence of cobalt ions in different coordination environments. Herein, a potential for the glasses for developing blue bandpass filters is suggested. The preliminary work carried out stimulates further research concerning the potential of vitrification with P₂O₅ for the management or upcycling of the LiCoO₂ cathode material from spent LIBs.