Spent Graphite from Depleted Li-Ion Batteries as Functional Additives for Methanol-Tolerant Oxygen Reduction Reaction Electrocatalyst

Abstract

Graphite material was recovered from end-of-life Li-ion batteries and exfoliated using Hummer’s method. This exfoliated graphite (EFG) was added as functional additives in various weight percentages (wt %) to a catalyst slurry composed of 20 wt % Pt/FAB (platinum on a functionalized acetylene black) and Nafion to study oxygen reduction reactions (ORRs) in the presence and absence of MeOH in acidic medium. Herein for the first time, we demonstrate the exploration of EFG from spent graphite as a conductive additive to selectively reduce oxygen in the presence of methanol and protect Pt from CO poisoning by utilizing the edge functionalities of the exfoliated graphite. Additionally, the EFG acts as an electronic conductor between the catalyst particles. The physicochemical and electrochemical results indicate that the incorporation of EFG improves the ORR performance, in both the presence and absence of MeOH, and demonstrate enhanced MeOH tolerance. The addition of 10 wt % of recovered EFG in the electrocatalyst exhibited a lower methanol oxidation current (2.5 mA·cm^–2) while the catalyst alone studies exhibited a higher current (6 mA·cm^–2) in 3 M methanol in 0.1 M HClO₄ electrolyte.