Synthesizing High‐quality Graphene from Spent Anode Graphite and Further Functionalization Applying in ORR Electrocatalyst

Abstract

A novel green and low‐cost synthesis route converting spent graphite anode from lithium‐ion batteries (LIBs) into graphene nanosheets was reported for the first time. The impurities in spent graphite were eliminated by calcining and acidic leaching. Compared with the typical Hummers method, notable oxidation efficiency enhancement was observed through introducing a 5 : 1 mixed suspension of H2SO4 and H3PO4 with slightly increased KMnO4, then high‐quality graphene sheets were obtained through glucose, thermal reduction and subsequent liquid exfoliation. By simply and efficiently chemical nitrogen doping, graphene sheets showed excellent oxygen reduction catalytic performance, which is even better than commercial Pt/C catalyst, allowing it to be a promising low‐cost catalyst candidate for fuel cells. Since LIBs and fuel cell are considered as the major two power sources for electric vehicles in very near future, we believe that synthesizing few‐layer graphene with few defects and functionalized graphene catalyst from spent LIBs paves a path towards to the full utilization of battery materials and thus reduces impacts on environment from developing electric vehicles.

Graphene from Spent Lithium‐Ion Batteries

“…Besides, nitrogendoped graphene was synthesized with a simple chemical doping approach, which can be used as an oxygen reduction reaction catalyst in fuel cells. [47] Yu et al [55] reported that the Modified Hummers method could be effectively used for impurity removal from recovered graphite and simultaneous conversion of it into 2D graphene oxide. In another study, Schiavi et al [56] proposed simultaneous production of rGO and LiÀ Mn-rich cathode material from spent LIB waste.…”

“…Unlike natural graphite, anode graphite has organic and metallic impurities; treating with N-methyl-2-pyrrolidone (NMP), ethanol, and diluted water can remove these impurities. [43] Ruan et al [47] reported thermal treatment (600 °C) to decompose binders and other organic pollutants followed by acidic leaching (H 2 SO 4 & HCL) to eliminate metallic impurities. Other studies mentioned using de-ionized water to remove the Liimpurity and heating with dimethylformamide (DMF) to dissolve the binder.…”

“…CoO produced by the hydrometallurgical route was combined with rGO using the sol‐gel process followed by heat treatment to create the hybrid material, which showed promising properties as an electrochemical sensor of ascorbic acid in an aqueous solution [46] . Ruan et al [47] . reported a low‐cost synthesis route for graphene nanosheets (few‐layer graphene) from anode graphite for the first time.…”

“…Then high‐quality few‐layer graphene or graphene nanosheets were obtained via glucose thermal reduction and ensuing liquid exfoliation. Besides, nitrogen‐doped graphene was synthesized with a simple chemical doping approach, which can be used as an oxygen reduction reaction catalyst in fuel cells [47] . Yu et al [55] .…”

A Novel Low-Temperature Fluorination Roasting Mechanism Investigation of Regenerated Spent Anode Graphite via TG-IR Analysis and Kinetic Modeling

“… 21 Ruan et al successfully synthesized high-quality graphene from spent anode graphite and further applied functionalization in carbon-based redox ORR electrocatalyst, which has better methanol resistance and stability. 22 …”