Preparation of Onion-like Synthetic Graphite with a Hierarchical Pore Structure from Anthracite and Its Electrochemical Properties as the Anode Material of Lithium-Ion Batteries

Graphite is commonly used as the anode material for lithium-ion batteries (LiBs). However, as natural graphite is unevenly distributed worldwide and its exploitation cost is continuously increasing, there are growing appeals for developing high-performance synthetic graphite as the anode material of LiBs. In this work, synthetic graphite with an onion-like porosity-rich structure was obtained from anthracite, and its electrochemical performance as the anode material of LiBs was investigated. The results reveal that the presence of Fe2O3 content in anthracite could regulate the carbon matrix to form an onion-like structure. The oxidation and heat treatment were helpful to expand the interlayer spacing of the graphite sheets, and the subsequent KOH activation could create a considerable amount of mesopores and micropores in the graphite, which could offer more chances for the intercalation–deintercalation of lithium ions and provide more sites and paths for the accommodation and transportation of lithium ions. As a result, the obtained graphite exhibited a favorable electrochemical performance regarding charging–discharging capability, cyclic voltammetry, rate performance, and cycling stability. The findings could provide an alternative method for the preparation of anode materials for LiBs and may have implications for taking advantage of anthracite resources.