Microwave-Irradiation-Assisted Combustion toward Modified Graphite as Lithium Ion Battery Anode

A rapid method to high-yield synthesis of modified graphite by microwave irradiation of partially oxidized graphite (oxidized by H₂SO₄ and KMnO₄) is reported. During the microwave irradiation, electrical arc induced flame combustion of Mn₂O₇ and vaporization and decomposition of H₂SO₄ to form O₂ and SO₂, which helped to decompose graphite within 30 s. The modified graphite boosts its ability to support the intercalation and diffusion of Li⁺ ions. As an anode material for lithium ion batteries, the modified graphite displays high reversible capacity of 373 mA·h/g, approaching the theoretical value of 372 mA·h/g. Long cycling performance of 410 charge-discharge cycles shows the capacity is retained at 370 mA·h/g, demonstrating superior stability. The improved cycling stability is attributed to the formation of a stable solid electrolyte interface film with the help of in situ formed S-based compounds on a graphite sheet. This work demonstrated a simple and effective method to alter carbon structures for improving energy storage ability.