Exfoliated graphite via ball-milling for enhanced microwave absorption and electrochemical energy storage application

Abstract

Graphite and its derivatives are one of the emerging materials in energy storage and microwave absorption application. In the present study, exfoliated graphite generated from a high-pure graphite precursor through a cost-effective and environmentally friendly planetary ball milling technique has been evaluated for its supercapacitive and microwave absorption properties. The exfoliated graphite exhibits a two-fold increase in surface area compared to the high-pure graphite. The O/C ratio increased to 16.69% due to the presence of oxygen groups after ball milling, enhancing the microwave absorption and electrochemical energy storage performance of exfoliated graphite. Remarkably, the exfoliated graphite shows an enhanced microwave absorption of ∼59.15% across 8.2-12.4 GHz. Further for the realisation of the practical application, simulation study has been incorporated showing a minimum reflection loss of -25.53 dB at 9.7 GHz combining with a ferrite material. It also exhibits an excellent specific capacitance value of 177 Fg^-1 at a current density of 0.5 Ag^-1 for three electrode system. When assembled as a symmetric two-electrode system the exfoliated graphite exhibits an energy density of 1.66 Whkg^-1 with a power density of 420 Wkg^-1. This study provides a detailed investigation of exfoliated graphite as a potential material for microwave absorption and electrochemical energy storage.