Ion Intercalation Induced Capacitance Improvement for Graphene‐Based Supercapacitor Electrodes

Abstract Here we demonstrate a facile electrochemical method that can substantially improve the capacitance of graphene‐based electrodes while still retaining their excellent rate capability. This method involves two ion‐intercalation steps (lithium‐ion intercalation and perchlorate‐ion intercalation), followed by hydrolysis of perchlorate ion intercalation compounds. Lithium ion intercalation mainly leads to surface exfoliation, whilst the hydrolysis of perchlorate ion intercalation compounds functionalizes the graphene surface with oxygen moieties. Electrochemically treated graphitic paper electrode shows 1000 times enhancement in areal capacitance. Without the need of post‐treatment annealing, the treated graphitic paper maintains an outstanding rate capability of 84 % (0.5 mA cm⁻² to 5 mA cm⁻²). The same strategy can also be extended to boost the gravimetric capacitance of lightweight 3D printed graphene aerogels. The treated graphene aerogel achieved an outstanding gravimetric capacitance of 101.7 F g⁻¹ (10 A g⁻¹) with an excellent rate capability of 81.6 % (0.5 A g⁻¹ to 10 A g⁻¹).