A simple and scalable strategy for preparation of high density graphene for high volumetric performance supercapacitors

Highlights: • A strategy for preparing HDGF for high performance supercapacitors is reported. • HDGF with a density of 1.10 g cm⁻³ delivers a capacitance up to 261 F cm⁻³. • The as-prepared HDGF exhibits excellent electrochemical performance. -- Abstract: Graphene is considered to be a promising candidate as electrode material for supercapacitor due to its unique structure and excellent electrochemical properties. Nevertheless, the extremely low bulk packing density of graphene hinders its application. Here, a novel strategy for preparing high density graphene flakes (HDGF) for high-performance supercapacitors is reported. HDGF is simply prepared by shredding thermally reduced graphene oxide film into small pieces. High packing density, as well as fast electron and ion transportation have been achieved simultaneously by breaking the continuity of graphene film, while keeping its dense structure. The as-prepared HDGF exhibits high gravimetric capacitance (237 F g⁻¹) and volumetric capacitance (261 F cm⁻³) simultaneously, as well as excellent cycling stability with 98% of its initial capacitance after 10,000 cycles. Moreover, the symmetrical supercapacitor using HDGF as the electrode materials can obtain volumetric capacitances of up to 16 Wh L⁻¹ at a power density of 88 W L⁻¹ in the aqueous system. This strategy provides a new way to design high volumetric capacitance supercapacitors for energy storage applications in the future.