▎ 摘　　要

A simple, low-cost and energy-effective method has been developed in this work to fabricate giant graphene sheets by double microwave assisted exfoliations of expandable graphite. The graphene sheets, which are large (10-100 microns) in size and thin (1-10 nm) in thickness, manifest superior electrochemical performance for energy storage, achieving 221 F g(-1) capacitance after 5000 cycles at 10 mV s(-1) in a symmetric capacitor measurement and 400 mA h g(-1) in a coin-type Li-ion battery after 300 cycles at 0.5 A g(-1).