Self-assembly of free-standing surface-oxidized multilayer graphene film for high volumetric supercapacitors

To maximize the performance of a supercapacitor at a device level, it is essential to increase the volumetric capacitance of electrodes and decrease the fraction of inactive components. However, it is still a challenge to achieve these two goals. Here, we prepared surface-oxidized multi-layer graphene (SMG) by a facile electrochemical method. The unique thickness and oxygen groups facilitate the balance of the porosity and density and benefit the preparation of free-standing graphene electrodes. The preparation method of free-standing SMG electrode exhibits all-sided superiorities, including simple, environmental, energy-saving, high-stability, etc. Furthermore, SMG can achieve a high capacitance of 217.6 F cm−3 and landmark energy density of 120.27 Wh L−1, which provides a potential perspective for practical applications in energy storage.