High-performance 2.6 V aqueous symmetric supercapacitor based on porous boron doped diamond via regrowth of diamond nanoparticles

Abstract Having a wider potential window and higher stability than other traditional sp2-based carbon electrodes, heavily boron-doped diamond (BDD) electrode with three-dimensional porous nanostructure can considerably enhance the specific capacitance, making it one of the most promising electrode materials. In the work, we present a simple and reproducible method to create such a porous BDD film by using self-assembly seeding approach and microwave plasma chemical vapor deposition (MPCVD). The fabricated porous BDD electrode exhibits an enhanced capacitance of 17.18 mF cm−2, and an outstanding stability of about 95% charge retention after 10000 cycles in aqueous solution in three-electrode system. Moreover, the specific capacitance can be further enhanced by producing multilayer films. By using porous BDD as electrodes, a 2.6 V aqueous symmetric supercapacitor with specific capacitance of 25.48 mF cm−2 is obtained. The capacitance retention is about 91.5% after 10000 CV cycles. The energy and power densities of the device are about 5.46 Wh kg−1 and 2.9 kW kg−1, respectively. The fabrication of this porous BDD film with high capacitance and high stability is free of template, binder, as well as etching process, which may have potential impact on many applications for future energy storage devices.