Nanostructured Boron-Doped Ultra-Nanocrystalline Diamond Micro-Pyramids: Efficient Electrochemical Supercapacitors

The miniaturization of electrochemical supercapacitors (EC-SCs) requires electrode materials that are both durable and efficient. Boron-doped diamond (BDD) films are an ideal choice for EC-SC due to their durability and exceptional electrochemical performance. In this study, nanostructured boron-doped ultra-nanocrystalline diamonds (NBUNCD) are fabricated on Si micro-pyramids (SiP) using a simple reactive ion etching (RIE) process. During the etching process, the high aspect ratio and the induction of sp2 graphite in these nanorod electrodes achieved a maximum specific capacitance of 53.7 mF cm-2 at a current density of 2.54 mA cm-2, with a 95.5% retention after 5000 cycles. Additionally, the energy density reached 54.06 mu W h cm-2 at a power density of 0.25 mu W cm-2. A symmetric pouch cell using NBUNCD/SiP exhibited a specific capacitance of 0.23 mF cm-2 at 20 mu A cm-2, an energy density of 31.98 mu W h cm-2, and a power density of 0.91 mu W cm-2. These superior EC properties highlight NBUNCD/SiP's potential for advancing miniaturized supercapacitors with high capacitance retention, cycle stability, and energy density.