Direct Growth of\nVertical Graphene on Fiber Electrodes\nand Its Application in Alternating Current Line-Filtering Capacitors

Fiber-shaped electrochemical capacitors (FSECs) have\ngarnered substantial\nattention to emerging portable, flexible, and wearable electronic\ndevices. However, achieving high electronic and ionic conductivity\nin fiber electrodes while maintaining a large specific surface area\nis still a challenge for enhancing the capacitance and rapid response\nof FSECs. Here, we present an electric-field-assisted cold-wall plasma-enhanced\nchemical vapor (EFCW-PECVD) method for direct growth of vertical graphene\n(VG) on fiber electrodes, which is incorporated in the FSECs. The\ncustomized reactor mainly consists of two radio frequency coils: one\nfor plasma generation and the other for substrate heating. Precise\ntemperature control can be achieved by adjusting the conductive plates\nand the applied power. With induction heating, only the substrate\nis heated to above 500 °C within just 5 min, maintaining a low\ntemperature in the gas phase for the growth of VG with a high quality.\nUsing this method, VG was easily grown on metallic fibers. The VG-coated\ntitanium fibers for FSECs exhibit an ultrahigh rate performance and\nquick ion transport, enabling the conversion of an alternating current\nsignal to a direct current signal and demonstrating outstanding filtering\ncapabilities.