Redox-etching induced porous carbon cloth with pseudocapacitive oxygenic groups for flexible symmetric supercapacitor

Constructing high-performance electrodes with both wide potential window (e.g. ≥ 2 V in aqueous electrolyte) and excellent mechanical flexibility represents a great challenge for supercapacitors. Because of the outstanding conductivity and flexibility, carbon cloth (CC) has shown unlimited prospects for constructing flexible electrodes, but is rarely used directly as electrode material due to its electrochemical inertness and small specific surface area. To tackle these two critical limitations, we design a novel redox-etching strategy to synthesize CC-based electrode with 3D interconnecting pore structure. The sponge-like highly porous CC was further activated by strong oxidant to form abundant oxygenic groups, which occupy the interior and surface of current collector to render substantial pseudocapacitance. The as-synthesized CC electrode yielded an impressive capacitance of 4035 mF cm−2 at 3 mA cm−2 and satisfying cycling durability in a wide potential range of −1 – 1 V vs. SCE, which surpass the majority of reported CC-based electrodes. A symmetric supercapacitor with stable voltage of 2 V is assembled and delivers remarkable energy density of 6.57 mWh cm−3. Significantly, the device demonstrates an unparalleled flexibility with no capacitive decay after 100 bending cycles. This facile chemical etching and post-treatment processes are designed for large-scale manufacturing of the CC electrodes by providing high surface area and abundant electrochemically active sites, promising for industry application. The innovative synthetic strategy opens up new opportunities for high-performance flexible energy storage.