Monocrystalline FeMnO₃ on Carbon Cloth for Extremely High-Areal-Capacitance Supercapacitors

Flexible supercapacitors with extremely high areal capacitances are of great significance in wearable electronics. Here, we report fast fabrication of high mass loading monocrystalline FeMnO3 on highly conductive carbon cloth (CC) textiles within just 1 min through a molten salt route. The heavily loaded (10.7 mg cm–2), binder-free FeMnO3@CC electrode exhibits a preeminent highest areal capacitance of 11.02 F cm–2 when working as a negative electrode at 2 mV s–1, thanks to the monocrystalline characteristic and the activated carbon substrate. Because of the multivalence change, it is appropriately applied as electrodes in a symmetric supercapacitor, which operates at an extremely high potential (1.6 V) and achieves outstanding areal performance (capacitance of 3.6 F cm–2 at 10 mA cm–2, energy density of 1.28 mWh cm–2 at 8.12 mW cm–2) as well as excellent gravimetric and volumetric properties. We also record an outstanding cycling stability at 10 mA cm–2, which is 91% of the first areal capacitance maintained after 20 000 cycles. This study reveals an encouraging application prospect when considering the low-cost, fast-fabrication of supercapacitor electrodes exhibiting merits of high mass loading, hierarchical structure, boosted conductivity, and structural stability.