Maximizing utilization of carbon fibers by bimetallic-catalytic etching and electrochemical modification for difunctional aqueous supercapacitors

Carbon fiber cloth with high utilization is urgently needed for portable and wearable electronics. We report herein an interconnected 3D primitive outer layer by utilizing two disparate catalytic etching behaviors based on a bimetallic layered double hydroxide precursor. After subsequent electro-modification, the resulting carbon cloth textile was directly applied as a free-standing electrode. The comprehensive strategy not only furnishes carbon fiber textiles with a loosely graphitic outer layer and hierarchical porosity, but also enables the efficient incorporation of oxygen functionalities onto the surface while retaining high mechanical strength and conductivity. The optimal electrode exhibits superhydrophilicity and delivers an impressive areal capacitance of 1089 mF cm−2 and a widened potential of −1.3–0 V. Upon further coupling with onion-like MnO2/carbon cloth and Zn foil, an asymmetric device with enhanced energy density (7.17 mW h cm−3) and a novel hybrid Zn-ion supercapacitor with a long cycling life are assembled, respectively. This synthetic strategy provides new insights into the etching of carbonaceous materials and may open up enormous possibilities for the pretreatment of carbon substrates.