Boosting Pseudocapacitive Performance of KNb3O8 Nanorods by Growing on Textile Carbon Cloth and Carbon Layer Coating

This work describes the successful growth of electroactive KNb3O8 nanorods on the flexible and conductive activated textile carbon cloth (aTC) for supercapacitor application. The KNb3O8 nanorods on aTC (aTC-KNb3O8) exhibit reversible redox reactions in 3.0 M aqueous KOH electrolyte and store charges through surface ion adsorption and K+ insertion. Moreover, coating a layer of carbon by oxidative polymerization of dopamine yields the aTC-KNb3O8@C with substantially improved capacitive performances. The carbon serves as protective layer that not only offers double-layer capacitance and enhances the conductivity but also dramatically improves the cycling life of the composite electrode. Accordingly, the aTC-KNb3O8@C electrode delivers specific areal capacitance of 1439 mF cm(-2) (corresponding to 470 F g(-1) of KNb3O8) at 8 mA cm(-2) and retains 86% capacitance at current density up to 50 mA cm(-2). Moreover, the aTCKNb(3)O(8)@C electrode also retains 71% of its initial capacitance after cycling the electrode for 10 000 cycles. These performances are much better than those of aTC-KNb3O8 electrode, making the aTC-KNb3O8@C to be one of promising candidates with potential applications in supercapacitor K and Li-ion battery.