Enhanced voltage and capacitance in flexible supercapacitors using electrospun nanofiber electrolytes and CuNi2O3@N-Doped omnichannel carbon electrodes

Abstract

Developing functional solid polymer electrolytes (SPEs) is crucial for flexible, lightweight, and portable supercapacitors. This work presents an electrospinning approach to fabricate SPEs using poly(vinyl alcohol)-sodium chloride (PVA-NaCl) nanofibers (PNNF). CuNi₂O₃ nanoparticles deposited on nitrogen-doped omnichannel carbon nanofibers (CuNi₂O₃@N-OCCFs), coated onto a carbon cloth (CC), serve as the positive electrode, enhancing faradaic capacitance. Meanwhile, the rationally designed N-OCCFs, also coated onto CC, function as the negative electrode, providing a high-surface-area, and facilitating rapid electron transport. Comprehensive characterization revealed insights into the morphology and chemical composition of both electrodes and the PNNF electrolyte. An all-solid-state asymmetric flexible supercapacitor (AFSC) device, CuNi₂O₃@N-OCCFs-1.5//N-OCCFs-1.5, was assembled using PNNF as both the electrolyte and separator and evaluated against devices employing gel and aqueous electrolytes. The PNNF electrolyte enabled a wider potential window (2.2 V) compared to gel (2.0 V) and liquid (1.8 V) electrolytes. The AFSC achieved an impressive energy density of 63.6 Wh kg⁻¹ at a power density of 1100 W kg⁻¹, with 96.2% capacitance retention after 6000 charge/discharge cycles at 10 A g⁻¹. When two devices were connected in series, they powered a red LED for 5.33 min and a blue LED for 1.43 min, demonstrating practical applicability. This study provides a simple and effective strategy for fabricating high-energy–density AFSCs with excellent cycling stability and broad potential for flexible electronics.

Graphical Abstract