Interconnected Vanadyl Pyrophosphate Nanonetworks as a Flexible Electrode for High-Voltage and Long-Life Li-Ion Supercapacitors

Abstract

Engineering vanadium-based materials with high conductivity,superiorredox performance, and high operating voltage has attracted widespreadattention in energy storage devices. Herein, we demonstrated a simpleand feasible phosphorization technique to design three-dimensional(3D) network-like vanadyl pyrophosphate ((VO)(2)P2O7) nanowires on flexible carbon cloth (CC) (VP-CC). Thephosphorization process enabled the VP-CC to increase the electronicconductivity, and the interconnected nano-network of VP-CC opens pathwaysfor fast charge storage during the energy storage processes. Specifically,the 3D VP-CC electrodes and LiClO4 electrolyte designedas a Li-ion supercapacitor (LSC) demonstrate a maximum operating windowof 2.0 V with a superior energy density (E (d)) of 96 mu Wh cm(-2), power density (P (d)) of 10,028 mu W cm(-2), and outstanding cycling retention (98%) even after 10,000 cycles.In addition, a flexible LSC assembled utilizing VP-CC electrodes witha PVA/Li-based solid-state gel electrolyte exhibits a high capacitancevalue of 137 mF cm(-2) and excellent cycling durability(86%) with a high E (d) of 27 mu Wh cm(-2) and P (d) of 7237 mu Wcm(-2). Considering excellent energy storage features,the highly conductive vanadium-based material has been utilized asan ideal electrode for various flexible/wearable energy storage deviceswith superior performance.