Spatially confined synthesis of vanadium nitride nanodots intercalated carbon nanosheets with ultrahigh volumetric capacitance and long life for flexible supercapacitors

High volumetric capacitance electrode materials are highly desirable for miniaturized and portable capacitive storage devices. Herein, a spatially confined strategy to prepare 0D-in-2D pillared lamellar hybrid comprising vanadium nitride nanodots intercalated carbon nanosheets (VNNDs/CNSs) is proposed for promising capacitive material with high volumetric capacitance. The VNNDs/CNSs shows an ultrahigh volumetric capacitance of 1203.6 F cm(-3) at 1.1 A cm(-3) and rate capability of 703.1 F cm(-3) at 210 A cm(-3) surpassing those of carbon, transition metal oxides/nitrides. Even the 150 mu m-thick film electrode comprising VNNDs/CNSs has a volumetric capacitance of 867.1 F cm(-3). Moreover, the VNNDs/CNSs electrode exhibits extraordinary cycling stability with 90% capacitance retention after 10,000 cycles. The all-solid-state symmetric flexible supercapacitor based on VNNDs/CNSs electrodes boasts a high volumetric energy density/power density of 30.9 Wh L-1/64, 500 W L-1 with 91% capacitance retention after 10000 cycles, rendering promising applications in high-performance flexible supercapacitors. The strategy provides an insight into the rational design of compact, robust and highly conductive electrode materials with high volumetric capacitances and long life.