Flexible electrode materials based on WO3 nanotube bundles for high performance energy storage devices

Abstract The demand for high performance energy storage devices such as supercapacitors and lithium-ion batteries has prompted people to design and develop new electrode materials. In this work, WO3 nanotube bundles as the electrode materials are prepared by a template- and surfactant-free hydrothermal process. As anode materials for supercapacitor, WO3 nanotube bundles possess an area capacitance of 2575 mF/cm2 at a current density of 3 mA/cm2 and cyclic durability of 85.1% retention after 6000 cycles and a specific capacitance of 615.7 F/g at a current density of 1 A/g. The as-fabricated asymmetric supercapacitor presents a high energy density and cycle abilities after 10,000 cycles. The as-synthesized products are also applied as binder-free Li-ion batteries anode, revealing high discharge capacity at the first discharge and a stable capacity after 200 cycles. Excellent electrochemical performance of the as-synthesized WO3 products for supercapacitors and lithium ion batteries could be ascribed to their unique tube-like structures.