One-step wet-spinning assembly of twisting-structured graphene/carbon nanotube fiber supercapacitor

Abstract Graphene fiber-based supercapacitors hold great promise as flexible energy-storage devices. However, simultaneously achieving high ion-transport ability in electrode and electrolyte layer, which is crucial for realizing the high electrochemical performance, still remains challenging. Here, a facile and effective strategy to solve the problem was proposed by developing a twisting-structured graphene/carbon nanotube (CNT) fiber supercapacitor via one-step wet-spinning process with customized multi-channel spinneret. The remarkable structure features of the resulting fiber supercapacitor with wrinkled and thin electrolyte layer, and well-developed porosity of fiber electrode favored the rapid infiltration and transport of electrolyte ions inside the electrode, as well as between electrode and electrolyte, thus boosting high specific capacitance of 187.6 mF cm−2 and energy density of 30.2 μWh cm−2, and featuring long cycling life (93% capacitance retention after 10000 cycles) and excellent flexibility. Moreover, the specific capacitance and energy density could be further improved to 267.2 mF cm−2 and 66.8 μWh cm−2, respectively, when MnO2 was incorporated into the fiber.