Highly Surface-Wrinkled and N-Doped CNTs Anchored on Metal Wire: A Novel Fiber-Shaped Cathode toward High-Performance Flexible Li-CO2 Batteries

Li-CO2 batteries are regarded as a promising candidate for the next-generation high-performance electrochemical energy storage system owing to their ultrahigh theoretical energy density and environmentally friendly CO2 fixation ability. Until now, the majority of reported catalysts for Li-CO2 batteries are in the powder state. Thus, the air electrodes are produced in 2D rigid bulk structure and their electrochemical properties are negatively influenced by binder. The nondeformable feature and unsatisfactory performance of the cathode have already become the main obstacles that hinder Li-CO2 batteries toward ubiquity for wearable electronics. In this work, for the first time, a flexible hybrid fiber is reported comprising highly surface-wrinkled and N-doped carbon nanotube (CNT) networks anchored on metal wire as the cathode integrated with high performance and high flexibility for fiber-shaped Li-CO2 battery. It exhibits a large discharge capacity as high as 9292.3 mAh g(-1), an improved cycling performance of 45 cycles, and a decent rate capability. A quasi-solid-state flexible fiber-shaped Li-CO2 battery is constructed to illustrate the advantages on mechanical flexibility of this fiber-shaped cathode. Experiments and theoretical simulations prove that those doped pyridinic nitrogen atoms play a critical role in facilitating the kinetics of CO2 reduction and evolution reaction, thereby enabling distinctly enhanced electrochemical performance.