An integrally bilayered flexible cathode woven from CNTs for homogeneous hosting and fast electrocatalytic conversion of Li2O2 in Li-O2 battery

Abstract

Due to the ultrahigh theoretical energy density, Li-O2 batteries are considered as potential candidates for power accessories for wearable electronic devices. An effective oxygen-breathing cathode is essential to enable high cyclic stability in Li-O2 batteries. Herein, an integrally bilayered, freestanding flexible Li-O2 battery cathode is constructed by in-situ growth of a layer of microflowers (which is an assembly of nitrogen-doped carbon nanotubes embedded with cobalt nanoparticles) on the surface of a CNT-interwoven film. Owing to the integrally bilayered structural feature and its compositional merits, such three-dimensionally conductive network provides a large space and surface area for homogeneous hosting and also enables efficient electrocatalytic conversion of the insulating Li2O2 solids. Thus obtained cathode delivers a large full capacity of 8.03 mAh cm−2; it also exhibits a low charge potential of approximately 3.6 V and excellent cyclic stability for stable operation up to nearly 2 months at a capacity of 0.1 and 1 mAh cm−2. Moreover, being flexible and binder-free, the cathode is highly robust, which can withstand repetitive folding and unfolding. A co-axial Li-air battery was fabricated accordingly, which exhibits excellent tolerance to bending deformation, showing great potential for application in flexible and wearable electronics.