Carbon Nanotubes/Carbon Fiber Paper Supported MnO2 Cathode Catalyst for Li−Air Batteries

Lithium-Air batteries (LABs) are considered as one of the most promising energy conversion systems for delivering large specific energy. However, practical applications still face major challenges, including poor rate capability, short cycle life and low round-trip efficiencies. Here we report a novel strategy to improve the catalytic activity of MnO2 through the combination of three-dimensional (3D) MnO2 and carbon nanotubes/carbon fiber paper (CNTs/CFP) with binder-free structure. Side reactions related to the binder are precluded in this design. The presence of CNTs not only promotes the formation of 3D structure of air electrode, but directs the uniform deposition of MnO2. When applied as a cathode in LABs, the as-prepared MnO2/CNTs/CFP electrode achieves comparable specific capacity (with a discharge capacity of 8723.5 mAh∙g-1(CNTs+MnO2) at 100mA∙g-1). The encouraging electrochemical performance is found to benefit from free-standing nanoporous structures, which provide more active sites for enabling oxygen reduction. It is also attribute to the decreased side reactions.