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

Lithium−air batteries (LABs) are considered 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 3D MnO2 and carbon nanotubes/carbon fiber paper (CNTs/CFP) with a binder‐free structure. Side reactions related to the binder are precluded in this design. The presence of CNTs not only promotes the formation of a 3D structure of the 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 100 mA 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 attributed to the decreased side reactions. Binder‐free and freestanding: The in situ formation of a binder‐free and freestanding 3D MnO2/CNTs/CFP electrode increases the use efficiency of the catalyst. It achieves a good specific capacity, with a discharge capacity of 8723.5 mAh g−1(CNTs+MnO2) at 100 mA g−1.