Controllable Electrochemical Fabrication of KO-Decorated Binder-Free Cathodes for Rechargeable Lithium-Oxygen Batteries.

Understanding the electrochemical property of superoxides in alkali metal oxygen batteries is critical for the design of a stable oxygen battery with high capacity and long cycle performance. In this work, a KO-decorated binder-free cathode is fabricated by a simple and efficient electrochemical strategy. KO nanoparticles are uniformly coated on the carbon nanotube film (CNT-f) through a controllable discharge process in the K-O battery, and the KO-decorated CNT-f is innovatively introduced into the Li-O battery as the O diffusion electrode. The Li-O battery based on the KO-decorated CNT-f cathode can deliver enhanced discharge capacity, reduced charge overpotential, and more stable cycle performance compared with the battery in the absence of KO. In situ formed KO particles on the surface of CNT-f cathode assist to form LiO nanosheets in the Li-O battery, which contributes to the improvement of discharge capacity and cycle life. Interestingly, the analysis of KO-decorated CNT-f cathodes, after discharge and cycle tests, reveals that the electrochemically synthesized KO seems not a conventional electrocatalyst but a partially dissolvable and decomposable promoter in Li-O batteries.