α-MnO2 hollow clews for rechargeable Li-air batteries with improved cyclability

Lithium-air (Li-air) batteries have attracted worldwide attention due to their high energy density (11140 Wh kg −1 ) comparable to gasoline. In this work, we have synthesized the α-MnO 2 hollow clews via a simple method and characterized them by X-ray diffraction and scanning electron microscope. Interestingly, cycle performance of Li-air batteries is improved greatly when using the α-MnO 2 hollow clews as the catalyst. The first discharge capacity is 596 mAh g −1 , and the charge capacity is 590 mAh g-1 at the current density of 0.1 mA cm −2 between 2.0 and 4.2 V using the Vulcan XC-72 as the carbon material. Additionally, by re-assembling new batteries with the used lithium foil, separators and cathode separately, we find that the cathode is the key role to end the Li-air battery life.