Effect of the thickness of single-walled carbon nanotube electrodes on the discharge properties of Li–air batteries

Abstract We prepared electrodes of a variety of thicknesses with single-walled carbon nanotubes (SWCNTs) to investigate the effects of electrode thickness on various properties of LABs, including capacity and discharge voltage. The electrode thickness was easily controlled between 29 and 138 μm by adjusting the weight of the SWCNTs dispersed in methanol. From the results of discharge tests under the flow conditions of O2 at atmospheric pressure, it was revealed that the discharge capacity and voltage of the LABs varied depending on the electrode thickness. Notably, in the case of atmospheric pressure, the thinnest 30-μm electrode demonstrated three times higher capacity per unit weight compared with the 125-μm electrode. Moreover, the thinner electrodes also provided top performance with respect to discharge voltage. We also performed discharge tests under increased O2 pressure at 3 atm. In this case, the capacity also increased in relation to decreasing thickness of the electrode, though the trend was slightly different compared with that of the discharge tests carried out at atmospheric pressure. Although thickness is generally an essential parameter for electrochemical devices, it was further revealed here that thickness plays an important role in LABs with respect to the O2 concentration in the electrolyte.