Preparation of NiO/multiwalled carbon nanotube nanocomposite for use as the oxygen cathode catalyst in rechargeable Li-O₂ batteries

NiO/multiwalled carbon nanotube (NiO/MWCNT) nanocomposites have been prepared and used for a Li-O₂ battery cathode catalyst. Electrochemical measurements demonstrate that the batteries with NiO/MWCNT catalyst have a discharge capacity of 2,500 mAh g^-1, a charge capacity of 2,100 mAh g^-1, and a rechargeable ability performing better than Ketjenblack (KB) and MWCNTs. KB has the largest discharge capacity (2,700 mAh g^-1) due to the highest surface area and pore volume but the worst charging behavior due to poor mass transport in the small-width pore (2.48 nm). MWCNTs have a much better charging performance owing to a larger pore width (8.93 nm) than carbon black. NiO/MWCNTs have the largest charge capacity because of the facilitated mass transport in the comparatively large pores (7.68 nm) and the increased catalytic ability produced by the NiO nanoparticles. These improvements are also responsible for the best cycle and rate performances of the nanocomposites among the three catalysts.