β-FeOOH decorated highly porous carbon aerogels composite as a cathode material for rechargeable Li–O2 batteries

Abstract

A composite of β-FeOOH–carbon aerogels (FCAs) was designed and prepared via a simple hydrothermal method. The samples were characterized by X-ray diffraction, field emission scanning electron microscopy and N₂ adsorption/desorption measurements. It is found that the composite possesses a large pore volume and, especially, has a high proportion of mesopores. The material was studied as an O₂ electrode for non-aqueous lithium–O₂ batteries and the electrochemical performance of the electrode was evaluated by using galvanostatic discharge–charge processes and cyclic voltammetry (CV). The FCAs electrode exhibits excellent performance and delivers a discharge capacity of up to ∼10 230 mA h g_{carbon+catalyst}⁻¹ at 0.1 mA cm⁻² and a high C-rate performance with a discharge capacity of ∼6110 mA h g_{carbon+catalyst}⁻¹ at 0.2 mA cm⁻² and ∼4270 mA h g_{carbon+catalyst}⁻¹ at 0.5 mA cm⁻², it also exhibits a stable discharge voltage plateau at 2.75 V and a charge voltage plateau of ∼3.75 V, and shows a good cycle performance. The excellent electrochemical performance of the FCAs is attributed to the synergistic effect of the good catalytic activity of β-FeOOH and the high porosity of the carbon aerogels. These results demonstrate that the carbon aerogels are suitable for the skeleton material to load the catalyst and the FCAs can be an outstanding material for the cathode of Li–O₂ batteries.