Thanks to the highest capacity of lithium metal (3.86 × 103 mA h g-1) and inexhaustible oxygen in the atmosphere, lithium-air battery offers the promise of a remarkably high theoretical specific energy density up to ~11 kW h g-1, which is comparable to that of conventional fuels [1]. However, the development of lithium-air batteries is hindered by the high overpotential, low rate capacity, and poor cycling performance. The cathode has been shown to be the bottle-neck of rechargeable lithium-air batteries, wherein the sluggish oxygen reduction/evolution reaction (ORR/OER, especially OER) kinetics not only results in a large overpotential, but also causes the poor rechargeability. Thus, it is of great significance and urgency to enhance the electrochemical performances of the cathode. One effective way is to design high efficient catalysts to reduce the charge overpotential. Despite the precious Ru based catalysts have shown promising results as a catalyst for lithium-air batteries, its scarcity and high price will restrict the wide application. As a result, other non-noble transition metal/metal oxides (e.g., MnOx, CoOx) with activities for ORR and/or OER have drawn great interests for lithium-air batteries [2, 3]. Oxides of iron, which in the same group of Ru in the periodic table, however, is less investigated.
Herein, we proposed a facile method to fabricate Fe2O3/carbon nanocomposite cathode materials in which Fe2O3 nanoparticles with a diameter of 4-6 nm are deposited onto the carbon surface, as shown in Figure 1. The electro-catalytic activities were investigated by linear sweeping voltammetry (LSV) and discharge-charge profiles. The results show a lower onset potential and a larger OER current density, suggesting that Fe2O3 is an effective OER catalyst. Moreover, a non-aqueous lithium-oxygen battery with this cathode demonstrates a remarkably 430 mV lower charge overpotential and a dramatically improved cycling life.
More detailed experimental results will be presented in the meeting. And some possible mechanisms of the catalytic effect will also be discussed.