NiFe-layered double hydroxides: a bifunctional O2 electrode catalyst for non-aqueous Li-O2 batteries

Ascertaining an appropriate cathode material for the Li-O-2 battery system is one of the main tasks at present. To deal with this, in this study, a highly active and stable NiFe-layered double hydroxide (LDH) is synthesized via a hydrothermal method. The characterisation results showed the presence of LDH nanoplates covered with Ni and Fe nanoparticles. In addition to the as prepared NiFe-LDH, its calcinated products at three different temperatures, 300, 500 and 800 degrees C are also studied for the oxygen reduction reaction (ORR) in a non-aqueous electrolyte by using cyclic voltammetry and rotating disc electrode (RDE) techniques. The as prepared NiFe-LDH exhibits a comparatively greater catalytic activity for ORR than its calcinated products. Li-O2 battery tests are then carried out to further evaluate the catalytic activity of the products in 1.0 M LiPF6 in tetraethylene glycol dimethyl ether (TEGDME). NiFe-LDH exhibited superior catalytic performance with a specific discharge capacity of similar to 3218 mA h g(-1) at 0.1 mA cm(-2). The discharge plateau appears at 2.75 V which is close to theoretical potential (2.9-3.1 V) for Li2O2 formation. A stable specific discharge capacity of similar to 1728 mA h g(-1) is obtained even after 30 cycles at 0.1 mA cm(-2). The discharge-recharge voltage gap is about similar to 0.9 V.