CoNi-doped C–N/CNT nanocomposites as cathodic catalysts of neutral Zn–air battery

Abstract

A neutral zinc–air battery has unique characteristics. One of the key issues for its normal operation is how to ensure that the cathode catalyst can effectively electrocatalyze oxygen reduction reaction (ORR) in a neutral solution. Here, we report a simple preparation of CoNi-doped C–N/CNT nanocomposite catalysts (CoNi/C–N/CNT) by pyrolysis of a mixture of nickel/cobalt salt, carbon nanotube (CNT), dicyandiamide (DCD), and ethylenediamine. The prepared CoNi/C–N/CNT nanocatalysts are composed of CoNi nanoparticles, hollow tubular C–N nanocomposites obtained from CoNi salts and DCD, and CNT added. Among the synthesized catalysts, the Co3Ni2/C–N/CNT45 has a high and stable ORR current density of 6.2 mA cm−2 in 0.5 mol L−1 KNO3 solution. Neutral Zn–air battery with the carbon paper coated with the CoNi/C–N/CNT nanocomposite as an air electrode and metal Zn as an anode was assembled. For the catalyst Co3Ni2/C–N/CNT45, the neutral Zn–air battery in 0.5 mol L−1 KNO3 solution presents an open-circuit voltage of 1.16 V and a maximum power density of 50.1 mW cm−2. Moreover, the constant discharging current density of 100 and 150 mA cm−2 can last respectively 88 and 28 h until complete consumption of the Zn foil anode.