Ln_1-xA_xCoO₃ (Ln = Er, La; A = Ca, Sr)/Carbon Nanotube Composite Materials Applied for Rechargeable Zn/Air Batteries

Calcium- and strontium-substituted rare earth cobaltate powders with the perovskite structure (ABO 3 ) are synthesized by coprecipitation, ceramic, complexation, and microemulsion processes. On these metal oxide particles, a carbon nanotube composite material was prepared by a catalytic hydrocarbon dissociation reaction. The material was tested for a possible application as an oxygen electrode in zinc/air batteries. Through a systematic characterization of the produced materials, the common strategy of screening processes for new materials can be replaced by the tailoring of an optimized functional material. To study the influence of the synthesis route and substitution at the A site on the crystallographic structure, the materials were characterized by X-ray diffraction (XRD) and electron microscopy (EM). Phase formation, reactivity, and stability were monitored by high-temperature X-ray diffraction and thermoanalytical (TA) experiments. The electrochemical activities of the samples for oxygen evolution was measured in a three-electrode arrangement.