Carbon-Free Cathode Materials Based on Titanium Compounds for Zn-Oxygen Aqueous Batteries

The impact of global warming has required the development of efficient new types of batteries. One of the most promising is Zn-O2 batteries because they provide the second biggest theoretical energy density, with relevant safety and a cycle of life long enough to be fitted for massive use. However, their industrial use is hindered by a series of obstacles, such as a fast reduction in the energy density after the initial charge and discharge cycles and a limited cathode efficiency or an elevated overpotential between discharge and charge. This work is focused on the synthesis of titanium compounds as catalyzers for the cathode of a Zn-O2 aqueous battery and their characterization. The results have shown a surface area of 350 m2/g after the elimination of the organic templates during heat treatment at 500 degrees C in air. Different thermal treatments were performed, tuning different parameters, such as intermediate treatment at 500 degrees C or the atmosphere used and the final temperature. Surface areas remain high for samples without an intermediate temperature step of 500 degrees C. Raman spectroscopy studies confirmed the nitridation of samples. SEM and XRD showed macro-meso-porosity and the presence of nitrogen, and the electrochemical evaluation confirmed the catalytic properties of this material in oxygen reaction reduction (ORR)/oxygen evolution reaction (OER) analysis and Zn-O2 battery tests.