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 °C in air. Different thermal treatments were performed, tuning different parameters, such as intermediate treatment at 500 °C or the atmosphere used and the final temperature. Surface areas remain high for samples without an intermediate temperature step of 500 °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.