Urchin-like core-shell TiO2/alpha-MnO2 nanostructures as an active catalyst for rechargeable lithium-oxygen battery

Abstract

A selection of appropriate electrocatalysts with a unique design is a promising solution to promote oxidation and reduction reactions in lithium-oxygen (Li-O-2) batteries. Here, an effective integrated design of urchin-like core-shell TiO2/alpha-MnO2 nanostructure is constructed to develop an efficient catalyst electrode for Li-O-2 batteries. For this purpose, TiO2 nanoparticles are biosynthesized by an eco-friendly process using flower extract of Matricaria chamomilla as both reducing and stabilizing agents. Then, MnO2 nanocrystals are grown on the surface of TiO2 nanoparticles under different reaction times to observe their evolution in terms of morphology and crystalline structure of MnO2. The electrochemical behavior of the as-prepared core-shell TiO2/alpha-MnO2 nanostructures is evaluated in Li-O-2 cells. The TiO2/alpha-MnO2 electrode is exhibited a lower overpotential and higher specific capacity than the bare TiO2 electrode. This could have resulted from the bifunctional catalytic activity of TiO2 and alpha-MnO2 coupled with urchin-like MnO2 nanostructures. Furthermore, the internal resistance of the cell is recorded using electrochemical impedance spectroscopy technique, and reactions of the Li' and O-2 on the cathode surface are investigated by cyclic voltammetry. (C) 2021 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.