Investigation of molybdenum oxide as a catalyst for non-aqueous lithium oxygen batteries

Abstract

Today, one of the biggest problem which the world have to get over is the global warming and the main reason of global warming is the greenhause gasses which are released due to usage of fossil fuels in transportation applications. Therefore, alternative energy sources are needed but it is not sufficient itself. Suitable energy storage systems are also necessary and these systems have to provide very high amount of energy density and eficiency in order to replace fossil fuels. In that case batteries are very promising technologies however, there is no manufactured battery type in the market which can provide required high energy and power density, so new and more effective technologies have to be investigated for this purpose. One of the best candidates of such technologies is the Li-O2 battery which is based on the Li-O2 electrochemical couple. Li-O2 batteries can achieve approximately ten times higher energy density than that of current state-of-the-art Li-ion batteries by storing the discharge product Li2O2 which occurs as a result of reaction between Li anode and active cathode material, O2, on the porous cathode material. However, there are various challenges to overcome including high OERORR overpotentials, parasitic side reactions and poor cyclability in order to built commercial Li-O2 batteries. Especially, unwanted side product formation on the cathode-electrolyte interface is the major challenge itself because these insulator side products accumulate on the cathode surface during cycling and prevent electrical and ionic transportation which cause drastic capacity fading. That is why various catalyst materials have been investigated in order to facilitate the reaction between Li-O2 electrochemical couple. In this study, we investigated molybdenum oxide which is decorated on multiwalled carbon nanotube catalyst support as an efficient electrocatalyst for Li-O2 batteries. Several synthesis methods and parameters have been utilized in order to enhance its performance and adapt it for our application. Morphological, structural, chemical and electrochemical characterizations have been carried out by using X-Ray Diffraction, X-Ray Photoelectron Spectroscopy, Scanning Electron Microscopy and Transmission Electron Microscopy.