Nanostructured Materials for Advanced Electrochemical Energy Storage Applications

Abstract

This dissertation discusses work aimed at developing and improving nanostructured materials for electrochemical energy storage, specifically electrochemical double layer capacitors (EDLCs) and lithium-ion batteries (LIBs). This was achieved through a combination of templating, precursor selection, and heteroatom doping to control the morphology and composition of the materials for improved performance in both types of energy storage. The first part of the thesis discusses EDLCs. First, a new method to produce soft-templated carbon materials is described. This process allows for improved production of mesoporous carbon made through soft templating. The work continues with using ionic liquids to dope nitrogen into hard templated mesoporous carbon. This led to a 40% improvement in specific capacitance due to improved conductivity. The section concludes with an investigation of physical and electrochemical properties of twelve ionic liquid electrolytes to determine which parameters are most important to achieve a high energy density. The second part discusses my work on LIBs, starting with a design of a low-cost electrochemical cell for in-situ X-ray diffraction monitoring during galvanostatic cycling. It continues with the development of a novel cathode material, Li8ZrO6, with a high lithium content. In this material, the redox activity is localized on oxygen atoms. Li8ZrO6 displays initial capacities higher than those of commercial materials but has large polarization. The capacity is further improved with transition metal doping, leading to a final specific capacity of over 175 mAh/g after 140 cycles at a rate of C/5.