A study on the effect of structure and chemical composition of electrode materials on the electrochemical characteristics for the next-generation high-energy alkali metal ion batteries

Abstract

With the rapid expansion in energy demands for portable devices, alkali metal (Li, Na, and K) ion batteries (AIBs) are achieving great attention as one of the most promising energy storage devices owing to the large energy storage and high power. Currently, traditional lithium-ion batteries (LIBs) are widely used, however, this type of battery has many problems in performance should be addressed such as safety, reliability, and cost. Particularly, the most actively studied are as follows; (1) increasing the gravimetric/volumetric energy storage and power, (2) enhancing the cyclability, (3) solving the safety concerns (in particular, the explosion problem), and (4) replacing the lithium and using resource-abundant sodium as a charge carrier. Despite the numerous studies have been conducted, most of the studies focused only on fragmentary performance without considering the overall design of the battery, and these may operate differently from the results of the study in an actual environment. In this thesis, the solution to the problems faced by the traditional batteries will be suggested by focusing on the fundamental improvement methods for the electrode active materials consisting of the batteries and the efficient battery configuration. Particularly, with respect to the potential active materials candidates for next-generation batteries, the problems they have in the actual operating environment of batteries have been illuminated, and the solution is proposed through the improvement of materials. The first topic of this thesis (Chapter 1) includes an overview of AIBs, in which the common structure of the device, working mechanisms, and the current state-of-art performances and technologies with their limitations. The next topic of this thesis (Chapter 2) is a study on next-generation LIBs fabricated with lithium metal anode (LMA) for demonstrating the higher gravimetric/volumetric energy and operating cell voltage. This topic contains the study on the battery design using LMA to have an advantage in the gravimetric and volumetric energy storage in the actual battery operating condition. The final topic (Chapter 3) is a study on the development of sodium-ion batteries (SIBs) that use resource-abundant sodium as a charge carrier. The search for an active materials pair capable of demonstrating the performance comparable to the state-of-art LIBs and the problems and solutions of the active materials in a battery operating condition were studied.