Development of composite anode materials for high capacity sodium-ion batteries

Abstract

The demand for lithium-ion batteries has ever increased in almost all portable electronic devices and electric vehicles nowadays. However, it is believed that this increasing demand for lithium-ion batteries in these applications could potentially be limited due to the scarcity of lithium resources in the world's known lithium reserves, which could significantly affect the cost and availability of lithium in the future. Sodium is the fourth most abundant element on earth, and sodium reserves are spread over a wide area. At the same time, the amount of lithium in the earth's crust is only 20 ppm, while the abundance of Na in the earth's crust is about 2%. Thus, sodium ion batteries are considered an economical alternative energy source to lithium-ion batteries in the future. As a result, research and development of appropriate anode, cathode, electrolyte, separator, and binder for sodium ion batteries with high electrochemical performance is required. In this doctoral thesis study, three alternative anode materials for sodium ion batteries were synthesized and tested. The first part, it is aimed to improve the electrochemical properties of titanium dioxide by doping with an iron atom at various ratios of titanium dioxide. In the second part, to improve the low electrochemical performance of titanium dioxide, one-dimensional anode material was synthesized by the electrospinning method. In the third part, a composite anode material with polyaniline polymer was synthesized as a solution to the pulverization of tin oxide anode material due to high volume expansion by the sodium ion alloying reaction.