Tailoring ketene-derived carbon anodes and electrolyte interactions for sodium-ion batteries

As the world faces the challenges of climate change and the increasing demand for sustainable energy, the development of efficient and scalable energy storage systems becomes critical. While lithium-ion batteries have been at the forefront of energy storage due to their high energy density and long cycle life, concerns surrounding the limited supply, environmental impact, and rising costs of lithium have spurred interest in alternative technologies. Sodium-ion batteries offer a promising solution as sodium is abundant, widely available, and cost-effective. However, challenges such as lower energy density, shorter cycle life, and less stable electrochemical performance compared to lithium-ion batteries still need to be addressed for sodium-ion batteries to reach their full potential. This dissertation aims to explore advanced strategies for improving the performance of sodium-ion batteries by focusing on the development of heteroatom-doped carbon materials for use as anodes, as well as optimizing electrolyte compositions. Firstly, a novel approach is introduced for tailoring the chemical and structural properties of carbon materials using ketene chemistry. By leveraging Meldrum’s acid as a precursor, this method efficiently generates ketene intermediates under mild conditions, offering a versatile pathway for creating a wide variety of functionalized carbon materials. Meldrum’s acid derivatives synthesized by Knoevenagel condensation with heterocyclic compounds such as pyrrole, furan and thiophene allow precise control of electronic, structural and physicochemical properties of the carbon materials, making them suitable for sodium-ion battery applications as they can tune a wide range of chemical and structural properties by simply changing a single heteroatom in the precursor structure. These heteroatom-doped carbons show improvements in key performance metrics such as work function, initial coulombic efficiency, and plateau capacity, making them promising candidates for sodium-ion battery anodes. The second part of this dissertation examines the interactions between heteroatom-doped carbon anodes and different electrolyte compositions, with a particular focus on sulfur-doped carbon materials. The research systematically investigates the effects of ether- and ester-based electrolytes on sodium-ion transport, solid-electrolyte interphase formation, and overall battery performance. Sulfur-doped carbon anodes demonstrate superior electrochemical behavior, especially in ether-based electrolytes such as dimethoxyethane and diethylene glycol dimethyl ether. These electrolytes improve ion transport and form thinner, more stable solid-electrolyte interphase layers, resulting in higher specific capacities and better cycling stability compared to ester-based systems. This study provides insights into the synergistic effects of heteroatom doping and electrolyte composition, emphasizing their role in optimizing sodium-ion battery performance.