Design and Electrochemical Performance of Sodium-Based Batteries

Autor: Zhang, Qipeng
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Druh dokumentu: Dissertation
Popis: Low-cost, high-performance energy storage solutions are in great demand for applications such as vehicle electrification and electricity generation from renewable sources. Lithium-based batteries have emerged as strong contenders due to their high energy density and stability. However, their reliance on scarce lithium reserves and high production costs makes them impractical for many applications. Sodium-based batteries (SBBs) are gaining traction as a more affordable option, with costs of $50 to $100 per kWh and an abundant resource base. Despite these advantages, SBBs still face many obstacles, primarily due to limited research on sodium-based chemistries. Additionally, sodium-based batteries have inherent limitations, including lower energy capacity and reduced cycle life, which restrict their viability for long-term use. This thesis addresses several critical challenges faced by SBBs and explores new strategies for enhancing their performance and viability for large-scale applications. First, a low-concentration, non-flammable electrolyte consisting of 0.3 M NaPF6 in a mixed solvent was formulated and tested in SBBs. This electrolyte significantly improves the cyclability and performance of SBBs across a wide temperature range, with high-capacity retention at both elevated and sub-zero temperatures. Molecular simulations reveal that the improved ion-pairing underpins the exceptional performance. This development addresses major challenges in SBBs by offering a safer, more cost-effective solution for large-scale applications. Second, sodium-sulfur (Na-S) batteries were explored to achieve high energy densities. An external acoustic field was implemented to enhance Na-S battery performance by inhibiting the shuttle effect and reducing dendrite growth, two key challenges in Na-S systems. This method offers a scalable, non-chemical solution to improve cycle life and efficiency, making Na-S batteries a more viable candidate for large-scale energy storage. This progress, along with the high theoretical capacity of Na-S batteries, helps address the limitations not resolved by the electrolyte engineering work of SBBs. Third, the mechanisms of Na2Sx (x≤2) precipitation in sodium-sulfur (Na-S) and sodium-oxygen-sulfur (Na/O2-S) systems were investigated. The results reveal that higher-order sodium polysulfides display the lowest current density, indicating a stronger driving force is needed to initiate their reaction. In Na/(O2)-S systems, the transition from high-order to low-order oxy-sulfur intermediates demands less energy compared to Na-S systems. The insights gained here help further optimize Na-S/Na/(O2)-S batteries to enhance their performance and cycle life. Together, the work in this dissertation addressed several critical needs in the development of SBBs and helped advance their commercialization.
Doctor of Philosophy
As the demand for affordable and efficient energy storage grows, especially to support electric vehicles and electricity generation from renewable sources, new types of batteries are needed. While lithium-based batteries are commonly used due to their high energy capacity, they rely on scarce and expensive lithium resources, making them impractical for large-scale applications like storing energy for electrical grids. This has led researchers to explore sodium-based batteries, which use sodium, a much more abundant and cost-effective element. However, sodium-based batteries still face challenges, such as lower energy capacity and shorter lifespan compared to their lithium counterparts. This thesis focuses on improving sodium-based battery performance to make them a more viable option for large-scale energy storage. The first project introduces a new, safer, low-cost electrolyte that significantly enhances the performance of sodium-based batteries, even in extreme temperatures. This solution improves the battery's ability to retain its energy over multiple charging cycles, addressing some of the key issues in current sodium-based battery technology. In the second project, the focus shifts to sodium-sulfur (Na-S) batteries, which offer the potential for higher energy storage due to sulfur's high capacity. To address common issues in Na-S batteries, such as the polysulfide shuttle effect and dendrite formation, a novel acoustic approach is explored. This method reduces the migration of polysulfides between the electrodes, which preserves capacity, and also suppresses the growth of dendrites on the sodium metal anode, improving both safety and battery lifespan. As a result, the efficiency and durability of Na-S batteries are significantly enhanced, bringing them closer to practical, large-scale applications. Despite these advancements, some fundamental questions remain about how sodium polysulfides form and behave inside Na-S batteries. The third project focuses on understanding the precipitation and interaction of these compounds under different conditions. Gaining insight into these processes is essential for further enhancing battery performance and ensuring long-term reliability. In conclusion, this thesis explores several innovative strategies to improve the design and performance of sodium-based batteries, which help make them more practical for large-scale energy storage applications and ultimately contribute to a more sustainable future.
Databáze: Networked Digital Library of Theses & Dissertations
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