Structural and electrochemical studies of novel sodium-ion battery electrode materials

DPhil项目涉及新型钠离子电池电极材料的合成和表征。虽然锂离子电池已经改变了我们这个全球互联的世界，并在许多方面帮助定义了我们的世界，但它们在数字电子产品之外的社会中所能普及的程度是有资源和性能限制的。因此，钠离子电池正变得越来越重要，因为它们提供了比当前和未来的锂离子电池技术更可持续、更具成本效益和更安全的能量存储解决方案。钠离子电池在工作温度在20摄氏度到60摄氏度之间时，达到了比商用磷酸铁锂电池更高的能量密度。最初的目标是固定应用，如基于电网的存储，这些最近的发展表明，钠离子电池也可能对交通行业产生影响。钠离子电池正极材料比锂离子电池正极材料要复杂得多。这个项目中要探索的正极材料有两个非常不同的晶体成分，包括一个八面体配位的Na+相(O_3)和一个Na+配位为三方棱柱的第二相(P_2)。本项目要探索的负极材料是硬碳。它们类似于石墨，但石墨烯层涡轮增压无序。阳极的碱化有两种不同的机制--离子插层和金属纳米钠在孔道中聚集。本论文的目标是：1)结合热力学、结晶学和电化学技术，全面了解这些材料在操作条件下的化学和结构演变；2)探索正极材料中非化学计量比和结构无序的本质，并将这些性质与电池性能相关联；3)提出并合成新型电池正极组合物，以优化功率、能量密度和材料成本；4)了解和优化负极中的固溶和脱盐机理。该项目属于EPSRC能源研究领域，特别是能源储存。该公司一半由EPSRC提供资金，另一半由Faradion Ltd.提供资金。Faradion正在开发使用钠离子技术的下一代先进、低成本电池材料，用于固定的大幅面应用。

The DPhil project involves the synthesis and characterisation of novel sodium-ion battery electrode materials. While lithium-ion batteries have transformed and, in many ways, helped define our globally-connected world, there are resource and performance limits to the extent in which they can pervade our society much beyond digital electronics. As a consequence, sodium-ion batteries are becoming of increasing importance because they offer a more sustainable, cost effective and safer energy storage solution than both current and future lithium-ion battery technologies. Sodium-ion batteries have reached higher energy densities than commercial lithium iron phosphate batteries at operating temperatures between 20oC and 60oC. Originally targeted at stationary applications, such as grid-based storage, these recent developments suggest that sodium-ion batteries may also impact on the transportation industry. The material in a sodium-ion battery cathode is more complex than its lithium-ion cathode material equivalent. The cathode materials to be explored in this project have two very distinct crystalline components consisting of a phase (O3) with octahedrally co-ordinated Na+ and a second phase (P2) where the Na+ co-ordination is trigonal prismatic. The anode materials to be explored in this project are hard carbons. These are analogous to graphite, but with the graphene layers turbostratically disordered. Sodiation of the anode occurs in two different mechanisms - ionic intercalation and metallic nano-sodium clustering in the pores. The thesis aims are: 1) to develop a comprehensive understanding of the chemical and structural evolution of these materials under operating conditions using a combination of thermodynamic, crystallographic and electrochemical techniques 2) to explore the nature of non-stoichiometry and structural disorder in the cathode materials and correlate these properties with battery performance 3) to propose and synthesise novel battery cathode compositions which optimise power and energy density and materials cost 4) to understand and optimise sodiation and desodiation mechanisms in the anode. This project falls within the EPSRC Energy research area, specifically energy storage. It is funded half by EPSRC and half by Faradion Ltd. Faradion is pioneering the next generation of advanced, low-cost battery materials using sodium-ion technology for stationary large-format applications.