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，并在许多方面帮助定义了我们全球互联的世界，但在某种程度上，它们可以渗透到我们的社会，远远超出数字电子产品。因此，钠离子电池变得越来越重要，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储能解决方案。钠离子电池在20 ℃至60 ℃的工作温度下达到了比商业磷酸铁锂电池更高的能量密度。最初针对固定应用，如基于电网的存储，这些最新的发展表明钠离子电池也可能影响运输行业。钠离子电池阴极中的材料比锂离子阴极材料更复杂。在该项目中探索的阴极材料具有两种非常不同的晶体组分，由具有八面体配位Na+的相（O3）和其中Na+配位为三角棱柱的第二相（P2）组成。在这个项目中要探索的阳极材料是硬碳。它们类似于石墨，但石墨烯层是无序的。阳极的钠化以两种不同的机制发生-离子嵌入和金属纳米钠在孔隙中聚集。本论文的目的是：1）使用热力学，晶体学和电化学技术2）探索阴极材料中的非化学计量和结构无序的性质，并将这些性质与电池性能相关联3）提出和合成优化功率和能量密度以及材料成本的新型电池阴极组合物4）理解和优化阳极中的钠化和去钠化机制。该项目属于EPSRC能源研究领域的福尔斯，特别是能源存储。Faradion公司是下一代先进的低成本电池材料的先驱，使用钠离子技术用于固定式大尺寸应用。

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.