SusChem: Development and fundamental investigation of high capacity cathode materials for high energy and low cost Na-ion batteries

该项目解决了运输和风能和太阳能发电技术产生的间歇性电力供应的能源存储系统。这些应用的一个潜在解决方案是使用钠离子电池，这种电池可以利用广泛可用的国内资源。钠离子电池的功能机制与锂离子电池相似，但成本更低，因为钠比锂丰富得多。目前，钠离子电池的性能主要受到正极材料的限制。现有的钠离子电池正极材料大多存在容量小、循环寿命短的问题。此外，这些电极材料通常使用钴和镍等贵金属，这增加了成本。该项目旨在开发低成本、高性能的新型阴极材料，其基础是锰这种最丰富的元素之一的氧化物。阴极材料的设计采用了基于基础科学的策略，使阴极可以充放电循环数百次，而性能下降最小。在教育方面，该项目将促进固态化学和电化学领域的知识。该项目的进展和新发现将包括在本科和研究生课程中，并通过暑期课程传播给高中教师和学生。该项目的成果将加快钠离子电池的开发和商业化，从而显著提高储能技术的可持续性。在连续电化学充放电循环中，正极材料晶体结构的稳定性是钠离子电池获得长循环寿命的关键。本课题的重点是合理设计具有层状结构的新型氧化锰钠正极材料。新的策略是通过将选定的元素掺杂到锰位点来稳定它们的结构。掺杂有望有效延缓或减轻钠嵌入和脱嵌过程中的相变，从而实现高容量和长循环寿命。所设计的材料将被合成并进行电化学测试。多种先进的表征方法，如原位x射线衍射，将用于研究电化学循环过程中材料晶体结构的变化。通过对合成、电化学测试和结构表征结果的解读，揭示层状正极材料结构稳定性的见解，验证假设，验证材料设计策略并进一步完善，以指导下一代高性能钠离子电池正极材料的开发。

This project addresses energy storage systems for the transportation and the intermittent supply of electricity generated by wind and solar power technologies. One potential solution for these applications is the use of sodium-ion batteries that utilizes widely available and domestic resources. Sodium ion batteries have similar functioning mechanisms as lithium ion batteries but cost less, as sodium is much more abundant than lithium. Currently, the performances of sodium ion batteries are mainly limited by the cathode electrode materials. Most of the existing cathode materials of sodium ion batteries suffer from low capacity and short cycle life. In addition, precious metals such as cobalt and nickel are typically used in these electrode materials, which increases the cost. This project aims to develop low cost and high performance novel cathode materials based on the oxides of one of the most abundant elements, manganese. The cathode materials are designed using strategies derived from fundamental science that allow the cathode to be charge-discharge cycled for hundreds of times with minimal performance degradation. For educational impacts, the project will advance knowledge in the fields of solid state chemistry and electrochemistry. The progress and new findings of the project will be included in undergraduate and graduate courses and disseminated to high school teachers and students through summer programs. The outcomes of the project will expedite the development and commercialization of sodium ion batteries, and therefore significantly improve the sustainability of energy storage technologies. The stability of the crystal structure in cathode electrode materials in continuous electrochemical charge-discharge cycles is key to obtain long cycle life in sodium ion batteries. This project focuses on rational design of novel sodium manganese oxide cathode materials with layered structures. Novel strategies are used to stabilize their structure by doping selected elements into the manganese sites. The doping is expected to effectively delay or mitigate the phase transitions during the sodium intercalation and deintercalation processes, therefore allowing high capacity and long cycle life. The designed materials will be synthesized and electrochemically tested. Multiple advanced characterization methods such as in situ X-ray diffraction will be used to investigate the changes of the crystal structure of the materials during electrochemical cycling. By interpreting the results from synthesis, electrochemical tests, and structure characterizations, insights on the structural stability of the layered cathode materials will be revealed, the hypotheses will be validated, and the materials design strategies will be verified and further refined to guide the development of next generation high performance cathode electrode materials for sodium ion batteries.