Understanding the Degradation Mechanisms in Phosphorous-Carbon Hybrid Anodes for Sodium-Ion Batteries

非技术摘要电能储存是未来可再生能源电网的重要组成部分，具有高能效、高稳定性和高弹性。由于钠前驱体的廉价和丰富，钠离子电池与广泛使用的锂离子电池相比具有显著的优势。磷基材料具有高容量、低成本等优点，有望成为钠离子电池的负极材料。然而，与锂离子电池中的合金负极类似，磷在充放电过程中经历了约300%的体积变化，导致活性物质粉化，固体电解质界面生长不稳定，循环性能差。在固态NAD材料化学计划的支持下，本研究项目致力于通过了解磷基负极材料的降解机理，使低成本、高性能、长循环的钠离子电池更接近实际应用。这种电池将使风能和太阳能等间歇性可再生能源得到更大程度的整合，减少对化石燃料的依赖，并提高电网的整体效率、稳定性和弹性。该研究项目还加强了女性和少数族裔对科学和工程的参与，并激发了宾夕法尼亚州立大学学生对快速发展的纳米结构储能材料研究领域的兴趣。该奖项的研究目标是通过综合实验-建模方法揭示磷-碳杂化材料作为钠离子电池负极材料的电化学驱动机械降解的潜在机制。在实验上，原位的透射电子显微镜研究允许原子尺度的相变和破坏机制的观察。结合低成本、可扩展的合成方法和先进的全电池测试和表征，实验研究团队能够构建混合材料在电化学循环过程中的微观结构、形貌和成分演变的原子尺度图像。所提出的多尺度模型与实验表征无缝结合，以确定主要的退化机制，并相应地优化材料设计。一体化的实验-建模方法有助于促进开发高性能储能材料的变革性进展。

Non-Technical AbstractElectrical energy storage is a key component of the renewables-friendly future power grid with high-energy efficiency, stability, and resilience. Sodium ion batteries have a significant advantage over widely used Lithium ion batteries, owing to the low cost and abundance of sodium precursor. Phosphorus-based materials are promising as anodes for sodium ion batteries due to their high capacity and low cost. However, similar to alloy anodes in lithium ion batteries, phosphorus undergoes ~300% volume change during charge/discharge, leading to pulverization of the active materials, unstable growth of the solid electrolyte interphase, and poor cyclability. With the support of the Solid State nad Materials Chemistry program, this research project strives to bring low-cost, high-performance, long-cycling sodium ion batteries closer to real-world applications by understaning the degradation mechanisms of phosphorus-based anode materials. Such batteries would enable greater integration of intermittent renewable power sources such as wind and solar, decrease dependence on fossil fuels, and improve the overall efficiency, stability, and resilience of the power grid. The research project also enhances involvement of women and minorities in science and engineering, and stimulates the interests of students at Penn State in the fast-evolving research field of nanostructured energy storage materials.Technical AbstractThe research objective of this award is to uncover the underlying mechanisms of electro-chemically driven mechanical degradation in phosphorus-carbon hybrids as anode materials for sodium ion batteries through an integrated experimental-modeling approach. Experimentally, in situ TEM studies allow atomic-scale observation of phase transformation and failure mechanisms. Combined with the low-cost, scalable synthesis methods and advanced full-cell battery testing and characterization, the experimental studies enable the research team to build an atomic-scale picture of microstructure, morphology, and composition evolution of the hybrids during electrochemical cycling. The proposed multiscale models seamlessly integrate with the experimental characterizations to identify the leading degradation mechanisms and accordingly optimize the material designs. The integrated experimental-modeling approach helps foster transformative progress for developing high-performance energy storage materials.