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

电能存储是可再生能源友好型未来电网的关键组成部分，具有高能效、稳定性和弹性。钠离子电池具有成本低、钠前驱体丰富等优点，与目前广泛应用的锂离子电池相比具有显著优势。磷基材料因其高容量、低成本而成为钠离子电池极具发展前景的阳极材料。然而，与锂离子电池中的合金阳极类似，磷在充放电过程中会发生~300%的体积变化，导致活性物质粉碎化，固体电解质界面生长不稳定，可循环性差。在固态与材料化学项目的支持下，该研究项目致力于通过了解磷基负极材料的降解机制，使低成本、高性能、长循环的钠离子电池更接近实际应用。这种电池将使间歇性可再生能源（如风能和太阳能）能够更好地整合，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。该研究项目还提高了妇女和少数民族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纳米结构储能材料快速发展的研究领域的兴趣。该奖项的研究目标是通过综合实验建模方法揭示作为钠离子电池负极材料的磷碳混合材料的电化学驱动机械降解的潜在机制。实验上，原位TEM研究允许原子尺度的相变和失效机制观察。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，实验研究使研究团队能够建立电化学循环过程中混合材料的微观结构、形态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，以识别主要的降解机制，并相应地优化材料设计。综合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.