Collaborative Research: Mechanistic understanding of chemomechanics in phase-changing electroceramics for sodium-ion batteries

非技术性SUMMARY钠离子化学为充电电池提供了当前锂离子技术的重要替代方案，其最大优势是天然资源丰富、成本低、材料选择范围更广，因此为降低美国稀有元素储量较低的风险提供了关键战略。然而，与锂反应相比，钠化学会对电极造成相当大的机械变形，并产生更多的应力和退化，从而危及电池性能。该项目由材料研究部陶瓷项目支持，旨在通过新的实验、数据分析和建模方法的紧密结合，建立对电池退化的基本理解。这些知识对于阐明钠基电池的老化机制至关重要，这些机制协同作用有助于开发用于相同应用的增强可靠性的材料。普渡和弗吉尼亚理工大学之间的多方面合作为培养STEM相关职业的劳动力提供了独特的培训机会，尤其与满足清洁能源行业的需求有关，预计清洁能源行业在未来几十年将大幅增长。这项研究还提供了一个平台，以继续招募和聘用代表不足的群体，并教育未来的科学家关于收敛的研究技能和创业培训。技术总结该项目旨在通过对缺陷的机理研究-晶格尺度的电荷耦合，单个粒子中的相-应力耦合，以及钠离子电池复合电极中粒子网络的统计，实现对相变电子陶瓷电极中化学力学的全面了解。研究基于这样的假设：(I)局部结构对称性的破坏不仅导致纳米尺度上的晶格扭曲和应力梯度，而且还影响晶格中的电荷分布；(Ii)材料缺陷的随机性与单个粒子中的相不均匀耦合，导致应力/应变分布与传统的核壳模式大不相同；以及(Iii)在复合电极中，电荷不均匀、机械损伤和电化学活动共同演化，导致电池中动态的离子/电子网络。根据这一假设，该项目包括以下研究任务。(I)利用受控合成、同步加速器分析技术和计算建模，量化缺陷特征，并在纳米尺度上绘制缺陷-充电-成分图。(2)利用颗粒工程设计和表面涂层设计，了解单个电子陶瓷颗粒中的相-应力耦合。(3)利用机器学习识别复合电极中粒子网络的特征指标，了解粒子网络在运行条件下的动态演化，解释机械退化对电池性能的影响。总体而言，这项研究跨越了从晶格尺度到复合电极的基本理解，并为从机理上理解储能材料的化学机械降解奠定了基础。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARYSodium-ion chemistry provides a significant alternative to the current lithium-ion technology for rechargeable batteries with its foremost advantage of natural abundance, low cost, and much wider choices of material selection, therefore providing a critical strategy to reduce the risk of the low reserve of scarce elements in the US. However, compared to lithium reactions, sodium chemistry poses a considerable mechanical deformation to the electrodes and creates more stress and degradation that compromise battery performance. This project, supported by the Ceramics Program within the Division of Materials Research, seeks to create a fundamental understanding of battery degradation via a close integration of novel experiments, data analysis, and modeling approaches. Such knowledge is crucial to elucidating the aging mechanisms of sodium-based batteries, which synergistically contribute to the development of materials of enhanced reliability for the same applications. The multifaceted collaboration between Purdue and Virginia Tech provides unique training opportunities for developing workforce for STEM related careers, with particular relevance to meeting the demand of the clean energy industries, which is expected to grow significantly in the coming decades. The research also provides a platform to continue the recruitment and engagement of the underrepresented groups and to educate future scientists on convergent research skills and entrepreneurial training.TECHNICAL SUMMARYThe project aims to achieve a holistic understanding of chemomechanics in phase-changing electroceramic electrodes through mechanistic studies of defects-charge coupling at the lattice scale, phase-stress coupling in single particles, and statistics of the particle network in the composite electrodes of sodium-ion batteries. The research is based on the hypothesis that: (i) the breakdown of the local structural symmetry not only induces lattice distortion and stress gradient at the nanoscale but also impacts the charge distribution in the lattice, (ii) the stochastic nature of material defects is coupled with the phase inhomogeneity in the single particles that gives rise to a stress/strain profile largely deviated from the conventional core-shell pattern; and (iii) in composite electrodes, the charge heterogeneity, mechanical damage, and electrochemical activities co-evolve, resulting in a dynamic ionic/electronic network in the cell. Following the hypothesis, the project includes the following research tasks. (i) Quantify the defect characteristics and map the defects-charging-composition at the nanoscale using controlled synthesis, synchrotron analytical techniques, and computational modeling. (ii) Understand the phase-stress coupling in the single electroceramic particles using the designs of grain engineering and surface coating. (iii) Identify the characteristic metrics of particle network in composite electrodes using machine learning, understand the dynamic evolution of particle network under operating conditions, and interpret the impact of mechanical degradation on battery performance. Overall, the research spans the basic understanding from the lattice scale up to the composite electrode and lays a foundation of mechanistic understanding of chemomechanical degradation in energy storage materiaThis award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.