Nordstrand Johan, Toledo-Carrillo Esteban, Vafakhah Sareh, Guo Lu, Yang Hui Ying, Kloo Lars, Dutta Joydeep
Functional Materials, Applied Physics Department, School of Engineering Sciences, KTH Royal Institute of Technology, AlbaNova Universitetscentrum, 106 91 Stockholm, Sweden.
Pillar of Engineering Product Development, Singapore University of Technology and Design, Singapore 487372.
ACS Appl Mater Interfaces. 2022 Jan 12;14(1):1102-1113. doi: 10.1021/acsami.1c20910. Epub 2021 Dec 22.
Prussian blue (PB) and its analogues (PBAs) are drawing attention as promising materials for sodium-ion batteries and other applications, such as desalination of water. Because of the possibilities to explore many analogous materials with engineered, defect-rich environments, computational optimization of ion-transport mechanisms that are key to the device performance could facilitate real-world applications. In this work, we have applied a multiscale approach involving quantum chemistry, self-consistent mean-field theory, and finite-element modeling to investigate ion transport in PBAs. We identify a cyanide-mediated ladder mechanism as the primary process of ion transport. Defects are found to be impermissible to diffusion, and a random distribution model accurately predicts the impact of defect concentrations. Notably, the inclusion of intermediary local minima in the models is key for predicting a realistic diffusion constant. Furthermore, the intermediary landscape is found to be an essential difference between both the intercalating species and the type of cation doping in PBAs. We also show that the ladder mechanism, when employed in multiscale computations, properly predicts the macroscopic charging performance based on atomistic results. In conclusion, the findings in this work may suggest the guiding principles for the design of new and effective PBAs for different applications.
普鲁士蓝（PB）及其类似物（PBAs）作为钠离子电池及其他应用（如水脱盐）的有前景材料正受到关注。由于有可能探索许多具有工程化、富含缺陷环境的类似材料，对作为器件性能关键的离子传输机制进行计算优化有助于实际应用。在这项工作中，我们应用了一种涉及量子化学、自洽平均场理论和有限元建模的多尺度方法来研究PBAs中的离子传输。我们确定氰化物介导的阶梯机制是离子传输的主要过程。发现缺陷对扩散是不允许的，并且随机分布模型准确预测了缺陷浓度的影响。值得注意的是，在模型中包含中间局部极小值是预测实际扩散常数的关键。此外，发现中间态势是PBAs中嵌入物种和阳离子掺杂类型之间的一个重要差异。我们还表明，当在多尺度计算中采用阶梯机制时，基于原子结果能正确预测宏观充电性能。总之，这项工作中的发现可能为设计用于不同应用的新型有效PBAs提供指导原则。
