A combined multiscale modeling and experimental study on surface modification of high-volume micro-nanoparticles with atomic accuracy
A combined multiscale modeling and experimental study on surface modification of high-volume micro-nanoparticles with atomic accuracy
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DOI：
10.1088/2631-7990/ac529c
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发表时间：
2022-02
影响因子：
14.7
通讯作者：
Zoushuang Li;Junren Xiang;Xiao Liu;Xiaobo Li;Lijie Li;B. Shan;Rong Chen
中科院分区：
文献类型：
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作者：
Zoushuang Li;Junren Xiang;Xiao Liu;Xiaobo Li;Lijie Li;B. Shan;Rong Chen
在原子和接近原子尺度的微纳米粒子的表面改性是非常重要的，以提高其在各种应用中的性能，包括大容量电池，持久发光等。流化床原子层沉积（FB-ALD）是一种有前途的原子级制造技术，提供了大量的颗粒材料上的纳米薄膜。然而，纳米粒子由于具有很强的内聚力而容易团聚，这对薄膜的保形性非常不利，也阻碍了纳米粒子的真实的应用。本文采用多尺度计算流体力学和离散元方法（CFD-DEM）对超声振动辅助FB-ALD反应器中的颗粒流化过程进行了从微观到宏观的数值模拟，并进行了实验验证。不同的振动振幅和频率的影响的流体动力学，颗粒速度和固体体积分数的分布，以及团聚体的大小进行了研究。结果表明，超声振动可明显增强颗粒获得动能以克服颗粒间团聚力的关键动力源--流体湍动能。此外，超声波振动的应用被发现，以减少在流化床中的平均团聚体的大小。这必然有利于整个FB-ALD反应器和团聚体中的热传递和前体扩散，这可以大大缩短涂覆时间并提高膜的保形性以及前体利用率。模拟结果与电池实验结果吻合较好，验证了多尺度CFD-DEM模型的有效性。该研究为原子级颗粒涂层从实验室规模到工业应用的批量生产提供了重要指导。
Surface modification for micro-nanoparticles at the atomic and close-to-atomic scales is of great importance to enhance their performance in various applications, including high-volume battery, persistent luminescence, etc. Fluidized bed atomic layer deposition (FB-ALD) is a promising atomic-scale manufacturing technology that offers ultrathin films on large amounts of particulate materials. Nevertheless, nanoparticles tend to agglomerate due to the strong cohesive forces, which is much unfavorable to the film conformality and also hinders their real applications. In this paper, the particle fluidization process in an ultrasonic vibration-assisted FB-ALD reactor is numerically investigated from micro-scale to macro-scale through the multiscale computational fluid dynamics and discrete element method (CFD-DEM) modeling with experimental verification. Various vibration amplitudes and frequencies are investigated in terms of their effects on the fluid dynamics, distribution of particle velocity and solid volume fraction, as well as the size of agglomerates. Results show that the fluid turbulent kinetic energy, which is the key power source for the particles to obtain the kinetic energy for overcoming the interparticle agglomeration forces, can be strengthened obviously by the ultrasonic vibration. Besides, the application of ultrasonic vibration is found to reduce the mean agglomerate size in the FB. This is bound to facilitate the heat transfer and precursor diffusion in the entire FB-ALD reactor and the agglomerates, which can largely shorten the coating time and improve the film conformality as well as precursor utilization. The simulation results also agree well with our battery experimental results, verifying the validity of the multiscale CFD-DEM model. This work has provided momentous guidance to the mass manufacturing of atomic-scale particle coating from lab-scale to industrial applications.