Chen Shu-Han, Chen Chia-Chin
Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan.
Phys Chem Chem Phys. 2024 Sep 25;26(37):24689-24698. doi: 10.1039/d4cp02727b.
Mixed ionic-electronic conductors are widely used as electroactive materials in energy applications. The contact of a mixed conductor with another phase plays a crucial role in charge storage and transport in energy devices. However, the interfacial chemistry at the heterojunctions comprising mixed conductors and its interplay with the bulk chemistry remains imperative yet inadequately understood. This study addresses the fundamentals of space charge effects by exploring the equilibrium situations for contacts consisting of mixed conductors. From the perspective of defect chemistry, and by unifying the bulk and interfacial conditions with the electrochemical potential, our treatment allows for predicting the built-in potential at heterojunctions, profiling the space charge distributions, and evaluating the resulting interfacial charge storage and transport. The treatment can be related to experimental characterization, including coulometric titration, conductivity, and capacitance measurements at electrochemical interfaces in all-solid-state batteries. Besides, our treatment also highlights the significance of size and doping effects in nanocrystalline electrodes. This work provides a comprehensive framework for understanding and engineering the heterojunctions in electrochemical devices.
混合离子-电子导体作为电活性材料在能源应用中被广泛使用。混合导体与另一相的接触在能量装置中的电荷存储和传输中起着关键作用。然而，由混合导体组成的异质结处的界面化学及其与体相化学的相互作用仍然至关重要但尚未得到充分理解。本研究通过探索由混合导体组成的接触的平衡情况来解决空间电荷效应的基本问题。从缺陷化学的角度出发，并通过将体相和界面条件与电化学势统一起来，我们的处理方法能够预测异质结处的内建电势，描绘空间电荷分布，并评估由此产生的界面电荷存储和传输。该处理方法可以与实验表征相关联，包括全固态电池中电化学界面处的库仑滴定、电导率和电容测量。此外，我们的处理方法还强调了纳米晶电极中尺寸和掺杂效应的重要性。这项工作为理解和设计电化学装置中的异质结提供了一个全面的框架。
