水性可充电电池被认为是电化学储能最可靠的解决方案之一,和离子(例如,H+或OH-)传输对其电化学性能至关重要。然而,由于模型假设与现实的偏差,建模和数值模拟通常无法描述实际的离子传输特性。实验方法,包括激光干涉测量,拉曼,核磁共振成像,受到系统复杂性和离子检测受限的限制,这使得很难检测特定的离子,如H+和OH-。在这里,通过创新性地引入激光扫描共聚焦显微镜,实现了离子传输的原位可视化。以中性锌空气电池为例,使用pH敏感探针,在电池运行过程中观察到与离子迁移过程相关的实时动态pH变化。结果表明,在硫酸锌电解液中浸泡后,Zn电极附近的pH值显着变化,发生脉动,这表明了强烈的自腐蚀析氢反应和反应强度的周期性变化。相比之下,镀锌电极板的pH变化较弱,证明了其显著的缓蚀效果。对于空气电极,提出了放电和充电过程中离子传输的异质性。随着电流密度的增加,离子输运特性从扩散优势逐渐演变为对流-扩散优势,揭示了对流在电池内部离子传输过程中的重要性。这种方法开辟了一种研究电池内部离子传输的新方法,指导性能增强的设计。
Aqueous rechargeable batteries are regarded as one of the most reliable solutions for electrochemical energy storage, and ion (e.g., H+ or OH-) transport is essential for their electrochemical performance. However, modeling and numerical simulations often fall short of depicting the actual ion transport characteristics due to deviations in model assumptions from reality. Experimental methods, including laser interferometry, Raman, and nuclear magnetic resonance imaging, are limited by the complexity of the system and the restricted detection of ions, making it difficult to detect specific ions such as H+ and OH-. Herein, in situ visualization of ion transport is achieved by innovatively introducing laser scanning confocal microscopy. Taking neutral Zn-air batteries as an example and using a pH-sensitive probe, real-time dynamic pH changes associated with ion transport processes are observed during battery operation. The results show that after immersion in the zinc sulfate electrolyte, the pH near the Zn electrode changes significantly and pulsation occurs, which demonstrates the intense self-corrosion hydrogen evolution reaction and the periodic change in the reaction intensity. In contrast, the change in the pH of the galvanized electrode plate is weak, proving its significant corrosion inhibition effect. For the air electrode, the heterogeneity of ion transport during the discharging and charging process is presented. With an increase of the current density, the ion transport characteristics gradually evolve from diffusion dominance to convection-diffusion codominance, revealing the importance of convection in the ion transport process inside batteries. This method opens up a new approach of studying ion transport inside batteries, guiding the design for performance enhancement.