Dynamic Laser Interferometry Unveils Interfacial Ion Dynamics and Dendrite Evolution in Zn Electrodeposition

The formation of dendrites during zinc electrodeposition is a pivotal challenge that limits the performance and lifespan of rechargeable zinc batteries. Using a high-resolution laser interferometric imaging platform (2.2 μm spatial, 50 ms temporal, 10–3 M concentration), we directly visualized Zn2+ concentration gradients at the electrode–electrolyte interface. A four-stage evolution model for dendrite growth was identified, with each stage governed by distinct local concentration fields: (I) mossy growth under a uniform concentration distribution; (II) heterogeneous deposition driven by emerging concentration inhomogeneity; (III) localized, accelerated growth in regions of high concentration alongside depletion zones approaching zero; and (IV) preferential deposition confined to high-concentration regions at dendritic tips. Guided by this mechanism, pulsed current was applied to modulate the concentration field, reducing the average dendrite growth rate by 42% compared to galvanostatic deposition. This work provides fundamental insights into zinc electrodeposition and offers a framework for studying other metal battery systems.