Operando Visualization and Multi-scale Tomography Studies of Dendrite Formation and Dissolution in Zinc Batteries

Rechargeable metal batteries form the next generation of energy storage devices aiming to replace lithium-ion technology. Nonetheless, these batteries suffer from dendrites formation during repeated battery charging. Understanding how dendrites form is a key to building safer batteries. In the current work, we report multi-scale tomography studies of formation and dissolution of the dendrites in rechargeable zinc batteries. Using operando radiography we found that the dendrites form on surface inhomogeneities, with larger dendrites formed at higher current. The dendrite dissolution and regrowth results in formation of a porous metal network sparsely attached to the anode. The presence of separator does not prevent dendritic growth. Dendrites start growing inside, filling the submicron pores as dense deposits and penetrate the separator. They continue growing on top of the separator, forming a compact entangled network that cannot be re-dissolved back, causing permanent battery failure.