Electrochemical Modeling of Dendrite Initiation in Solid-State Batteries

Solid-state batteries have emerged as a promising technology for next-generation energy storage systems, offering enhanced safety and higher energy densities compared to conventional liquid-electrolyte batteries. However, the practical realization of solid-state cells—particularly anode-free designs—remains hindered by the persistent challenge of dendrite formation. These filament structures can compromise performance and safety by inducing internal short circuits, accelerating capacity fade, and posing the risk of battery failure. Understanding and controlling dendrite formation is crucial to unlocking the full potential of solid-state batteries. [1] [2] [3] This work presents a model of the spatial distribution of ionic flux during electrodeposition in battery systems to elucidate the conditions that govern dendrite initiation. The model employs an electro-quasi-static framework with nonlinear boundary conditions representing charge transfer kinetics, implemented within ABAQUS software. The analysis reveals that dendrite onset is intimately tied to the formation of singular current fields at the electrode surface. This phenomenon is governed by the interplay between electrode geometry and an intrinsic electrochemical length scale, which arises from the balance of ionic conductivity and interfacial charge transfer kinetics described by the Butler–Volmer equation. When the electrode dimension greatly exceeds this length scale, a pronounced current density singularity develops at the electrode edge. In contrast, when the electrode size is comparable to the electrochemical length scale, the singularity is suppressed, leading to a more uniform flux profile. These relationships between electrode length scales and the current density distribution along the interface reveal how geometrical effects could influence the probability of local dendrite initiation. These findings are further explored through experimental observations of electrodes with different sizes. By elucidating this mechanism, the results offer new insights into understanding the underlying mechanisms that influence dendrite formation in solid-state batteries. [1] Kazyak, E., Garcia-Mendez, R., LePage, W. S., Haslam, C., Sakamoto, J., & Dasgupta, N. P. (2020). Li Penetration in Ceramic Solid Electrolytes: Operando Microscopy Analysis of Morphology, Propagation, and Reversibility. Matter, 2(4), 1025–1048. [2] Choudhury, R., Wang, M., & Sakamoto, J. (2020). The Effects of Electric Field Distribution on the Interface Stability in Solid Electrolytes. Journal of The Electrochemical Society, 167(14), 140501. [3] Swamy, T., Park, R., Sheldon, B. W., Rettenwander, D., Porz, L., Berendts, S., Fleig, J., & Wilkening, M. (2018). Lithium Metal Penetration Induced by Electrodeposition through Solid Electrolytes: Example in Single-Crystal Li 6 La 3 ZrTaO 12 Garnet. Journal of The Electrochemical Society, 165(16), A3648–A3655.