论文和技术资料

All-solid-state batteries (ASSBs) are promising candidates for next generation energy storage systems due to their improved safety and higher energy density enabled using lithium metal and non-flammable solid electrolytes. However, manufacturing-induced imperfections at the Lithium|Solid Electrolyte (Li|SE) interface can significantly affect battery performance and durability, as this evolving region is the site of complex electrochemical and mechanical interactions during cycling.

The origin of this coupling lies in the volume changes associated with lithium stripping and plating. These deformations generate stresses at the interface, which modify the local electrochemical equilibrium, thereby influencing the distribution of current density and lithium ions. Furthermore, the inherent roughness of the Li|SE interface promotes heterogeneous stress and current density distributions, leading to localized lithium deposition and stripping. Such interfacial instabilities can accelerate contact loss, reducing the effective contact area for later cycling, thus increasing the interfacial resistance, and potentially triggering dendrite growth and ultimately limiting battery performance and lifetime.

Although several electro-chemo-mechanical models have been proposed to investigate Li|SE interfaces, accurately capturing the effects of interfacial roughness remains challenging because of the strongly coupled and multiscale nature of the underlying phenomena. Most existing studies rely on simplified sinusoidal or Gaussian asperity geometries [1-3]. In addition, while lithium exhibits significant creep deformation even at room temperature [4], the role of time-dependent deformation mechanisms in the evolution of Li|SE interface remains insufficiently explored.

In this work, building upon the mechanics-coupled secondary current distribution model proposed by Nadeau et al. [1], a 2D electro-chemo-mechanical model is developed to investigate the influence of self-affine interfacial roughness on the behavior of Li|LLZO interface during lithium stripping. The implementation of the rough interface in COMSOL Multiphysics® is illustrated in Figure 1. Rough surfaces were generated using the spectral synthesis approach, enabling the statistical characteristics of the interface topography to be controlled through fractal descriptors.

The model is implemented using the Secondary Current Distribution (SCD) and Solid Mechanics (SM) interfaces available in COMSOL Multiphysics®. The SCD interface is used to solve charge conservation and ionic conduction within the single-ion conducting LLZO solid electrolyte, while electronic conduction is considered in the lithium electrode. The SM interface is applied by assuming linear elastic behavior for LLZO, creep deformation of lithium metal, and frictionless mechanical contact between opposing asperities. A pseudo-transient finite-element formulation is employed to capture the evolution of the Li|LLZO interface during stripping. The simulations will provide distributions of stress, strain, contact pressure, ionic potential, and current density within the Li|LLZO interface. The results are expected to provide a deeper understanding of the electro-chemo-mechanical mechanisms induced by interfacial roughness and their impact on the evolution of Li|LLZO interface during stripping. Such insights may contribute to the development of interface-engineering strategies improving the cycling stability of ASSBs. In this context, the model will be used to estimate the stack pressure conditions required for lithium plastic flow to compensate for stripping-induced volume loss and maintain interfacial contact.