Cross-Length-Scale Microscopy Characterization of Solid-State Batteries

Abstract

Solid-state batteries (SSBs) are regarded as the key next-generation energy storage technology owing to their superior theoretical energy density, intrinsic safety, and broad operating temperature window. However, scientific challenges such as interfacial instability, lithium dendrite growth, contact failure, and chemomechanical degradation hinder their development. Elucidating these failure mechanisms via cross-length-scale characterizations play an important role in the development of high-performance SSBs. This review systematically summarizes the applications of optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and their derivative techniques (such as cryogenic OM, cryogenic SEM, cryogenic Focused ion beam, and cryogenic TEM) in the cross-length-scale characterization of SSBs. It reveals the failure mechanisms, including interfacial instability, lithium dendrite, and contact loss from macro (∼mm) to atomic levels (∼0.1 nm). Cryogenic techniques effectively mitigate the characterization difficulties associated with electron beam sensitive materials (e.g., sulfide-based SSEs and lithium metal) by employing low-temperature stabilization and low-dose imaging protocols, thereby facilitating the integration of multimodal data across scales to construct a comprehensive understanding of the system. Despite remaining challenges in areas such as electron beam damage, in situ characterization, and data integration, the synergistic advancement of cryogenic electron microscopy, complex in situ platforms, and artificial intelligence-driven data analysis is expected to significantly accelerate the development and commercialization of high-performance SSBs.