The influence of interfaces represents a critical factor affecting the use of solid-state batteries (SSBs) in a wide range of practical industrial applications. However, our current understanding of this key issue remains somewhat limited. Therefore, this review presents the mechanisms and advanced characterization techniques associated with interfaces in SSBs. First, we compare liquid- and solid-state batteries and emphasize the challenges in solid-solid interfaces. Second, we discuss different aspects of interfaces including interphase formation, cathode-electrolyte interface, anode-electrolyte interface, and interparticle interface, which contain a detailed description of the formation mechanisms and current research. Third, the characterization strategies for effective interfacial observation and analysis are summarized and discussed. In particular, two unique characterization techniques, vibrational sum-frequency generation spectroscopy and on-chip single-nanowire battery characterization, are highlighted. Lastly, we summarize the scientific issues associated with solid-solid interfaces and provide our perspectives to better understand the fundamental issues and improve the performance of SSBs.

接口的影响是影响固态电池（SSB）在许多实际工业应用中使用的关键因素。但是，我们对这个关键问题的当前理解仍然有限。因此，本文将介绍与SSB中的接口相关的机制和高级表征技术。首先，我们比较液态和固态电池，并强调固态接口中的挑战。其次，我们讨论了界面的不同方面，包括相间形成，阴极-电解质界面，阳极-电解质界面和粒子间界面，其中包含对形成机理和当前研究的详细描述。第三，总结和讨论了有效界面观察和分析的表征策略。特别是，突出了两种独特的表征技术，即振动总和频率生成光谱法和片上单纳米线电池表征。最后，我们总结了与固-固界面有关的科学问题，并提供了我们的观点，以更好地理解基本问题并改善SSB的性能。