Battery interface behavior is a critical factor determining battery performance, but the complex chemical composition and nanoscale dynamic evolution impose extremely high demands on the precision of characterization techniques. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) has emerged as a core technique in battery interface research, with its unique advantages such as ultra-high sensitivity, nanoscale spatial resolution, and three-dimensional chemical imaging capabilities. This review systematically introduces the technical principles and development process and functional characteristics of TOF-SIMS, focusing on summarizing its advances and strengths in studying electrode interface evolution, electrolyte decomposition, and ion migration. Using representative interface components as examples, it provides an in-depth discussion on the analytical strategies and principles for accurate identification through cluster ions, providing crucial support for enhancing the reliability of data interpretation. Furthermore, this review explores emerging trends, including the development of in-situ TOF-SIMS and its integration with multi-modal characterization techniques. Finally, proposing development directions including standard database construction, machine learning-assisted data analysis, and wide-temperature-range in-situ characterization to advance TOF-SIMS as a standardized and synergistic technology for battery interface research.

Sodium ion batteries (SIBs) are a promising alternative to lithium-ion batteries for large-scale energy storage due to their cost-effectiveness and enhanced safety. Layered transition metal oxides (LTMOs) represent one of the most fascinating electrode materials owing to their superior specific capacity, environmental benignity, and facile synthesis. However, they are confronted with challenges, such as irreversible phase transition, structural instability, and insufficient battery performance. Notably, entropy engineering emerges as an effective strategy to mitigate the above issues in energy storage research. This strategy aims to achieve precise composition control and optimized structure–property relationships, thereby enabling LTMOs to overcome the aforementioned limitations. This review focuses on medium- and high-entropy oxides (MEOs and HEOs), highlighting their design principles, growth mechanisms, and applications in layered oxide cathodes for SIBs. Through an in-depth analysis of electrochemical performance, phase transition behavior, and disorder structure regulation, we provide comprehensive insights into the application prospects and optimization pathways of MEO/HEO materials in advanced SIBs. Current challenges are also discussed, offering valuable insights and perspectives to overcome the performance bottlenecks of SIBs and facilitate their large-scale deployment.

All-solid-state batteries (ASSBs) are emerging as critical energy storage systems due to their potential for higher energy density, safety, and reliability, making them a research priority in renewable energy technologies. Among ASSBs, inorganic solid electrolytes (ISEs) and layered oxide cathode materials (LOCMs) have gained substantial attention for their high ionic conductivity, chemical stability, and electrochemical performance. However, the interface between ISEs and LOCMs plays a crucial role in determining overall ASSB performance, as interfacial issues can severely hinder lithium-ion transport and reduce battery cycle life. Despite extensive research, a comprehensive understanding of interfacial degradation mechanisms between LOCMs and ISEs in ASSBs remains incomplete and requires further investigation. Therefore, this review systematically examines the origins of poor thermodynamic and electrochemical compatibility, as well as the contact loss caused by volumetric changes in LOCMs. Integrative modifications of LOCMs are highlighted as effective strategies to mitigate these issues. Furthermore, advanced characterization techniques are discussed for their abilities to provide multiscale insights into interface structure and chemical valence.

High-capacity Li-rich oxide materials have received extensive attention due to their unique anion–cation charge compensation involvement. However, the high operating voltage, poor cycling performance, unsafe oxygen evolution, and voltage decay limit their industrial application. The emergence and development of solid-state batteries offer a great opportunity to solve these issues by replacing flammable and unstable liquid electrolytes with solid electrolytes. Meanwhile, utilization of high-capacity Li-rich oxide cathodes enables to establish high-energy-density solid-state batteries with wide voltage ranges, light weight, and high mechanical properties. This review summarizes the recent progress of Li-rich oxide materials and solid electrolytes, emphasizing their major advantages, interface challenges, and modification approaches in the development of Li-rich solid-state batteries. We also propose possible characterization strategies for effective interfacial observation and analyses. It is hoped that this review should inspire the rational design and development of better solid-state batteries for application in portable devices, electric vehicles, as well as power grids.