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.

Anode-free sodium metal batteries hold significant promise for high-energy-density storage but face critical challenges related to sodium deposition dynamics and interfacial instability. Traditional approaches, such as alloy-based current collectors or fluorinated interfaces, often suffer from irreversible volume expansion or corrosive fabrication processes. This study introduces a solvent co-intercalation-mediated in situ sodiophilic interface engineering strategy to overcome these limitations. A graphitized carbon-modified aluminum current collector dynamically regulates interfacial evolution through solvated sodium-ion co-intercalation during initial cycling, prompting the formation of a C-NaF interface with ultralow Na⁺ adsorption energy. This sodiophilic interface not only facilitates uniform sodium nucleation by providing abundant sodium-philic sites but also encourages the preferential decomposition of anions in the electrolyte, leading to the creation of a robust and NaF-rich solid electrolyte interphase. Consequently, the asymmetric half-cell delivers an ultralow nucleation overpotential (9.7 mV at 0.5 mA cm⁻²) and maintains an average coulombic efficiency of 99.8% over 400 cycles at 1 mA cm⁻². When combined with a Na₃V₂(PO₄)₂O₂F (NVPOF) cathode, the full cell achieves an energy density of 363 Wh kg⁻¹ with 80% capacity retention after 250 cycles at 0.5 C. This work integrates molecular-level dynamic interfacial engineering with macroscopic electrochemical stability, providing a scalable industrial solution for next-generation battery systems.

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.

Layered Li-rich oxides have attracted much attention because of higher capacity than that of traditional layered oxides (more than 250 mAh g⁻¹). However, the intrinsic issues of Li-rich cathode materials suffer from lattice oxygen loss, poor rate capability, voltage fade, and limited cycle life. To tackle these problems, the Li-rich cathode containing intergrown layer and spinel phases was proposed, and this heterostructure material meets the requirements of high energy and stable surface with a fast Li⁺ diffusion channel. Herein, we review the recent progress and in-depth understanding about heterostructure including microstructure and morphology, performance of advancement and degradation mechanisms, and modification strategies. Special attention is given to the high-performance energy mechanism as follows: (a) spinel phase and oxygen vacancy jointly enhance the lattice structure and prevent the irreversible oxygen release, (b) higher capacity is achieved by promotion of activation of Li2MnO3 phase and control of the activation rate to realize stable long-term cyclability, and (c) spinel phase provides the 3D interconnected Li⁺ diffusion channels and protects the surface region from side reactions. The other issue that aroused interest is the undesirable changes of phase transition and degradation mechanisms as follows: (a) the key reconstruction process is to produce a “good” spinel to maintain the surface and interior structure stability. (b) It is significant to figure out the structure degradation and phase transition mechanism in the cycled heterostructure. This review aims to provide inspiration and opportunities for the design of high-energy-density cathode materials, thereby bridging the gap between laboratory research and practical battery applications.

Tremendous studies have been engaged in exploring the application of solid-state electrolytes (SSEs) as it provides opportunities for next-generation batteries with excellent safety and high energy density. Among the existing SSEs, newly developed halide SSEs have become a hot spot owing to their high ionic conductivity up to 1 mS cm⁻¹ and their stability against high-voltage cathode. As a result, halide SSEs have been shown to be promising candidates for all-solid-state lithium batteries (ASSLBs). Here, we review the progress of halide SSEs and available modification strategies of halide SSE-based batteries. First, halide SSEs are divided into four different categories, including halide SSEs with divalent metal, trivalent metal, tetravalent metal, and non-metal central elements, to overview their progress in the studies of their ionic conductivity, crystal structure, conductive mechanism, and electrochemical properties. Then, based on their existing drawbacks, three sorts of modification strategies, classified as chemical doping, interfacial modification, and composite electrolytes, along with their impacts on halide SSE-based batteries, are summarized. Finally, some perspectives toward halide SSE research are put forward, which will help promote the development of halide SSE-based batteries.

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.

Layered Ni-rich materials for lithium-ion batteries exhibit high discharge capacities but degraded cyclability at the same time. The limited cycling stability originates from many aspects. One of the critical factors is the intrinsic insulating residual lithium compounds and the rock-salt (NiO) phase on the surface of particles. In this work, LiNi_0.8Co_0.1Mn_0.1O₂ material is etched with a trace amount of boric acid and used as a model to demonstrate the influences of weak acid treatment on the surface phase regulations. After the etching process, the pH of the material is reduced from 12.08 to 11.82, along with a lower cation mixing degree and promoting electrochemical performances. Corresponding measurements demonstrate that weak acids such as H₃BO₃ can also etch the NiO phase on the surface to adjust the surface of the particles to a pure layered structure. This process improves the lithium-ion diffusion and electron transport in the interface between material and electrolyte, consequently leading to better cycling performance and rate capability. This study provides a novel strategy and comprehensive understanding of acid modification and surface phase regulation process of Ni-rich cathode materials for lithium-ion batteries.