ZHANG Haitao¹ ，WU Yangchen²

1. Institute of Smart City and Intelligent Transportation， Southwest Jiaotong University， Chengdu 611756， China；2. School of Electrical Engineering， Southwest Jiaotong University， Chengdu 611756， China

Abstract

Significance The dual-carbon goals have spurred a significant shift in the industry, accelerating transformation and imposing higher requirements on lithium battery technologies. Driven by innovations in downstream applications, the demand for lithium batteries with higher energy density and enhanced safety has increased. Traditional liquid batteries utilizing flammable organic electrolytes are susceptible to thermal runaway, which may trigger chain reactions leading to battery pack failure and increased fire risks. Consequently, solid-state battery technology has emerged as an innovative solution, garnering growing research attention. By replacing flammable liquid electrolytes with solid-state alternatives, these batteries inherently mitigate the risks of fire and explosion while significantly improving safety performance. Moreover, solid-state batteries effectively suppress dendrite formation, thereby substantially enhancing energy density, stability, and reliability. Despite significant progress in developing highly conductive solid-state electrolytes, most all-solid-state batteries still suffer from constrained rate performance, primarily attributed to the interfacial impedance at the solid-state electrolyte-electrode interface. However, the precise mechanisms governing this impedance remain experimentally elusive. Optimizing the solid electrolyte-powder electrode interface continues to be one of the pivotal challenges in propelling its commercialization.

Progress In recent years, significant breakthroughs have been made in solid-state electrolyte-electrode interface research, with the focus evolving from basic theoretical exploration to addressing key scientific challenges. Based on fundamental principles，three interface types were investigated theoretically. The inherent causes for poor interfacial contact, stability issues, and impeded ionic conduction were analyzed. Moreover, the intrinsic connection between interfacial contact resistance, electrochemical stability, and ionic transport kinetics was systematically elucidated, thereby laying a solid foundation for interfacial optimization. Methodologically, advanced simulation techniques have emerged as powerful tools for investigating interfacial phenomena and predicting material behaviors. Phase-field simulations were used to model both interfacial layer formation and electrolyte microstructure evolution. Finite element analysis was used to quantitatively characterize the interface thermal behavior and stress distribution. This combined approach provides multidimensional insights into the anisotropic characteristics of lithium dendrite growth. In addition, finite element simulation was used to model battery aging processes during solid-state battery development. First-principles calculations haven proven particularly valuable for studying interfacial charge transfer mechanisms and reaction kinetics, while density functional theory (DFT) provided an efficient approach to predicting the electrode-electrolyte interfacial reactions. Nevertheless, limitations persist in accurately simulating dynamic contact behaviors at complex powder/porous-electrolyte interfaces. To address these interfacial challenges, several innovative strategies were proposed. The introduction of transition interlayers reduced interface resistance and enhanced cycle stability by increasing interfacial contact. Structural optimization strategies, particularly through sandwich configurations and three-dimensional architectures, have emerged as a promising research direction for enhancing interfacial contact. Furthermore, interfacial engineering through buffer layer design and stabilizer incorporation enhanced electrolyte-electrode interface contact, thereby improving solid-state battery performance. Additionally, a comprehensive understanding of charge behaviors under electric fields is considered crucial for achieving stable interfaces.