Constriction and Contact Impedance of Ceramic Solid Electrolytes

The performance of solid-state batteries (SSBs) is significantly limited by the degradation of solid-solid interfaces, driven by void formation and loss of contact, which leads to an increase in impedance. In this study, we comprehensively explore the effects of recoverable and unrecoverable interfacial contact areas at the electrode/Li₆PS₅Cl interface and their contributions to the observed impedance increase. By systematically varying contact geometries and applying different pressures, we distinguish their individual impacts on impedance spectra and quantify their influence on interfacial resistance and ion transport. Experimental findings demonstrate that interfacial resistance strongly depends on recoverable contact area and applied pressure, exhibiting power-law scaling behavior with exponents of -1 and -0.5, respectively. Additionally, distributed contact configurations exhibit reduced impedance due to minimized potential gradients and a more uniform potential profile. Continuum simulations of these geometries yield interfacial resistance values that are consistent with experimental observations. Notably, the behavior of solid electrolytes under high pressures emerges as a critical factor influencing interfacial performance. This work provides quantitative insights into the role of recoverable and unrecoverable contact losses in SSB impedance and evaluates strategies to mitigate their effects. [1]

1. Limon, M.S.R., Duffee, C. and Ahmad, Z., 2024. Constriction and contact impedance of ceramic solid electrolytes.
arXiv preprint arXiv:2501.00600. https://doi.org/10.48550/arXiv.2501.00600