Time-resolved impedance spectroscopy analysis of aging in sulfide-based all-solid-state battery full-cells using distribution of relaxation times technique

Electrochemical impedance spectroscopy (EIS) is a useful non-destructive technique for investigations of various electrochemical systems, including batteries. Although EIS provides abundant information over cell performance, its interpretation is often found to be challenging due to overlapping of time constants. To address the complexity and better understand the battery cell behaviors, the distributions of relaxation times (DRT) technique is employed, which facilitates deconvolutions of the frequency domains. In this study, DRT analysis was conducted to understand the electrochemical responses of all-solid-state battery full-cells made with argyrodite Li₆PS₅X (where X = Cl and Br) electrolyte. Through DRT analysis accompanied by EIS, we effectively identified and quantified the impedance sources of the full-cells. Both cathode/solid-electrolyte and anode/solid-electrolyte interfaces were examined, exploring various factors that govern all-solid-state battery performances, such as interface morphology, cathode coating, and external pressure. The extensive studies conducted using EIS – DRT combination thoroughly elucidate the degradation mechanisms in full-cells, while offering strategies to further develop the all-solid-state battery system for enhanced performances and stabilities.