Comprehensive Operando Visualization of the Electrochemical Events in the Cathode/Anode Layers in Thin-Film-Type All-Solid-State Lithium-Ion Batteries

Abstract

The spatially resolved and quantitative observation and analysis of an all-solid-state lithium-ion battery (ASSLiB) under operating conditions play an important role in understanding the reaction or degradation mechanisms of the battery system. In this study, the chemical state distribution of a LiCoO2 cathode and Fe2(MoO4)3 anode layers in a thin-film-type ASSLiB under operating conditions is visualized in the single field of view from a cross-sectional direction using full-field transmission microscopy with X-ray absorption fine structure spectroscopy. Operando measurements during stepped charge/discharging processes revealed the different tendencies of the redox percolation of Co and Fe in the cathode and anode layers, respectively, during the charging/discharging process according to the difference in their lithiation/delithiation mechanisms. We also determine that structural and chemical degradation occurs in both layers after repeating charge–discharge cycling. In the cathode layer, the electrode is exfoliated and the Co in the entire layer becomes more oxidized after degradation, while in the anode layer, Fe2(MoO4)3 decomposes into γ-Fe2O3 and causes the layer to crack.

Progress and Perspective of Controlling Li Dendrites Growth in All‐Solid‐State Li Metal Batteries via External Physical Fields

“…In this regard, nondestructive 3D visualization using X‐CT is suited for battery research that can detect the internal structure evolution of electrodes. [ 80,104–109 ] Due to its nondestructive nature, X‐ray imaging offers unparalleled capabilities for exploring the evolution of Li dendrites in response to various cycling conditions. In this section, the application of XCT to understand Li penetration through SEs is detailed.…”