Owing to an absence or lack of soft (and/or liquid) components, electrochemo-mechanical effects are imperative for all-solid-state batteries (ASBs) based on inorganic solid electrolytes (SEs). As this aspect has been overlooked, relevant investigation has remained scarce. In this work, the development of a new operando differential electrochemical pressiometry (DEP) for ASBs is reported. The time- (or capacity-) derivative differential pressure signals (dP/dt or dP/dQ) reflecting corresponding differential volume changes of electrode active materials feature the specific state of charges (SOCs). This finding leads to a precise estimation of the SOCs of graphite (Gr) electrodes in LiNi0.70Co0.15Mn0.15O2 (NCM)/Gr all-solid-state full cells using sulfide SEs with varying capacity ratios of negative to positive electrodes (n/p ratios); this is corroborated by complementary analysis using a three-electrode electrochemical cell and ex situ X-ray diffraction measurements. Furthermore, electrochemo-mechanical behaviors of NCM/Gr full cells with Gr electrodes employing SEs excluding or including reductively unstable Li10GeP2S12 are investigated. Notable volume changes caused by lithiation of Li10GeP2S12 are detected. Importantly, significantly delayed SOC for Gr caused by a severe side reaction with Li10GeP2S12 is disclosed by the operando DEP result.
Bibliographical noteFunding Information:
This work was supported by Hyundai Motors, by the Technology Development Program to Solve Climate Changes and by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (NRF2017M1A2A2044501 and NRF‐2018R1A2B6004996).
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All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics