Communication Dans Un Congrès Année : 2024

Deep insight into reactivity of Li3PS4 electrolyte for solid Li-Ion batteries towards humidity using large instruments

Résumé

Wide commercialization of Li-ion batteries (LIBs) for electric transport stimulates a demand for saferbatteries with higher energy density. Thiophosphate solid electrolytes (TSEs) for LIBs are one of the mostpromising candidates to replace a classical liquid electrolyte with volatile components owing to their highionic conductivity values and appropriate mechanical properties for processing [1]. However, one of themain drawbacks of TSEs is their high sensitivity towards humidity even in trace amounts. The reactivitywith water and moisture impacts the electrochemical properties of the electrolytes and leads to toxic H2Semissions. This aspect plays a crucial role for the choice of LIB manufacturing environment (dry roomcharacteristics) and requires fine understanding of underlying mechanisms to optimize a performance /cost ratio for solid-state batteries (SSBs).In the present study, a unique combination of characterisation methods was applied to investigate thereaction between densified Li3PS4 pellet and different levels of humidity (dew point (DP) -40 °C andDP=12 °C for 15 min and 2 h) from chemical and morphological/microstructural points of view. H2S gasevolution was accurately quantified upon a TSE exposure to humid atmosphere using a home-made flow-through setup with differentiation between surface and bulk pellet reactivity [2]. Further, top-viewpropagation of Li3PS4 pellet degradation was investigated using SEM and EDX techniques showingfractures generated through gas released leading to some increase in the pellet porosity at DP= -40 °C;apparition of cracks and oxygen content raise in case of DP = 12 °C exposure. The bulk of the exposedpellets was probed using non-destructive X-ray nanotomography (ESRF, ID16b). Different scenarios wereobserved at low and high levels of humidity during 15 min and 2 h of the pellet exposure (see Fig.).Degradation front containing large pores and cracks propagated up to 50 μm to the depth of the pellet(~400 μm total thickness) after 2 h of exposure to DP= 12 °C. X-ray diffraction-computed tomography(XRD-CT, ESRF, ID15a) was employed to observe structural changes in 3D for Li3PS4 SE upon itsreaction with humidity at different depths. Minor changes were find in crystalline structure of Li3PS4 afterDP= -40 °C exposure while a reaction at DP=12 °C provoked formation of new phases propagating up to90 μm depth of the pellet. Some of newly formed compounds were identified, i.e. P2S2O3, Li2HPO3, P2O5and Li2S2O6.2H2O. Structural strains for Li3PS4 crystalline phase after its exposure to DP=12 °C wererevealed thanks to advanced XRD-CT analysis. Finally, the impact of the pellet exposure to humidity atdifferent conditions on its ionic conductivity was investigated. As a result of this study, a solid link was found between the morphological, microstructural, chemicaldegradation of the TSE and its ionic conductivity upon reaction with water. It was evidenced that the crackformation and propagation to the bulk of TSE pellet is a result of a complex cyclic mechanism, whichincludes chemical attack of H2O molecules on Li3PS4 pellet surface, creation of mechanical strain for theTSE lattice, formation of solid degradation products and gaseous H2S, crack propagation due to the strainrelease and the gas evolution, further penetration of water to the bulk of the pellet, etc. To the best of ourknowledge, this is a first comprehensive study of reaction between SSE and humidity taking into accountall the aspects above. This work contributes to understanding of key triggers for TSE deterioration incontact with different concentrations of water and to definition of proper environment for solid-statebatteries production and handling.
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Dates et versions

cea-04935941 , version 1 (07-02-2025)

Identifiants

  • HAL Id : cea-04935941 , version 1

Citer

Irina Profatilova, Ivan Leteyi Mfiban, Victor Vanpeene, Vasily Tarnopolskiy, Lise Daniel, et al.. Deep insight into reactivity of Li3PS4 electrolyte for solid Li-Ion batteries towards humidity using large instruments. ECS PRIME 2024, Oct 2024, Honolulu, United States. ⟨cea-04935941⟩
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