Electrode–electrolyte interface stability in solid state electrolyte systems: influence of coating thickness under varying residual stresses

Claas Hüter,Egbert Figgemeier,Robert Spatschek,Martin Finsterbusch,Luke Wells,Shuo Fu

doi:10.3934/matersci.2017.4.867

Claas Hüter, Egbert Figgemeier + Show 4 more

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https://doi.org/10.3934/matersci.2017.4.867

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Abstract

We introduce a model of electrode–electrolyte interfacial growth which focuses on the effect of thin coating layers on the interfacial stability in prestressed systems. We take into account transport resulting from deposition from the electrolyte, from capillarity driven surface diffusion, and from changes of the chemical potential due to the elastic energy associated with the interface profile. As model system, we use metallic lithium as electrode, LLZO as electrolyte and Al2O3 as a thin film interlayer, which is a highly relevant interfacial system in state of the art all-solid-electrolyte batteries. We consider the stability of the electrode-coating-electrolyte interface depending on the thickness of the thin film interlayer and the magnitude of the elastic prestresses. Our central approach is a linear stability analysis based on the mass conservation at the planar interface, employing approximations which are appropriate for solid state electrolytes (SSEs) like LLZ, a thin Li metal electrode and a thin coating layer with a thickness in the range of nanometres.

Highlights

The presented work focuses on the effect of varying interlayer thickness on the stability of the electrode–electrolyte interface, subjected to elastic prestresses
We introduce a model of electrode–electrolyte interfacial growth which focuses on the effect of thin coating layers on the interfacial stability in prestressed systems
Our central approach is a linear stability analysis based on the mass conservation at the planar interface, employing approximations which are appropriate for solid state electrolytes (SSEs) like LLZ, a thin Li metal electrode and a thin coating layer with a thickness in the range of nanometres

Summary

Introduction

The presented work focuses on the effect of varying interlayer thickness on the stability of the electrode–electrolyte interface, subjected to elastic prestresses. Since all-solid-state batteries (ASBs) can be manufactured using these electrolytes, even in the event of short circuiting via metallic dendrites, a harmful thermal runaway of the cell is intrinsically impossible. The SSE–electrode interface exhibits interfacial impedances of about 1000 Ω/cm, presenting a major obstacle to the widespread implementation in ASBs due to insufficient power densities. Mitigation strategies against this drawback were explored recently, as experimental work on aluminum oxide coatings in SSEs showed that the interfacial impedance can be drastically reduced [6]

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