On the mechanisms of stress relaxation and intensification at the lithium/solid-state electrolyte interface

Under electrochemical cycling, stress intensification and relaxation within small volumes at the lithium/solid-state electrolyte (SSE) interface are thought to be critical factors contributing to mechanical failure of the SSE and subsequent short-circuiting of the device. Nanoindentation has been used to examine the diffusion-limited pressure lithium can support in the absence of active dislocation sources at high homologous temperatures. Based on the underlying physics of this deformation mechanism, a simple perturbation model coupling local current density, elastic stress, and diffusional creep relaxation is introduced. Combining this analysis with the indentation results, it is possible to describe a defect length scale which is too large for effective diffusional creep relaxation, but too small for efficient dislocation multiplication. In this instance, the properties of the SSE may become critical, and relevant indentation results of the SSE are described. The final outcome of the proposed analysis is a newly developed deformation mechanism map.