(680a) Revealing SEI Breakdown during Lithium Deposition and Dissolution | AIChE

(680a) Revealing SEI Breakdown during Lithium Deposition and Dissolution

Authors 

Cui, Y., Stanford University
Bent, S. F., Stanford University
The solid electrolyte interphase (SEI) is an important component of lithium metal batteries. It influences lithium-ion transport, impacts the kinetics of lithium-electrolyte reactions, and modulates the morphology of lithium metal. These factors play a crucial role in the Coulombic efficiency of lithium metal batteries. However, a deep understanding of the SEI’s significance is lacking, partly due to the limited methods available for measuring its physical properties. In this work, we introduce techniques from electrochemistry and microscopy to quantify and understand the implications of SEI breakdown, an important physical property. Using constant-current chronopotentiometry and Tafel analysis, we show that the SEI breaks down at high current densities during both lithium deposition and dissolution. We find that the current density threshold for SEI breakdown varies with battery electrolytes, and that this breakdown is detrimental to Coulombic efficiency during both lithium deposition and dissolution. Furthermore, we observe that high performance electrolytes do not undergo SEI breakdown under typical battery cycling conditions. Our atomic force microscopy measurements suggest that increasing the SEI’s Young’s modulus and improving its homogeneity can reduce the likelihood of its breakdown. Our findings highlight the impact of SEI breakdown on lithium metal battery cyclability and identify a key property which influences SEI breakdown.