Origin of Heterogeneous Stripping of Lithium in Liquid Electrolytes

Abstract

Lithium metal batteries suffer from low cycle life. During discharge, parts of the lithium are not stripped reversibly and remain isolated from the current collector. This isolated lithium is trapped in the insulating remaining solid-electrolyte interphase (SEI) shell and contributes to the capacity loss. However, a fundamental understanding of why isolated lithium forms and how it can be mitigated is lacking. In this article, we perform a combined theoretical and experimental study to understand isolated lithium formation during stripping. We derive a thermodynamic consistent model of lithium dissolution and find that the interaction between lithium and SEI leads to locally preferred stripping and isolated lithium formation. Based on a cryogenic transmission electron microscopy (cryo TEM) setup, we reveal that these local effects are particularly pronounced at kinks of lithium whiskers. We find that lithium stripping can be heterogeneous both on a nanoscale and on a larger scale. Cryo TEM observations confirm our theoretical prediction that isolated lithium occurs less at higher stripping current densities. The origin of isolated lithium lies in local effects, such as heterogeneous SEI, stress fields, or the geometric shape of the deposits. We conclude that in order to mitigate isolated lithium, a uniform lithium morphology during plating and a homogeneous SEI are indispensable.

Synergistic Effect of CO2 in Accelerating the Galvanic Corrosion of Lithium/Sodium Anodes in Alkali Metal–Carbon Dioxide Batteries

“…These results demonstrate that the overall framework of the as-formed RIL structure is formed during the Li electrodissolution process, and its continuous growth during battery cycling could inevitably lead to the capacity decay of the Li–CO 2 cells. Previous studies , demonstrate that Li electrodissolution can be inhomogeneous due to the metallurgical factors of Li, SEI, and stripping current density. This nonuniform Li stripping process facilitates the formation of the porous RIL.…”

Overcoming Challenges: Extending Cycle Life of Aqueous Zinc‐Ion Batteries at High Zinc Utilization through a Synergistic Strategy

“…The primary determinant of the dissolution site priority is mainly due to localized factors, such as local stress fields or localized passivation products, resulting from nonuniform local effects. [13] The base-stripping of dendrites is a common phenomenon. [14] This may be due to the current density at the base is higher, resulting in a faster deposition rate at the base, which leads to the formation of smaller-diameter whiskers that are more prone to be broken.…”

Nucleation of Pitting and Evolution of Stripping on Lithium-Metal Anodes

“…Unlike the extensively studied Li deposition process, the number of studies for Li stripping is relatively small. , These studies focused on the morphology of Li after cycles and electrode polarization in the two-electrode system , and paid less attention to the early-stage stripping at the initial cycle. Nonuniform stripping will alter the surface roughness and lead to dendritic Li deposition, negatively impacting subsequent deposition/stripping cycles. ,,− Hence, it is critical to understand the mechanism of Li stripping and develop new strategies to facilitate uniform stripping.…”

“…In most of the morphology studies of Li deposition/stripping, optical microscopy (OM), ,, scanning electron microscopy (SEM), ,, and transmission electron microscopy ,, are widely used. Pei et al used OM to study the nucleation and growth of electrodeposited Li on the copper (Cu) current collector .…”