Electrochemical Atomic Force Microscopy Study on the Dynamic Evolution of Lithium Deposition

Abstract

Lithium metal is one of the most promising anode materials for lithium-ion batteries; however, lithium dendrite growth hinders its large-scale development. So far, the dendrite formation mechanism is unclear. Herein, the dynamic evolution of lithium deposition in etheryl-based and ethylene carbonate (EC)-based electrolytes was obtained by combining an in situ electrochemical atomic force microscope (EC-AFM) with an electrochemical workstation. Three growth modes of lithium particles are proposed: preferential, merged, and independent growth. In addition, a lithium deposition schematic is proposed to clearly describe the morphological changes in lithium deposition. This schematic shows the process of lithium deposition, thus providing a theoretical basis for solving the problem of lithium dendrite growth.

Nanoscale characterization of the solid electrolyte interphase and lithium growth by atomic force microscopy

“…For example, Kelvin probe force microscope (KPFM) mode is widely used to measure the work function or surface potential of the sample. [70][71][72] Shi et al 73 used KPFM to distinguish the surface properties of SEI at the top and edge in deposited Li particles. In addition, the PeakForce TUNA mode utilizes the quantum tunneling effect to measure the electrical conductivity of the sample.…”

“…(A) In situ AFM testing of lithium metal growth process. 73 (B) Correlation between particle size and density of lithium metal deposited over time using varying concentrations of electrolyte. 87 (C) The growth behavior of lithium metal is limited by SEI.…”

“…87 (C) The growth behavior of lithium metal is limited by SEI. 42 (A) Adapted with permission from Shi et al, 73 Copyright 2023, Licensee MDPI. (B) Adapted with permission from Wang et al, 87 Copyright 2022, American Chemical Society.…”

“…Shi et al 73 used AFM to summarize the lithium metal growth modes into three categories: (1) preferential growth, where one particle's growth inhibits surrounding particles' simultaneous growth (Figure 7A, blue box); (2) merged growth, where several particles combine to form a larger particle (Figure 7A, green box); and (3) independent growth (Figure 7A, yellow box). They also observed that almost all lithium particles followed a unique pattern: during initial growth, the longitudinal and transverse growth rates were comparable, but over time, the transverse growth rate slowed down, leading to a shift in depositional morphology from hemispherical to cylindrical.…”

“…Growth behavior of lithium metal evaluated by AFM. (A) In situ AFM testing of lithium metal growth process 73 . (B) Correlation between particle size and density of lithium metal deposited over time using varying concentrations of electrolyte 87 .…”