Temporal Evolution of Lithium Metal Microstructures During Ultra-High-Capacity Stripping/Plating Cycles.

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• The morphology of deposited lithium (Li) is crucial for the stability and reversibility of lithium-metal batteries (LMBs).
• Crystallographic features influence Li deposition morphology, but crystal orientation and evolution under varying conditions are not fully understood.

Purpose of the Study:

• To investigate the microstructural evolution of Li during electrodeposition at ultra-high capacities and over repeated cycling.
• To elucidate the relationship between interphasial properties, deposition kinetics, and Li microstructure in LMBs.

Main Methods:

• Utilized scanning electron microscopy (SEM) for high-resolution imaging of Li microstructures.
• Employed electron backscatter diffraction (EBSD) to analyze crystallographic orientation and grain structure.
• Studied Li electrodeposition at capacities up to 12 mAh cm⁻² and during extended cycling.

Main Results:

• Layer-by-layer epitaxial Li growth with coherent lattice orientation occurs under homogeneous interphase and slow kinetics.
• Deterioration of interphase homogeneity at high capacities or extended cycling leads to island-like deposits with random grain orientation.
• Inhomogeneous interphase and faster kinetics promote whisker-like Li deposits.

Conclusions:

• Maintaining interphase homogeneity and stability is essential for coherent lattice matching and layer-by-layer epitaxial Li growth.
• Cohesive interactions can lead to isolated single-crystalline grains, but interphase control is key for uniform deposition.
• Insights gained can guide the design of stable interphases and optimize conditions for durable, high-capacity LMBs.