Electrolyte-Dependent Pressure Sensitivity Governs Lithium Deposition Stability in Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Mechanical Engineering

Background:

• Stack pressure is a known method for controlling lithium deposition in lithium metal batteries.
• The influence of electrolytes on stack pressure's effectiveness and the underlying mechanisms are not fully understood.

Purpose of the Study:

• To systematically investigate how stack pressure affects lithium deposition across various electrolytes.
• To elucidate the mechanisms behind the electrolyte-dependent pressure sensitivity of lithium deposition.

Main Methods:

• Systematic investigation of Li deposition under pressure across diverse electrolytes.
• Electrochemical-mechanical modeling to analyze stress distribution and Li redistribution.
• Development of a quantitative pressure sensitivity descriptor for anode-free pouch cells.

Main Results:

• Pressure sensitivity of Li deposition is linked to the morphology of early-stage Li growth.
• Porous, filamentary Li structures show high pressure responsiveness; bulk-like Li structures exhibit stable cycling.
• Dendritic Li morphologies cause stress concentration and creep-driven redistribution, unlike homogeneous stress in bulk deposits.

Conclusions:

• Stack pressure's impact on Li deposition is critically dependent on the electrolyte and resulting Li morphology.
• Optimal stack pressures can be identified based on electrolyte-specific properties.
• Findings provide mechanistic insights and engineering guidelines for designing stable lithium metal batteries using stack pressure.