How much Li is needed for anode in Li metal battery?

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Battery life in Li metal batteries is commonly linked to Li quantity.
• Lower N/P ratios often indicate harsher conditions and shorter lifespans due to Li consumption.
• Factors like solid electrolyte interphase (SEI) growth and electrolyte depletion complicate failure mechanisms, hindering optimal Li anode guidelines.

Purpose of the Study:

• To investigate the relationship between Li anode thickness, SEI evolution, and electrochemical performance in Li metal batteries.
• To elucidate the finite nature of fresh Li consumption and its impact on battery failure.
• To establish a correlation between Li consumption and SEI growth for improved battery design.

Main Methods:

• Utilized Li||nickel-cobalt-manganese (NCM811) cells with ester-based electrolytes.
• Tracked the cycling-dependent evolution of Li metal anodes with varying thicknesses.
• Monitored the concurrent development of the solid electrolyte interphase (SEI) and electrochemical performance.

Main Results:

• Fresh Li consumption is finite, ceasing upon Li depletion or inadequate electrolyte wetting of the Li/SEI interface.
• This cessation marks a critical point, leading to rapid capacity decline due to Li unavailability.
• A direct correlation was observed between fresh Li consumption and SEI growth.

Conclusions:

• Understanding the finite nature of Li consumption is crucial for Li metal battery longevity.
• The interplay between Li depletion, electrolyte wetting, and SEI growth dictates battery failure.
• Findings provide insights for developing strategies to enhance long-term cycling stability in Li metal batteries.