Quantification of the Dynamic Interface Evolution in High-Efficiency Working Li-Metal Batteries.

Area of Science:

• Battery Technology
• Materials Science
• Electrochemistry

Background:

• Lithium (Li) metal anodes are crucial for next-generation high-energy-density batteries.
• Low reversibility and lithium loss impede the practical application of Li metal batteries.

Purpose of the Study:

• To quantitatively analyze inactive lithium evolution during Li metal battery cycling.
• To understand the interplay between Li loss, electrolyte chemistry, and solid electrolyte interphase (SEI) structure.

Main Methods:

• Quantitative differentiation of inactive Li forms (dead Li⁰ and SEI Li⁺).
• Tuning SEI chemistry using film-forming additives to control inactive Li evolution.
• Investigating the role of electrolyte additives like 1,3-dioxolane.

Main Results:

• Inactive Li loss is determined by the relative growth rates of dead Li⁰ and SEI Li⁺.
• Tuning SEI chemistry with 1,3-dioxolane created a uniform multilayer SEI.
• The optimized SEI structure decreased dead Li⁰ and SEI Li⁺ growth rates.

Conclusions:

• Understanding and controlling inactive Li evolution is key to improving Li metal battery performance.
• Tailoring SEI chemistry via additives offers a viable strategy for enhancing Li cycling reversibility.
• The study provides fundamental insights into Li metal anode degradation mechanisms.