An Amphiphilic Molecule Induced Anion-Enrichment Interface for Next-Generation Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Robust electrode/electrolyte interphases are critical for stable lithium (Li) metal batteries (LMBs).
• Current electrolytes often face challenges in achieving long-term electrochemical stability.
• Anion-enrichment interfacial design is a promising strategy for enhancing LMB performance.

Purpose of the Study:

• To investigate the use of an amphiphilic molecule, nonafluoro-1-butanesulfonate (NFSA), for electrolyte engineering in LMBs.
• To elucidate the functions of NFSA in the electrolyte and at the anode/electrolyte interphase.
• To demonstrate the improved electrochemical performance and stability of LMBs using NFSA-modified electrolytes.

Main Methods:

• Electrolyte modification using the amphiphilic molecule nonafluoro-1-butanesulfonate (NFSA).
• Theoretical and experimental analyses of electrolyte and interphase properties.
• Electrochemical testing of Li||Cu, Li||Li, and Li||LiFePO4 full cells under various conditions.

Main Results:

• NFSA creates a stable interphase enriched with anion-derived inorganic compositions on the Li electrode.
• Li||Cu cells demonstrated stable operation for over 200 cycles with low irreversible capacity loss (2.4 mAh cm⁻²).
• Li||Li cells showed extended cycle life (>1500 h) with minimal overpotential (36.5 mV).
• Full cells with LiFePO4 cathodes maintained over 80% capacity after 500 cycles under demanding conditions (limited Li, high loading, lean electrolyte).

Conclusions:

• NFSA acts as an effective electrolyte additive for fabricating robust electrode/electrolyte interphases in LMBs.
• The anion-enrichment strategy significantly enhances the electrochemical stability and cycle life of Li metal anodes.
• The developed electrolyte enables high-performance full cells, even under challenging operational parameters, paving the way for practical LMBs.