Stable LiF-Rich Electrode-Electrolyte Interface toward High-Voltage and High-Energy-Density Lithium Metal Solid...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-rich layered oxide (LRLO) materials offer high capacity but suffer from poor stability due to oxygen release during charging.
• Existing lithium metal batteries face challenges with voltage decay, cycle stability, and rate performance when using LRLO cathodes.

Purpose of the Study:

• To develop a novel quasi-solid-state electrolyte (QSSE) for lithium metal batteries utilizing LRLO materials.
• To address the stability and performance issues associated with LRLO materials in batteries.
• To investigate the formation and protective effects of a LiF-rich electrode-electrolyte interface (EEI).

Main Methods:

• Fabrication of a fluorinated QSSE using a simple thermal polymerization method.
• Electrochemical characterization including ionic conductivity, electrochemical stable window, rate performance, and cycling stability tests.
• X-ray photoelectron spectroscopy (XPS) analysis to investigate the composition and structure of the electrode-electrolyte interface (EEI).

Main Results:

• The developed QSSE demonstrated high ionic conductivity (6.4 × 10^-4 S cm^-1) and a wide electrochemical stable window (up to 5.6 V).
• XPS analysis confirmed the in situ generation of a LiF-rich EEI, which effectively protected the LRLO material from degradation.
• The LiF-rich EEI also promoted uniform lithium-ion plating/stripping, suppressing lithium dendrite formation.
• LRLO/QSSE/Li batteries achieved a high initial capacity (209.7 mA h g^-1) and excellent capacity retention (80.8% after 200 cycles at 0.5C).

Conclusions:

• The fluorinated QSSE effectively mitigates the issues of LRLO materials by forming a protective LiF-rich EEI.
• This LiF-rich EEI design is crucial for enhancing the safety and performance of quasi-solid-state lithium metal batteries.
• The study offers a promising strategy for developing high-performance and stable energy storage devices based on LRLO cathodes.