Immense Reduction in Interfacial Resistance between Sulfide Electrolyte and Positive Electrode

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Low interfacial resistance is crucial for all-solid-state Li batteries.
• The precise origin of interfacial resistance in sulfide electrolytes remains unclear.

Purpose of the Study:

• Quantitatively determine interfacial resistance in a model thin-film Li battery.
• Identify the root cause of high interfacial resistance.
• Investigate the efficacy of buffer layers in mitigating resistance.

Main Methods:

• Fabrication of a thin-film Li battery model with amorphous Li3PS4 solid electrolyte and LiCoO2 electrode.
• Measurement of interfacial resistance.
• Analysis of interfacial layer formation.
• Evaluation of Li3PO4 buffer layer impact.

Main Results:

• High interfacial resistance was observed at the electrolyte-electrode interface.
• Spontaneous formation of an interphase mixed layer was identified as the primary cause.
• A 10 nm Li3PO4 buffer layer drastically reduced interfacial resistance by 2800-fold.

Conclusions:

• The interfacial resistance in these solid-state Li batteries originates from an interphase mixed layer.
• Buffer layers, such as Li3PO4, are effective in suppressing interphase formation and lowering interfacial resistance.
• This provides a viable strategy for enhancing the performance of sulfide-based all-solid-state Li batteries.