Temperature Dependence of Lithium Anode Voiding in Argyrodite Solid-State Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Batteries

Background:

• Void formation at the lithium (Li)/ceramic electrolyte interface in all-solid-state batteries leads to high local current densities, dendrite growth, and eventual cell failure during operation.
• Understanding and mitigating these interfacial issues are crucial for the development of safe and high-performance solid-state batteries.

Purpose of the Study:

• To investigate the effect of temperature and stack pressure on void formation at the Li/Li₆PS₅Cl interface.
• To determine the critical current densities for stable cycling under varying conditions.
• To analyze the influence of pressure and temperature on the interfacial charge-transfer resistance.

Main Methods:

• Electrochemical cycling of Li/Li₆PS₅Cl solid-state battery interfaces.
• Systematic variation of temperature (25 °C to 80 °C) and stack pressure (1 MPa to 5 MPa).
• Measurement of critical current densities before voiding and cell failure.
• Analysis of interfacial charge-transfer resistance as a function of pressure and temperature.

Main Results:

• Void formation at the Li/Li₆PS₅Cl interface is reduced at elevated temperatures, increasing the critical current density from <0.25 mA cm^-2 at 25 °C to 0.5 mA cm^-2 at 80 °C (at 1 MPa).
• Increasing stack pressure to 5 MPa and temperature to 80 °C enables stable cycling at significantly higher current densities (2.5 mA cm^-2).
• Interfacial charge-transfer resistance is dependent on both pressure and temperature, requiring higher pressures at low temperatures (-20 °C) for low resistance.

Conclusions:

• The plastic deformation of Li metal significantly influences the performance of Li anodes in solid-state cells.
• Optimizing temperature and stack pressure is critical for suppressing interfacial voiding and achieving high-performance solid-state batteries.
• Challenges remain in implementing Li metal anodes due to their mechanical behavior under operational conditions.