Fast lithium-ionic conduction in a new complex hydride-sulphide crystalline phase

Area of Science:

• Materials Science
• Electrochemistry
• Solid-state Chemistry

Background:

• All-solid-state batteries (ASSBs) offer enhanced safety and energy density compared to conventional lithium-ion batteries.
• Development of solid electrolytes with high ionic conductivity, wide electrochemical stability, and good mechanical properties is crucial for practical ASSB applications.
• Existing solid electrolytes often face challenges related to conductivity, stability, or processability.

Purpose of the Study:

• To synthesize and characterize a new crystalline solid electrolyte material.
• To evaluate the electrochemical performance and stability of the new electrolyte.
• To demonstrate the feasibility of using this electrolyte in a functional all-solid-state battery.

Main Methods:

• Synthesis of a new crystalline phase from a 90LiBH4:10P2S5 mixture.
• Measurement of ionic conductivity at various temperatures.
• Assessment of thermal stability and electrochemical potential window.
• Fabrication and testing of a bulk-type all-solid-state TiS2/InLi battery.

Main Results:

• A new crystalline phase was successfully derived from the 90LiBH4:10P2S5 mixture.
• The material exhibits high lithium-ionic conductivity (log(σ/S cm(-1)) = -3.0 at 300 K).
• The electrolyte demonstrates stability up to 473 K, a wide potential window (0-5 V), and favorable mechanical properties.
• The TiS2/InLi ASSB incorporating this electrolyte showed repeated battery operation at 300 K.

Conclusions:

• The newly developed crystalline phase is a promising solid electrolyte material for all-solid-state batteries.
• Its high ionic conductivity, thermal stability, and electrochemical window make it suitable for practical battery applications.
• The successful demonstration in a TiS2/InLi battery highlights its potential for enabling safe and efficient energy storage solutions.