Pseudo-ternary LiBH₄·LiCl·P₂S₅ system as structurally disordered bulk electrolyte for all-solid-state lithium...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• All-solid-state batteries (ASSBs) require advanced electrolytes for improved safety and energy density.
• Lithium borohydride (LiBH4) and phosphorus pentasulfide (P2S5) based materials are explored for ionic conductivity.

Purpose of the Study:

• To investigate the properties of the mixed system LiBH4-LiCl-P2S5 as a potential solid-state electrolyte.
• To characterize its ionic conductivity, structural behavior, and electrochemical stability.
• To evaluate its performance in a functional all-solid-state battery cell.

Main Methods:

• Amorphization by heating above 60 °C.
• Ionic conductivity measurements.
• Structural analysis and characterization.
• Electrochemical stability window determination.
• Battery cell testing with Li anode and TiS2 cathode.
• Operando synchrotron X-ray diffraction.

Main Results:

• The LiBH4-LiCl-P2S5 system amorphizes upon heating, significantly increasing Li+ conductivity to ~10^-3 S cm^-1 at room temperature.
• The amorphous phase exhibits an activation energy of 0.40(2) eV.
• The material demonstrates good electrochemical stability up to 5 V (vs. Li+/Li) and ductility.
• Battery cells using this electrolyte achieved 93% capacity retention over 10 cycles at 50 °C.
• Operando XRD provided insights into the (de)lithiation mechanisms.

Conclusions:

• The amorphized LiBH4-LiCl-P2S5 system is a promising solid-state electrolyte for ASSBs.
• Its combination of ionic conductivity, electrochemical stability, and mechanical properties is advantageous.
• Further research can optimize this material for high-performance energy storage applications.