Germanium-Free Dense Lithium Superionic Conductor and Interface Re-Engineering for All-Solid-State Lithium Batteries...

Area of Science:

• Solid-state electrolytes
• Materials science
• Electrochemistry

Background:

• High cost of germanium (Ge) in Li10GeP2S12 (LGPS) hinders its economic viability.
• Conventional synthesis of solid electrolytes is time-consuming, energy-intensive, and requires inert environments.

Purpose of the Study:

• To develop a cost-effective silicon-based solid electrolyte (Li10SiP2S12, LSiPS).
• To optimize synthesis using microwave heating for reduced time and cost.
• To improve the interfacial stability in all-solid-state lithium-metal batteries.

Main Methods:

• Microwave (MW) heating for rapid synthesis of LSiPS.
• Ball milling and optimized heating profiles for synthesis.
• Interface modification using a gradient interlayer between Li anode and LSiPS.
• Fabrication and testing of all-solid-state lithium-metal batteries (ASSLIBs).

Main Results:

• Rapid synthesis of LSiPS in ~120 minutes without vacuum sealing or Ar-purging.
• Dense nanoflake morphology with finer crystallite size achieved via MW heating.
• High fraction (~89%) of the conductive tetragonal phase in LSiPS confirmed by NMR.
• Improved Li/LSiPS/Li symmetric cell performance: 1800 h at 0.2 mA/cm² and 500 h at 1.0 mA/cm².
• ASSLIBs demonstrated excellent cycling with ~110 mAh/g reversible capacity after 300 cycles.

Conclusions:

• LSiPS offers a cost-effective alternative to LGPS for solid-state batteries.
• Microwave-assisted synthesis significantly reduces production time and cost.
• Interface engineering is crucial for stable and high-performance solid-state lithium-metal batteries.