Multipaths Li⁺ Migration and In Situ Interfacial Alloying of Composite Solid-State Electrolyte Enables...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Batteries

Background:

• Polyethylene oxide (PEO)-based electrolytes suffer from interfacial instability and lithium dendrite formation in all-solid-state lithium metal batteries (ASSLMBs).
• Addressing these challenges is crucial for the development of safer and higher-performance ASSLMBs.

Purpose of the Study:

• To develop a novel composite solid-state electrolyte (CPE) using porous BiF₃ nanoparticles within a PEO matrix.
• To enhance interfacial stability, ionic conductivity, and suppress lithium dendrites in ASSLMBs.

Main Methods:

• Synthesis of porous BiF₃ nanoparticles via a one-step precipitation method.
• Incorporation of BiF₃ into PEO to form a CPE.
• Density functional theory (DFT) calculations to understand Li⁺ transport mechanisms.
• Electrochemical testing of Li|Li symmetrical cells and Li|LFP/NCM811 full cells.

Main Results:

• BiF₃ nanoparticles promote lithium salt dissociation and provide channels for Li⁺ transport.
• In situ alloying reaction forms a stable Li_xBi/LiF composite solid electrolyte interphase (SEI), inhibiting dendrite growth.
• Li|Li symmetrical cells achieved stable cycling over 6000 hours at 0.1 mA cm^-2.
• Li|LFP and Li|NCM811 full cells demonstrated excellent electrochemical performance and stability across a wide temperature range.

Conclusions:

• The PEO-5%BiF₃ CPE exhibits enhanced interfacial stability and high ionic conductivity.
• The developed CPE effectively suppresses lithium dendrites, enabling long-term stable cycling.
• The material shows significant potential for practical applications in high-performance and safe ASSLMBs.