Rational Design of a Cross-Linked Composite Solid Electrolyte for Li-Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Solid-state electrolytes (SSEs) face challenges with interfacial issues in solid-solid contact.
• Developing stable and conductive SSEs is crucial for advanced battery technologies.

Purpose of the Study:

• To create a cross-linked composite solid electrolyte (CSE) by integrating Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP) into a poly(vinylene carbonate) (PVCA) and ethoxylated trimethylolpropane triacrylate (ETPTA) matrix.
• To investigate the electrochemical properties and interfacial behavior of the novel PEL electrolyte for all-solid-state batteries.

Main Methods:

• In situ thermal polymerization was used to synthesize the poly(vinylene carbonate) (PVCA)─ethoxylated trimethylolpropane triacrylate (ETPTA)─Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP) (PEL) composite solid electrolyte.
• Electrochemical characterization, including ionic conductivity, Li⁺ transference number, and electrochemical stability window measurements, was performed.
• All-solid-state coin cells (NCM622|PEL|Li) were assembled and tested for cycling performance.

Main Results:

• The PEL electrolyte exhibited significantly enhanced ionic conductivity (1.011 × 10^-4 S cm^-1) and a Li⁺ transference number (t_Li⁺) of 0.451 due to LAGP incorporation.
• An improved electrochemical stable window of 4.68 V was achieved.
• The assembled NCM622|PEL|Li coin cell demonstrated a low interfacial resistance, an initial discharge capacity of 169.7 mA h g^-1, and 70% capacity retention over 100 cycles at 0.2 C.

Conclusions:

• The developed cross-linked composite solid electrolyte (PEL) effectively addresses interfacial challenges in solid-state batteries.
• The enhanced electrochemical properties and cycling stability make PEL a promising candidate for high-performance and safe all-solid-state lithium-ion batteries.