In-situ cross-linked multifunctional polymer electrolyte buffer layers for high-performance garnet solid-state...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Batteries

Background:

• Garnet electrolytes like Li6.75La3Zr1.75Ta0.25O12 (LLZTO) offer high ionic conductivity and stability for solid-state batteries.
• Poor electrolyte/electrode interface contact in all-solid-state batteries (ASSBs) leads to increased interface impedance and limits performance.

Purpose of the Study:

• To develop an interface buffer layer to improve contact between LLZTO solid electrolytes and electrodes.
• To enhance the electrochemical performance and stability of garnet-based solid-state lithium metal batteries (SSLMBs).

Main Methods:

• An in-situ crosslinking strategy was used to form a multifunctional polymer electrolyte (MPE) buffer layer on the LLZTO surface.
• Electrochemical impedance spectroscopy, cyclic voltammetry, and battery cycling tests were performed to evaluate interface properties and cell performance.

Main Results:

• The MPE layer significantly reduced interface impedance to 103.4 Ω cm², increased critical current density to 1.2 mA cm⁻², and enabled 950 hours of stable cycling in Li symmetric cells.
• The MPE layer widened the electrochemical window to 5.2 V and facilitated uniform Li+ deposition/stripping, inhibiting dendrite growth.
• Full cells with LiFePO4 (LFP) and LiNi0.5Co0.2Mn0.3O2 (NCM523) cathodes demonstrated excellent capacity retention (87% after 200 cycles for LFP, 98% after 100 cycles for NCM523).

Conclusions:

• The MPE buffer layer effectively addresses the interface challenges in garnet-based SSLMBs.
• This approach provides a simple yet effective strategy for fabricating stable, high-performance solid-state lithium metal batteries.
• The improved interface contact and stability contribute to enhanced cycling life and safety in SSLMBs.