Compatible Interfaces Constructed by Surficial Indiumization on Garnet Solid Electrolyte for Long-Cycling...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Composite solid electrolytes (CSEs) using PVDF-HFP and LLZTO are promising for high-energy all-solid-state lithium metal batteries (ASSBs).
• A critical challenge is the Li2CO3 passivation layer on LLZTO, which hinders Li+ transport and degrades PVDF-HFP.
• This layer impedes ion transport at interfaces and causes dehydrofluorination of the polymer binder.

Purpose of the Study:

• To develop a method to stabilize the LLZTO surface and improve interfacial compatibility in CSEs.
• To enhance the performance and air stability of PVDF-HFP/LLZTO based composite solid electrolytes for ASSBs.

Main Methods:

• Surficial indiumization of LLZTO using lithium acetate, forming a LiInO2 (LIO) layer.
• Characterization of the modified LLZTO (LIO-LLZTO) and the resulting CSE (LIO-CSE).
• Electrochemical testing of Li|LIO-CSE|Li and Li|LIO-CSE|LiFePO4 cells.

Main Results:

• The 4 nm LIO layer effectively converted Li2CO3, preventing PVDF-HFP dehydrofluorination and improving air stability.
• The LIO-CSE exhibited enhanced ionic conductivity (3.1 × 10^-4 S cm^-1) and Li+ transference number (0.673).
• Li|LIO-CSE|Li cells showed stability for 3100 h, and Li/LIO-CSE/LiFePO4 cells retained 81.8% capacity after 1000 cycles.

Conclusions:

• Lithium acetate-assisted indiumization provides a robust strategy to stabilize LLZTO surfaces in CSEs.
• The modified CSE (LIO-CSE) demonstrates improved interfacial compatibility, ionic conductivity, and electrochemical performance.
• This approach offers a promising pathway for developing high-performance and stable all-solid-state lithium metal batteries.