Stabilization of Garnet/Liquid Electrolyte Interface Using Superbase Additives for Hybrid Li Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Batteries

Background:

• Solid-electrolyte/electrode interface compatibility is crucial for battery performance.
• Hybrid electrolytes, incorporating liquid electrolyte into solid-state systems, offer a potential solution.
• Garnet-based solid electrolytes like Li7La3Zr1.5Ta0.5O12 (LLZT) are promising but face interfacial challenges.

Purpose of the Study:

• To investigate the effect of n-butyllithium (n-BuLi) on the performance of LiFePO4/Li hybrid cells.
• To improve the solid-electrolyte/electrode interface stability in garnet-based solid-state batteries.
• To understand the mechanisms by which n-BuLi enhances battery cycling performance.

Main Methods:

• Fabrication of LiFePO4/Li hybrid cells using LLZT solid electrolyte and conventional carbonate-based liquid electrolyte.
• Addition of a small amount of n-BuLi to the hybrid electrolyte system.
• Electrochemical cycling of the modified cells at room temperature with current densities of 100 and 200 μA cm⁻² for up to 400 cycles.

Main Results:

• The modified hybrid cells demonstrated significantly improved cycling performance compared to unmodified cells.
• The cells achieved excellent solid/liquid electrolyte interface stability, enduring 400 cycles.
• n-BuLi addition led to enhanced interfacial lithium-ion transport and suppressed undesirable side reactions.

Conclusions:

• n-Butyllithium is an effective additive for improving the interfacial compatibility and cycling stability of garnet-based hybrid solid-state batteries.
• The proposed hybrid electrolyte concept with n-BuLi shows great promise for next-generation lithium-ion batteries.
• n-BuLi's multi-faceted role includes retarding liquid electrolyte decomposition, suppressing ion exchange, and passivating the interface for better performance.