Composite electrolytes engineered by anion acceptors for boosted high-voltage solid-state lithium metal batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Solid-state batteries (SSBs) offer a safer alternative to conventional lithium-ion batteries by eliminating flammable liquid electrolytes.
• Improving the energy density and ionic conductivity of SSBs is crucial for their commercial viability.

Purpose of the Study:

• To develop a novel composite solid-state electrolyte with enhanced ionic conductivity and a wide voltage window.
• To investigate the mechanism by which anion acceptors improve electrolyte performance and stability.
• To demonstrate the potential of the new electrolyte in high-energy density SSBs.

Main Methods:

• Synthesis of a composite electrolyte (PLFB) incorporating tris(trimethylsilyl) borate (TMSB) as an anion acceptor within a PVDF-HFP-LLZTO-LiTFSI matrix.
• Electrochemical characterization, including ionic conductivity measurements and cyclic voltammetry.
• Analysis of electrolyte composition and properties using theoretical calculations and experimental techniques.
• Assembly and testing of a full SSB cell using a high-voltage cathode (LiNi0.8Co0.1Mn0.1O2) and lithium metal anode.

Main Results:

• The developed PLFB electrolyte exhibits excellent Li+ transference numbers (tLi+=0.92) at room temperature.
• The electrolyte demonstrates a wide voltage window suitable for high-voltage cathode coupling.
• The PLFB-based SSB shows high capacity retention (86% after 400 cycles) with a lithium metal anode.
• The addition of TMSB as an anion acceptor was found to stabilize the electrolyte interface and improve Li+ transport.

Conclusions:

• The incorporation of TMSB as an anion acceptor is an effective strategy to enhance the performance of solid-state electrolytes.
• The developed PLFB electrolyte facilitates dendrite-free interfaces and efficient Li+ transport, paving the way for safer, high-energy SSBs.
• This work offers new insights for designing advanced solid-state electrolytes for next-generation energy storage devices.