Supramolecular Polymer Ion Conductor with Weakened Li Ion Solvation Enables Room Temperature All-Solid-State Lithium...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• All-solid-state lithium metal batteries (ASSLMBs) require improved durability, interfacial stability, and room temperature performance.
• High interfacial resistance at the Li metal/electrolyte interface hinders ASSLMB cycling, particularly below 30°C.
• Simultaneously achieving desired properties in ASSLMBs remains a significant challenge.

Purpose of the Study:

• To develop a solid polymer electrolyte that mitigates interfacial resistance in ASSLMBs.
• To enable stable ASSLMB operation at reduced temperatures, approaching room temperature.
• To explore the application of halogen-bonding chemistry in solid polymer electrolytes for lithium-ion transport.

Main Methods:

• Synthesis of a supramolecular polymer ion conductor (SPC) utilizing halogen-bonding interactions.
• Incorporation of 1,4-diiodotetrafluorobenzene and ethylene oxide moieties to create "weak solvation" for Li+ ions.
• Characterization of the SPC's ionic conductivity, Li+ transference number, and interfacial properties with lithium metal.

Main Results:

• The SPC exhibits weakened O-Li+ coordination due to halogen bonding, facilitating rapid Li+ transport and a high transference number.
• A unique Li2O-rich solid electrolyte interphase (SEI) forms on the lithium metal surface, significantly lowering interfacial resistance.
• Stable ASSLMB cycling is achieved down to 10°C, demonstrating enhanced performance at reduced temperatures.

Conclusions:

• The developed SPC effectively addresses the interfacial resistance challenge in ASSLMBs.
• Weak Li+ solvation, achieved through halogen bonding, is crucial for high performance solid polymer electrolytes at room temperature.
• This work highlights the potential of halogen-bonding chemistry for designing advanced solid-state electrolytes for next-generation batteries.