Multirole Integrated Filler Design for Polymer-in-Salt Electrolytes Enables Long-Life, Safe Solid-State Lithium...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Polymer-in-salt (PIS) electrolytes are crucial for solid-state lithium batteries, but face challenges like interfacial degradation and poor ionic conductivity-mechanics balance.
• Residual solvents and inherent material limitations hinder the practical application of PIS electrolytes in high-performance batteries.

Purpose of the Study:

• To develop a multi-role integrated filler strategy to overcome limitations in PIS electrolytes.
• To enhance interfacial stability, ionic conductivity, and mechanical properties of PIS membranes for solid-state batteries.

Main Methods:

• Incorporation of CaF2 filler into the PIS electrolyte to engineer defect chemistry and interfaces.
• Fabrication of ultra-thin PIS membranes using a roll-to-roll scalable method.
• Electrochemical testing of lithium symmetric cells and full cells with LiFePO4 or NCM811 cathodes.

Main Results:

• CaF2 filler promoted salt dissociation and ion-conducting sites via fluorine vacancy defects, enhancing ionic conductivity to 3.32 × 10^-4 S cm^-1.
• In situ generated LiF/Li-Ca interphase suppressed solvent decomposition and dendrite formation, enabling stable cycling for 1600 h in symmetric cells.
• Full cells demonstrated high-capacity retention over 1000 cycles, and CaF2's thermal stability improved pouch cell safety.

Conclusions:

• The single-component CaF2 filler strategy effectively addresses performance bottlenecks in polymer electrolytes.
• This approach offers a scalable and cost-effective pathway for developing practical solid-state lithium batteries.
• The integrated filler design significantly improves ionic conductivity, interfacial stability, and overall battery safety.