Lignin-Based Separators for Lithium-Ion Batteries via a Dry Fibrillation Method

Area of Science:

• Materials Science
• Electrochemistry
• Sustainable Chemistry

Background:

• Separators are vital in lithium-ion batteries (LIBs) for safety and performance.
• Current polyolefin separators have limitations like poor thermal stability and wettability.
• These limitations impact the safety and lifespan of LIBs, especially in electric vehicles.

Purpose of the Study:

• To develop a novel, single-layer ultrathin separator for LIBs using lignin.
• To evaluate the thermal stability and cycling performance of the lignin-based separator.
• To explore the potential of sustainable, bio-derived materials in advanced battery technologies.

Main Methods:

• Fabrication of a 15 µm single-layer separator from lignosulfonate via dry fibrillation.
• Assessment of intrinsic thermal stability and wettability.
• Electrochemical testing in graphite||NMC811 and Si-Gr||NMC811 cells to evaluate cycling performance.

Main Results:

• Demonstrated an ultrathin (15 µm) lignin-based separator with exceptional thermal stability.
• Achieved improved cycling performance in LIBs attributed to sulfonate groups promoting stable interfaces.
• The dry fibrillation method showed low energy consumption and high material conversion (100%).

Conclusions:

• Lignin-based separators offer a sustainable and high-performance alternative to conventional polyolefin separators.
• The abundant sulfonate groups enhance interfacial stability and reduce resistance in LIBs.
• This work provides inspiration for next-generation functional separators for high-performance LIBs.