Lignin-Based Separators for Lithium-Ion Batteries

Executive Summary

Lithium ion batteries are currently ubiquitous in numerous applications. In these batteries, the separator plays a crucial role by physically separating the anode and cathode to prevent electrical short circuits while allowing the flow of ions through the electrolytes. Common materials used for separators include polyolefins such as polypropylene (PP) and polyethylene (PE), both derived from fossil fuels. However, despite their widespread use, PP and PE separators face challenges related to thermal stability and environmental sustainability. Researchers at Michigan State University have recently developed a new separator based on lignin, a sustainable material derived from wood. The separator provides superior thermal stability, enhanced safety, improved mechanical strength and is eco-friendly.

Description of the Technology

The technology involves lignosulfonate-based separator formulated with polymer binders and manufactured by a dry fibrillation process. Separators down to 15 microns have been produced with outstanding performance as tested in graphite||NCM811 or Si-Gr||NCM811 cells. Extensive coin cell testing has been conducted and compared to benchmark Celguard^TM 2325. Mechanical properties, thermal stability and electrochemical testing up to 400 cycles have been done.

Benefits

Simple, low cost, scalable manufacturing
Uses renewable materials
Exceptional thermal stability with low shrinkage, up to 300^oC, thus providing improved battery safety
Increased cycle life by 60% compared to benchmark Celguard^TM 2325.

Applications