Tuning the mechanical and electrochemical properties of NMC622 dry electrodes via the incorporation of fluorine free co-binders to dry fibrillation processing

Dry electrode manufacturing is a solvent-free process for preparing battery electrodes, eliminating the need for costly drying stages, solvent recovery systems and electrode thickness limitations associated with traditional slurry-cast electrodes. To date, much of the progress and research surrounding dry processing is based on a PTFE binder owing to its near-unique ability to deform and generate thin polymer fibrils under moderate temperature and applied shear. This polymer fibrillation technique is ubiquitous in dry manufacturing, particularly for continuous roll-to-roll manufacturing processes. PTFE, a fluoropolymer, likely to be subject to upcoming environmental regulations for fluoropolymer and PFAS-related materials. Here, we investigate alternative fluorine-free binder candidates in conjunction with reduced quantities of PTFE. Using these fluorine-free co-binders, we show that it is possible to reduce overall PTFE content (up to 75%) while maintaining the mechanical processability of the electrode. We demonstrate how the different microstructures of the electrodes, generated from the particle interactions during mixing, contribute to the bulk properties of the electrode with the ability to tune the mechanical properties of electrodes through informed choice of fluorine-free co-binders. These results constitute major steps towards lowering the reliance of dry electrode fibrillation on PTFE, significantly mitigating potential environmental impacts of dry electrode manufacturing.