Research into the manufacturing of LIB electrodes is constantly evolving with new active materials, improved binders, and improved drying techniques to more efficiently produce high-quality electrodes. However, the one constant in all these endeavors is that electrode research and manufacture still generally rely on a slurry-coating process, where large amounts of potentially toxic solvents are necessary for slurry production. As such, solvent-free, also known as dry-process (DP), electrode processing has been proposed to solve the conventional lithium-ion battery electrodes fabrication disadvantages, such as high equipment costs for solvent reclamation, currently seen in industry.

Currently, the solvent-free, state-of-the-art electrodes use polytetrafluoroethylene (PTFE) as a binder and the PTFE is fibrillized and dispersed in the dry powder mixture using a jet mill. One key solvent-free electrode shortcoming is that PTFE is not electrochemically stable for the anode, traditionally resulting in initial capacity losses of greater than 30% and poor mechanical strength, effectively limiting solvent-free processing to cathodes. A second shortcoming is that solvent-free electrodes generally require the addition of fibrillization promoters or processing steps that add cost and detract from performance by limiting active material content in the final electrodes.

In a recent development, Navitas and its internal partners of Cabot, Arkema, the University of Tennessee, Knoxville, and Oak Ridge National Laboratory have shown the capability to produce both solvent-free anodes and cathodes utilizing an advanced dry-electrode process (ADEP) that also enables high-throughput production of next generation battery electrodes. These electrodes have improved mechanical strength, sufficient to withstand roll-to-roll manufacturing, and the anodes demonstrate an initial capacity loss of less than 15%. The group has demonstrated roll-to-roll production of solvent-free electrodes at quasi-industry standard active material compositions (90-92%) without the reliance of previously used fibrillization promoters, even at reduced PTFE concentrations in the formulation. Navitas has recently demonstrated the large format lamination of the initially formed, or “free-standing,” electrodes after they have been produced in roll-to-roll manufacturing and the integration of solvent-free electrodes in dual-layer and multi-layer pouch cells using typical industry tooling and cell production techniques.

Key words: solvent-free, dry-process, fibrillization, next generation lithium-ion batteries (NGLB), advanced dry-electrode process (ADEP), initial capacity loss, free-standing, roll-to-roll, pouch cell