Solventless Stable Active Material Dispersions for High Performance Li-Ion Electrodes

摘要

We have developed an inexpensive original melt solventless extrusion process for the production of Li-ion cathodes and anodes of high energy density. This process consists in the following steps: First, active filler dispersions are obtained in the melt using a combination of a permanent binder at low content < 5wt% and an inexpensive commercial sacrificial binder. The dispersions are then cast on the current collector using a calendering process to yield 50-250 micrometer coatings. The sacrificial binder is then degraded thermally at high speed at low temperature below 250℃ to yield an electrode of tailored porosity possessing an improved adhesion to the collector compared to conventional PVDF solvent processed electrodes. Melt formulations were developed for several conventional Li-ion cathodes, namely LFP, NCA, NMC and conventional Li-ion anodes. A large range of loadings could be achieved, from 4 to 40 mg/cm2. Electrochemical performances in half cells will be presented, demonstrating high capacity and cyclability for high loadings, as well as the performances at high rates, up to 10 C. This process and its advantages regarding the associated facilities, throughput, dispersion stability and electrode performances will be detailed.