PVDF Latex As a Binder for Positive Electrodes in Lithium-Ion Batteries

The present work shows a way to develop an industrial organic solvent-free process for lithium-ion battery electrodes manufacturing. The process uses a water-based slurry to cast the electrodes, using poly vinylidene-fluoride (PVDF) as a polymeric binder. The use of aqueous PVDF latex as a binder in positive electrodes is of difficult integration in existing production lines due to the low stability of lithium cobalt oxide (LiCoO2) in an aqueous environment. The use of electroless plating solves this issue by coating LiCoO2 particles with a copper-based layer stable to water. The presence of copper on the surface of the powders is confirmed by means of SEM, XRF and conductivity measurements of the powders. Electrochemical characterization of the electrodes has been carried out with cycling tests in coin cells, confirming the cycling stability during charge/discharge cycles. Cycling performances of the water-based cathodes containing coated active material particles are comparable to a reference NMP-based cathode, while uncoated particles show a sensibly lower capacity retention during cycling. The possibility of up-scaling the metallization process has been tested with the use of a semi-industrial pilot filter dryer.