Effect of drying temperature on binder/current collector interfacial adhesion in electrode manufacturing of Li-ion batteries

Li-ion battery manufacturing process parameters are critical to the electrode properties and the final cell electrochemical performance. During the electrode drying process, the drying temperature plays a critical role on the binder migration, which affects the interfacial adhesion between the electrode and the current collector. However, the influence of the temperature on the properties of the binder material and the binder/current collector interface is yet unknown. In this work, we studied the effect of drying temperature on the interfacial adhesion between the binder and the current collector by direct coating of polyvinylidene fluoride (PVDF) solution on Al foil and then drying at various temperatures. The interfacial adhesion strength between the PVDF and the Al foil was significantly increased, from 9.72 N/m (dried at room temperature) to > 665.80 N/m (dried at 200 ℃) with increased temperature. DSC and XRD analyses showed the changes in the crystalline forms of PVDF under different drying temperature. This work revealed that the drying temperature during electrode manufacturing should be considered from the aspects of both binder migration in mid-stage and PVDF crystalline properties in late-stage solvent drying.