Today, lithium-ion battery production technology is based on a wet electrode manufacturing process. The electrodes’ constituent materials, the active material, an electron conductive material and a polymeric binding material, are mixed together with the use of organic solvents or water in order to create a slurry. The role of the solvent is to relax and extend the polymer chains in order to encompass the active material and electron conductive particles into a mechanically stable matrix. One significant disadvantage of the wet processing is the enormous amounts of energy needed in order to remove the solvent or water once the slurry is applied on the current collectors. During the last years, a lot of research has been focused on the development of methods based on dry processing for lithium-ion battery electrode preparation. In this way, not only are energy consuming steps avoided, but also the use of toxic organic solvents is prevented.
In this work, a novel method for dry anode preparation is presented. The binder properties are of vital importance for the processability of the mix of materials that form the electrode. Therefore, the aim of the current study, is to determine the process parameters concerning different binding materials. Polyethylene oxide (PEO) with a molecular weight 100 kg mol-1, is a polymeric compound that has a low crystal melting temperature of around 60 oC and becomes viscous bellow 100 oC, making it an ideal candidate for dry processing, in comparison to commonly used Carboxymethyl cellulose (CMC) and Polyvinylidene fluoride (PVDF). In order to achieve optimal adhesion of the material, a PEO/carbon black rich mixture is initially precoated onto the copper current collector and then, the active material rich mixture is pressed on the precoated layer. By this procedure, precoating ensures a mechanical as well as an electric connection to the current collector while, at the same time, it provides a surface for the active material to attach and merge.