Solvent-free additive manufacturing of electrodes for Li-ion batteries

A new Li-ion battery electrode manufacturing process using a solvent free additive manufacturing method has been developed. Li-ion battery electrodes consist of active material particles, a binder additive, and a conductive additive. Traditionally, Li-ion battery electrodes are manufacturing using the slurry casting technique. In this method, the electrode materials are mixed with a solvent to create a slurry. Electrodes fabricated in this method are readily implemented for small platforms, such as portable electronics. However, this method isn\u27t as economically viable in large platforms due to high material and manufacturing costs. High material and manufacturing costs are mostly attributed to the use of organic solvents, typically N-methyl-pyrrolidone, to dissolve the binder additive. A drying line is needed to evaporate the solvent from the electrode layer and an expensive recovery system is needed to collect the evaporated solvent. In total, the use of NMP attributes ~14.5% to the overall Li-ion battery cell costs. The solvent-free manufacturing method has been developed to eliminate these problems. In this method, the electrode materials are dry mixed and directly deposited on to the current collector. Therefore, uniform distribution of the electrode particles during the mixing process is the driving factor for the solvent-free additive manufactured batteries. The distribution of dry electrode materials was studied through experimental mixing studies, mixing models, and mixing simulations to better understand how the electrode material\u27s surface properties effect the final distribution of electrode particles. Afterwards, Li-ion batteries were assembled with solvent-free manufactured electrodes and compared to slurry-cast electrodes with similar specifications --Abstract, page iv