Gelatin and Alginate Binders for Simplified Battery Recycling

Abstract

The water-soluble biopolymers, gelatin and sodium alginate, were investigated as potential alternative binders for use in lithium-ion battery anodes. The polymers were modified using a deep eutectic solvent (DES) made from choline chloride and glycerol. It was found that the addition of the DES resulted in greater plasticity and adhesion with respect to the unmodified binders and also to the current commonly used PVDF or CMC/SBR binders. Both the modified gelatin and sodium alginate binders are dispersible in water and can be rapidly delaminated by using mild ultrasound. These latter points are key steps in the function of the anode material and the subsequent recycling at the end of life. Imaging of the coatings formed using scanning electron microscopy and atomic force microscopy showed that the two types of binders dispersed themselves differently around the graphite particles, with the gelatin binder being distributed across the entire electrode surface, whereas the sodium alginate binder remained located at the hydrophilic edge planes of the graphite.