Design principles for LiFePO4 electrodes with improved recyclability

Abstract

To improve sustainability of lithium-ion battery electrodes there is a need to design in recycling at the manufacturing stage. In this work, a method to improve LiFePO₄ recovery rates through binder and electrode microstructure design is presented. Electrodes are produced by tape cast and direct ink writing methods with biopolymer, aqueous binder systems: carboxy-methyl cellulose with styrene butene rubber, or sodium alginate, with and without a secondary solvent rheology modifier, octanol. The recovery rate of the active material is measured after a short low power ultrasound delamination process, performed in water. Electrodes which exhibit good wettability, as observed through low contact angles, and low tortuosity, delaminate faster with higher recovery rates. Improvements from 2% to 60% black mass recovery is observed with CMC-SBR electrodes with the addition of octanol in the electrode inks, and from 79% to 86% in direct-ink printed compared to tape cast electrodes when using alginate binders. These results highlight the importance of electrode design in the circular manufacturing and recycling of LIBs and lay the groundwork for future research into new design principles for printed electrodes.