Glyoxalated polyacrylamide as a covalently attachable and rapidly cross-linkable binder for Si electrode in lithium ion batteries

Abstract

Recently, investigation of Si-based anode materials for rechargeable battery applications garnered much interest due to its exceptionally high capacity. High-capacity Si anode (~4,200 mAhg⁻¹) is highly desirable for the replacement of conventional graphite anode (< 400 mAhg⁻¹) for large-scale energy-storage applications such as in electric vehicles (EVs) and energy storage systems (ESSs) for renewable energy sources. However, Si-based anodes suffer from poor cycling stability due to their large volumetric changes during repeated Li insertion. Therefore, development of highly efficient binder materials that can suppress the volume change of Si is one of the most essential parts of improving the performance of batteries. We herein demonstrate highly cross-linked polymeric binder (glyoxalated polyacrylamide) with an enhanced mechanical property by applying wet-strengthening chemistry used in paper industry. We found that the degree of cross-linking can be systematically adjusted by controlling the acidity of the slurry and has a profound effect on the cell performance using Si anode. The enhanced cycle performance of Si nanoparticles obtained by treating the binder at pH 4 can be explained by its strong interaction between the binder and Si surface and current collector, and also rigidity of binder by cross-linking.