Low-cost and sustainable corn starch as a high-performance aqueous binder in silicon anodes via in situ cross-linking

Abstract

In situ cross-linked corn starch is used as a binder in silicon (Si) composite anodes for enhancing the cycling stability of lithium-ion batteries. The corn starch binder is in situ cross-linked by maleic anhydride during the fabrication of Si anodes. The cross-linking reaction of corn starch is investigated by infrared spectroscopy, solid-state 13C nuclear magnetic resonance spectroscopy and thermal gravimetric analysis. The results show that the hydroxy groups of corn starch react with maleic anhydride to form ester linkages, which eventually form a three-dimensional network structure. The cross-linked corn starch binder significantly enhances the adhesion of the Si/conductive carbon composite on the copper current collector. Peeling test experiments show that the adhesion force of the cross-linked corn starch binder is 4.9 times higher than that of the corn starch binder without cross-linking. Moreover, the cell performance tests show that the Si composite cathode with the cross-linked corn starch binder exhibits a high specific capacity of 3720 mAh g−1 and enhances cycle-life performance. This in situ cross-linking approach underscores the potential of corn starch, which is a low-cost and environmentally sustainable material, as a binder for the Si composite electrodes to improve its electrochemical performance.