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

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, solidstate C-13 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 com 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.