Biopolymer Binders for Low‐Temperature Operation of TiNb2O7 Anode in Li‐Ion Batteries

Abstract

The widespread use of lithium‐ion batteries underlines the criticality of a more sustainable cell fabrication. Here, three biopolymers gelatin, pectin, and deoxyribonucleic acid (DNA) are investigated as binders for the TiNb2O7 anode material in Li cells in a temperature range between 0 and 60 ºC and compared to conventional binder polyvinylidene fluoride (PVDF). The use of biopolymers is motivated by their own environmental friendliness and the possibility to implement an aqueous electrode processing. A specific charge capacity of at least 200 mAh g−1 is found for all binders at 0 °C when testing the cycling performance of TiNb2O7 at 77.5 mA g−1 (1C rate). However, low‐rate cycling at 60 °C shows decreasing capacity for all biopolymers due to the swelling effect and continuous contact loss to the current collector, what also reflects in lowering the overall Li‐diffusion coefficient. This effect becomes less pronounced at 0 °C and high current densities, making biopolymers competitive with commercial PVDF. The electrodes with DNA binder demonstrate overall the most stable performance, arising from the biopolymer intactness and a thin solid–electrolyte interface layer. At 0 °C, the electrode with DNA provides 150 mAh g−1 at 775 mA g−1 for at least 500 discharge–charge cycles.