Root-inspired self-healing binder enabling robust micron-sized SiO electrodes with durable lithium storage stability

Abstract

Silicon monoxide (SiO) is highly attractive as an anode material for high-energy lithium-ion batteries (LIBs) due to its significantly higher specific capacity. However, its practical application is hindered by substantial volume expansion during cycling, which leads to material pulverization and an unstable solid electrolyte interphase (SEI) layer. Inspired by the natural root fixation in soil, we designed a root-like topological structure binder, cassava starch-citric acid (CS-CA), based on the synergistic action of covalent and hydrogen bonds. The abundant –OH and –COOH groups in CS-CA molecules effectively form hydrogen bonds with the –OH groups on the SiO surface, significantly enhancing the interfacial interaction between CS-CA and SiO. The root-like topological structure of CS-CA with a high tolerance alleviates the mechanical stress generated by the volume changes of SiO. More encouragingly, the hydrogen bond action among CS-CA molecules produces a self-healing effect, which is advantageous for repairing damaged electrodes and preserving their structural integrity. As such, the CS-CA/SiO electrode exhibits exceptional cycling performance (963.1 mA h g⁻¹ after 400 cycles at 2 A g⁻¹) and rate capability (558.9 mA h g⁻¹ at 5 A g⁻¹). This innovative, topologically interconnected, root-inspired binder will greatly advance the practical application of long-lasting micron-sized SiO anodes.