Silicon Composite Electrodes with Dynamic Ionic Bonding

Silicon (Si) composite electrodes are developed with increased cycle lifetimes and reliability through dynamic ionic bonding between active Si nanoparticles and a polymer binder. Amine groups are covalently attached to Si nanoparticles via surface functionalization. Si composite electrodes are fabricated by combining the Si nanoparticles with a poly(acrylic acid) (PAA) binder. The formation of ionic bonds between amine groups on Si particles and carboxylic acid groups on the PAA binder is characterized by X-ray photoelectron spectroscopy and Raman spectroscopy. Si composite anodes with ionic bonding demonstrate long term cycling stability with capacity retention of 80% at 400 cycles at a current density of 2.1 A g⁻¹ and good rate capability. The dynamic ionic bonds effectively mitigate the deterioration of electrical interfaces in the composite anodes as suggested by stable impedance over 300 cycles.