Electrosprayed silicon-embedded porous carbon microspheres as lithium-ion battery anodes with exceptional rate capacities

Silicon-embedded porous carbon microspheres with an exceptional conductive framework for ions and electrons were obtained by electrospraying a mixed polymer solution of polystyrene and polyvinylpyrrolidone, containing silicon nanoparticles, carbon nanotubes and carbon blacks, and subsequent heat treatment. In the composite microspheres, silicon particles were embedded in the porous carbon framework composed of interwoven carbon nanotubes, filled carbon blacks and interconnected amorphous carbon derived from polymers. The cage-like porous carbon microspheres could not only accommodate the volume expansion of silicon but also ensure a robust electrical contact, fast transport for electrons and ions. Therefore, the silicon/carbon anode exhibits a high capacity of 1325 mAh g ⁻¹ at 0.2 A g ⁻¹ after 60 cycles and superior rate capability with a capacity of 925 mAh g ⁻¹ at a large current density of 5 A g ⁻¹.