Graphene interleaved SiOx/C spheres Via molecular polymerization as high-stability lithium-ion battery anodes

Abstract

SiOx/carbon composite materials are a promising candidate for lithium-ion battery anodes because of their high capacity. However, their widespread application is hindered by poor electrical conductivity, and stability due to the volume expansion during cycling. Herein, electrodes comprised of spherical carbon-coated silicon oxide particles, interleaved between electrochemically exfoliated graphene, were prepared via molecular polymerization followed by physical mixing. The spherical silicon oxide was obtained by the carbonization of the reaction product between dialdehyde and (3-aminopropyl) trimethoxysilane. The interleaved graphene flakes both provided electrically conductive pathways between particles and formed a porous supporting structure between the silicon oxide particles and the graphene flakes, enabling a buffering for the volume expansion. A range of SiOx/C-G anodes are obtained by adjusting the content of graphene. The assembled batteries with an optimal graphene ratio (SiOx/C: G = 2:1 (w/w)) exhibit superior Li-ion storage behavior, including high cycle stability, with capacity retention of 88.6 % and high coulombic efficiency of 99 % after 250 cycles under 0.1 A·g−1. Promisingly, it was verified that with the support from the outer robust graphene layer and the porous support structure, the volume expansion of silicon oxide particles during lithiation/delithiation processes was suppressed, leading to a more stable solid electrolyte interface (SEI) layer.