Chemical fixation of CO2 on activated Si: Producing graphitic carbon-stabilized Si particles for Li-storage

Abstract

Converting CO2 into enhanced Li-storage materials is significant for meeting the challenges of both ever-increasing greenhouse gas and unsatisfactory energy-density of Li-ion battery. Here, a novel silicothermic reaction is developed for reduction of CO2 with Ni-activated Si into graphitic carbon (GC) in autoclave, producing well-dispersed GC-Si composites (SGC). To realize the reaction, Ni crystals are pre-anchored on Si surface, which is demonstrated for not only lowering the reaction temperature by enhancing the absorption of CO2, and suppressing the formation of inert SiC, but also facilitating the graphitization of generated carbon. Analysis of the kinetic process and cycling stability confirm the SGC electrode exhibits better Li-ion storage performance than Si electrode in term of electron/ion diffusion, the mechanical integrity and chemically stability of the solid electrolyte interphase, retaining a capacity of 845.3 ​mA ​h ​g−1 after 380 cycles at 2.0 ​A ​g−1. The full cell consisted of a SGC-graphite-blend anode and LiCoO2 cathode is also assembled and investigated.