A sandwich-like porous hard carbon/graphene hybrid derived from rapeseed shuck for high-performance lithium-ion batteries

Abstract

Hard carbon becomes a candidate for anode materials due to its rich resources and abundant lithium storage sites. However, amorphous carbon with poor stability and electronic conductivity limits its electrochemical performance. In response, this work synthesizes a sandwich-like porous hard carbon/graphene hybrid (HC/G) with graphene sandwiching the hard carbon via a KOH-assisted one-step pyrolysis process from rapeseed shuck. The highly ordered graphene layers constitute conductive multi-dimensional paths for fast electronic transport and supply sufficient electrons for redox reactions. Moreover, the sandwiching graphene layers provide mechanical support, which effectively adapts volume change to stabilize the whole structure. The porous hard carbon with numerous defects and CO groups could provide more adsorption sites and redox reactions for lithium storage. When serving as anode material, HC/G displays a stable lithium storage capacity of 623 mAhg−1 at a current density of 100 mAg−1 after 500 cycles, and exhibits a superior rate performance that of 381 and 308 mAhg−1 even at a higher rate of 2000 and 5000 mAg−1, respectively. This work sheds a light on the high-value use of waste rapeseed shuck for eco-friendly and low cost lithium-ion batteries anode material.