Porous core-shell B-doped silicon–carbon composites as electrode materials for lithium ion capacitors

Abstract

Development of anode materials of high capacities, rate capability, and cycling stability is critical for lithium ion capacitors (LICs). Composite electrode design, combining advantages of constituent component materials, is a promising approach for the purpose. Porous core-shell B-doped silicon-carbon spheres, B–Si@1RFC, of small sizes (150 nm) and high specific capacities are successfully synthesized with a one-pot method, followed by carbonization, magnesiothermic reduction, and B-doping, to be composited with reduced graphene oxide (rGO) porous structure of excellent structural and electrical properties to serve as an outstanding anode material, B–Si@1RFC/rGO, for LICs. The LIC, assembled by coupling the B–Si@1RFC/rGO anode with a glucose-derived carbon nanosphere cathode of ultrahigh specific surface areas (1947 cm2 g−1) and pore volumes (2.04 cm3 g−1), delivers a high energy density of 149 Wh kg−1 at a power density of 0.328 kW kg−1 and maintains a decent energy density of 82.1 kW kg−1 at a high power density of 49.3 kW kg−1, together with an excellent cycling stability of retaining 74.4% of the initial energy density after 10,000 cycle operations at 5 A g−1.