Search

Abstract Nanostructured Fe 3 O 4 , as a typical transition metal oxide material, has been widely used as high capacity anode in lithium ion batteries (LIBs). In order to further exerting its Li storage capacity, herein, we reported a rationally designed dual carbon shells coated Fe 3 O 4 nanoparticle (NP) superlattices with mesoporous carbon (MC) and N-doped carbon (NC) as the dual shells. The inner mesoporous carbon shell could effectively buffer the volume change and promote the conductivity of Fe 3 O 4 NP superlattices, and the outside N-doped carbon shell can ease the structure pulverization. N-doped carbon@mesoporous carbon@Fe 3 O 4 NP superlattices (NC@MC@Fe 3 O 4 NP superlattice) showed superior electrochemical performance, including high specific capacity (838 mAh/g at 0.5 A/g after 150 cycles), unique rate capacity (322 mAh/g at 5 A/g) and ultrahigh cycling capacity (576 mAh/g at 2 A/g after 500 cycles). Highlights • Dual carbon layers coating Fe 3 O 4 nanoparticle superlattices. • N-doped carbon layer and mesoporous carbon layer was prepared by one facile step reaction. • NC@MC@Fe 3 O 4 nanoparticle superlattices show high specific capacity and rate performance. [ABSTRACT FROM AUTHOR]

Silicon is a potential next generation anode material for lithium-ion battery, however, its commercial application was hindered by its poor electronic conductivity and huge volume change upon lithiation. Herein, Si@N-doped carbon nanoparticles with commercial Si nanoparticle as the core and N-doped carbon as the shell were prepared by a facial, low-cost and scalable one-step method using ionic liquid (3-cyanopyridine/H 2 SO 4 ) as both of the N and C sources. While using as anode material for lithium-ion batteries, Si@N-doped carbon exhibited a high reversible capacity of 725 mAh/g after 100 discharge/charge cycles at a current density of 420 mA/g, about twice higher than that of Si@C, a control sample prepared by a similar process using sucrose as the carbon precursor, which showed a capacity of 360 mAh/g after 100 cycles at 420 mA/g. The improved electrochemical performance could be ascribed to the stable core-shell structure of the nanocomposite and more importantly the doping of N element into the carbon shell. Furthermore, this work also provides a versatile strategy for preparation of core-shell N-doped carbon coated nanoparticles. [ABSTRACT FROM AUTHOR]