title: N-Doped carbon coated hollow Ni(x)Co(9-x)S8 urchins for a high performance supercapacitor.
abstract: N-doped carbon coated NixCo9-xS8 (NixCo9-xS8@C) hollow urchins have been synthesized via a two-step solvothermal synthesis and an in situ polymerization in dopamine together with a post-annealing process. The characterization indicated that NixCo9-xS8@C hollow urchins have urchin-like morphology and a uniform size distribution. Furthermore, there is a complete phrase transformation from the as obtained NiCo2S4/NixCo9-xS8 hybrid to NixCo9-xS8 during the thermal annealing process. More importantly, as electrochemical materials, NixCo9-xS8@C has a high specific capacitance (1404.0 F g(-1) at 2.0 A g(-1)) and excellent cycling performance (95.8% capacitance retention of the highest value after 2000 cycles). These results can be attributed to the coating of N-doped carbon, which gives the composite good conductivity. Additionally, the phase transformation from NiCo2S4/NixCo9-xS8 to NixCo9-xS8 during the thermal annealing greatly enhanced the redox reaction of the Co and Ni species.
authors.affiliation: School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, Inner Mongolia, China.
authors.forename: Yufei
authors.initials: Y
authors.lastname: Zhang
authors.forename: Chencheng
authors.initials: C
authors.lastname: Sun
authors.forename: Haiquan
authors.initials: H
authors.lastname: Su
authors.forename: Wei
authors.initials: W
authors.lastname: Huang
authors.forename: Xiaochen
authors.initials: X
authors.lastname: Dong