title: Ternary Ni-Co-F Nanocrystal-Based Supercapacitors.
abstract: Ternary nickel cobalt fluoride (Ni-Co-F) nanocrystals are constructed solvothermally for use as the positive electrode materials in supercapacitors. The optimal Ni-Co-F (Ni/Co=2:1) shows slight chemical shifts in X-ray diffraction (XRD) data and X-ray photoelectron spectra (XPS) compared with bare Ni-F and Co-F. The Ni-Co-F (Ni/Co=2:1) exhibits typical square nanocrystal morphology together with a mesoporous surface structure, as observed through TEM observations and nitrogen sorption measurements. Owing to the stronger synergistic effect of Ni and Co redox species originated from the richer Ni and Co surface electroactive sites, Ni-Co-F (Ni/Co=2:1) shows superior performances of specific capacitance, rate capability, and charge-transfer kinetics (564 F g-1at 1 Ag-1, 418 F g-1at 16 Ag-1, 449 Ω) compared with all the other Ni-Co-F candidates. Moreover, the activated carbon (AC)//Ni-Co-F (Ni/Co=2:1) asymmetric capacitor designed based on charge balance delivers superior energy and power densities (18.4 Wh kg-1, 6.64 kW kg-1) together with longer cycle life (77 % retention after 10 000 cycles at 4 A g-1).
authors.affiliation: Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan, 411105, P. R. China.
authors.forename: Xudong
authors.initials: X
authors.lastname: Li
authors.affiliation: Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan, 411105, P. R. China.
authors.forename: Rui
authors.initials: R
authors.lastname: Ding
authors.affiliation: Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan, 411105, P. R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Shi
authors.affiliation: Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan, 411105, P. R. China.
authors.forename: Qilei
authors.initials: Q
authors.lastname: Xu
authors.affiliation: Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan, 411105, P. R. China.
authors.forename: Enhui
authors.initials: E
authors.lastname: Liu
keywords: electrochemistry; nanoparticles; nickel cobalt fluorides; solvothermal reactions; supercapacitors