1D-on-1D core–shell cobalt iron selenide @ cobalt nickel carbonate hydroxide hybrid nanowire arrays as advanced battery-type supercapacitor electrode

Sluggish kinetics and poor structural stability are two main obstacles hampering the exploration of transition metal selenides (TMSs) for supercapacitor. Developing a reasonable core-shell heterostructure with unique morphology is an effective approach to resolve these issues. Herein, a core-shell cobalt iron selenide (CoFe2Se4) @ cobalt nickel carbonate hydroxide (CoNi-CH) heterostructure is directly fabricated on carbon cloth via an electrodeposition method followed by a hydrothermal reaction. In this well-defined heterostructure, one-dimensional (1D) CoFe2Se4 nanowires function as the cores and CoNi-CH nanowires as the shells, which combines the merits of highly conductive CoFe2Se4 for rapid electron transfer and highly electroactive CoNi-CH for multiple redox reactions. Further, the intimate interaction between CoNi-CH and CoFe2Se4 realizes large surface area with hierarchical network and generates rich heterointerfaces with modified the electronic structure. By virtue of its facile 1D-on-1D nanoarchitecture and synergistic effect, the CoFe2Se4@CoNi-CH electrode delivers a increased specific capacity of 218.6 mAh g-1 at 1 A-1 and enhanced rate capability (65.5% at 20 A g-1) compared with pure CoFe2Se4 and CoNi-CH. Besides, a hybrid supercapacitor is established by coupling CoFe2Se4@CoNi-CH cathode and porous carbon anode, which enjoys a maximum energy density of 67.3 Wh kg-1 at 765.9 W kg-1 and prominent durability with 85.4% of capacity retention over 20,000 cycles.