Xiaolian Huang,Shuang Men,Hui Zheng,Dong-Dong Qin,Xiongwu Kang
Graphical NiCoSe 4 microspheres derived from NiCo-MOFs display excellent electrochemical performance as anode materials for sodium-ion batteries. Binary transition metal selenides have been more promising than single transition metal selenides as anode materials for sodium-ion batteries (SIBs). However, the controlled synthesis of transition metal selenides, especially those derived from metal-organic-frameworks with well-controlled structure and morphology is still challenging. In this paper, highly porous NiCoSe 4 @NC composite microspheres were synthesized by simultaneous carbonization and selenization of a Ni−Co-based metal-organic framework (NiCo-MOF) and characterized by scanning electron microscopy, transition electron microscopy, X-Ray diffraction, X-Ray photoelectron spectroscopy and electrochemical techniques. The rationally engineered NiCoSe 4 @NC composite exhibits a capacity of 325 mAh g −1 at a current density of 1 A g −1 , and 277.8 mAh g −1 at 10 A g −1 . Most importantly, the NiCoSe 4 @NC retains a capacity of 293 mAh g −1 at 1 A g −1 after 1500 cycles, with a capacity decay rate of 0.025 % per cycle.
Lijun Du,Ning Lv,Jiashuai Li,Jiayi Zhang,Yilan Chen,Yalin Zhang,Zhen Li,Xianqiang Huang,Jujie Luo
NiCoSe 4 nanoflowers were synthesized on carbon fiber felt (CFF) by microwave method, and the effects of microwave time and microwave power on the morphology, physical phase and performance of NiCoSe 4 @CFF were explored. The results display that the nanostructured NiCoSe 4 prepared under the microwave irradiation of 1000 W for 120 s is uniformly loaded on the CFF. The NiCoSe 4 @CFF electrode exhibits a superior specific capacity of 1653.6F g −1 at 1A/g and maintains a superior cycling performance of 87.05 % of the initial capacitance over 150,000 cycles. In addition, the flexible supercapacitor fabricated with NiCoSe 4 @CFF as the cathode exhibits excellent flexibility and flexural strength. As an effective catalyst for oxygen evolution reaction (OER), NiCoSe 4 @CFF demonstrates a low overpotential of 0.358 V, a relatively small Tafel slope of 115.93 mV dec −1 and an excellent lifetime at 10 mA cm −2 .
Synthesis of NiHCCo precursors via simple co-precipitation and nickel–cobalt tetraselenide composites grown on nitrogen-doped reduced graphene oxide (NiCoSe4/N-rGO) were fabricated using solvothermal method. The introduction of N-rGO used as a template effectively prevented agglomeration of NiCoSe4 nanoparticles and provided more active sites, which greatly increased the electrochemical and electrical conductivity for NiCoSe4/N-rGO. NiCoSe4/N-rGO-20 presents a remarkably elevated specific capacity of 120 mA h g−1 under current density of 1 A g−1. NiCoSe4/N-rGO-20 demonstrates an excellent cycle life and achieves a remarkable 83% retention rate over 3000 cycles with 10 A g−1. NiCoSe4/N-rGO-20//N-rGO asymmetric supercapacitor was constructed based on the NiCoSe4/N-rGO-20 as an anode, N-rGO as cathode by using 2 mol l−1 KOH as an electrolyte. NiCoSe4/N-rGO-20//N-rGO ASC demonstrates an ultra-big energy density of 14 Wh kg−1 and good circulation stability in the power density of 902 W kg−1. It is doubled in comparison to the NiCoSe4/N-rGO-20//rGO asymmetric supercapacitor (7 Wh kg−1). The NiCoSe4/N-rGO-20//N-rGO ASC capacity retention is still up to 93% over 5000 cycles (5 A g−1). The results reveal that this device would be a prospective cathode material of supercapacitors in actual applications.
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