Co₉S₈nanoparticle-decorated carbon nanofibers as high-performance supercapacitor electrodes

Abstract

a This work reported Co 9 S 8 nanoparticle-decorated carbon nanofibers (CNF) as a supercapacitor electrode.By using a mild ion-exchange method, the cobalt oxide-based precursor nanoparticles were transformed to Co 9 S 8 nanoparticles in a microwave hydrothermal process, and these nanoparticles were decorated onto a carbon nanofiber backbone. The composition of the nanofibers can be readily tuned by varying the Co acetate content in the precursor. The porous carbon nanofibers offered a fast electron transfer pathway while the well dispersed Co 9 S 8 nanoparticles acted as the redox center for energy storage. As a result, high specific capacitance of 718 F g À1 at 1 A g À1 can be achieved with optimized Co 9 S 8 loading. The assembled asymmetric supercapacitor with Co 9 S 8 /CNF as the cathode showed a high energy density of 23.8 W h kg À1 at a power density of 0.75 kW kg À1 and good cycling stability (16.9% loss over 10 000 cycles).

Controlled Preparation of Hollow and Porous Co9S8 Microplate Arrays for High-Performance Hybrid Supercapacitors

“…The energy density reaches as high as 25.49 Wh kg –1 at a power density of 800 Wh kg –1 , and it still maintains an energy density of 16.67 Wh kg –1 even at an ultrahigh power density of 8000 Wh kg –1 . The energy and power densities of the device are much higher than those of other materials, such as CoS nanoflower//AC (15.58 Wh kg –1 at 700.12 W kg –1 ), Co–S–P//AC (17.9 Wh kg –1 at 266.6 W kg –1 ), Co 9 S 8 nanoparticle@CNF//AC (23.8 Wh kg –1 at 750 W kg –1 ), hierarchical Co 9 S 8 //AC (21.3 Wh kg –1 at 130 W kg –1 ), Co 9 S 8 @NiCo 2 O 4 //AC (24.85 Wh kg –1 at 222 W kg –1 ), and Co 9 S 8 /NS-C//AC (14.85 Wh kg –1 at 681.82 W kg –1 ) . As shown in Figure f, after 5000 cycles, the HSC can still maintain 92% of the initial capacitance, indicating the excellent cycling stability of the device.…”

Facile synthesis of mesoporous NixCo9−xS8 hollow spheres for high-performance supercapacitors and aqueous Ni/Co–Zn batteries

“…[12][13][14] In addition to consideration of the conductivity, the electrochemical performance is also dependent on the accessible surface area of transition metal based micro/nanomaterials, [15][16][17] thus a lot of effect has been devoted to synthesizing electrode materials with large surface areas and porous structures. For example, the reported morphology and synthesis strategies include ion exchange reaction, 6 microwave irradiation, 18 sacri-cial metal salt hard templates 19 and derivation from metalorganic framework precursors via a sulfuration process. 20,21 Considering the complexity and multiple steps of the template transformation method, it is worth developing a simple method without a template to obtain hollow sphere structures.…”

“…In recent years, as an important transition metal sulfide, Co 9 S 8 has been regarded as one of the most attractive electrode materials with a high theoretical specific capacity (5449 F g −1 at 0.45 V), 1 low cost and non-toxic nature, however, the presence of sluggish ion transport kinetics and low conductivity limits its application in the energy storage field. Thus a lot of efforts have been devoted to improving the conductivity by conductive metals or carbonaceous supports, 2–6 ion-doping, 7 constructing hierarchical composites, 8 graphene hybridization, 9,10 carbon coating, 11 and constructing hetero-phase interfaces. 12–14 In addition to consideration of the conductivity, the electrochemical performance is also dependent on the accessible surface area of transition metal based micro/nanomaterials, 15–17 thus a lot of effect has been devoted to synthesizing electrode materials with large surface areas and porous structures.…”

Co-Co9S8-NC particles anchored on 3D hyperfine carbon nanofiber networks with a hierarchical structure as a catalyst promoting polysulfide conversion for lithium–sulfur batteries

“…1d) of the CNF/Co-Co 9 S 8 -NC sample show that the E b of S 2p at 161.8 and 162.8 eV belongs to the S 2p3/2 and S 2p1/2, which is consistent with the peak position of Co 9 S 8 reported in the literature. 55 The peak at 168.4 eV corresponds to the SO 4 2− and was attributed to experimental residue. 56 Fig.…”