Electrostatic self-assembly assisted hydrothermal synthesis of bimetallic NiCo2S4@N, S co-doped graphene for high performance asymmetric supercapacitors

An Integrated Cathode Engineered by Hierarchical Honeycomb‐Like Copper‐Molybdenum Sulfide Nanosheets for Hybrid Supercapacitor with Improved Energy Storage Capability

“…Amazingly, the HSC can still hold a high energy density of 50.56 Wh kg −1 at 2136.4 W kg −1 . It should be noted that the highest energy density of our‐assembled HSC is higher than those of the similar devices reported recently, such as NiCo 2 S 4 /BPC//BPC (38.5 Wh kg −1 at 853.1 W kg −1 ), [72] NCS‐G 3 //G (33.8 Wh kg −1 at 799.8 W kg −1 ), [73] FSNCS//AC (28.8 Wh kg −1 at 375 W kg −1 ), [74] CuCo 2 S 4 /NF 8 //AC (51.8 Wh kg −1 at 700 W kg −1 ), [75] FeCo 2 S 4 @Ni@Gr//AC (65.8 Wh kg −1 at 849 W kg −1 ), [76] NiCoS/d‐Ti 3 C 2 //AC ( 22.6 Wh kg −1 at 400 W kg −1 ), [77] Zn−Ni−S//PMCN (52.4 Wh kg −1 at 551.7 W kg −1 ), [78] and is also superior to others listed in Table S4. The cyclic stability measurement of the HSC is conducted at 50 mA cm −2 for 10000 GCD cycles, and the result is provided in Figure 5e.…”

Electrostructural Compatibility of Battery-Type Diffuse-Porous Co9S8–NiCo2S4/Defective Reduced Graphene Oxide and Flaky FeS/Nitrogen-Doped Defective Reduced Graphene Oxide for Ultra-High-Performance All-Solid-State Hybrid Pseudocapacitors

“…The deconvoluted peak at the binding energy of 163.11 eV results due to the inherence of S n 2– (polymeric sulfions) in Co 9 S 8 –NiCo 2 S 4 /D-rGO . The signature of low coordinated S n 2– also indicates the presence of Co 9 S 8 phase in Co 9 S 8 –NiCo 2 S 4 /D-rGO . These peaks are characteristic of typical metal–sulfur bonds in Co 9 S 8 –NiCo 2 S 4 /D-rGO.…”

“…10 The signature of low coordinated S n 2− also indicates the presence of Co 9 S 8 phase in Co 9 S 8 −NiCo 2 S 4 /D-rGO. 47 These peaks are characteristic of typical metal−sulfur bonds in Co 9 S 8 − NiCo 2 S 4 /D-rGO. The very broad deconvoluted peak centered at the binding energy of 164.72 eV is characteristic of neutral sulfur or of sulfur loosely bound to the metals present in Co 9 S 8 −NiCo 2 S 4 /D-rGO.…”

Response Surface Methodology Optimization in High-Performance Solid-State Supercapattery Cells Using NiCo2S4–Graphene Hybrids

“…Recently, ternary Ni-Co sulfides with rich redox-active sites and variable valence states, such as Ni 2+ /Ni 3+ , Co 2+ /Co 3+ , and Co 3+ /Co 4+ , during the charging and discharging process have been suggested as promising battery-type materials for supercapatteries; however, the low conductivity, easy agglomeration, and poor electrochemical stability of ternary Ni-Co sulfides present a series of problems to be tackled [ 6 , 7 ]. Many results have reported that the combination of high conductivity materials, such as reduced graphene oxide (rGO) or graphene (G) and Ni-Co sulfides using a hydrothermal process, can achieve a synergistic effect, leading to enhanced electrochemical performance [ 8 , 9 , 10 , 11 , 12 ]. Dong et al [ 9 ] prepared Ni x Co y S 4 nanosheets (various Ni-Co ratios) on rGO using a hydrothermal method, and found that the Ni 1.64 Co 2.40 S 4 /rGO electrode delivers a high specific capacitance of 1089 F g −1 at 1 A g −1 .…”

“…Dong et al [ 9 ] prepared Ni x Co y S 4 nanosheets (various Ni-Co ratios) on rGO using a hydrothermal method, and found that the Ni 1.64 Co 2.40 S 4 /rGO electrode delivers a high specific capacitance of 1089 F g −1 at 1 A g −1 . He et al [ 12 ] synthesized the NCS/G hybrid using the hydrothermal process to investigate the effect of amounts of thioacetamide on the electrochemical performance; they showed that graphene effectively enhances the structural stability of the as-prepared NCS/G. Traditional hydrothermal approaches for the preparation of NCS@G composite materials are dependent on the change of one independent variable parameter, such as Ni-Co or Ni-S ratios, Ni-Co sulfides g ratio, and hydrothermal time, while keeping all other variables constant.…”