In situ growth of binder-free CNTs@Ni–Co–S nanosheets core/shell hybrids on Ni mesh for high energy density asymmetric supercapacitors

Abstract

A facile two-step method has been developed to synthesize 3D core/shell-structured composites (CNTs@Ni–Co–S) composed of ternary nickel cobalt sulfide nanosheets (Ni–Co–S) as the shell and carbon nanotubes (CNTs) as the core on a flexible Ni mesh (Ni@CNTs@Ni–Co–S).

Hierarchical FeCo2S4@FeNi2S4 Core/Shell Nanostructures on Ni Foam for High‐Performance Supercapacitors

“…Furthermore, to evaluate the energy storagea bility of the FeCo 2 S 4 @FeNi 2 S 4 //graphene ASC, Figure 5f shows the Ragone plots based on the galvanostaticd ischarge curves. The assembled ASC delivers ah igh energy density of 47.37 Whkg À1 at a power density of 800 Wkg À1 .E ven at ah igherp owerd ensity of 8000Wkg À1 ,t he ASC can still retain an energy density of 17.73 Whkg À1 .T he values are superior to those of many previously reported ASCs, such as NiCo 2 S 4 @PPy-50//AC (34.62 Whkg À1 at 120.19 Wkg À1 ), [26] Ni@CNTs@Ni-Co-S// CC@CNTs (46.5 Whkg À1 at 800 Wkg À1 ), [27] CoNi 2 S 4 //AC (33.9 Whkg À1 at 409 Wkg À1 ), [28] CuCo 2 S 4 //AC (44.1 Whkg À1 at Figure 5. Electrochemicalperformance of the FeCo 2 S 4 @FeNi 2 S 4 //graphene ASC.…”

3D Hierarchical NiCo Layered Double Hydroxide Nanosheet Arrays Decorated with Noble Metal Nanoparticles for Enhanced Urea Electrocatalysis

“…[28,29] The Co 3 + /Co 2 + ratio of the bimetallic NiCoÀ LDH was increased by 3 %, 5.6 %, and 8.9 % with the deposition of Ag, Pd, and Au atoms, respectively. Similarly, the fitting of Ni 2p XPS core-level ( Figure S2B) exhibits two pairs of peaks at the low binding energy region (Ni 2p 3/2 ) and high energy region (Ni 2p 1/2 ), assignable to Ni 2 + and Ni 3 + [30,31] In addition, two satellite peaks can be clearly seen in both high and low binding energies. The intense shakeup satellites suggest that Ni 2 + species are predominant at the hierarchical heterostructures.…”

“…[31b] The spin-orbit splitting values of Co 2p 1/2 / Co 2p 3/2 and Ni 2p 1/2 /Ni 2p 3/2 for the as-synthesized hybrids are much consistent with those reported for NiCoÀ LDH. [29][30][31] The above XPS results indicate that the hybrids possess a mixed valence comprising Ni 2 + /Ni 3 + and Co 2 + /Co 3 + ions on their surfaces, [32] which can sufficiently influence the electrochemical redox processes and lead to remarkable catalytic properties for urea electrooxidation.…”

Ultrathin Nickel–Cobalt Phosphate 2D Nanosheets for Electrochemical Energy Storage under Aqueous/Solid‐State Electrolyte

“…CV curves of the flexible device with a potential window of 0.0–1.4 V at different scan rates were measured. As shown in Figure a, there is a distinct reduction peak under various scan rates from 5 to 30 mV s −1 , not an ideal rectangular shape, and the double‐layer capacitance characteristic of these curves is not pronounced, indicating that the capacitance characteristics are mainly because of pseudocapacitive processes, which are attributed to the Faradic pseudocapacitance of nickel–cobalt phosphate. It may be mainly because there is slight charge imbalance of two electrodes and the resistance of the PVA/KOH gel electrolyte is slightly larger than that of aqueous electrolyte, which does not affect the charge and discharge performance of the supercapacitor .…”