Carbon-Encased Mixed-Metal Selenide Rooted with Carbon Nanotubes for High-Performance Hybrid Supercapacitors

Abstract

Transition metal-based compounds with high theoretical capacitance and low cost represent one class of promising electrode materials for high-performance supercapacitors. However, their low intrinsic electrical conductivity impedes their capacitive effect and further limits their practical application. Rational regulation of their composition and structure is, therefore, necessary to achieve a high electrode performance. Herein, a well-designed carbon-encased mixed-metal selenide rooted with carbon nanotubes (Ni-Co-Se@C-CNT) was derived from nickel–cobalt bimetallic organic frameworks. Due to the unique porous structure, the synergistic effect of bimetal selenides and the in situ growth of carbon nanotubes, the composite exhibits good electrical conductivity, high structural stability and abundant redox active sites. Benefitting from these merits, the Ni-Co-Se@C-CNT exhibited a high specific capacity of 554.1 C g−1 (1108.2 F g−1) at 1 A g−1 and a superior cycling performance, i.e., 96.4% of the initial capacity was retained after 5000 cycles at 10 A g−1. Furthermore, a hybrid supercapacitor assembled with Ni-Co-Se@C-CNT cathode and activated carbon (AC) anode shows a superior energy density of 38.2 Wh kg−1 at 1602.1 W kg−1.

CoP Quantum Dots Embedded in Carbon Polyhedra through Co─P─C Bonding Enabling High‐Energy Lithium‐Ion Capacitors

“…As shown in Figure 7e, the capacity retention of the assembled LIC device is 80% (only 0.0013% capacity decay per cycle), and the CE is also near 100%, reflecting the excellent cycle stability, which precedes that of most previously reported CoP-based LICs as shown in Figure 7f. Ragone plots acquired from the GCD measurements reveal that the LIC achieves the maximum energy density of 170.2 Wh kg −1 at a power density of 155.5 W kg −1 , and the maximum power density of 10.08 kW kg −1 is achieved with an energy density of 58.8 Wh kg −1 , which is superior to those previously reported LIC devices (Figure 7f), [34][35][36][37][38][39][40][41][42] such as AC//Mn-CoP, [40] AC//CoP/rGO, [39] graphene//Ni-CoP@C@CNT. [38]…”

Recent advances in Ni-materials/carbon nanocomposites for supercapacitor electrodes

“…The electrochemical properties of supercapacitors on the basis of Ni materials and CNTs composite electrodes are reported in Table 2 144–163 The nanocomposite CNTs/NiCo 2 S 4 showed remarkable capacitive properties. In the structure of the asymmetric supercapacitor, it exhibited energy and power densities of 43.3 W h kg −1 and 800 W kg −1 .…”

“…Also, its usage in a supercapacitor with a Co(OH) 2 / NiCo@NCNTs/CC negative electrode led to 52.8 W h kg À1 of energy density. 155 Yuan et al 156 investigated a supercapacitor based on the Ni-Co-Se/C-CNTs electrode and achieved a specific capacitance of 1108.2 F g À1 . They mentioned the power and energy densities of Ni-Co-Se/C-CNTs//AC supercapacitors were 38.2 W h kg À1 and 1602.1 W kg À1 , respectively.…”

“…Ternary nickel cobalt sulfide/oxides and carbon nanotube composites. The electrochemical properties of supercapacitors on the basis of Ni materials and CNTs composite electrodes are reported in Table 2 [144][145][146][147][148][149][150][151][152][153][154][155][156][157][158][159][160][161][162][163] The nanocomposite CNTs/NiCo 2 S 4 showed remarkable capacitive properties. In the structure of the asymmetric supercapacitor, it exhibited energy and power densities of 43.3 W h kg À1 and 800 W kg À1 .…”

“…157 NiCo sulfide (NiCo 2 S 4 ) was prepared with the help of a shadow mask printing method on a flexible PET substrate using homemade ink comprised of PTFEm, CNTs, NiCo 2 S 4 , carbon nanotubes, and terpineol. The NiCo 2 S 4 electrode revealed a high specific capacitance of 1401 F g À1 while the 156…”