Synthesis of the Urchin‐Like NiS@NiCo₂S₄ Composites on Nickel Foam for High‐Performance Supercapacitors

Abstract

A simple hydrothermal treatment process was used to prepare urchin‐like NiS@NiCo2S4 composites on Ni foam, which were then employed as binder‐free and conductive‐agent‐free electrodes for pseudocapacitors. The as‐synthesized composites have significant capacitive performance because of the novel porous structure. A specific capacitance up to 14.32 F cm−2 was obtained at a current density of 5 mA cm−2, which was far higher than that of pristine NiCo2S4 nanotube arrays (about 8.4 F cm−2). More importantly, Ni@NiS@NiCo2S4 and activated carbon (AC) were assembled as the positive and negative electrode, respectively, in an asymmetric supercapacitor, which possesses prominent performance. In addition to 78.7 % capacitance retention when cycling at 50 mA cm−2 for 5000 cycles, the as‐fabricated Ni@NiS@NiCo2S4//AC device exhibits a high energy density of 38.96 Wh kg−1 and power density of 339.62 W kg−1 at a current density of 10 mA cm−2.

Graphitic Carbon Nitride-Induced Multifold Enhancement in Electrochemical Charge Storage of CoS–NiCo2S4 for All-Solid-State Hybrid Supercapacitors

“…Moreover, the CoS–NiCo 2 S 4 /GCN||N-rGO ASSHSC device retains ∼67% of E D at the maximum P D condition, whereas the CoS–NiCo 2 S 4 ||N-rGO ASSHSC device retains ∼58% of E D at the maximum P D condition. Contextually, the Ragone ( E D vs P D ) plots for CoS–NiCo 2 S 4 /GCN||N-rGO and CoS–NiCo 2 S 4 ||N-rGO ASSHSC devices are shown in Figure K, where the E D vs P D values of the devices are shown to be significantly larger than some of the reported NiCo 2 S 4 -based devices. ,− The heterochemical integration of GCN with CoS–NiCo 2 S 4 significantly improves the deliverable energy density and rate performance of the corresponding ASSHSC device. This is ascribed to the GCN-supplemented electro-microstructural assertiveness of the heterocomposite (CoS–NiCo 2 S 4 /GCN), which inductively facilitates the lowly impeded bulk mobility of electroactive ions and lowly resisted integrated charge transmission in the electrode material and electrode/electrolyte interface during the surface- and diffusion-controlled electrochemical processes .…”

“…(A) CV profiles of N-rGO, CoS–NiCo 2 S 4 , and CoS–NiCo 2 S 4 /GCN measured at a scan rate of 10 mV s –1 ; (B) CV profiles of CoS–NiCo 2 S 4 ||N-rGO and CoS–NiCo 2 S 4 /GCN||N-rGO ASSHSC devices measured at a scan rate of 10 mV s –1 ; (C) contribution (%) of surface-controlled (capacitive-type) and diffusion-controlled (battery-type) specific capacitance to the overall specific capacitance of the CoS–NiCo 2 S 4 /GCN||N-rGO ASSHSC device as estimated from the CV measurements; (D) contribution (%) of surface-controlled (capacitive-type) and diffusion-controlled (battery-type) specific capacitance to the overall specific capacitance of the CoS–NiCo 2 S 4 ||N-rGO ASSHSC device as estimated from the CV measurements; (E) GCD profiles of CoS–NiCo 2 S 4 ||N-rGO and CoS–NiCo 2 S 4 /GCN||N-rGO ASSHSC devices measured at a current density of 10 mA cm –2 ; (F) C A ( areal capacitance ) vs applied current density plots for CoS–NiCo 2 S 4 ||N-rGO and CoS–NiCo 2 S 4 /GCN||N-rGO ASSHSC devices; (G) C ( mass specific capacity ) vs applied current density plots for CoS–NiCo 2 S 4 ||N-rGO and CoS–NiCo 2 S 4 /GCN||N-rGO ASSHSC devices; (H) C a ( area specific capacity ) vs applied current density plots for CoS–NiCo 2 S 4 ||N-rGO and CoS–NiCo 2 S 4 /GCN||N-rGO ASSHSC devices; (I) Nyquist plots of CoS–NiCo 2 S 4 ||N-rGO and CoS–NiCo 2 S 4 /GCN||N-rGO ASSHSC devices, the inset shows the corresponding Nyquist plots in the high frequency region; (J) Imaginary capacitance ( C ″) vs frequency plots for the CoS–NiCo 2 S 4 ||N-rGO and CoS–NiCo 2 S 4 /GCN||N-rGO ASSHSC devices, the inset shows the real capacitance ( C ′) vs frequency plots for the CoS–NiCo 2 S 4 ||N-rGO and CoS–NiCo 2 S 4 /GCN||N-rGO ASSHSC devices; (K) Ragone plots ( E D vs P D ) of CoS–NiCo 2 S 4 ||N-rGO and CoS–NiCo 2 S 4 /GCN||N-rGO ASSHSC devices, the power and energy densities of few devices based on sulfide-based materials and/or their heteronanocomposites containing Ni and Co as the positive electrode materials are also presented for comparison; ,− and (L) capacitance retention profiles of CoS–NiCo 2 S 4 ||N-rGO and CoS–NiCo 2 S 4 /GCN||N-rGO ASSHSC devices during multiple charge discharge cycles.…”

Electrochemical capacitance properties of pre-sodiated manganese oxide for aqueous Na-ion supercapacitors

“…27 Also, there is growing interest on transition metal suldes such as CuCo 2 S 4 , Co 3 S 4 , NiCo 2 S 4 etc., because of their high specic capacitance values. [28][29][30][31] Abuali et al synthesized CuCo 2 S 4 nanoparticles in polyaniline hollow spheres, which can exhibit a SC of 1120 F g −1 at a specic current of 1 A g −1 . 29 However, these materials exhibit their capacitance properties in alkali solutions, which are not environmentally friendly.…”