Multidimensional Carbon-Modified NiCo₂O₄/Ni–Co–S Nanocomposite Electrode Material for High-Energy Asymmetric Supercapacitors

Abstract

The synergistic effect of the electrochemical double-layer and pseudocapacitance electrode materials has been extensively used to improve the performance of composite electrodes for supercapacitors (SCs). However, the energy density of SCs is still unsatisfactory for practical utilization. Herein, a C-NiCo 2 O 4 /C@Ni−Co−S electrode is ingeniously devised through coupling the interior of 0D/2D carbon-modified NiCo 2 O 4 and the external sheath of Ni−Co−S nanosheets. The 0D carbon quantum dot doping can effectively avoid the agglomeration of NiCo 2 O 4 nanoparticles and improve the electronic conductivity. 2D carbon as the intermediate layer can ameliorate the physical/chemical stability of the electrode. Ni−Co−S nanosheets can improve the areaspecific capacitance of the electrode and thus enhance the energy density of the device. As expected, the C-NiCo 2 O 4 /C@Ni−Co−Selectrode delivers an outstanding specific capacitance of 2396 F g −1 (7.9 F cm −2 ) at 3 A g −1 and excellent cycling stability (92% after 10 000 cycles). Furthermore, a quasi-solid-state asymmetric supercapacitor (ASC) using C-NiCo 2 O 4 /C@Ni−Co−S as positive electrode and active carbon (AC) as negative electrode exhibits a high energy density of 95 Wh kg −1 at 0.9 kW kg −1 and an excellent cycle performance. Our work reveals that this reasonable structure design is very effective for achieving a high-performance positive electrode for practical SC applications.

Construction of Cu-Doped Ni–Co-Based Electrodes for High-Performance Supercapacitor Applications

“…It can be seen from the figure that the GCD curves of the Ni–Co–Cu oxide electrode have two obvious voltage platforms, implying the occurrence of the Faraday reaction, which is consistent with the CV test results . In addition, all GCD curves of the Ni–Co–Cu oxide electrode have symmetrical shapes, which means that the electrode has good electrochemical behavior . The obvious redox peak in Figure e and the nonlinear charge–discharge curves in Figure f both indicate the pseudocapacitance storage mechanism of the electrode.…”

“…With the gradual increase of the scan rate, all CV curves of the Ni–Co–Cu oxide electrode maintain almost the same shape. What’s more, the peak of the anode moves to positive potential and the peak of the cathode moves to negative potential, implying that a rapid Faraday reaction occurs at the electrode/electrolyte interface . GCD curves of the Ni–Co–Cu oxide electrode at different current densities (3, 5, 8, 10, 15, and 20 A/g) are shown in Figure f.…”

In Situ Growth of Core–Shell Heterostructure CePO4@CuCo2S4 As Advanced Electrodes for High-Performance Supercapacitor

“…In the CePO 4 @CuCo 2 S 4 core–shell heterostructure, electron transfer is from CuCo 2 S 4 to CePO 4 , which leads to electron accumulation on CePO 4 and hole accumulation on CuCo 2 S 4 . , The electron accumulation of CePO 4 is conducive to the occurrence of redox reactions . The accumulation of holes in CuCo 2 S 4 facilitates the reaction, as holes are usually the active sites for oxidation reactions . Therefore, the heterogeneous interface adds the active site of the reaction and speeds up the interfacial electronic interaction, which can further support the electrochemical performance …”

“…44 The accumulation of holes in CuCo 2 S 4 facilitates the reaction, as holes are usually the active sites for oxidation reactions. 45 Therefore, the heterogeneous interface adds the active site of the reaction and speeds up the interfacial electronic interaction, which can further support the electrochemical performance. 46 The advantage of CePO 4 @CuCo 2 S 4 /NF (porous structure, heterogeneous interface, good charge transfer ability, etc.)…”

Review on Microfluidic Construction of Advanced Nanomaterials for High-Performance Energy Storage Applications

“…As the assembly building blocks of the electrode, nanomaterials have gained great attention in energy storage applications because of their unique nano/microscale effect and enlarged physical chemistry nature. − From the perspective of dimensionality and shape, the nanomaterials contain nano/micro building blocks (nanoparticles, nanosheets, and microspheres), one-dimensional (1D) microfibers, and two-dimensional (2D) macrofabrics. − In this regard, the nano/micro building blocks are divided into nanoparticles [such as metal–organic frameworks (MOFs), conducting polymer, and metallic oxide], − nanosheets [such as graphene, MXene, black phosphorus (BP), and molybdenum disulfide (MoS 2 )], − and microspheres [such as graphene microspheres, carbon nanotube (CNT) microspheres, and hierarchical carbon microspheres]. − The 1D microfibers are constructed by nano/micro building blocks via a spinning strategy, such as a wet-spinning graphene and MXene fiber, dry-spinning CNT fiber, and electrospinning carbon fiber. − On the basis of the as-prepared 1D microfibers, the 2D macrofabrics can be further achieved by chemical cross-linking and residual-solvent-caused heat-welding between adjacent fibers, which have become important parts in energy storage applications. , For fiber preparation methods, the freedom in spinning solution guarantees that the wet spinning can be broadly used to prepare various microfiber/macrofabrics by the coagulation bath reaction. However, the non-volatile residual solvent, redundant polymer scaffold, uncontrollable fluidic force field (fluidic interfacial tension and kinetic diffusion), and many local turbulences will result in a disordered microstructure and inhomogeneous morphology.…”