High Energy Density Asymmetric Supercapacitors Research Articles

The phosphorous-doped 2D nanosheet assembled 3D Mn2V2O7 microflowers on Ni foam as a binder-free electrode for high energy density asymmetric supercapacitor application

In recent times, transition-metal oxides have been recognized as highly promising candidates for supercapacitor applications. Nevertheless, their progress in diverse fields has been hindered by challenges such as poor electrical conductivity and a shortage of active reaction centers. Doping heteroatoms would overcome these drawbacks and enhance the supercapacitor properties in transition metal oxides. Herein, the phosphorous-doped 2D nanosheet assembled 3D Mn2V2O7 micro flowers were grown on the Nickel foam using the hydrothermal method and successively phosphatized in a tube furnace, which was utilized as a binder-free supercapacitor electrode. The synthesis process involved varying the concentration of phosphorus (P), resulting in the successful formation of uniform P-decorated Mn2V2O7 microflowers. The unique microflower structure and doping P into the Mn2V2O7 material enhance the electrochemical properties with a specific capacity of 850C g−1 (1545 F g−1) at 1 A g−1 in a three-electrode cell. Moreover, the assembled Mn2V2O7–600/NF//AC device delivers a specific capacity of 258C g−1 (211 F g−1) at 1 A g−1 with a remarkable rate of 47 % at a high current density of 20 Ag −1. The device achieved a maximum energy density of 43.2 Wh kg−1 at a power density of 604.7 W kg−1, and it maintained 91 % of initial capacity after 10,000 charge/discharge cycles at 20 A g−1. These results suggest that the P-doping 2D nanosheet assembled 3D Mn2V2O7 could be promising electrode materials for supercapacitor applications.

Synergistic effects of haematite/hausmannite anchored graphene hybrids in high-energy density asymmetric supercapacitors

Addressing the critical demand for advanced energy storage systems (ESSs) amid escalating global energy needs and population growth, this study pioneers the synthesis of graphene-supported haematite and hausmannite (Gr@Mn3O4@Fe2O3/NF) ternary composite cathodes. These cathodes are tailored for high-performance asymmetric supercapacitors (ASCs), leveraging an economically viable process of fabrication. This innovation represents a significant leap forward, employing cost-effective techniques without compromising efficiency. Synchrotron X-ray absorption spectroscopy (XAS) analysis reveals a distinct blend of Fe and Mn valences, confirming the composite's unique structure. Electrochemical assessment underscores the superior capability of the electrodes, registering an unprecedented specific capacitance of ∼854 F/g in aqueous electrolytes, far surpassing traditional electrodes. Additionally, the composite electrodes maintain ∼70 % capacitance retention and about ∼94 % coulombic efficiency under a high current density of 4 A/g. In an ASC configuration, pairing the Gr@Mn3O4@Fe2O3/NF cathode with an anode made of AC, the ASC achieves the highest capacitance of ∼139 F/g, an energy density of ∼156.3 Wh/kg at a power density of ∼1439 W/kg, coupled with outstanding cyclability in a 1.5 V. This research delineates a scalable pathway for fabricating cost-efficient, high-energy density SCs, heralding a new era of portable electronic devices with enhanced energy storage capabilities.

Ammonium Ion-Pre-Intercalated MnO2 on Carbon Cloth for High-Energy Density Asymmetric Supercapacitors.

With the continuous development of green energy, society is increasingly demanding advanced energy storage devices. Manganese-based asymmetric supercapacitors (ASCs) can deliver high energy density while possessing high power density. However, the structural instability hampers the wider application of manganese dioxide in ASCs. A novel MnO2-based electrode material was designed in this study. We synthesized a MnO2/carbon cloth electrode, CC@NMO, with NH4+ ion pre-intercalation through a one-step hydrothermal method. The pre-intercalation of NH4+ stabilizes the MnO2 interlayer structure, expanding the electrode stable working potential window to 0-1.1 V and achieving a remarkable mass specific capacitance of 181.4 F g-1. Furthermore, the ASC device fabricated using the CC@NMO electrode and activated carbon electrode exhibits excellent electrochemical properties. The CC@NMO//AC achieves a high energy density of 63.49 Wh kg-1 and a power density of 949.8 W kg-1. Even after cycling 10,000 times at 10 A g-1, the device retains 81.2% of its capacitance. This work sheds new light on manganese dioxide-based asymmetric supercapacitors and represents a significant contribution for future research on them.

Heterostructured SnSe-MnSe@rGO as a composite electrode for Li-ion batteries and high energy density asymmetric supercapacitors

Systematically fabricated hybrid nanomaterials have good outer walls and inherent features, which can significantly improve energy storage capabilities. Herein, we demonstrated the successful preparation of heterostructure SnSe-MnSe nanomaterials anchored reduced Graphene oxide using the hydrothermal method. The SnSe-MnSe@rGO is used as the composite electrode for lithium-ion battery and supercapacitor applications. The SnSe, MnSe, and SnSe-MnSe materials were also prepared and compared their performances with the SnSe-MnSe@rGO material. The first cycle charge/discharge capacity of SnSe-MnSe@rGO was 484.6/641.9 mAhg−1 at 0.1Ag−1 with coulombic efficiency of 75.49 %. After 1000 cycles at 1Ag−1, the SnSe-MnSe@rGO delivered the discharge capacity of 175.7 mAhg−1 at 1Ag−1 with 72.75 % retention of capacity. For supercapacitor application, the SnSe-MnSe@rGO exhibits the battery-type energy storage mechanism and provides a specific capacity of 210. 8 mAhg−1 at 1 Ag−1 with superior rate capability and it withstands 94 % of initial capacity after 5000 GCD cycles at 20 Ag−1 in three-electrode electrochemical cells. The asymmetric type such as activated carbon//SnSe-MnSe@rGO device delivers the capacity of 105.8 mAhg−1 and shows a high energy density of 84.7 Whkg−1 with the power density of 810.5 Wkg−1 at 1 Ag−1. The device holds 89 % of its initial capacity retention after 10,000 continuous GCD cycles at 10 Ag−1. This study emphasizes a comprehensive and fundamental understanding of the reaction mechanisms at the heterostructures, as well as the strategic design of composite materials for constructing advanced electrodes in the realm of sustainable energy storage applications.

Effect of fluoride (CoF2) based electrode material for high energy and power density asymmetric flexible supercapacitors

Herein, an asymmetric supercapacitor (ASC) device was assembled by employing the pristine CoF2 as active positive electrode material and activated carbon (AC) as negative electrode material. The CoF2 electrode exhibited an outstanding electrochemical behavior with enhanced specific capacitance (Cs) of 872 F/g at 1 A/g current density in three electrode configurations. The reversible Faradaic redox reactions in CoF2 instigate the formation of cobalt-oxyfluorides and generating the mixed valence state of Co (Co2+ and Co3+) which improves its electrical conductivity and electrochemical behaviors. Furthermore, the room temperature paramagnetic nature of CoF2 increases the gradient force of ions which could possibly increase the redox reactions at the electrolyte/electrode interface. The constructed asymmetric device structure of CoF2//AC revealed a quasi-rectangular shaped cyclic voltametric curve and symmetrical semi-triangular shaped galvanostatic charge-discharge profiles, respectively, which affirms the combined electric double layer capacitance and pseudocapacitive nature by its hybrid assembly. Hence, the constructed CoF2//AC ASC demonstrated a remarkable specific capacitance of 141 F/g, energy density of 44.06 Wh.Kg−1, and power density of 422.97 W.Kg−1 at 1 A/g with the high cell voltage of 1.5 V. The CoF2//AC ASC device retained c.a. 92 % of its initial capacitance and attained over 96 % of Coulombic efficiency after 2000 cycles of charge-discharge profiles at 1 A/g, which suggests the high electrochemical stability. This admirable electrochemical performance and the origin towards the magneto-capacitance of CoF2 could pave a new way to explore next generation high-performance supercapacitors.

A Nix:Vy–Se nanoparticle decorated hierarchical porous Zn–Co–P nanowire array electrode for high energy density asymmetric supercapacitors

Using a novel bi-metallic Nix:Vy–Se/Zn–Co–P heterogeneous electrode as a high-performance positive electrode, a high energy density asymmetric solid-state supercapacitor device is fabricated.

MOF derived hierarchical ZnNiCo-LDH on vapor solid phase grown CuxO nanowire array as high energy density asymmetric supercapacitors

MOF derived hierarchical ZnNiCo-LDH on vapor solid phase grown CuxO nanowire array as high energy density asymmetric supercapacitors

Fabrication of ZnSnO3@In2O3 core-shell based 1D microfiber heterostructure for high energy density asymmetric supercapacitors

Core-shell microfibers have witnessed a substantial demand surge in developing supercapacitors (SCs) owing to their enhanced conductivity, high surface area, and structural stability. Here, we report a facile low-cost electrospun ZnSnO3 @In2O3 core-shell microfibers heterostructure for SC application. The distinct fibrous morphology and synergistic incorporation of Zinc (Zn), Tin (Sn), and Indium (In) demonstrate significantly enhanced electrochemical performance while assembled in an asymmetric SC (ASC) by utilizing ZnSnO3 @In2O3 core-shell as positive and activated carbon (AC) as negative electrode. The ASC device exhibits an excellent specific capacitance of 160 F/g at 1 A/g along with a maximum specific energy of 40 Wh/kg. The ASC also records 86.95% capacitance retention with an exceptional 90% coulombic efficiency retention over 15,000 cycles at 15 A/g. This novel ZnSnO3 @In2O3 core-shell//AC signifies great potential in achieving high-performance electrochemical energy storage devices.

In situ boron-doped flower-like NiS2@NC with sulfur vacancy composites for high energy density asymmetric supercapacitors

In response to the challenges posed by the intricate synthesis process and low conductivity of nickel-based hydroxides, a straightforward and environmentally friendly method was proposed for the preparation of B-doped α-Ni(OH)2(α-Ni(OH)2–B). Additionally, B-doped NiS2@NC composites with sulfur vacancies (B-Sv-NiS2@NC) were prepared through nitrogen-doped carbon coating and vulcanization process. The resulting B-Sv-NiS2@NC electrode materials exhibited a specific capacity of 659C g−1 under a high specific potential (ΔV) of 1.0 V vs. Hg/HgO. Asymmetric supercapacitors α-Ni(OH)2–B//YP-80 and B-Sv-NiS2@NC//YP-80 were constructed and obtain 128.45C g−1 and 199.5C g−1 specific capacity at 0.5 A g−1 and 0.7 A g−1, respectively. Meanwhile, the α-Ni(OH)2–B//YP-80 and B-Sv-NiS2@NC//YP-80 demonstrated energy densities of 30.33 Wh kg−1 and 47.1 Wh kg−1 under 1.7 V working voltage window, respectively. The cycle capacity retention rates of the two devices reached 96% (8000 cycles) and 116% (10,000 cycles). The surface pseudocapacitance mechanism and charge transfer mechanism of α-Ni(OH)2–B and B-Sv-NiS2@NC were revealed by first principles DFT. The findings of the study demonstrate that the introduction of B doping significantly augmented the adsorption of OH− and facilitated the surface redox reaction. The OH− adsorption energy increased to −1.43 eV upon the incorporation of B and Sv, indicating that the adsorption of OH− on the B-Sv-NiS2@NC surface was more stable, thereby promoting a swift electrochemical reaction. The improved electronic structure of the material, coupled with the increased number of electrochemical active sites, resulted in enhanced OH− adsorption, accelerated redox reaction, and improved charge transfer, ultimately leading to improved electrochemical performance.

Facile hydrothermal synthesis of MoS2 nano-worms-based aggregate as electrode material for high energy density asymmetric supercapacitor

Nowadays, supercapacitors and batteries are trending electrochemical energy storage devices. However, their low energy density and uncertain power density limited their applications, respectively. Recently, the latest innovation in energy storage devices, called hybrid supercapacitors, has appeared as an eventual energy storage device that demonstrates a hybrid storage mechanism of both supercapacitors and batteries. In this work, MoS2 has been prepared by the facile hydrothermal method, characterized by different techniques, and applied as an electrode in supercapacitors and supercapatteries. The XRD patterns and EDX confirm the successful synthesis of MoS2 with an average crystallite size of 62.25 nm, while the SEM images show the randomly oriented nanoworms of MoS2. The XPS spectrum depicts the presence of variable oxidation states of molybdenum (Mo4+and Mo6+) in the MoS2. The electrochemical performance shows that the highest specific capacitance and specific capacity reached 1866.66 F/g and 1119.99 C/g, respectively, at a scan rate of 5 mV/s for MoS2. The asymmetric supercapacitor device is made from (Graphite/MoS2) using as a working electrode and activated carbon as a cathode, which are separated by filter paper. Furthermore, the Dunn's model is utilized to evaluate of capacitive and battery mechanisms and shows the dominant role of diffusive and surface-controlled developments at low and high scan rates, respectively, owing to the change in diffusion time of electrolyte species. The fabricated device shows an energy density and power density of 103.51 Wh/kg and 3807.59 W/kg at a current density of 1 and 7 A/g, respectively, with 93.52% capacity stability and 99.8% coulombic efficiency. This excellent performance of MoS2 is believed to be a potential electrode candidate for asymmetric supercapacitor applications.

High energy density asymmetric supercapacitors enabled by La-induced defective MnO2 and biomass-derived activated carbon

This study reports a high energy density asymmetric supercapacitor enabled by La-induced defective MnO2 and biomass-derived activated carbon. Our findings reveal that the incorporation of La ions enhances the conductivity of α-MnO2, resulting from a significant increase in lattice defects that provide a greater redox active surface area. In the three-electrode system, the synthesized La-doped MnO2 and activated carbon from empty palm bunches (AC-EPB) achieved a maximum capacity of 202 F g−1 and 178 F g−1 at 0.5 A g−1, respectively. In the assembled La0.2Mn0.8O2//AC-EPB asymmetric supercapacitor, we achieved an outstanding energy density of 32.8 Wh Kg−1 at a power density of 4500 Wh Kg−1 while maintaining 97.2% of initial capacity after 5,000 cycles. This research provides new insights into the preparation of defective pseudocapacitive materials by rare-earth metal for energy storage applications.

Binary nickel cobalt oxide (NixCo3-xO4) nanostructures as stable and high-energy density asymmetric supercapacitor electrode material

Nickel cobalt oxides are very desirable for a wide range of scientific research and practical applications due to their smooth redox activity and unquestionable parameter optimization freedom. This report examines the capacitive behaviour of hydrothermally fabricated nickel cobalt oxide nanostructures for potential application in the field of energy storage. According to the findings of our research, the morphology of the nickel-cobalt oxides is highly dependent on reaction time as well as the ratio of Ni/Co. When NiO, NixCox-3O4(I) and NixCox-3O4(II) are deposited on nickel foam, the fabricated electrodes show a specific capacitance of 291, 590, 1948 F g-1 respectively, scanned at 5 mVs−1 in an aqueous electrolyte containing 4 M KOH. The NixCox-3O4(II) electrode shows less cycle fatigue as its initial capacitance dropped by just 17% even after 10k cycles and demonstrating low impedance confirmed by electrochemical impedance spectroscopy (EIS). Moreover, the solid state asymmetric capacitor fabricated by using NixCox-3O4(II) as positive and activated carbon as negative electrode demonstrates the specific energy and power of 38 Whkg−1, 3.3 kW kg−1respectively. These remarkable electrochemical properties, characterized by exceptional stability and high energy density, demonstrated by the NixCox-3O4(II) based electrode unequivocally establish it as an indispensable and highly promising electrode material for utilization in electrochemical energy storage devices.

Facile one-pot synthesis of porous NiCoP@reduced graphene oxide composite as active electrode material for high energy density asymmetric supercapacitor

The superior properties of nanomaterials with a special structure can provide prospects for highly efficient supercapacitors for energy storage applications. Herein, a facile one step hydrothermal process is developed for the synthesis of NiCoP@reduced graphene oxide (NiCoP@RGO) composite as electrode for electrochemical supercapacitors. Furthermore, we report the improvements in the materials technology, demonstrating the NiCoP@RGO nanocomposite electrode with an excellent specific capacitance of 1541–1301 Fg−1 at 1–20 Ag−1, high capacitance retention of 92%, and long cycle life of 5000 cycles. The practical application is showcased in an asymmetric supercapacitor with a high active-material loading. Besides, an asymmetric supercapacitor assembled using the NiCoP@RGO as cathode active material and the activated carbon (AC) as anode active material exhibited a high capacitance of 146 Fg−1 at 1 A g−1 and a high energy density of 49.8 Whkg−1 at a power density of 1245.8 Wkg−1 at an operating voltage of 0–1.6 V, suggesting its promising application as a high-performance electrical energy storage device.

Mixed Phase Nickel‐Cobaltite for High Energy Density Asymmetric Supercapacitor using Cathodic Overpotential Synthesis Route

AbstractFor flexible solid‐state electronics, it is essential to accelerate the transition to renewable materials and environmentally friendly manufacturing procedures. Symmetric supercapacitors (SCs) have a limited voltage window and capacity, hampering their use in practical applications such as portable electronics, hybrid vehicles, and transportation. To improve the energy density of supercapacitors, the strategy of using an advanced pseudo‐capacitive electrode in an asymmetric device configuration is feasible and effective. Here, we report on the design and synthesis of hierarchical honeycomb‐like morphology with controlled Ni/Co molar ratios of NiCo2O4 (NCO) coatings on flexible stainless‐steel substrates utilizing high cathodic overpotential deposition. The NCO electrode retains 90.5% of the three‐electrode capacitance (911 F g−1, or 594 C g−1) even after increasing the current density to 10 A g−1 (∼10 times). Furthermore, we have fabricated a 1.5 V asymmetric supercapacitor (ASC, NCO//AC); such a device delivers maximum specific energy and specific power of 76.8 Wh kg−1 and 16858 W kg−1 in 2 M KOH electrolyte and excellent cycling stability (∼88% retention after 5000 cycles).

Cobalt disulfide/carbon nanofibers with mesoporous heterostructure and excellent hydrophilicity for high energy density asymmetric supercapacitor

Cobalt disulfide/carbon nanofibers with mesoporous heterostructure and excellent hydrophilicity for high energy density asymmetric supercapacitor

MOF-derived NiCo-LDH Nanocages on CuO Nanorod Arrays for Robust and High Energy Density Asymmetric Supercapacitors.

Layered double hydroxide (LDH) is widely explored in supercapacitors on account of its high capacity, adjustable composition and easy synthesis process. Unfortunately, solitary LDH still has great limitations as an electrode material due to its shortcomings, such as poor conductivity and easy agglomeration. Herein, nanoflakes assembled NiCo-LDH hollow nanocages derived from a metal-organic framework (MOF) precursor are strung by CuO nanorods formed from etching and oxidation of copper foam (CF), forming hierarchical CuO@NiCo-LDH heterostructures. The as-synthesized CuO@NiCo-LDH/CF shows a large capacitance (5607 mF cm-2 at 1 mA cm-2 ), superior rate performance (88.3 % retention at 10 mA cm-2 ) and impressive cycling durability (93.1 % capacitance is retained after 5000 cycles), which is significantly superior to control CuO/CF, CuO@ZIF-67/CF, NiCo-LDH/CF and Cu(OH)2 @NiCo-LDH/CF electrodes. Besides, an asymmetrical supercapacitor consists of CuO@NiCo-LDH/CF and activated carbon displays a maximum energy density of 47.3 Wh kg-1 , and its capacitance only declines by 6.8 % after 10000 cycles, demonstrating remarkable cycling durability. The advantages of highly conductive and robust CuO nanorods, MOF-derived hollow structure and the core-shell heterostructure contribute to the outstanding electrochemical performance. This synthesis strategy can be extended to design various core-shell heterostructures adopted in versatile electrochemical energy storage applications.

Exploration, of magnetic sesquioxide nanocomposite as a potential electrode material for the fabrication of high energy density asymmetric supercapacitors

upercapacitor electrode materials with multiple redox-active sites and superior electrical conductivity are highly desirable for future energy storage devices in a cost-effective manner. Here, the nanocomposite (NC) based on the sesquioxides of iron oxide-chromium oxide (Fe2O3-Cr2O3) is synthesized by a one-step hydrothermal approach. Fe2O3-Cr2O3 NC electrode delivers a high specific capacity of 544.2 Cg−1 at the scan rate of 10 mV/s. Trasatti method reveals the charge storage mechanism of Fe2O3-Cr2O3 NC providing the total, outer, and inner capacity of 1118, 71.3, and 1047 Cg−1 respectively. In addition, the low solution resistance (RS) and charge transfer resistance (Rct) of 0.75 and 0.06 Ω respectively are being evaluated by Electrochemical Impedance Spectroscopy (EIS) analysis. Furthermore, the faradic charge–discharge curves with prolonged discharge time are achieved for the Fe2O3-Cr2O3 NC electrode material with the maximum specific capacity of 814 Cg−1 at the current density of 1 Ag−1 and the capacitive retention of 79.2 % is maintained after 5000 consecutive charge–discharge cycles. Hence, the asymmetric supercapacitor (ASC) device is being constructed using Fe2O3-Cr2O3 cathode and activated carbon (AC) anode, delivering a high energy density of 77.17 Wh kg−1 corresponding to the power density of 650 W kg−1.

Tuning the morphology and size of NiMoO4 nanoparticles anchored on reduced graphene oxide (rGO) nanosheets: The optimized hybrid electrodes for high energy density asymmetric supercapacitors

• Porous NiMoO 4 NPs/rGO composite has been prepared through a facile hydrothermal approach followed by thermal treatment. • NiMoO 4 NPs/rGO composite electrode exhibits high specific capacitance of 2056 Fg -1 and long cyclic stability of 91.4 % after 10,000 cycles. • An asymmetric supercapacitor with high energy density and long cycle life is fabricated. In order to improve the capacitive performance of supercapacitors, NiMoO 4 electrode materials were successfully prepared by a simple and low cost hydrothermal route, and the morphology, microstructure and properties of the materials were successfully optimized by adding reduced graphene oxide (rGO). Electrochemical and sophisticated physical property tests are used to examine the qualities of items. As a supercapacitor electrode material, the NiMoO 4 /rGO composite performed admirably. The specific capacitance reached 2056 Fg -1 at a current density of 2 Ag -1 , which is greater than standard NiMoO 4 at the same current density (788 Fg -1 ). After 1000 charge/discharge cycles, NiMoO 4 /rGO retains 91.1 % of its initial capacitance. NiMoO 4 /rGO composites can be used in asymmetric supercapacitors, and the asymmetric supercapacitor device offers a high power density (60. 2 Whkg -1 ) and energy density (750.5 Whkg -1 ) when used as the positive electrode and activated carbon as the negative electrode. A combination of mesoporous-NiMoO 4 nanoparticles with a high specific surface area and good interaction with conductive rGO is responsible for the improved electrochemical performance of NiMoO 4 /rGO.

Self-supported nickel iron selenide@nickel cobalt boride core-shell nanosheets electrode for asymmetric supercapacitors

Optimizing the electrode structure and interface is a promising approach to achieve high energy density asymmetric supercapacitors. In this study, a core–shell heterostructure based on crystalline nickel iron selenide (NiSe2-Fe3Se4) and amorphous nickel cobalt boride (NiCoB) is for the first time in-situ fabricated on carbon cloth substrate though a hydrothermal approach, a selenization process, followed by a chemical precipitation method. In this well-defined hybrid material (denoted as NiSe2-Fe3Se4@NiCoB), the close combination of NiSe2-Fe3Se4 nanosheets core and NiCoB nanosheets shell results in a large specific surface area with rich open channels, and numerous crystalline/amorphous interfaces with regulated electronic structure. Owing to its unique hierarchical pore architecture and synergistic effect of dual battery-type materials, the resultant NiSe2-Fe3Se4@NiCoB electrode displays a specific capacity of 887.0C g−1 at 1 A g−1, wonderful rate retention (71.3% at 20 A g−1), and good cycling stability (86.4% after 5000cycles). Additionally, the assembled NiSe2-Fe3Se4@NiCoB//porous carbon asymmetric supercapacitor illustrates a remarkable energy density of 72.7 Wh kg−1 at 710.7 W kg−1, and exceptional cycling life with capacity retention of 91.1% over 20,000cycles.

Boosting the energy density of supercapacitors by designing both hollow NiO nanoparticles/nitrogen-doped carbon cathode and nitrogen-doped carbon anode from the same precursor

• The hollow NiO/NC was designed based on the Kirkendall effect. • 2. The pure NC with hollow structure was prepared using the same precursor. • 3. DFT calculations prove that NiO/NC and NC have excellent electrochemical performance. • 4. High-energy–density asymmetric supercapacitor of 40.2 Wh kg −1 was achieved. Designing the transition metal oxide-based electrode with hollow nanostructure is of great importance for high-performance supercapacitors. Here, the hollow NiO encapsulated in a nitrogen-doped carbon matrix (NiO/NC) is synthesized by using the precursor of Ni-based metal–organic complex based on the Kirkendall effect. With the same precursor, the hollow NC is obtained by removing the Ni element through an acid etching method. Density functional theory (DFT) calculations convince that both hollow NiO/NC and NC have high electrical conductivity and adsorption energy for OH – , demonstrating their high practicability for supercapacitor applications. In a three-electrode system, the NiO/NC sample prepared under 700 °C displays a high specific capacitance (1026 F g −1 at 1 A g −1 ) and excellent cycle stability (80.2% capacity retention over 8000 cycles). Importantly, a high energy density of 40.2 Wh kg −1 was achieved based on the asymmetric supercapacitor assembled with NiO/NC cathode and NC anode. This work provides new insights on designing high-performance electrode materials to boost supercapacitor performance using the same precursor.