rGO Asymmetric Supercapacitor Research Articles

Experimental and theoretical insights into colossal supercapacitive performance of graphene quantum dots incorporated Ni3S2/CoS2/MoS2 electrode

Transition metal sulfides (TMS) are promising electrode materials for supercapacitor applications due to their unmatchable advantages. To overcome the deficiency of individual metal sulfides, the combination of one or more pseudocapacitive transition metals with conductive carbon material can be a plausible solution. In this work, a simple and one-step hydrothermal synthesis method is used to fabricate the flower-like Ni3S2/CoS2/MoS2 (NCMS) and Ni3S2/CoS2/MoS2-GQDs (NCMS-G) directly on Ni foam and used it as a binder-free electrode for high-performance supercapacitor applications. The NCMS-G-2.5 electrode possessed colossal specific capacitance (2364 Fg−1 at the current density of 2 Ag−1), excellent rate capability (55 % at the current density of 10 Ag−1), as well as good cycling stability (93 % retention after 10,000 cycles at the current density of 20 Ag−1). Furthermore, assembled NCMS-G-2.5//rGO asymmetric supercapacitor (ASC) device delivered an excellent energy density of 84.8 Wh kg−1 and superior cycling performance (98 % capacitance retention after 10,000 cycles). We have investigated the interactions between Ni3S2/CoS2/MoS2 and carbon based nanostructure GQDs employing state-of-the-art Density Functional Theory (DFT) simulations. The interactions between Ni3S2/CoS2/MoS2 and GQDs is not only long range van der Waals interactions, but also chemical interactions involving charge transfer from metal 3d orbital to C 2p orbital of GQDs are also present. Due to this synergic effect, there is enhancement in electronic states near Fermi level which may improve the conductivity of the hybrid structure. Enhanced quantum capacitance, improved conductivity and increased surface area for the hybrid structure may attribute towards superior charge storage performance for the hybrid structures which support experimental data. It is expected that the fabricated, unique, 3D flower NCMS-G-2.5 has potential prospects for developing advanced and high-performance energy storage devices.

Nickel Cobalt LDH/Graphene Film on Nickel-Foam-Supported Ternary Transition Metal Oxides for Supercapacitor Applications

Layered double hydroxides (LDHs) of transition metals have attained significant attention for supercapacitor applications due to their excellent charge storage, low internal resistance, and superior electrochemical stability. Here, a nanocomposite of reduced graphene oxide/nickel cobalt layered double hydroxide (rGO/NiCo LDH) on the surface of nickel foam (NF) containing hierarchical nickel cobalt copper transition metal oxides (TMOs) is prepared through two-step processes of electrochemical and coprecipitation methods. The TMOs/rGO/NiCo LDH nanocomposite is characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman, X-ray energy-dispersive (EDS), and X-ray photoelectron (XPS) spectroscopies as well as by transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM), elemental mapping analysis, nitrogen adsorption/desorption, and contact angle measurements. The supercapacitive behavior of the electrodes has been investigated through cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) measurements, and electrochemical impedance spectroscopy (EIS). The study has shown that the synergetic effect and the electrochemical properties have considerably improved when the layered double hydroxides are synthesized in the presence of rGO. The TMOs/rGO/NiCo LDH nanocomposite exhibits an excellent specific capacitance of 2763 F g–1 at a current density of 1 A g–1 and a stability of 85% after 3000 GCD cycles at a current density of 24 A g–1. Also, a TMOs/rGO/NiCo LDH//rGO asymmetric supercapacitor device is constructed with an aqueous KOH electrolyte, which shows a capacitance of 244 F g–1 at a current density of 1 A g–1. The device attains the highest energy density of 34 Wh kg–1 and power density of 2500 W kg–1, with an excellent cycling stability of 100% after 3000 GCD cycles at a current density of 10 A g–1.

Controlling the electrochemical activity of dahlia-like β-NiS@rGO by interface polarization.

Transition metal sulfides have become more and more important in the field of energy storage due to their superior chemical and physical properties. Herein, dahlia β-NiS with a rough surface and β-NiS@reduced graphene oxide (rGO) have been green synthesized by a one-step hydrothermal method. The interface characteristics of β-NiS@ rGO composites have been systematically studied by XPS, Raman, and first-principles calculations. It is found that the residual O atoms in the interface and the polarization charge generated by them play an important role in performance enhancement. The NiS@rGO composite material has the best electrochemical performance when the C/O ratio is 6.48. Furthermore, we designed a NiS@rGO//rGO asymmetric supercapacitor with a potential window of 1.7 V. Its excellent energy density and power density demonstrate the advantages of the optimized NiS@rGO electrode. When the power density is 850 W kg-1, the energy density can reach 40.4 W h kg-1. Even at a power density of up to 6800 W kg-1, the energy density can be maintained at 17.6 W h kg-1. These encouraging results provide a possible pathway for designing asymmetric supercapacitors with ultra-high performance and a feasible strategy for the precise control of electrochemical performance.

NiCoSe4 nanoparticles derived from nickel–cobalt Prussian blue analogues on N-doped reduced graphene oxide for high-performance asymmetric supercapacitors

Synthesis of NiHCCo precursors via simple co-precipitation and nickel–cobalt tetraselenide composites grown on nitrogen-doped reduced graphene oxide (NiCoSe4/N-rGO) were fabricated using solvothermal method. The introduction of N-rGO used as a template effectively prevented agglomeration of NiCoSe4 nanoparticles and provided more active sites, which greatly increased the electrochemical and electrical conductivity for NiCoSe4/N-rGO. NiCoSe4/N-rGO-20 presents a remarkably elevated specific capacity of 120 mA h g−1 under current density of 1 A g−1. NiCoSe4/N-rGO-20 demonstrates an excellent cycle life and achieves a remarkable 83% retention rate over 3000 cycles with 10 A g−1. NiCoSe4/N-rGO-20//N-rGO asymmetric supercapacitor was constructed based on the NiCoSe4/N-rGO-20 as an anode, N-rGO as cathode by using 2 mol l−1 KOH as an electrolyte. NiCoSe4/N-rGO-20//N-rGO ASC demonstrates an ultra-big energy density of 14 Wh kg−1 and good circulation stability in the power density of 902 W kg−1. It is doubled in comparison to the NiCoSe4/N-rGO-20//rGO asymmetric supercapacitor (7 Wh kg−1). The NiCoSe4/N-rGO-20//N-rGO ASC capacity retention is still up to 93% over 5000 cycles (5 A g−1). The results reveal that this device would be a prospective cathode material of supercapacitors in actual applications.

Ni-Co-Fe layered double hydroxide coated on Ti3C2 MXene for high-performance asymmetric supercapacitor

Ti3C2 MXene is a material with great potential in the field of supercapacitors. A coating structure NiCoFe-LDH/Ti3C2 composite material was prepared via coating nano-scaled NiCoFe-LDH on micron-scaled Ti3C2 MXene through surface functional groups. NiCoFe-LDH composite shows an excellent specific capacity of 1990F g-1 in 1 M KOH at a current density of 1 A g−1, and maintain a specific capacity of 84.8% after 5000 cycles of charging and discharging at a current density of 10 A g−1. NiCoFe-LDH/Ti3C2// RGO asymmetric supercapacitor (ASC) was prepared in a 1 M KOH electrolyte system with the above materials and RGO as positive and negative electrodes respectively. At power densities of 895.1 and 9000 W kg−1, NiCoFe-LDH/Ti3C2//rGO ASC exhibits excellent energy densities of 54.4 and 32.5 W h kg−1 respectively. The significance of this work is that a coating structure NiCoFe-LDH/Ti3C2 MXene composite morphology was successfully synthesized for the first time which showed excellent electrochemical performance in the application of supercapacitors. The proposed method may provide the possibility to synthesize other similar metal hydroxide and MXene composite structures and provide their electrochemical properties.

N, B co-doped and Crumpled Graphene Oxide Pseudocapacitive Electrode for High Energy Supercapacitor

N, B co-doped graphene oxide (NB-GO) establishes a novel electronic structure owing to the distinctive B and N coupling significantly differs from the conventional electrical double-layer mechanism of carbon-based electrodes. The remarkable electrochemical properties of NB-GO are owed by the high content of N (4.61 at.%), and B (4.41 at.%) shrinkages charge transfer resistance, and inflation of the surface polarity as well as pseudocapacitive electro-active sites. The new motifs B-N, C-N, and C-B-N contribute affluent and stable redox-active sites for enhanced pseudocapacitive properties of NB-GO compared to that of the un-doped GO and B doped GO (B-GO), including excellent specific capacitance (885 Fg−1), outstanding rate capability (525 Fg−1 at 10 Ag−1) and good cycle stability (77.8%) retained till 10,000 continuous cycles. NB-GO//RGO asymmetric supercapacitor (ASC) demonstrate an affordable energy density of 23.23 Wh/kg consistent with a massive power density of 872 W/kg with 80% capacitance retention after 10,000 cycles. Therefore, a facile hydrothermal route will be a successful method for synthesizing NB-GO as an alternative for metal oxide/sulfide and polymer-based pseudocapacitive electrode materials for supercapacitor applications.

Textile-based supercapacitors for flexible and wearable electronic applications

Electronic textiles have garnered significant attention as smart technology for next-generation wearable electronic devices. The existing power sources lack compatibility with wearable devices due to their limited flexibility, high cost, and environment unfriendliness. In this work, we demonstrate bamboo fabric as a sustainable substrate for developing supercapacitor devices which can easily integrate to wearable electronics. The work demonstrates a replicable printing process wherein different metal oxide inks are directly printed over bamboo fabric substrates. The MnO2–NiCo2O4 is used as a positive electrode, rGO as a negative electrode, and LiCl/PVA gel as a solid-state electrolyte over the bamboo fabrics for the development of battery-supercapacitor hybrid device. The textile-based MnO2–NiCo2O4//rGO asymmetric supercapacitor displays excellent electrochemical performance with an overall high areal capacitance of 2.12 F/cm2 (1,766 F/g) at a current density of 2 mA/cm2, the excellent energy density of 37.8 mW/cm3, a maximum power density of 2,678.4 mW/cm3 and good cycle life. Notably, the supercapacitor maintains its electrochemical performance under different mechanical deformation conditions, demonstrating its excellent flexibility and high mechanical strength. The proposed strategy is beneficial for the development of sustainable electronic textiles for wearable electronic applications.

Electrochemical Performance of rGO/NiCo2O4@ZnCo2O4 Ternary Composite Material and the Fabrication of an all-Solid-State Supercapacitor Device

An rGO/NiCo₂O₄@ZnCo₂O₄ (RNZC) ternary composite material is synthesized using a simple hydrothermal method. In this report, we demonstrate the effect of rGO concentration on the electrochemical behavior of the rGO/NiCo₂O₄@ZnCo₂O₄ composite materials. The specific capacity values of the ternary composite materials increase with rGO concentration up to 50 mg. Furthermore, on increasing the rGO concentration, the capacity value decreases. Among the prepared samples, the composite with 50 mg of rGO (RNZC3) exhibits a maximum specific capacity of 1197 C g–¹ at a current density of 1 A g–¹. We also demonstrate the design of a supercapacitor device with high specific energy density using RNZC3. The RNZC3//RNZC3 symmetric supercapacitor device exhibits a maximum energy density of 62 W h kg–¹. In the case of an asymmetric supercapacitor device, the applied potential range is extended beyond the water decomposition range. Enhancement of the potential window ensures to achieve a high energy density. The RNZC3//rGO asymmetric supercapacitor device reaches the highest energy density of 71 W h kg–¹ and the corresponding power density is 0.98 kW kg–¹.

Synthesis of CuO@CoNi LDH on Cu foam for high-performance supercapacitors

Core-shell nanostructured compounds are considered as promising electrode materials for supercapacitors in virtue of their facile accessibility to active sites and high electrical conductivity, yet always limited by low capacity or poor cyclic stability because of the weak combination or shedding of active materials from the substrate. To address this issue, we first synthesize three-dimensional (3D) CuO cross-linked nanosheet aggregates grown on Cu foams (CF) by wet chemical oxidation, and further demonstrate the growth of ultra-thin cobalt-nickel layered double hydroxides (CoNi LDH) onto the core of 3D CuO cross-linked nanosheet aggregates by electrodeposition. In this way, we find that the cross-linked CuO@CoNi LDH growing on Cu foams has stronger adhesive force. The as-prepared core-shell nanohybrid (CF@CuO@CoNi LDH) is featured with a high specific capacity (319.4 mAh·g−1 at 1 A·g−1), excellent rate performance and long cycling stability. The as-assembled CF@CuO@CoNi LDH 1–4//RGO asymmetric supercapacitor (ASC) delivers an ultra-high energy density of 92.5 Wh·kg−1 at a power density of 400 W·kg−1, as well as an excellent cycling performance with capacitance retention of 83.8% after 8000 cycles at 5 A·g−1. These results indicate that the cross-linked hybrid is a high-performance electrode material for supercapacitors, and could provide new insight into the synthesis of novel core-shell nanomaterials.

Hydrothermal Synthesis of Humate‐Layer‐Based Bimetal Organic Framework Composites as High Rate‐Capability and Enery‐Density Electrode Materials for Supercapacitors

AbstractA humate‐layer‐based bimetal organic framework (HA‐NiCo‐BPDC) material is successfully synthesized using humate layers obtained by ultrasonic‐hydrothermal peeling as a substrate and BPDC as a ligand via a hydrothermal approach. It exhibits a porous composite structure in which flower‐like NiCo‐BPDC nanosheets are loaded on humate layers, originating a guiding effect of humate layers on the NiCo‐BPDC growth. HA‐NiCo‐BPDC owns a similar crystal structure to NiCo‐BPDC, in which humate and BPDC ions have coordinated with nickel or cobalt ions to form carboxylates. Nickel and cobalt ions present positive divalent states, and they have close ability to coordinate with BPDC or humate ions. Owing to unique hierarchical architectures and fascinating synergetic effects between NiCo‐BPDC nanosheets and humate layers, HA‐NiCo‐BPDC has high specific capacitance and rate capability, and low internal resistance and charge transfer resistance. It exhibits better rate capability than NiCo‐BPDC and larger specific capacitance than HA−Ni(Co)‐BPDC. Moreover, HA‐NiCo‐BPDC//rGO asymmetric supercapacitor has wide operating potential window, high energy density and cycling stability. All those show that HA‐NiCo‐BPDC composites are a promising electrode material for supercapacitors. This study exploits a novel way for value‐added applications of humates and their natural sources “humic acids”.

Controllable synthesis of reduced graphene oxide/nickel hydroxide composites with different morphologies for high performance supercapacitors

This work aims to synthesize reduced graphene oxide/nickel hydroxide composites, recorded as rGO/Ni(OH)2, with different morphologies (nanoflakes, sticks, flowers and cubes) and analyze how different additional agents (tween−80 and sodium oxalate) affect their microstructure and electrochemical performance. We put forward here a simple, low cost and controllable chemical reaction method to large−scale production of rGO/Ni(OH)2 composites with high performance. At a charge and discharge current density of 1 A/g, the specific capacitance of the rGO/Ni(OH)2 composite electrodes is 1670.4, 1866.8, 890.6 and 366.9 F/g for nanoflakes, sticks, flowers and cubes, respectively. Comparatively, the specific capacitance of the rGO/Ni(OH)2 nanoflakes, sticks, flowers and cubes keep 79.5%, 29.2%, 85.3% and 34.9%, respectively, when the current density changes from 1 to 20 A/g, and the capacitance remains respectively 172%, 15%, 90% and 100% of their initial values after 3000 cycles. Furthermore, the assembled rGO/Ni(OH)2 nanoflakes//rGO asymmetric supercapacitor shows a wide voltage window (0–1.6 V), stable cycling performance (capacitance retains 158% after 3000 cycles), excellent specific energy density (54.1 Wh/kg at a power density of 1.0 kW/kg and 26.79 Wh/kg at a power density of 30.9 kW/kg). The successful preparation of rGO/Ni(OH)2 with various morphologies paves a new way for tailoring the microstructure and optimizing the electrochemical performance of graphene−based composite electrodes for high performance supercapacitor applications.

Trifunctional of Phosphorus-Doped NiCo2O4 Nanowire Materials for Asymmetric Supercapacitor, Oxygen Evolution Reaction, and Hydrogen Evolution Reaction.

Nowadays, transition-metal oxides are regarded as the most potential materials for the supercapacitor and electrocatalyst. However, the poor electrical conductivity and insufficient active sites limited their development in various fields. Herein, we report the method of phosphorous-doped NiCo2O4 (named as P-NCO) prepared by the two-step strategy: the NiCo2O4 nanostructure is grown on the nickel foams by hydrothermal treatment and subsequently phosphatized in a tube furnace. Successfully, the rich oxygen vacancies and the P element introduced into the NiCo2O4 structure obviously improve the electrical conductivity, and the resulting P-NCO NWs/NF material shows an ultrahigh specific capacitance of 2747.8 F g-1 at 1 A g-1 and a prominent rate performance (maintain 50% at 100 A g-1). Furthermore, the assembled P-NCO NWs/NF//RGO asymmetric supercapacitor has an energy density of 28.2 W h kg-1 even at a high power density of 7750.35 W kg-1. After 10,000 cycles, the capacitance still also has an 88.48% retention rate. As an electrocatalyst, P-NCO NWs/NF has an excellent hydrogen evolution reaction (55 mV at 10 mA cm-2) and oxygen evolution reaction (300 mV at 10 mA cm-2) activities in 1 M KOH solution. This study provides an effective strategy to prepare multifunctional materials.

Facile synthesis of hierarchical NiCoP nanowires@NiCoP nanosheets core–shell nanoarrays for high-performance asymmetrical supercapacitor

Transition metal phosphides have been regarded as reliable supercapacitor electrode materials and extensively researched. In this work, a facile three-step way has been taken to synthesize NiCoP@NiCoP core–shell nanoarrays directly grown on carbon cloth, which was used as a high-performance supercapacitor electrode. Compared with the NiCo-LDH precursor and NiCoP nanowire and NiCoP nanosheet, NiCoP@NiCoP core–shell composite shows higher electrochemical performance owing to the integration of the advantages of phosphides and core–shell structure. To be specific, the as-fabricated NiCoP C–S electrode exhibits great electrochemical performance with high specific capacitance (1492.5 F g−1 at 1 A g−1), good rate performance (68.82% of the initial specific capacitance at 15 A g−1) and outstanding cycling stability (maintains 80.9% of the initial capacitances after 5000 cycles at 10 A g−1). Moreover, the assembled NiCoP C–S//rGO asymmetric supercapacitor device delivers a high energy density of 48.13 Wh kg−1 at the power density of 1125 W kg−1 and it still retains 20.94 Wh kg−1 at a high power density of 11250 W kg−1, indicating its great possibility of practical application.

Phytic acid modified manganese dioxide/graphene composite aerogel as high-performance electrode materials for supercapacitors

Incorporating manganese dioxide (MnO2) with reduced oxide graphene (RGO) holds great potential as favourable supercapacitor electrodes for energy storage applications. In order to improve the adhesive strength and stability, we synthesized a phytic acid (PA)-linked MnO2/RGO aerogel (MnO2/P-RGO) through a simple self-assembled hydrothermal and freeze-drying method. Herein, PA as a bridge could accelerate the firm immobilization of MnO2 on RGO sheets to synthesize the composite aerogel with a three-dimensional (3D) layered porous structure. The 3D MnO2/P-RGO composite aerogel as a supercapacitor electrode could achieve the high specific capacitance of 645 F g−1 under the current density of 1 A g−1 and 410 F g−1 at 40 A g−1. Furthermore, the composite aerogel exhibits remarkable long-term stability, 94.9% of the initial capacitance after 10,000 cycles under the high current density of 20 A g−1. Moreover, the assembled MnO2/P-RGO//RGO asymmetric supercapacitor (ASc) shows the maximum energy density of 59.2 W h kg−1at 1.48 kW kg−1 and could remain 28.8 W h kg−1 at the maximum power density of 57.6 kW kg−1. Additionally, the MnO2/P-RGO//RGO ASc also exhibits excellent long cycling stability with 91.6% of the initial capacitance after 10,000 cycles at 20 A g−1, indicating its promising practical application for high-efficiency supercapacitors.

Facile synthesis of NiCoP nanosheets on carbon cloth and their application as positive electrode material in asymmetric supercapacitor

Transition metal phosphides (TMPs) are regarded as reliable supercapacitor electrode materials due to its high conductivity and excellent chemical activity. In this work, NiCo-LDH was synthesized via electrode position techniques, followed by one-step phosphating to convert the hydroxide into a phosphide. The obtained NiCoP shows 3D porous nanosheet stack structure, which provides a larger specific surface area and more active sites. The as-fabricated electrode exhibits good electrochemical performance with high specific capacitance (1142.84 F g−1 at 1 A g−1), good rate capabilities (62.07% of the initial specific capacitance at 10 A g−1), and outstanding cycle stability (maintains 74.5% of initial capacitances after 5000 cycles at 10 A g−1). Owning to superior electrical conductivity and excellent redox activity of phosphide, its voltage window and cycle stability are significantly improved compared with NiCo-LDH. In addition, NiCoP was used as the positive electrode and rGO as the negative electrode to fabricate the NiCoP//rGO asymmetric supercapacitor, which delivers a voltage window of 1.5 V and a high energy density of 14.7 Wh kg−1 at a power density of 753.6 W kg−1.

In situ growth of CuCo2S4 nanocrystals on N, S-codoped reduced graphene oxide nanosheets for supercapacitors

The design and synthesis of an electrode material with high specific capacitance and superior cycle stability for supercapacitors is extremely desirable. CuCo2S4 nanocrystals uniformly grown on the surface of N, and S codoped reduced graphene oxide (CuCo2S4/N, S–RGO) nanosheets were achieved via a one-step hydrothermal method. In this process, doping, sulfuration, and reduction were simultaneously achieved using thiosemicarbazide as raw material. When applied as an electrode material for supercapacitors, CuCo2S4/N, S–RGO hybrids offered higher specific capacity compared to CuCo2S4 nanocrystals. Furthermore, a CuCo2S4/N, S–RGO//N, S–RGO asymmetric supercapacitor (ASC) was assembled. The as-prepared ASC delivered the specific energy of 10.8 Wh kg–1 at 400 W kg–1 and good cycle performance (88.9% retention for 5000 cycles). In addition, an ASC device can drive a mini-fan. Therefore, CuCo2S4/N, S–RGO hybrids are potential electrode materials for supercapacitors.

Nitrogen-doped double-layer graphite supported CuCo2S4 electrode for high-performance asymmetric supercapacitors

CuCo2S4 synthesized on the nitrogen-doped double-layer graphite (NDG) inter-layer revealed more uniform and smaller size than synthesized directly on Ni foam. From electrochemical measurements, the specific capacitance of CuCo2S4@NDG electrode was 1244 F g−1 at a current density of 50 A g−1, which was twice higher than the CuCo2S4@Ni electrode. In addition, the reduced graphene oxide (rGO) was used to assemble CuCo2S4@NDG//rGO asymmetric supercapacitor, revealing a high energy density (58.4 W h kg−1) for practical applications. Significantly, the NDG inter-layer improved the properties of asymmetric supercapacitor at high-rate and high energy density conditions effectively.

Solid-state chemical fabrication of one-dimensional mesoporous β-nickel molybdate nanorods as remarkable electrode material for supercapacitors

Simple solid-state chemical reaction was adopted to synthesize NiMoO4 nanomaterials with different crystal phase without the use of organic solvent or templating agent. The as-prepared NiMoO4·xH2O, α-NiMoO4 and β-NiMoO4 nanostructures were investigated as the electrode materials for supercapacitors. The β-NiMoO4 nanorods were composed of the nanoparticles, which exhibited relatively high specific capacitances about 1415 F g−1 at a charge density of 1 A g−1, 80.2% of the initial reversible capacity was maintained after 1000 cycles. The β-NiMoO4//rGO asymmetric supercapacitor (ASC) system was assembled in serials, which displayed high specific energy density of 29.3 Wh kg−1 at a high power density of 187 W kg−1. This ASC system can drive the light-emitting diode (LED) effectively and give out light about 40 min, even easily light two LEDs in serials for 20 min. The remarkable electrochemical performances make the as-prepared NiMoO4 nanostructures an excellent candidate as electrode materials for advanced supercapacitors.

LaMnO3/RGO/PANI Ternary Nanocomposites for Supercapacitor Electrode Application and Their Outstanding Performance in All-Solid-State Asymmetrical Device Design

The rapid growth of energy demand and lack of sustainable energy conversion/storage devices have made the supercapacitor an inevitable substitute to current storage systems. However, the major limitation to the cutting edge lies in superconductors’ relatively low energy density compared to batteries. Here, we report LaMnO3/RGO/PANI ternary composite fabricated via in situ polymerization route as an efficient electrode material with enhanced energy density. The all-solid-state designs of both LaMnO3/RGO/PANI∥LaMnO3/RGO/PANI symmetric supercapacitor and LaMnO3/RGO/PANI∥RGO asymmetric supercapacitor have been highlighted in this work. The asymmetric supercapacitor device exhibits a superior electrochemical performance (Sc = 111 F g–1 at 2.5 A g–1 and >50% retention at 20 A g–1) than a symmetric supercapacitor device although both of these devices have an appreciable electrochemical behavior. The asymmetric supercapacitor device delivers a maximum energy density of 50 Wh kg–1 at a power density of 2.25 kW kg–...

Fabrication of the porous MnCo2O4 nanorod arrays on Ni foam as an advanced electrode for asymmetric supercapacitors

In this work, the porous MnCo2O4 nanorod arrays on three-dimensional Ni foam (PMCN@NF) as electrode material have been fabricated through a mild co-precipitating reaction at room temperature followed by a subsequent thermal treatment. The PMCN@NF electrode material have been characterized by XRD, SEM, TEM, EDS-mapping, BET and XPS technologies. The capacitive performances of the PMCN@NF electrode have been investigated by CV, GCD and EIS. This porous structure possesses an average diameter of ∼6.7 nm. BET interface area is measured to be 105.6 m2 g−1 for this PMCN@NF electrode. This PMCN@NF electrode exhibits the good capacitance of 845.6 F g−1 (tested condition: 1 ampere per gram, 1 A g−1). After 2000 cycles test, it shows a 90.2% retention for specific capacitance of the first test. The MnCo2O4//rGO asymmetric supercapacitor with the stable opening voltage of 1.6 V delivers a maximum energy density of 53.7 Wh kg−1 (when the power density is 1600 W kg−1). When this power density up to 8000 W kg−1, it still achieves an energy density of 31.6 Wh kg−1. The cyclic stability of this device after 5000 cycles can achieve an initial capacitance retention of 82.0%. These results indicate that the porous MnCo2O4 nanorod arrays electrode material is a promising functional material for advanced energy conversion and storage equipment.