All-solid-state Asymmetric Supercapacitor Device Research Articles

Synthesis of 2D bi-metallic Zn/Cu metal-organic framework integrated graphene nanocomposites for all-solid-state asymmetric supercapacitors

In this work, a novel two-dimensional (2D) bi-metallic metal-organic frameworks (MOFs) consisting of zinc and copper metal centers with 1,3,5-tricarboxylic acid as a chief and efficient organic linker (Zn/Cu-BTC) and its composite with exfoliated graphene nanosheets (EGNSs) have been investigated for supercapacitor applications. The composites were synthesized via facile in-situ solvothermal process. Different spectroscopic, microscopic, and surface analyses confirmed the successful formation of porous electroactive composites, where 2D MOF nanosheets were vertically grown on the EGNS surfaces. In the two-electrode symmetric system, the as-synthesized Zn/Cu-BTC MOF@EGNS electrode achieved an enhanced specific gravimetric capacitance and equivalent volumetric capacitance of 1284.9 F/g and 813.3 F/cm3 at 0.5 A/g. It exhibits high-rate performance and prolonged cycling stability with >90 % retention after 8000 cycles. All-solid-state asymmetric supercapacitor (ASC) device was constructed with Zn/Cu-BTC MOF@EGNS composite and EGNS electrodes, where PVA-KOH membrane served as a separator-cum-electrolyte. The ASC device delivered a satisfactory energy density of 60.55 Wh kg−1 and a maximum power density of 10 kW kg−1 with an admirable cycling stability of 92 % after 10,000 charge-discharge cycles. In the future, this work can encourage manufacturing innovation.

A novel hierarchical core-shell structure of NiCo2O4@NiCo-LDH nanoarrays for higher-performance flexible all-solid-state supercapacitor electrode materials

In the present work a 3D hierarchical NiCo 2 O 4 @NiCo-LDH core-shell structure has been fabricated on activated carbon cloth through a facile hydrothermal strategy and an electrodeposition step. The core of the NiCo 2 O 4 nanowires forms the nanoarray backbone on carbon cloth while the shell of NiCo-LDH nanosheets extends the electrochemical active sites and generates mesoporous hierarchical channels to facilitate electron and ion transport. Therefore, with the optimized mass ratio of 1.9 between NiCo-LDH and NiCo 2 O 4 , such a core-shell structure enhanced the areal capacitance of the as-prepared NiCo 2 O 4 @NiCo-LDH electrode up to 6092 mF/cm 2 (or areal capacity of 0.846 mAh/cm 2 at 2 mA/cm 2 for the battery type pseudocapacitor) and obtain high specific capacitance of 1882 F/g under 1 A/cm 2 . The capacity retention rate can maintain 83.9 % after 5000 cycles at 30 mA/cm 2 . Furthermore, an all-solid-state asymmetric supercapacitor (ASC) was assembled using NiCo 2 O 4 @NiCo-LDH//activated carbon. Such an ASC exhibits a very high energy density of 49 Wh/kg at the power density of 750 W/kg and retains 30 Wh/kg at 7500 W/kg. The ASC shows its excellent cycling stability by keeping 83.3 % of initial capacity retention rate after 2000 cycles under 5 A/g. The assembled flexible all-solid-state supercapacitor with NiCo 2 O 4 @NiCo-LDH//activated carbon exhibits good mechanical stability and high specific capacity of 157 F/g under 1 A/g. The significantly improved electrochemical properties demonstrates the practical applications of the core-shell structure of NiCo 2 O 4 @NiCo-LDH on carbon cloth for novel ASC configuration design and development of next energy storage devices. • The unique NiCo 2 O 4 @NiCo-LDH cover-shell heterostructure greatly improve the electrochemical performance. • The NiCo 2 O 4 @NiCo-LDH//ACC electrode shows the high area capacitance of 6092 mF/cm 2 . • The NiCo 2 O 4 @NiCo-LDH//AC ASC device has good flexibility, high energy density and power density.

Boosting the Electrochemical Performance of Mn-doped CuCo2O4/CuO Heterostructures for All-Solid-State Asymmetric Battery-type Supercapacitors

The introduction of Manganese (Mn) ions (2+ ⇋ 3+ ⇋ 4+) to transition metal oxides proved to be a potential strategy to tailor the redox behavior of these materials for energy storage. We fabricate a lower electronegative element (i.e., Mn) doped copper cobaltite and copper oxide (CuCo2O4/CuO; CCO) heterostructures electrodes through the hydrothermal synthesis route. The ensued electrodes have a more than 2-fold improvement in specific capacity (382.9 C g−1) than the undoped CCO electrode (120.8 C g−1) at 1 A g−1. The all-solid-state asymmetric supercapacitor (ASC) practical device is constructed with higher Mn-doped CCO heterostructures as the positive electrode and activated carbon (AC) as the negative electrode. With a voltage window of 1.5 V, the fabricated ASC device has a high specific energy of 52.6 Wh kg−1 and specific power of 774.3 W kg−1. The long-term cyclic stability of 92% capacity retention after 5000 cycles at the current density of 4 A g−1. Additionally, two ASC devices are series-connected that can power up a red light-emitting diode (LED) display for more than 150 s, demonstrating the device’s efficient power delivery.

Hierarchical MnCo2O4@CuCo2O4 core-shell nanoarrays on carbon cloth as binder-free electrode for flexible all-solid-state asymmetry supercapacitors

Hierarchical core-shell nanowire arrays with a shell of CuCo2O4 nanosheets and a core of MnCo2O4 nanowires directly coated on the conductive carbon cloth (CC) are rationally designed and synthesized via a facile hydrothermal route with a post low-temperature thermal treatment in air. The binder-free MnCo2O4@CuCo2O4/CC composite material exhibits an enhanced performance (1241.0 C g−1 at 1 A g−1) compared with the MnCo2O4/CC (832.7 C g−1 at 1 A g−1) and CuCo2O4/CC (734.1 C g−1 at 1 A g−1). In addition, the MnCo2O4@CuCo2O4/CC electrode is assembled into a flexible all-solid-state asymmetric supercapacitor (ASC), which delivers a maximum specific energy of 62.0 Wh kg−1 at a specific power of 747.2 W kg−1 with 91.2% capacity retention after 10000 charge–discharge cycles at 8 A g−1. And the ASC device also exhibits 91.7% capacity retention at floating time over 200 h at 8 A g−1. Further, the MnCo2O4@CuCo2O4//AC device shows superior flexible performance while bending at various angles. These results make this MnCo2O4@CuCo2O4 core/shell composite to be a good candidate for flexible all-solid-state electrochemical capacitors applications.

Core-shell structured ZIF-7@ZIF-67 with high electrochemical performance for all-solid-state asymmetric supercapacitor

Zeolitic imidazolate frameworks (ZIFs) are considered as a promising material for energy storage in recent years. Here, core-shell structured ZIF-7@ZIF-67 is synthesized in this work. The core-shell structured material can promote electron transfer of inner-outer metals ions of ZIF-7@ZIF-67, quicken diffusion of electrolyte ions and improve the capacitance performance compared to the ZIF-7 and ZIF-67. ZIF-7@ZIF-67 delivers good energy storage ability with a specific capacitance of 518.9 F g−1 at a current density of 1 A g−1 and remarkable stability with a retention of 99.6% after 4000 cycles in the three-electrode system. Furthermore, an all-solid-state asymmetric supercapacitor (ASC) device is assembled based on core-shell structured ZIF-7@ZIF-67 as positive electrode. Impressively, the ASC device displays an energy density of 31 Wh kg−1 at a power density of 400 W kg−1 and an excellent cyclic stability with 99.5% retention after 10,000 cycles at a current density of 10 A g−1. Finally, two all-solid-state ASCs are contacted to power various lighting-emitting diodes (LED). The red LED can be kept glowing for over 10 min. These electrochemical characteristics suggest that core-shell structured ZIF-7@ZIF-67 is a potential material for energy storage device with long-life cyclic stability.

MgCo2O4@NiMn layered double hydroxide core-shell nanocomposites on nickel foam as superior electrode for all-solid-state asymmetric supercapacitors

In this work, MgCo2O4@NiMn layered double hydroxide (LDH) core-shell structured nanocomposites on Ni foam (NF) are synthesized by facile hydrothermal and calcination methods. MgCo2O4/NF is synthesized first via a hydrothermal reaction and annealing treatment, and then utilized to prepare MgCo2O4@NiMn-LDH/NF core-shell structured nanocomposites via the second hydrothermal process. It is found that the MgCo2O4@NiMn-LDH/NF nanocomposite prepared from 6 h hydrothermal reaction (MC@NM-LDH-2) exhibits an excellent specific capacitance of 3757.2 F g−1 (at 1 A g−1). Moreover, a high capacitance retention (86.9% after 6000 cycles) and a low internal resistance (Rs) (0.565 Ω) can be achieved. Furthermore, an all-solid-state asymmetric supercapacitor (ASC) is assembled using MgCo2O4@NiMn-LDH/NF-2 as positive electrode and activated carbon (AC) as negative electrode. The as-fabricated MgCo2O4@NiMn-LDH/NF-2//AC ASC shows a high energy density of 62.33 Wh kg−1 at 750 W kg−1. Meanwhile, the MgCo2O4@NiMn-LDH/NF-2//AC ASC device possesses an outstanding cycling stability of 93.7% retention of the initial capacitance after 6000 cycles and three ASC devices connected in series can light up a LED bulb for 15 min. Our results manifest that these core-shell structure MgCo2O4@NiMn-LDH nanocomposites could envision huge potential application in energy storage devices.

Facile construction of MgCo2O4@CoFe layered double hydroxide core-shell nanocomposites on nickel foam for high-performance asymmetric supercapacitors

In this work, hierarchical MgCo2O4@CoFe layered double hydroxide (LDH) core-shell nanowire arrays on Ni foam (NF) are synthesized by facile hydrothermal and calcination methods. MgCo2O4/NF has been first synthesized via a hydrothermal reaction and annealing treatment and then utilized to prepare MgCo2O4@CoFe-LDH/NF core-shell nanocomposites via the second hydrothermal reaction. It is found that the MgCo2O4@CoFe-LDH/NF core-shell nanocomposite prepared from 3 h hydrothermal reaction (MC@CF-LDH-3) exhibits an excellent specific capacitance of 903.15 C g−1 (2007 F g−1) at the current density of 1 A g−1. Moreover, a high capacitance retention (80.2% maintained after 5000 cycles) and a low internal resistance (Rs) (0.75 Ω) can be acquired. Furthermore, an all-solid-state asymmetric supercapacitor (ASC) is assembled using MgCo2O4@CoFe-LDH/NF-3 as the positive electrode and activated carbon (AC) as the negative electrode. The as-fabricated MgCo2O4@CoFe-LDH/NF-3//AC ASC shows a high energy density of 60.82 Wh kg−1 at 725 W kg−1. Meanwhile, the MgCo2O4@CoFe-LDH/NF-3//AC ASC device possesses an excellent cycling stability of 93.6% retention of the initial capacitance after 5000 cycles and two ASC devices connected in series can light up a LED bulb for 8 min. Our results manifest that this hierarchical MgCo2O4@CoFe-LDH composite has huge potential application in energy storage devices.

Direct growth of NiCo2O4 nanosheet arrays on 3D-Ni-modified CFs for enhanced electrochemical storage in flexible supercapacitors

The rapid development of wearable and portable smart equipment has led to a research boom in flexible energy storage devices. Herein, NiCo2O4 nanosheet arrays have been successfully grown on carbon fibers (CFs), which was firstly modified by the three-dimensional Ni (3D-Ni) to repair the cracks and grooves in the surface of CF. The obtained CFs@3D-Ni/NiCo2O4 electrode possesses a high specific capacity of 736 F/g at 1 A/g current density in the three-electrode system. More importantly, the composite showed excellent electrochemistry stability after temperature plummets. The all-solid-state asymmetric supercapacitor device (ASC) assembled by CFs@3D-Ni/NiCo2O4 delivers a wonderful specific capacity of 176 F/g, a high energy density 55 W h/Kg at 750 W/Kg, excellent cycling stability (about 97.84% after 2000 cycles), and high flexibility (almost no influence in electrical performance at various bending angles). This work has provided a promising method to prepare high performance of the flexible and lightweight energy storage equipment.

Nanoporous electrospun NiCo2S4 embedded in carbon fiber as an excellent electrode for high-rate supercapacitors

The intertwined fiber structure is advantageous as a structure of supercapacitor electrode material. In this paper, the NiCo2S4 embedded in carbon fiber (NiCo2S4/CF) has been prepared through hydrothermal vulcanization of electrospun NiCo2O4/carbon nanofibers precursor. It is a simple way to integrate the pseudocapacitive material with carbon, rendering high capacitance (1169 F g−1 at 1 A g−1), excellent rate capability (81.3% at 20 A g−1) and superior cycle stability (87.2% capacitance retention after 10,000 cycles). Afterwards, an all-solid-state asymmetric supercapacitor device (ASC) has been prepared with the NiCo2S4/CF positive electrode and porous carbon nanofiber negative electrode. When the power density of ASC is 878.3 W kg−1, the energy density can reach 28.8 Wh kg−1 with excellent cycle stability.

Fabrication of CuO@NiMoO4 core-shell nanowire arrays on copper foam and their application in high-performance all-solid-state asymmetric supercapacitors

Hierarchical CuO@NiMoO4 core-shell nanowire arrays were directly fabricated on three-dimensional (3D) copper foam (CF) with a facile two-step route coupled with a post-thermal treatment. The optimized CuO@NiMoO4 composite electrode achieved a high capacitance of 2600.0 F g−1 (3.9 F cm−2) at a current density of 3 mA cm−2. Besides, an all-solid-state asymmetric supercapacitor (ASC) was assembled using the CuO@NiMoO4 electrode as positive electrode and activated carbon (AC) as the negative electrode, which exhibited a high energy density of 42.28 W h kg−1 at a power density of 631.57 W kg−1 and retained 24.8 W h kg−1 even at a high power density of 12763.4 W kg−1. Furthermore, the ASC device showed a high cycling performance with 90.4% retention of its initial capacitance after 5,000 constant charge-discharge process at a high current density of 10 mA cm−2. Two ASC devices were further employed as the energy source for a 5 mm light emitting diode (LED) that was lightened for more than 5 min, demonstrating its great potential in next-generation energy storage device applications.

Preparation of NiMoO4-PANI core-shell nanocomposite for the high-performance all-solid-state asymmetric supercapacitor

In this work, the high conductivity nanocomposite of NiMoO4-PANI (polyaniline) is synthesized via chemical polymerization, while NiMoO4 nanorods are prepared with a solvothermal method. Furthermore, based on NiMoO4-PANI nanocomposite, we fabricate supercapacitor electrode, which shows an excellent chemical stability of 80.7% and a good specific capacitance of 1214 F g−1. In addition, we assemble an all-solid-state asymmetric supercapacitor (ASC) device, which uses NiMoO4-PANI and activated carbon (AC) as positive electrode and negative electrode, respectively. The ACS device demonstrates 33.07 Wh kg−1 at 240 W kg−1, 93 F g−1 at 0.3 A g−1 and a high retention value (about 98.6% of original value after 5000 cycles) of capacitance. Finally, two white LEDs can work for 15 min by using the ASC device (finished charging). Thus it can be seen that such unique properties of the binary nanocomposite strongly couple the advantages of the impressively high cyclic stability of NiMoO4 and good electrical conductivity of PANI, respectively, which mainly give credit to synergistic effects of NiMoO4 and PANI.

Hierarchical core-shell structures of P-Ni(OH)2 rods@MnO2 nanosheets as high-performance cathode materials for asymmetric supercapacitors.

The hierarchical porous structure with phosphorus-doped Ni(OH)2 (P-Ni(OH)2) rods as the core and MnO2 nanosheets as the shell is fabricated directly by growth on a three-dimensional (3D) flexible Ni foam (NF) via a two-step hydrothermal process. As a binder-free electrode material, this unique hybrid structure exhibits excellent electrochemical properties, including an ultrahigh areal capacitance of 5.75 F cm-2 at a current density of 2 mA cm-2 and great cyclic stability without capacitance loss at a current density of 20 mA cm-2 after 10 000 cycles. Moreover, an all-solid-state asymmetric supercapacitor (AAS) based on a P-Ni(OH)2@MnO2 hybrid structure on Ni foam as the cathode and activated carbon (AC) as the anode is successfully assembled to enhance value the electrochemical properties. The AAS device also shows excellent electrochemical properties including a large potential window of 0∼1.6 V, an areal capacitance is 911.3 mF cm-2 at a current density of 1 mA cm-2 and long-term cycling performance. Meanwhile, the AAS device also delivers a high energy density of 0.324 mW h cm-2 at a power density of 0.8 mW cm-2; and can easily light colorful light-emitting diode (LED) lights, suggesting that 3D P-Ni(OH)2@MnO2 hybrid composite has promising potential for practical use in high-performance supercapacitors.

Ni-Co-S/Co(OH)2 nanocomposite for high energy density all-solid-state asymmetric supercapacitors

Rational design and synthesis of hybrid structures consisting with multiple pseudocapacitive components are challenging to develop materials with a high energy density for conversion and storage applications. Herein, a novel and cost-effective two-step method has been developed to synthesize three-dimensional (3D) nickel cobalt sulfides (Ni-Co-S)/Co(OH)2 nanocomposite with synergistic effect to provide an excellent comprehensive electrochemical performance, which shows a high specific capacitance (1560.8 Fg−1 at 1 A g−1) and outstanding rate capability (953.3 Fg−1 at 30 A g−1). Subsequently, an all-solid-state asymmetric supercapacitor (ASC) was successfully assembled using Ni1-Co2-S/Co(OH)2 nanocomposite as the positive electrode, activated carbon (AC) as the negative electrode and an alkaline PVA gel (PVA/KOH) as electrolyte. The Ni1-Co2-S/Co(OH)2//AC all-solid-state ASC device with a voltage window of 1.6 V delivered a maximum energy density of 48.8 W h kg−1 at a power density of 800 W kg−1 with excellent cycle stability. Excitedly, two all-solid-state ASCs assembled in series under fully charged can effectively light up four parallel connected light-emitting diodes (LEDs) for around 10 min, and can power a white LED (working voltage, 3.0–3.4 V) effectively. These remarkable electrochemical performances of Ni1-Co2-S/Co(OH)2//AC are beneficial to their practical applications for high-performance energy storage.

High-performance flexible all-solid-state asymmetric supercapacitors from nanostructured electrodes prepared by oxidation-assisted dealloying protocol

Flexible all-solid-state energy storage devices that can function under considerably large mechanical deformation have shown great promise for portable electronics applications. However, conventional techniques are cumbersome in building cost-effective flexible all-solid-state energy storage devices, thus limiting their widespread applications. Here we report a flexible all-solid-state supercapacitor whose electrodes were prepared via a facile oxidation-assisted dealloying protocol for the first time. The electrodes demonstrate good flexibility and excellent performance. We assembled a prototype all-solid-state asymmetric supercapacitor (ASC) from the as-prepared Co3O4 flakes and γ-Fe2O3 nanoparticles as the positive and negative electrodes, respectively. The flexible ASC device possesses an extended operating voltage window of 1.7V and a high energy density of 38.1Wh/kg. We also demonstrated that four supercapacitor cells that were constructed in series illuminated 52 LEDs for at least 7min. The ASC device has excellent power density and energy density that comparable to the art-of-the-state supercapacitors reported in the literature, and retains good charge and discharge performance under different bending conditions. The synthesis strategy reported here may be beneficial to the low-cost mass production of nanostructured electrode materials for energy storage applications.

Synthesis and characterization of hierarchical Bi2MoO6/Polyaniline nanocomposite for all-solid-state asymmetric supercapacitor

Bi2MoO6/Polyaniline (PANI) hybrid nanocomposite with enhanced specific capacity and rate performance was synthesized by compositing Bi2MoO6 with the PANI layer using sodium lignosulphonate (SLS) as a dopant through a simple chemical polymerization. The Bi2MoO6/PANI (BMP) nanocomposite affords a large reaction surface area, an excellent structural stability, a large number of active sites, good strain accommodation, and fast electron and ion transportation compared with pure Bi2MoO6, which all are beneficial for improving the electrochemical performance. Hence, the Bi2MoO6/PANI electrode with 0.15g Bi2MoO6 (BMP-2) shows a high specific capacitance of 826Fg−1 at a current density of 1Ag−1 and capacitance retention of 75.5% after 3000 cycles at a current density of 5Ag−1, which is higher than pristine Bi2MoO6 and other electrodes. In addition, an all-solid-state asymmetric supercapacitor (ASC) fabricated by the BMP-2 electrode and activated carbon (AC) displays a high specific capacitance of 90.0Fg−1 and a high energy density of 31.9 Wh kg−1. Moreover, the BMP-2//AC ASC device exhibits high cycle stability, and 86.5% of its initial capacitance is retained after continuous 6000 cycles. Therefore, these results will promote a promising potential application of the Bi2MoO6/PANI nanocomposite for use as an effective electrode material in supercapacitors.

An Approach To Fabricate PDMS Encapsulated All-Solid-State Advanced Asymmetric Supercapacitor Device with Vertically Aligned Hierarchical Zn-Fe-Co Ternary Oxide Nanowire and Nitrogen Doped Graphene Nanosheet for High Power Device Applications.

We highlight the design and fabrication of a polydimethylsiloxane (PDMS) encapsulated advanced all-solid-state asymmetric supercapacitor (ASC) device consisting of hierarchical mesoporous zinc-iron-cobalt ternary oxide (ZICO) nanowire coated nickel (Ni) foam (ZICO@Ni foam) as a promising positive electrode and nitrogen doped graphene coated Ni foam (N-G@Ni foam) as negative electrode in the presence of PVA-KOH gel electrolyte. Owing to outstanding electrochemical behavior and ultrahigh specific capacitance of ZICO (≈ 2587.4 F/g at 1 A/g) and N-G (550 F/g at 1 A/g) along with their mutual synergistic outputs, the assembled all-solid-state ASC device exhibits an outstanding energy density of ≈40.5 Wh/kg accompanied by a remarkable long-term cycle stability with ≈95% specific capacitance retention even after 5000 charge-discharge cycles. The exclusive hierarchical ZICO nanowires were synthesized by a facile two-step process comprising of a hydrothermal protocol followed by an annealing treatment on a quartz substrate. While Zn2+ gives the stability of the oxide system, Fe and Co ions provide better electronic conductivity and capacitive response under vigorous cyclic condition. The extraordinary performance of as-fabricated ASC device resembles its suitability for the construction of advanced energy storage devices in modern electronic industries.

Well-Ordered Oxygen-Deficient CoMoO4 and Fe2O3 Nanoplate Arrays on 3D Graphene Foam: Toward Flexible Asymmetric Supercapacitors with Enhanced Capacitive Properties.

In this work, we report the development of well-ordered hydrogenated CoMoO4 (H-CoMoO4) and hydrogenated Fe2O3 (H-Fe2O3) nanoplate arrays on 3D graphene foam (GF) and explore their practice application as binder-free electrodes in assembling flexible all-solid-state asymmetric supercapacitor (ASC) devices. Our results show that the monolithic 3D porous GF prepared by solution casting method using Ni foam template possesses large surface area, superior electrical conductivity, and sufficient surface functional groups, which not only facilitate in situ growth of CoMoO4 and Fe2O3 nanoplates but also contribute the double-layer capacitance of the resultant supercapacitor. The well-ordered pseudocapacitive metal oxide nanoplate arrays standing up on 3D GF scaffold can provide efficient space and shorten the length for electrolyte diffusion from the outer to the inner region of the electrode material for Faradaic energy storage. Furthermore, one of our major findings is that the introduction of oxygen vacancies in CoMoO4 and Fe2O3 nanoplates by hydrogenation treatment can increase their electronic conductivity as well as improve their donor density and surface properties, which gives rise to a substantially improved electrochemical performance. Benefiting from the synergistic contributions of different components in the nanohybrid electrode, the resultant flexible ASC device with GF/H-CoMoO4 as the positive electrode and GF/H-Fe2O3 as the negative electrode achieves a wide operation voltage of 1.5 V and a maximum volumetric specific capacitance of 3.6 F cm-3, which is two times larger than that of the Ni/GF/CoMoO4//Ni/GF/Fe2O3 device (1.8 F cm-3), and the rate capability is up to 70% as the current density increases from 2 to 200 mA cm-3. Moreover, the Ni/GF/H-CoMoO4//Ni/GF/H-Fe2O3 device also exhibits a high energy density of 1.13 mWh cm-3 and a high power density of 150 mW cm-3, good mechanical flexibility with the decrease in capacitance of less than 4% after being bent inward to different angles and inward to 90° 200 times, and good cycling stability of 93.1% capacitance retention after 5000 cycles.

Flexible all-solid-state asymmetric supercapacitor assembled using coaxial NiMoO4 nanowire arrays with chemically integrated conductive coating†

In this work, we synthesized radially developed metal oxides (MOs) array of one-dimensional (1D) nanostructured NiMoO4 on highly conductive carbon cloth (CC) and put forward an effective strategy to greatly improve the supercapacitor performance by enhancing the structural integrity and electrical oneness of the MO-based electrode. The hybrid NiMoO4/ polyaniline (PANI) electrode exhibits a high areal specific capacitance of ca. 1.34Fcm−2 (1340Fg−1) at a current density of 1mAcm−2. In comparison, the pristine NiMoO4 nanowires (NWs) have a specific capacitance of ca. 1.142Fcm−2 (1142Fg−1) at the same current density. An outstanding capacitance retention for NiMoO4/PANI hybrid nanowire electrodes has been achieved (ca. 96.7% after 2000 cycles with an average coulombic efficiency of over 99.5%), which is superior to pure NiMoO4 (ca. 81% after 2000 cycles). Moreover, a flexible all-solid-state asymmetric supercapacitor (ASC) employing NiMoO4/PANI and commercial active carbon (AC) as the positive and negative electrodes, respectively, delivers a maximum specific energy of 99.26 Wh Kg−1 (297.78 mWh cm−2) and a maximum specific power of 10667WKg−1 (32.04mWcm−2). In addition, the ASC device demonstrates highly stable cyclic performance with outstanding and robust flexibility.

All-solid-state asymmetric supercapacitor based on reduced graphene oxide/carbon nanotube and carbon fiber paper/polypyrrole electrodes

Sandwich-like reduced graphene oxide/carboxylated multi-walled carbon nanotube (RGO/cMWCNT) hybrid film and the carbon fiber paper-supported polypyrrole (CFP/PPy) composite film were prepared by a vacuum-infiltration process and an electrochemical deposition method, respectively. Furthermore, a novel all-solid-state asymmetric supercapacitor (ASC) was fabricated using RGO/cMWCNT as the negative electrode and CFP/PPy as the positive electrode, separated with potassium polyacrylate/KCl gel electrolyte. Due to the unique structure, stable potential window and good capacitive performance of the two electrodes, the as-fabricated ASC can be cycled reversibly at a cell voltage of 1.6 V and displays outstanding performances with an energy density of 28.6 W h kg−1 and a power density of 15.1 kW kg−1. Additionally, our ASC device also presents a superior long cycle life with 93% capacitance retention after 2000 cycles.