Electrochemical Supercapacitive Properties Research Articles

Enzymatic synthesis of biocompatible polypyrrole with enhanced electrochemical properties for supercapacitors

This study focuses on the biocompatible and ecofriendly enzymatic synthesis of conductive polypyrrole (PPy) using mediators for supercapacitor electrode material. The work investigates the effects of various mediator systems on laccase-catalyzed oxidation of pyrrole and is confirmed through Fourier transform infrared spectroscopy (FTIR) and Ultraviolet (UV) visible spectroscopy. The x-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis has revealed that both mediators and laccase can produce crystalline and amorphous PPy with agglomeration of globular-shaped particles. The PPy-ABTS (2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) demonstrates higher decomposition temperatures, indicating superior thermal stability up to 400 °C. Electrochemical studies such as cyclic voltammetry (CV), galvanometric charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) revealed that PPy-ABTS possesses good electrochemical properties. Compared to other laccase-mediated materials synthesized PPy in this study, PPy-ABTS exhibits higher specific capacitance values (242 F g−1 by CV at 10 mV s−1 and 153 F g−1 by GCD at 1 A g−1), with a capacitance retention of nearly 90 % after 10000 cycles. Cytotoxicity study shows that PPy-ABTS has an IC50 value of 528 μg ml−1 against human breast adenocarcinoma (MCF-7) cells, indicating its biocompatibility. Consequently, PPy-ABTS emerges as a promising electrode material for high-performance supercapacitors. Its unreported biocompatibility opens up possibilities for diverse biomedical applications.

Preparation of N and O doped coal tar pitch based porous carbon for supercapacitor electrode

Coal tar pitch (CTP) is mainly composed of a mixture of polycyclic aromatic hydrocarbons, is almost hydrophobic, and has a low heteroatom content, which limits its surface function. During carbonization, it is prone to condensation and difficult to form pore structures, resulting in poor electrochemical performance for carbon electrode materials. Herein, nitrogen (N) and oxygen (O) doped hierarchical porous carbon (C-ANOCTP) was prepared by HNO3 oxidation and KOH activation using CTP as carbon precursor. The oxidation of HNO3 remarkably increases the hydrophilic functional groups containing N and O on the surface of CTP, improves the hydrophilicity of CTP surface, facilitates the activation process of KOH, promotes the development of carbon material pore structure and the generation of active sites, as well as the formation of defect structures. The specific surface area of C-ANOCTP obtained is 1130 m2/g, with O content of 10.29 at% and N content of 2.37 at%. The specific capacitance of C-ANOCTP in a three-electrode system with 6 M KOH electrolyte is as high as 410.51 F/g at 0.5 A/g. A symmetric supercapacitor is assembled in a 6 M KOH electrolyte using C-ANOCTP as electrode. When the power density is 25 W/kg, the energy density is 10.24 Wh/kg. After 10,000 cycles, the capacitance retention rate is still 90.03% and the coulomb efficiency is 100%. The high N and O content of porous carbon is prepared by simple HNO3 oxidation synergistic KOH activation and low temperature carbonization, which shows excellent electrochemical properties in supercapacitors, making CTP an ideal candidate material for high energy density supercapacitors.

Zinc Cobalt Sulfide/Reduced Graphene Oxide Nanocomposite for High‐Performance Asymmetric Supercapacitor: A Microwave‐Assisted Synthesis

In this work, the microwave‐assisted synthesis of ZnxCo1–xS/reduced graphene oxide (rGO) nanocomposite and the evaluation of its electrochemical properties for supercapacitor (SC) application are dealt with. The synergistic effect between ZnxCo1–xS and rGO along with the conducting network provided by rGO facilitates the conducive movement of ions and enhances the electrochemical performance of the nanocomposite. The stoichiometric ratio of Zn:Co:rGO plays a crucial role in the SC behavior of the material. In three electrode systems, a material shows a high specific capacitance of 1094 F g−1 at current density 1 A g−1. The material stores charge both diffusively as well as capacitively. An asymmetric SC with acetylene black as the negative electrode and ZnxCo1–xS/rGO as the positive electrode has a stable potential window 0–1.6 V. For the fabrication of the electrodes, Ni foam is used as the current collector. The energy density and power density of the SC are found to be 32.71 and 431.95 W kg−1, respectively. The Coulombic efficiency of the SC is found to be 107% while its capacitance retention is 86% after 10 000 galvanostatic charge–discharge cycles. The energy and power density of the SC are comparatively higher than many recently reported literature. The material exhibits superior electrochemical stability and reversibility and can be a suitable electrode material for SCs.

Hierarchical NiCo-LDHs/metal sulfides (V3S4, CuS, Mo2S3) heterostructures with improved electrochemical properties for asymmetric supercapacitors: A comparative study

A good approach to meet the high-performance requirements of supercapacitors is to introduce heterostructure to the transition metal sulfide electrodes. In this work, the hierarchical nanoflower-like NiCo-LDHs/V3S4 (NCs/V3S4) heterostructure is synthesized by the two-step hydrothermal process. The rational structure not only creates the sufficient active sites but also provides abundant ion/charge diffusion channels, facilitating the electrochemical reaction kinetics of the electrodes. NCs/V3S4 heterostructure, which advantages of the special structure and synergistic effect, exhibits a good rate capability and an exceptional specific capacitance of 1823.8 F g−1 at 1 A g−1 and 964.3 F g−1 at 30 A g−1. In addition, the assembled NCs/V3S4//AC asymmetric supercapacitors (ASCs) exhibit an exceptional energy density of 63.60 Wh kg−1 at a power density of 799.93 W kg−1 and good cycling stability with 99.04% capacitance retention after 6000 cycles, indicating that the strategy can improve ASCs stability and energy density. For comparison, NiCo-LDHs/Mo2S3//AC (NCs/Mo2S3//AC) and NiCo-LDHs/CuS//AC (NCs/CuS//AC) ASCs are assembled and the electrochemical performances of the three NCs/metal sulfides//AC ASCs are systematically investigated and compared. In conclusion, the distinctive structural design can successfully manage the interface charge states, ensuring the structural integrity of electrode materials and resulting in superior electrochemical performance.

Novel hierarchical core-shell NiCo2S4@NiWO4 nanowire arrays for high performance pseudocapacitor

In this paper, a novel NiCo2S4@NiWO4 honeycomb core-shell nanorod array significantly improved the electrochemical storage properties of supercapacitors. The characteristic architecture of the NiCo2S4@NiWO4 electrode showed a remarkable specific capacity of 1273.5 C g−1 at a current density of 1 A g−1. The asymmetric supercapacitor (ACS) had a high specific capacitance of 1502.4 C g−1 at a current density of 1 A g−1 as well as excellent cycling stability at a current density of 10 A g−1 (101.25 % cycling retention rate after 10,000 cycles), and an energy density of 334 Wh kg−1 with a power density of 2.38 kW kg−1. The research emphasized that a strong electronic coupling effect was observed at the interface of NiCo2S4 and NiWO4 and electron transfer from Ni-W-O to Ni-Co-S occurred around the interface, which further improved the electron transfer properties of electrode materials and hit the mark extends the life of the electrode and significantly improves the performance of energy storage systems.

Recent progress in graphene and its derived hybrid materials for high-performance supercapacitor electrode applications.

Graphene, the most fascinating 2D form of carbon with closely packed carbon atoms arranged in a layer, needs more attention in various fields. For its unique electrical, mechanical, and chemical properties with a large surface area, graphene has been in the limelight since its first report. Graphene has extraordinary properties, making it the most promising electrode component for applications in supercapacitors. However, the persistent re-stacking of carbon layers in graphene, caused by firm interlayer van der Waals attractions, significantly impairs the performance of supercapacitors. As a result, many strategies have been used to get around the aforementioned problems. The utilization of graphene-based nanomaterials has been implemented to surmount the aforementioned constraints and considerably enhance the performance of supercapacitors. This review highlights recent progress in graphene-based nanomaterials with metal oxide, sulfides, phosphides, nitrides, carbides, and conducting polymers, focusing on their synthetic approach, configurations, and electrochemical properties for supercapacitors. It discusses new possibilities that could increase the performance of next-generation supercapacitors.

Advances in Nickel-cobalt Electrode Materials for Supercapacitors

With the rapid development of society, supercapacitors have been widely studied in energy storage devices for their unique advantages of high energy density, good cycle stability, fast charge and discharge speed. However, the development of supercapacitors is limited by low energy density. To address this challenge, it is important to develop and prepare electrode materials with excellent electrochemical properties for supercapacitors. To improve the energy density of supercapacitors, nickel-cobalt electrode materials have been widely studied due to their advantages of high energy density, high safety and long life. In this review, the research progress in material morphology and microstructure of supercapacitors prepared from nickel-cobalt metal oxides/hydroxides, sulfides, selenides and phosphates in recent years is summarized and prospected.

Preparation and electrochemical properties of NiCo-layered double hydroxide supercapacitor

Layered double hydroxides (LDHs) are favorable pseudocapacitance electrodes due to their adjustable composition and low cost. Here, a series of NiCo-LDHs were prepared by a novel ammonia diffusion method at room temperature. Compared with other synthesis methods, this method is a simple, green, original and effective method. The morphology, structure, and elemental composition of NiCo-LDH electrode materials were characterized and their electrochemical properties were tested. The optimal honeycomb NiCo-LDH shows a specific capacitance (Cs) of 1463.2F·g−1 at 1 A·g−1, and the rate capacity is 75.2 % at 20 A·g−1. Particularly, the Cs is still 87.9 % after 2000 charge–discharge cycles at a high current density of 20 A·g−1. In addition, the hybrid supercapacitor with NiCo-LDH//activated carbon (AC) could show an energy density of 23.4 Wh·kg−1 at a power density of 900 W·kg−1, along with 73.4 % capacity retention after 5000 cycles.

Enhancement electrochemical properties of supercapacitors using hybrid CuO/Ag/rGO based nanoporous composite as electrode materials

Utilizing clean and renewable energy sources requires the development of effective, reliable, and reasonably priced electrodes for supercapacitors. Herein, a simple, cheap, and fast synthesis method was developed to synthesize CuO/Ag/RGO(S1) as electrode material for Supercapacitors. Also, the effect of adding different proportions of silica nanoparticles S2A (1CuO/1Ag/1RGO/0.5SiNp), S2B (1CuO/1Ag/1RGO/1SiNp), and S4 (1CuO/1Ag/1RGO/1.5 SiNp) on the electrochemical properties of the composite was also investigated. Among the four synthesized composites, composite S1, due to its porous structure, has better electrochemical parameters than the other three composites. Also, the correct combination of a metal base (CuO, Ag) and carbon base (Reduced graphene oxide) materials with the accurate synthesis method and the use of proper precursors (F127, Ag(NO3), Cu(NO3)2) made the S1 composite have an ideal electrochemical result(Specific capacitance: 936 F g−1, energy density: 130 Wh kg−1, power density: 500 W kg−1, cycle stability: 90% rate capability: 88%) Compared to the pure state of each of these materials and other similar hybrid compounds. The reason for such ideal electrochemical results, which distinguishes this project from other similar projects, is the synergistic effect of the combination of CuO, Ag, and RGO, along with the hierarchical porosity obtained in the correct synthesis method. In our opinion, CuO/Ag/RGO maybe a viable choice for electrocatalytic and energy storage applications that require distinct electrochemical performances.

ZIF-derived hollow cattail-shaped composites with hierarchical channels towards enhanced electrochemical properties for supercapacitors

Despite the achievement in generating various hollow architectures, designing hollow composites with hierarchical channels remains challenging to achieve excellent electrochemical energy storage performance. To address this issue, we developed an in situ self-assembly strategy to prepare hollow composites using zeolitic-imidazolate frameworks and carbon nanotubes (ZIF@CNT). These ZIF@CNT architectures with different appearances are prepared by adjusting the stirring rate during the reaction. Subsequently, the sulfurization strategy is applied to convert ZIF-67 to cobalt sulfide (CoS), resulting in the hollow CoS@CNT hybrids. These hierarchical channels include the hollow CoS cavities and CNT channels. The unique hollow composites with different dimensions played a synergistic effect between subunits, thus giving excellent electrochemical properties. The impact of particle cavity channel size on electrochemical properties was evaluated systematically. As expected, CoS@CNT with hollow cattail-shape structures (HCCoS@CNT) resulted in the optimal specific capacitance (1250 F/g) and cyclic stability (90.4 % for over 10,000 times of cycling at 10 A/g). The designed hybrid supercapacitor, HCCoS@CNT//active carbon (AC), delivered an exceptional energy density of 40 Wh kg−1 at 800 W kg−1 of the power density. Together, these findings provide a reference for preparing complex hollow structures as high-performance electrodes, clarifying the optimization of composites for improved electrochemical properties.

Conductive polymer electrode materials with excellent mechanical and electrochemical properties for flexible supercapacitor

Flexible supercapacitors can be applied in the field of wearable devices, which currently received much attention. As pseudocapacitive electrode material for flexible supercapacitors, PEDOT has been extensively investigated especially to improve the mechanical strength and flexibility of the electrode material, but most methods will disrupt its electrochemical performance. In this study, we designed and prepared a novel alveolate copolymer based on PEDOT by electrochemical polymerization, introducing a certain proportion of carbamate groups as side chains to form a cross-linked structure through hydrogen bonding. This copolymer has excellent flexibility due to intermolecular hydrogen bonding, and outstanding electrochemical performance, especially rate performance and cycling stability, because of the ion channel of copolymer which satisfy the rapid migration of ions. Flexible supercapacitor based on this copolymer electrode material still have 96.1 % capacity retention at high current densities (0.2 mA/cm2) compared to low current density (0.025 mA/cm2). The specific capacity retained 85 % of its initial capacity after 20,000 cycles, especially with almost no loss in capacity even after 1000 bending cycles. This alveolate copolymer with hydrogen bonding cross-linking structure provides a choice for obtaining flexible supercapacitors with excellent mechanical and electrochemical performance, which could be utilized as wearable energy storage devices.

Facile sonochemical synthesis of nanostructured FeWO4-rGO and CuCo2O4 nanocomposite for high-rate capability and stable asymmetric (CuCo2O4//FeWO4-rGO) supercapacitors

The present work reports iron tungstate (FeWO4) nanostructures with reduced graphene oxide (rGO) as a novel anode material for enhancing the electrochemical properties of asymmetric supercapacitors. The FeWO4-rGO composite nanostructures were successfully synthesized by the one-pot sonochemical method. The synthesized nanocomposites crystal structure and phase purity were investigated using the powder X-ray diffraction (XRD) technique. The Fourier transform infrared (FT-IR) spectrograms demonstrate the presence of functional groups in the composite. The composite's morphology was examined using the high-resolution transmission electron microscopy (HR-TEM) and the field emission scanning electron microscopy (FE-SEM), and it was observed that the FeWO4 nanostructures were uniformly distributed on the reduced graphene oxide surface. The cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) analyses were used to evaluate the electrochemical performance. After 5000 cycles at 10 mA cm− 2, the FeWO4-rGO composite achieved a better rate of efficiency and outstanding cycling performance, with capacitance retained at 68% and 77.8%, respectively. In 1 M Na2SO4, an asymmetric device (CuCo2O4//FeWO4-rGO composite) achieved a high energy density of 21.5 W.h Kg−1 and a power density of 147 W Kg−1. In the FeWO4-rGO nanocomposite, the reduced graphene oxide could enhance the conductivity and the free diffusion processes for the quick ion transport and easy ion access to the storage sites. The obtained results indicated that the FeWO4-rGO nanocomposite could be a good anode electrode material for the next-generation energy storage applications.

Direct growth of MnCoSe2 nanoneedles on 3D nickel foam for supercapacitor application

The present work reports the fabrication and performance studies of supercapacitors using MnCoSe2 nanoneedles-based electrodes. The MnCoSe2 nanoneedles-based supercapacitor electrode with a unique nanostructure exhibits an enhanced specific capacitance of 820 F g−1 and 386 F g−1 at 1 A g−1 in three-electrode and symmetric two-electrode configurations, respectively. The MnCoSe2 nanoneedles-based supercapacitor device has a specific energy of 54 Wh kg−1 at a specific power of 1 kW kg−1 and a superior cyclic stability of 95% retention after 10,000 charge-discharge cycles at 5 A g−1. Additionally, an asymmetric supercapacitor (ASC) device has been developed employing an anode based on rGO and a cathode based on MnCoSe2 nanoneedles. The asymmetric supercapacitor demonstrates an excellent gravimetric capacitance of 71 F g−1 at 1 A g−1 and an exceptional cycle life of 96% after 10,000 cycles. At a gravimetric power density of 227 W kg−1, the device produces a gravimetric energy density of 32 W h kg−1. The increased electrochemical performance can be ascribed to the three-dimensional nanowire-like surface morphology with a large electroactive site for enhanced redox reaction. Furthermore, high conductivity due to the presence of selenium provides rapid electron transfer and improves the electrochemical properties of supercapacitors. Accordingly, the present work indicates that the MnCoSe2 nanoneedles can be used as a potential electrode material for electrochemical energy storage applications.

Binder-free pinecone-like NiSe/MnSe nanostructure arrays via electrochemically controlled one-step synthesis towards high-performance semi-solid-state supercapacitor

Bimetallic selenides with nanostructures have attracted widespread interest to improve the electrochemical properties of supercapacitors due to their intrinsic properties such as high energy storage capacity, stability, and reliability. Herein, we report the novel synthesis of binder-free pinecone-like nanostructure arrays of Ni2MnSe4 on nickel foam via a facile electrodeposition technique. The electrode materials with various stoichiometric ratios of Ni:Mn as NixMn3-xSe4 (x = 1, 2, and 2.5) are synthesized to study the effect on their surface morphology and electrochemical properties. Ni2MnSe4 is optimized with pinecone-like structure arrays formed by intraconnected rough nanosheets (two-dimensional structure) with interconnected microstructures (pinecone structure), which further offers continuous channels for rapid electron/ion transfer and accelerates the diffusion kinetics of the counter ions, thus leading to improved capacitive property of the electrode material. The as-prepared Ni2MnSe4 electrode exhibits the areal capacitance value of 2160 mF cm−2 at 4 mA cm−2 with superior cycling stability (92 % of capacitance retention over 10,000 cycles). Additionally, the Ni2MnSe4 is utilized as a positive electrode for a semi-solid-state hybrid supercapacitor device (SHSC). The assembled SHSC delivers the energy and power density values of 0.15 mWh cm−2 and 15.51 mW cm−2, respectively with excellent prolonged cycling stability.

Tuning the electrochemical properties of carbon-based supercapacitors by composite preparation and cell asymmetries

The development of faster, safer and higher performance solid-state energy storage devices has motivated scientists to explore various strategies to obtain more efficient systems. In this work we evaluated the influence of different carbon material electrodes with a gel polymer electrolyte on the electrochemical properties of solid-state supercapacitors. The gel polymer electrolyte exhibited remarkable adhesive characteristics which allowed a good adherability and wettability of the gel electrolyte on the surfaces of all electrodes tested. Four types of supercapacitors were prepared and the influence of different types of electrodes and their combinations on the properties of supercapacitor was evaluated using electrochemical impedance spectroscopy, cyclic voltammetry and the galvanostatic charge/discharge technique that allows synchronous measurements of the cell voltage and the potential of the positive and negative electrodes. The asymmetric device with rGO (reduced graphene oxide) working on the negative electrode and f-MWCNT (acid functionalized multiwalled carbon nanotubes) on the positive electrode showed the best retention capacity for all studied properties (capacitance, energy density and power) after 2000 charge and discharge cycles. Flexible supercapacitor was also prepared, and various electrochemical parameters of the device were studied as a function of bending. We do not observe significant changes in its electrochemical properties after bending.

Acid substitutions for WO3 nanostructures synthesis by the hydrothermal route and its effect on physio-chemical and electrochemical properties for supercapacitors

In this study, we have developed a feasible and eco-friendly electrode material for supercapacitor (SCs) application by effectively synthesizing different morphological structures of tungsten oxide nanostructures (WO3-NSs). The concentrated acids play a crucial role in the synthesis of WO3-NSs and are employed to evaluate the electrochemical activity. The stable phase formation and the crystal structures of WO3-NSs were confirmed by thermogravimetric and X-ray analysis. From the field emission scanning electron microscope (FE-SEM), the hexagonal-shaped nanosheets, one-dimensional nanorods (1D NRs), and heterogeneous non-uniform agglomerated nanosheets were observed for the WO3-NSs. The presence of functional groups and the stretching-bending vibrations of WO bonds were detected by Fourier transform infrared, and Raman spectroscopy respectively. The transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) offers a more in-depth morphological, structural, and elemental composition and electronic states investigation of the optimized WO3-NRs. Additionally, the electrochemical properties of the WO3-NSs have been examined in 1 M KOH electrolyte using Nickel Foam (NF) as a current collector. Furthermore, the M-WO3-NF electrode reveals higher specific capacity (Csp) and gravimetric capacitance (Cg) of 72 mAh/g and 600 F/g with high energy density (Ed) of 17 Wh/kg, and power density (Pd) of 321 W/kg as well as the superior Columbic efficiency (96.9 %) at 5 mA/cm2. The M-WO3 electrode exhibits 91 % capacitive retention over 5000 cycles. The M-WO3-NF is used as the cathode and activated carbon (AC) as the anode in the design of an aqueous hybrid supercapacitor (AHSC) device. Notably, the M-WO3-NF//AC-NF device offers a Pd of 1060 W/kg at an Ed of 9 Wh/kg and remarkable electrochemical stability of 80 % over 3000 charge-discharge cycles. These results highlight the excellent electrochemical functionality and advantages of the M-WO3-NRs as a promising cathode for practical energy-storage systems.

Study on Electrochemical Performance of MnO@rGO/Carbon Fabric-Based Wearable Supercapacitors.

In this work, we reported the electrochemical performance of a type of carbon fabric-based supercapacitor by coating MnOx@rGO nanohybrids on carbon fabric with a simple one-step hydrothermal method. We studied the mass ratio of MnOx to rGO on the electrochemical properties of the carbon fabric-based supercapacitors. We found that as the mass ratio is 0.8:1 for MnO@rGO, the supercapacitor with a loading of 5.40 mg cm-2 of MnO@rGO nanohybrids on carbon fabric exhibits a specific capacitance of 831.25 mF cm-2 at 0.1 mA cm-2 current density. It also shows long-term cycling capacitance retention of 97.2% after 10,000 charge-discharge cycles at a current density of 0.4 mA cm-2. We speculate that the high electrochemical performance results from the strong interfacial bonding between the hierarchical architecture of MnO@rGO nanohybrids and carbon fabric.

Ni3S4 combined hydrophilic hydroxylated MWCNTs for high performance asymmetric supercapacitors

A composite material (Ni3S4-Q) of Ni3S4 combined with hydrophilic hydroxylated multi-walled carbon nanotubes (MWCNTs) was prepared by one-step method in the reactor. For comparison, hydrophilic MWCNTs were replaced by hydrophobic MWCNTs (Ni3S4-S), and pure Ni3S4 was synthesized without adding MWCNTs, so as to study the influence of the hydrophilicity and hydrophobicity of MWCNTs on the capacitive performance of Ni3S4. The contact Angle analysis shows that Ni3S4-Q has better hydrophilicity. The electrochemical cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy show that Ni3S4-Q has the highest specific capacitance and the lowest ion diffusion resistance. In addition, the asymmetric supercapacitor assembled by Ni3S4-Q and activated carbon has a maximum energy density of 51 Wh kg−1. This work strongly validated that hydrophilicity can improve the electrochemical properties of supercapacitors.

Excellent electrochemical performance of porous carbon by in situ nitrogen-doped derived from polyurethane

In this work, the application of high specific surface area nitrogen-doped porous carbon prepared from polyurethane (TPUC) as a supercapacitor electrode is reported. Five samples are prepared with KOH as activator at different activation temperatures and applied to research the electrochemical properties of supercapacitor. The problems of uneven distribution and loss of nitrogen atoms are solved by in situ doping. The conductivity and wettability of activated carbon are improved by nitrogen-doped. The maximum specific capacitance (up to 527 F g−1 at 0.5 A g−1) and outstanding cycling stability (up to 342 F g−1 after 10,000 cycles) are obtained by the TPUC-800 sample (specific surface area of 3575 m2 g−1). These features are explained for the improvement of the effective specific surface area and the shortened ion diffusion distance in carbon electrode due to nitrogen-doped and the enhancement of hydrophilicity of carbon surface. The results reveal that such a simple strategy of nitrogen-doped polyurethane is an efficient way to prepare promising nitrogen-doped porous carbons for supercapacitor with good performance.

Hyper-conjugated polyaniline delivering extraordinary electrical and electrochemical properties in supercapacitors

Conjugated polymers promise extremely-high theoretical supercapacitance to develop large capacitive storage devices. Existing conjugated polymers commonly realize their < 20% supercapacitance due to inferior electronic and electrochemical activities. Here we report hyper-conjugated effect to minimize energy level difference and carrier migration barrier in copolymerized polyaniline (PANI), a typical supercapacitive material. The hyper-conjugated effect efficiently promotes the elongation of conjugation system and the delocalization of π electrons. The largely increased number of free carriers in combination with the expanded range of carrier mobility guarantee 800% increments in electrical conductivity. Tests of symmetric supercapacitors with hyper-conjugated PANI show a high specific capacitance of 512 F g−1, excellent rate-capability and long-term cyclability. This work paves the way for designing conjugated polymers with remarkable electronic and electrochemical properties.