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Sol–gel‐based solution‐processed metal oxides have emerged as a key fabrication method for applications in thin film transistors both as a semiconducting and a dielectric layer. Here, a low‐temperature, green solvent‐based, non‐toxic, and cost‐effective solution shearing approach for the fabrication of thin aluminum oxide (AlOx) dielectrics is reported. Optimization of sustainability aspects like energy demand, and selection of chemicals used allows to reduce the environmental impact of the life cycle of the resulting product already in the design phase. Using this approach, ultra‐thin, device‐grade AlOx films of 7 nm are coated—the thinnest films to be reported for any solution‐fabrication method. The metal oxide formation is achieved by both thermal annealing and deep ultra‐violet (UV) light exposure techniques, resulting in capacitances of 750 and 600 nF cm−2, respectively. The structural analysis using microscopy and x‐ray spectroscopy techniques confirmed the formation of smooth, ultra‐thin AlOx films. These thin films are employed in organic field‐effect transistors (OFETs) resulting in stable, low hysteresis devices leading to high mobilities (6.1 ± 0.9 cm2 V−1 s−1), near zero threshold voltage (−0.14 ± 0.07 V) and a low subthreshold swing (96 ± 16 mV dec−1), enabling device operation at only ±0.5 V with a good Ion/Ioff ratio (3.7 × 105). [ABSTRACT FROM AUTHOR]

Supercapacitors display promising electrochemical performance with high power density and excellent cycle stability. However, their low energy density limits their advancement in a broader range of applications. To enhance their energy density, we proposed self-assembled spinel NiMn2S4 nanoflakes grown on nickel foam which we successfully prepared by a facile hydrothermal method. The NiMn2S4 electrode delivers a high capacitance of 2096.7 F g−1 at 1.0 A g−1, with an exceptional rate capability (~720.6 F g−1 at a very high current density of 100 A g−1) and good cycle stability (~85.1% retention of the initial capacitance after 7000 cycles with the Coulombic efficiency around 100%). The as-fabricated asymmetric supercapacitors based on NiMn2S4 nanoflakes//active carbon demonstrate an energy density of 73.6 W h kg−1 at 800.5 W kg−1 and adequate cycling performance of ~84.6% capacitance retention at 15 A g−1 after 10000 cycles. The results reveal that the nanostructured NiMn2S4 is an excellent electrode material for high-performance energy storage applications. [ABSTRACT FROM AUTHOR]

Engineering of conjugated microporous polymers (CMPs) with high porosity, redox activity, and electronic conductivity is of significant importance for their practical applications in electrochemical energy storage. Aminated‐multiwall carbon nanotubes (NH2‐MWNT) are utilized to modulate the porosity and electronic conductivity of polytriphenylamine (PTPA), which is synthesized via Buchwald‐Hartwig coupling reaction of tri(4‐bromophenyl)amine and phenylenediamine as constitutional units in a one‐step in situ polymerization process. Compared to PTPA, the specific surface area of core–shell PTPA@MWNTs has been greatly improved from 32 to 484 m2 g−1. The PTPA@MWNTs exhibites an improved specific capacitance, with the highest value 410 F g−1 in 0.5 M H2SO4 at a current of 10 A g−1 achieve for PTPA@MWNT‐4 due to the hierarchical meso‐micro pores, high redox‐activity and electronic conductivity. Symmetric supercapacitor assemble by PTPA@MWNT‐4 has a capacitance of 216 F g−1 of total electrode materials and retains 71% of initial capacitance after 6000 cycles. This study gives new insights into the role of CNT templates in the adjustment of molecular structure, porosity, and electronic property of CMPs for the high‐performance electrochemical energy storage. [ABSTRACT FROM AUTHOR]

Supercapacitors have attracted considerable attention due to their advantages, including being lightweight and having rapid charge–discharge, a good rate capability, and high cyclic stability. Electrodes are one of the most important factors influencing the performance of supercapacitors. Herein, a three-dimensional network of rough and porous micropebbles of CeCu2Si2 has been prepared using a one-step procedure and tested for the first time as a supercapacitor electrode. The synthesized material was extensively characterized in a three-electrode configuration using different electrochemical techniques, such as cyclic voltammetry (CV), galvanostatic charge and discharge (GCD) tests, and electrochemical impedance spectroscopy (EIS). CeCu2Si2 shows rather high mass-capacitance values: 278 F/g at 1 A/g and 295 F/g at 10 mV/s. Moreover, the material exhibits remarkable long-term stability: 98% of the initial capacitance was retained after 20,000 cycles at 10 A/g and the Coulombic efficiency remains equal to 100% at the end of the cycles. [ABSTRACT FROM AUTHOR]

Nowadays, iron (II) selenide (FeSe), which has been widely studied for years to unveil the high-temperature superconductivity in iron-based superconductors, is drawing increasing attention in the electrical energy storage (EES) field as a supercapacitor electrode because of its many advantages. In this study, very small FeSe particles were synthesized via a simple, low-cost, easily scalable, and reproducible solvothermal method. The FeSe particles were characterized using cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) measurements, and electrochemical impedance spectroscopy (EIS), revealing enhanced electrochemical properties: a high capacitance of 280 F/g at 0.5 A/g, a rather high energy density of 39 Wh/kg and a corresponding power density of 306 W/kg at 0.5 A/g, an extremely high cycling stability (capacitance retention of 92% after 30,000 cycles at 1 A/g), and a rather low equivalent series resistance (RESR) of ~2 Ω. [ABSTRACT FROM AUTHOR]

Transition metal sulfides (TMSs) have been regarded as greatly promising electrode materials for supercapacitors because of abundant redox electroactive sites and outstanding conductivity. Herein, we report a self-supported hierarchical Mn doped Co9S8@Co(OH)2 nanosheet arrays on nickel foam (NF) substrate by a one-step metal–organic-framework (MOF) engaged approach and a subsequent sulfurization process. Experimental results reveal that the introduction of manganese endows improved electric conductivity, enlarged electrochemical specific surface area, adjusted electronic structure of Co9S8@Co(OH)2 and enhanced interfacial activities as well as facilitated reaction kinetics of electrodes. The optimal Mn doped Co9S8@Co(OH)2 electrode exhibits an ultrahigh specific capacitance of 3745 F g−1 at 1 A g−1 (5.618 F cm−2 at 1.5 mA cm−2) and sustains 1710 F g−1 at 30 A g−1 (2.565 F cm−2 at 45 mA cm−2), surpassing most reported values on TMSs. Moreover, a battery-type asymmetric supercapacitor (ASC) device is constructed, which delivers high energy density of 50.2 Wh kg−1 at power density of 800 W kg−1, and outstanding long-term cycling stability (94% capacitance retention after 8000 cycles). The encouraging results might offer an effective strategy to optimize the TMSs for energy-storage devices.

In this paper, the non-polluting, non-toxic, and eco-friendly material-MnO2 electrodes were deposited on threedimensional porous nickel (Ni) foam by linear sweep voltammetry, and the entire electrodeposition process did not require sintering of the material, which was fast and convenient while avoiding unnecessary energy consumption and thus was environmentally friendly. Scanning electron microscopy (SEM) and transmission electron microscopy were used to examine the surface and microscopic characteristics of each sample (TEM). Chronoamperometry (CA), cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) were then used to determine the electrochemical characteristics of the manufactured samples. The result suggests that the MnO2-sv80 electrode sample at a scan rate of 80 mV/s-1 has excellent performance for the supercapacitor electrode. The specific capacitance was as high as 531.4 F g-1 at a current density of 1 A g-1 and remained at 223.2 F g-1 at an ultra-high current density of 20 A g-1, with capacitance retention of 42%. [ABSTRACT FROM AUTHOR]

• A high comprehensive performance electrode of CoMn 2 O 4 was prepared. • CoMn 2 O 4 electrode displayed a high specific capacitance of 2218.32 F g −1 at 1 A g −1 with good rate and cycle properties. • The aqueous asymmetric supercapacitor (AASC) possesses a high-energy density (83.85 Wh kg−1 at 800.03 W kg−1) and a cycling performance of up to 16,000 cycles. In this study, we successfully utilized nickel foam (NF) as a scaffold for the direct deposition of ultra-thin CoMn₂O₄ (CMOs) through a one-step electrochemical deposition method. This was followed by annealing to produce a stable, free-standing electrode. This electrode was then used to develop an aqueous asymmetric supercapacitor (AASC). The optimized electrode demonstrated an exceptionally high specific capacitance of 2218.32 F g −1 at 1 A g −1 and excellent cyclic stability, retaining 86.67 % of its capacitance after 6000 cycles. An AASC device was also constructed, employing CMOs on NF as the cathode and commercially available activated carbon (AC) on carbon cloth (CC) as the anode. This configuration achieved a high energy density of 83.85 Wh kg−1 at a power density of 800.03 W kg−1, with robust cycling stability (∼87.16 % retention after 16,000 cycles at 30.0 A g −1) and nearly 100 % Coulombic efficiency. These results surpass those of many state-of-the-art supercapacitors (SCs), highlighting the significant potential for practical applications. CoMn 2 O 4 on Ni foam was prepared as an integrated electrode for supercapacitors and exhibited high energy density and excellent cycling stability. [Display omitted] [ABSTRACT FROM AUTHOR]

An innovative and cost-efficient methodology is proposed for developing porous carbon materials from barley straw biomass waste using thiourea as dopant and FeCl 3 as activator. By varying precursor ratio and activation, porous carbon frameworks (BCF-Ts) with tailored porosity and N/S-doping were synthesized. BCF-Ts showed remarkable pore size distribution and high surface area responsible for enhanced electrochemical performance by enabling efficient ion transmission. The optimized N/S-doped activated carbon (BCF-T) exhibited high specific surface area of 938.7 m2 g−1. As supercapacitor electrode, BCF-T displayed exceptional performance including high specific capacitance of 496 F g−1, power density of 500.95 Wkg-1, and energy density of 42.02 Whkg−1 in KOH electrolyte. Moreover, BCF-T showed impressive cyclic stability, retaining 90.13 % capacitance after 2000 cycles. The tailored porosity, heteroatom doping, large surface area, and proper graphitization of BCF-T facilitated rapid ion diffusion, sufficient charge storage, and pseudocapacitance. This work provides valuable guidance on synthesizing high-performance porous carbon materials from biomass waste for supercapacitor applications. [Display omitted] • Novel sustainable synthesis of porous carbon from barley straw biomass waste. • Tailored porosity and N/S-doping by controlling precursor ratio and activation. • Outstanding electrochemical performance as supercapacitor electrode. • High specific capacitance of 496 F g−1; excellent cyclic stability (90 % over 2000 cycles). • Tunable porosity and doping enable enhanced ion transport and charge storage. [ABSTRACT FROM AUTHOR]

Supercapacitors have attracted considerable attention due to their advantages, including being lightweight and having rapid charge–discharge, a good rate capability, and high cyclic stability. Electrodes are one of the most important factors influencing the performance of supercapacitors. Herein, a three-dimensional network of rough and porous micropebbles of CeCu2Si2 has been prepared using a one-step procedure and tested for the first time as a supercapacitor electrode. The synthesized material was extensively characterized in a three-electrode configuration using different electrochemical techniques, such as cyclic voltammetry (CV), galvanostatic charge and discharge (GCD) tests, and electrochemical impedance spectroscopy (EIS). CeCu2Si2 shows rather high mass-capacitance values: 278 F/g at 1 A/g and 295 F/g at 10 mV/s. Moreover, the material exhibits remarkable long-term stability: 98% of the initial capacitance was retained after 20,000 cycles at 10 A/g and the Coulombic efficiency remains equal to 100% at the end of the cycles.

The evolution of advanced supercapacitors depends highly on the design and synthesis of electrodes with rational morphology and structure. In this paper, a facile methanol-assisted solvothermal method is reported for the synthesis of spherical hydrated manganese vanadate (MnV 2 O 6 ·2H 2 O)-reduced graphene oxide (rGO) nanosheets hybrid. In particular, the utilization of methanol can not only change the isotropy growth of MnV 2 O 6 but also suppresses the phase-transformation process (from orthorhombic to monoclinic) by preventing the deintercalation of crystal water. Remarkably, the MnV 2 O 6 ·2H 2 O exhibits a superior specific capacity of 1678.5 F g−1 which is nearly four times more than that of MnV 2 O 6 (410.2 F g−1) at 2 A g−1. After integrating with graphene, MnV 2 O 6 ·2H 2 O spheres are uniformly encapsulated by graphene sheets with a size reduction from 1 μm to 200 nm. And a "GO-assisted Ostwald ripen-splitting" mechanism is proposed to explain the formation of MnV 2 O 6 ·2H 2 O-rGO. Consequently, the MnV 2 O 6 ·2H 2 O-rGO hybrid exhibits significantly improved conductivity, enhanced specific capacity (1976.3 F g−1 at 2 A g−1) and good rate capability (1422.5 F g−1 at 10 A g−1 and 1155.5 F g−1 at 20 A g−1) as well as excellent cycling stability (94.2% capacitance retention after 10,000 cycles). Moreover, the assembled asymmetric supercapacitor using MnV 2 O 6 ·2H 2 O-rGO (the positive electrode) and activated carbon (the negative electrode) shows a superior energy density of 51.5 Wh⋅kg−1 at the power density of 849.2 W kg−1. [Display omitted] • A novel hybrid of spherical MnV 2 O 6 ·2H 2 O and rGO nanosheets was fabricated with a methanol-assisted solvothermal method. • A "GO assisted-Ostwald ripen process" mechanism is proposed to explain the formation of MnV 2 O 6 ·2H 2 O-rGO. • The oxygen containing functional groups of GO guarantee the uniform distribution and size reduction of MnV 2 O 6 ·2H 2 O spheres. • A high specific capacity of 1976.3 F g-1 is achieved at 2 A g-1. • The assembled ASC device delivers a high specific energy of 51.5 Wh·kg-1 within 1.7 V. [ABSTRACT FROM AUTHOR]

Nowadays, iron (II) selenide (FeSe), which has been widely studied for years to unveil the high-temperature superconductivity in iron-based superconductors, is drawing increasing attention in the electrical energy storage (EES) field as a supercapacitor electrode because of its many advantages. In this study, very small FeSe particles were synthesized via a simple, low-cost, easily scalable, and reproducible solvothermal method. The FeSe particles were characterized using cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) measurements, and electrochemical impedance spectroscopy (EIS), revealing enhanced electrochemical properties: a high capacitance of 280 F/g at 0.5 A/g, a rather high energy density of 39 Wh/kg and a corresponding power density of 306 W/kg at 0.5 A/g, an extremely high cycling stability (capacitance retention of 92% after 30,000 cycles at 1 A/g), and a rather low equivalent series resistance (RESR) of ~2 Ω.

The compactly stacked layers and the use of binders are detrimental to the rate performance and long cycle stability for V4C3Tx MXene. To solve this problem and add a new member to flexible electrodes, the multi‐layered V4C3Tx MXene is delaminated into nanoflakes (d‐V4C3Tx) with tetra‐n‐butylammonium hydroxide (TBAOH) and self‐assembled into the flexible film without binder. The d‐V4C3Tx film as a negative electrode delivers a high specific capacitance of 292.0 F g‐1 (622.4 F cm‐3) at 2 mV s‐1, remarkable rate performance (86.0% at 200 mV s‐1, 78.4% at 500 mV s‐1), and the splendid cycle stability (93.1% for 40 000 cycles, 82.9% for 60 000 cycles at 10 A g‐1). The excellent electrochemical performance for the d‐V4C3Tx film is attributed to the outstanding electrical conductivity (16 465.3 S m‐1), and the large interlayer spacing (2.1 nm), as well as the surface capacitive control mechanism. The asymmetric supercapacitor composed of d‐V4C3Tx film and activated carbon (AC) also shows high energy and power densities of 22.2 Wh L‐1 at 285.3 W L‐1. This work provides a novel flexible and more stable film (d‐V4C3Tx) electrode with long cycle life for supercapacitors, and further promotes the development for flexible supercapacitors. [ABSTRACT FROM AUTHOR]

Although room temperature ionic liquids (ILs) have emerged as potential next-generation electrolytes for their wide electrochemical stability window (ESW), the trade-off between this window and viscosity has hindered their widespread use in energy storage devices. Here, we present for the first time that such a trade-off can be balanced by mixing two ILs with the common anion ([NTf2]−) but different cations ([EMIM]+ and [N1114]+) together. The [EMIM] cation-based IL possesses low viscosity while the [N1114] cation-based IL exhibits wide ESW. Since the concentrations of each IL in the mixtures can result in different electrolyte properties, we demonstrate a systematic approach by exploring the properties of various concentration combinations. In addition, the corresponding cell voltage of their resulting graphene supercapacitors (SCs) accompanied based on the interaction between the binary ionic liquid and the electrodes, and the associated electrochemical performance were studied to determine the optimum electrolyte system for the highest SC energy density. The well-balanced viscosity/ESW trade-off is achieved in binary IL consisting 50 vol% [EMIM][NTf2] and 50 vol% [N1114][NTf2] as evident from the extraordinary electrode specific capacitance of 293.1 F g−1 and the ultrahigh SC energy density of 177 Wh kg−1, which approaches that of a lithium-ion battery.

Two hydrothermal techniques under microwave irradiation were used to synthesize γ-MnO2 from 90°C to 150°C in 10−30 min. The first technique is based on reducing KMnO4 with MnSO4, and the second one involves liquid-phase oxidation between MnSO4 and (NH4)2S2O8. The structures and morphologies of the samples were analyzed using X-ray diffraction, scanning electron microscopy, and N2 physisorption measurements. The electrochemical properties were evaluated through cyclic voltammetry and electrochemical impedance spectroscopy. The γ-MnO2 materials obtained by the first technique mainly exhibited nanorods with diameters of 40–60 nm, and the samples obtained by the second technique showed flower-like microspheres with diameters of 1−2 µm; each flower was composed of nanosheets with a thickness of 10−20 nm. The processing time directly depends on the size of the nanorods. The sample synthesized by the first technique at 150°C and 10 min has the highest specific surface area of up to 59.08 m2 g−1 and mean pore diameter of 34.11 nm. Furthermore, this sample exhibits a near-rectangular cyclic voltammetry curves and high specific capacitance of 331.3 F g−1 in 0.1 M Na2SO4 solution at 5 mV s−1 scan rate. [ABSTRACT FROM AUTHOR]

In this paper, we used cyclic voltammetry method to prepare manganese dioxide with different scanning rates of voltage on a three-dimensional porous nickel foam substrate. We systematically studied the influence of the scanning rate of electrodeposition on the morphology, structure, and electrochemical performance of the sample. According to the electrochemical performance, we found the optimal electrodeposition parameters, and the electrode prepared under this condition has a high specific capacitance (458 F g−1 and 286 F g−1 at the current density of 1 A g−1 and 10 A g−1) and low impedance. [ABSTRACT FROM AUTHOR]

Layered nickel‑cobalt double hydroxide (NiCo-LDH) with a high theoretical charge storage capacity has great potential to be used as a supercapacitor (SC) electrode. However, its low electronic conductivity, low stability, and aggregation tendency has been recognized as the main drawbacks. Herein, solvent-induced interfacial-confined process was used to synthesize an unusual brush-like heterostructure of NiCo-LDH vertically anchored on conductive MXene nanosheets, enabled by the solvent-induced effect of the polar hydroxyl group of ethylene glycol and the limited domain effect of MXene nanosheets. This unique brush-like structure promoted mass transfer and improves charge transport behaviours compared to the pure NiCo-LDHs. The resultant NiCo-LDH@MXene had an ideal larger peak pore size of 3.8 nm and BET specific surface area of 175.13 m2 g−1 compared to those of NiCo-LDH, which facilitates the exposure of active sites and mass transfer. In three-electrode configuration, NiCo-LDH@MXene provided a significant specific capacity of 1310 F g−1 at a 1 A g−1 current density. At a power density of 699.1 W kg−1, NiCo-LDH@MXene showcased a substantial energy density of 73.8 Wh kg−1 in a symmetric supercapacitor. At a 6 A g−1 current density, NiCo-LDH@MXene-based SC could retain 92.5% of its capacitance at the end of 10,000 charge and discharge cycles, underscoring its excellent stability in practical application. Electrochemical tests and DFT simulation further revealed enhanced ionic adsorption/transport and electron transport, more enriched active sites, and altered electrical configuration on account of the lower energy barrier for NiCo-LDH@MXene relative to NiCo-LDH. The synthesis route and the insights reported here pave a way toward advanced electrode design and development. [Display omitted] • Solvent-induced, interfacial-confined synthesis route to get 3D NiCo-LDH@MXene. • NiCo-LDH@MXene exhibited two faced, brush-like MXene anchored on NiCo-LDH arrays. • It had BET specific surface area of 175.13 m2 g−1 and peak pore size of 3.8 nm. • It showed 1310 F g−1 capacitance and 73.8 Wh kg−1 energy density in symmetric SC. • 92.5% capacitance retention at the end of 10,000 charge and discharge cycles. [ABSTRACT FROM AUTHOR]

Herein we show a construction of high-performance supercapacitor electrode made of cerium vanadate uniformly glazed over polypyrrole (CeVO 4 /Ppy) nanostructures by a simple hydrothermal method, which was characterized by various analytical techniques. Electrochemical studies on CeVO 4 /Ppy/Ni foam with 1 M KOH show a maximum specific capacitance of 1236 F/g at a current density of 0.75 A/g. These salient features, together with smart interactions between the interconstituents, CeVO 4 and Ppy, lead to high conductivity, specific capacitance, and cycling stability with retention of 92.6% capacitance in 10,000 cycles of GCD curves. Additionally, the asymmetric supercapacitor based on activated carbon (AC), AC//CeVO 4 /Ppy device delivers a high specific capacitance of 116 F/g and energy density of 52.2 Wh/Kg at power density of 675.9 W/kg along with high capacity retention of 77.80% after 10,000 cycles. This system could be scaled up to large-scale production of high power devices, which opens up lot of opportunities in modern electronic industrial applications. [Display omitted] • A new nanocomposite electrode of cerium vanadate uniformly glazed over polypyrrole (CeVO 4 /Ppy) is proposed. • The supercapacitor electrode shows specific capacitance as high as 1236 F/g at current density of 0.75 A/g. • The cycle tests show capacitance retention of 92.6% in huge 10,000 cycles. • The asymmetric device delivers an energy density of 52.2 Wh/Kg at the power density of 675.9 W/kg. [ABSTRACT FROM AUTHOR]

Expanding the interlayer spacing of the Ti 3 C 2 T x MXene structure is realized by intercalation of ethylenediamine (EDA), which is anchored on the surface of Ti 3 C 2 T x sheets by one side amino groups with N–Ti coordination bonds. The EDA-Ti 3 C 2 T x intercalation compound has a high specific surface area of 59.2 m2 g−1 with mainly mesopores. The EDA-Ti 3 C 2 T x possesses the low charge transfer resistances of ∼0.32/0.28 Ω in 1/3 M H 2 SO 4 aqueous electrolytes, respectively. A large specific capacitance of 486.2 F g−1 (1312.7 F cm−3) is obtained for EDA-Ti 3 C 2 T x at a scan rate of 2 mV s−1 in 1 M H 2 SO 4 electrolyte, showing its high capacitance property. A good specific capacitance of 249.4 F g−1 (673.4 F cm−3) is retained at larger scan rate of 100 mV s−1, indicating its significantly high rate capability. Higher specific capacitances of 563.3 (1520.9), 522.1 (1409.7), 485.1 (1309.8), 436.2 (1177.7), 356.2 (961.7) and 290.6 F g−1 (784.6 F cm−3) are achieved for EDA-Ti 3 C 2 T x at the scan rates of 2, 5, 10, 20, 50 and 100 mV s−1, respectively, in 3 M H 2 SO 4 electrolyte. The cyclic retention of EDA-Ti 3 C 2 T x after 10,000 cycles reaches 89.7% at 10 A g−1 in 3 M H 2 SO 4 electrolyte, showing the excellent cyclic stability. Image 1 • A MXene-based EDA-Ti 3 C 2 T x material with expanded interlayer spacing is obtained. • The EDA-Ti 3 C 2 T x has high surface area, abundant mesopore and enhanced crystallinity. • The EDA-Ti 3 C 2 T x shows high performance as supercapacitor electrode material. • The energy storage mechanism of EDA-Ti 3 C 2 T x in H 2 SO 4 electrolytes is described. [ABSTRACT FROM AUTHOR]

Biomass carbon materials have been widely used as electrode materials for super-capacitors (SC) due to their economic, environmental, and sustainable characteristics. In this work, we proposed that the Sapindus Mukorossi Peel (SMP) was used as a precursor to prepare a Sapindus Mukorossi Peel-based activated carbon material (SMPC) through carbonization and KOH activation. The morphology and structure of SMPC were characterized by various test methods. Cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) were used to characterize its electrochemical performance. The results show that SMPC has suitable pore size distribution, a large number of heteroatom functional groups and excellent electrical conductivity. In addition, the amount of activator also has an important influence on the performance of SMPC. When the mass ratio of carbon material to KOH is 1:3, the prepared sample SMPC-3 has the largest specific surface area (SSA) was 1254.5 m2/g. Moreover, SMPC-3 also has excellent electrochemical properties, high specific capacitance (at 1 A/g, the specific capacitance can reach 314.5F/g), good cycle stability (at 5 A/g, cyclic charge and discharge 5000 times, the specific capacitance is only lost by 4.2%.), superior rate performance (when the current density is increased from 0.5 A/g to 10 A/g, the specific capacitance retention rate is 80.4%). Assembling SMPC-3 // SMPC-3 into a symmetrical SC shows higher energy density (at 0.1 A/g, the energy density is 6.68 Wh/Kg) and power density (at 5 A/g, the power density is 3250 W/Kg).

Transition-metal tellurides have been investigated as novel anode materials for application in sodium-ion batteries (SIBs) due to their rich active sites and unique and controllable layered nanostructures. However, the weak structural strength and inferior intercalation/deintercalation kinetics inhibit the development of transition-metal tellurides. In this work, MoTe 2 /C composites with two different hollow nanostructures are designed and prepared. By adjustment of the precursor structure, MoTe 2 /C-2 exhibits superior sodium-storage performance because of its uniquely hollow nanostructure with self-assembled 2D flexible nanosheets grown on the external surface. MoTe 2 /C-2 delivers a higher specific capacity (276 mAh g -1 at 0.1 A g -1 after 300 cycles), much more than MoTe 2 /C-1 (201 mAh g -1 at 0.1 A g -1 after 300 cycles), and exhibits a long-time cycling performance (131 mAh g -1 at 1 A g -1 after 2000 cycles). The excellent sodium-storage performance derived from the rational structure design is beneficial for shortening the ion paths, facilitating the sodiation/desodiation process, and reinforcing the intrinsic structural stability, thus boosting the reaction kinetics and prolonging the cycling life. Meanwhile, the assembled full-cell maintains 101 mAh g -1 at 0.1 A g -1 after 50 cycles and lights an electric watch. The findings provide several new views for preparation of more transition-metal tellurides with multi-ion/electron migration channel engineering.

• A highly porous carbon obtained from inexpensive jujube fruits for supercapacitors. • The porous carbon has a large surface area (1,135 m2 g−1) with micro-pores network. • The porous carbon has an extra-large specific capacitance of 460 F g−1 at 1 A g−1. • The porous carbon keeps 92.2% of capacitance after 130,000 cycles at 50 A g−1. • The porous carbon based cell shows an excellent energy density of 23.7 Wh kg−1. Herein, we propose a new highly porous natural carbon material from renewable and inexpensive jujube fruits as a carbon source applied in supercapacitors. The combination of pre-carbonization and chemical activation approaches is employed to product hierarchical porous carbon from natural jujube fruits. The specific surface area of the prepared porous carbon is increased from 85.4 to 1135 m2 g−1 after the completion of NaOH activation at an optimized condition, which is beneficial to enhancing electrochemical performance of supercapacitors. A 3-electrode configuration was utilized to explore the electrochemical ability of porous carbon in 6 M KOH electrolyte. The acquired results demonstrate that porous carbon displays the specific capacitance of 587, 460 and 324 F g−1 at 0.1, 1 and 100 A g−1, respectively, which is confirmed by its admirable capacitance and rate behaviors. The porous carbon also shows a wonderful durability with a capacitance retention of 92.2% after 130,000 cycles at 50 A g−1. Moreover, the assembled symmetrical coin-like supercapacitors with wide potential window of 2.5 V in 1 M Et 4 NBF 4 /AN organic electrolyte offer a high energy density of 23.7 Wh kg−1 at 0.629 kW kg−1 with remaining 94% capacitance over 10,000 cycles at 30 A g−1, indicating its practical application prospect. As a result, the present study proves the natural jujube fruits is a promising sustainable carbon source for making more economical and efficient electrode material of high performance supercapacitors. [ABSTRACT FROM AUTHOR]

Rapid synthesis of Low-crystalline δ-MnO 2 nanotubes and adjusting its morphology by the hydrothermal reaction tor annealing treatment. The 1D low-crystalline and ultrathin MnO 2 -RT nanotubes consisted of tiny nanoflakes are rapid synthesized at ambient temperature through a facile oxidation-etching method, where Cu nanowires are served as sacrificial templates. Meanwhile, the MnO 2 -RT nanotubes can be undergone further nucleation and growth to generate 3D porous MnO 2 nanotubes by calcination treatment and hydrothermal reaction, respectively. Importantly, the high specific capacitance of 384.6 F g−1 is obtained at the current density of 0.25 A g−1 for the low-crystalline MnO 2 -RT nanotubes, owing to its ultra-thin wall thickness, high surface area and highly disordered structure. Furthermore, the cycle stability of the low-crystalline MnO 2 nanotubes can be improved by hydrothermal treatment, owing to the enhanced crystallinity. [ABSTRACT FROM AUTHOR]

This study presents a series of Coral reef-shaped composites' recipe prepared after synthesizing g-C 3 N 4 (G), in-situ polymerized pyrrole as polypyrrole (P) and Poly (styrene sulfonate or PSS or simply S taken in varied amounts), collectively denoted as GPS, that were further explored towards super-capacitive energy accumulation behaviour and a dye's photocatalytic gradation. After getting relevant and justifying advance characterization of the synthesized composites, super-capacitive applications of the composites were studied using the three techniques based on electrochemistry. Galvanostatic Charge Discharge validated the results as this composite (0.3 GPS) exhibited a noticeable energy density of 82.86 Wh/kg along with high power density as 224.3 W/kg at 1 A/g and specific capacitance as 1223.53 F/g at 10 mV/s using cyclic voltammetry. Excellent cyclic retention of 92.31% was observed for 0.3 GPS product over 6000 cycles. A pair of gadgets also lit for two minutes when charged for three minutes at 1.1 V using asymmetric device fabricated of 0.3 GPS. Photocatalytic activity of these composites was studied against Rose Bengal dye, with an appreciable degradation efficiency of 0.3 GPS as 89.85% and also with the efficiency 74.23% after six degradation rounds. Thus, the composite evidences about its dual properties with both the functionalities working successfully. [Display omitted] • Coral reef-like composite series of g-C 3 N 4 , polypyrrole and PSS (GPS) synthesized for the first time • The nanocomposite is implemented for electrical energy storage and degradation of Rose Bengal dye • GPS exhibits 1217.67 F/g at 1 A/g with excellent retention of 92.31% over 6000 cycles • A noticeable energy density of 82.86 Wh/kg with a power density of 224.3 W/kg with supercapacitor device fabrication • It showed a dye degradation efficiency of nearly 90% with 72.43% retention even after 6 runs [ABSTRACT FROM AUTHOR]

Biowaste-derived hierarchical porous carbon materials and understanding their structure-property relationship have a significant impact on the development of low-cost and high-performance supercapacitors. Herein, we report the effective one-step construction of large specific surface area and hierarchical porous carbon materials (CPC) using waste corncobs as raw material and investigated the relationship between intrinsic pore characteristics and specific capacitance. The textural properties such as surface area and pore characteristics, are controlled by modulating the various activating agent, carbonization temperature and time. The as-prepared porous carbon material (particularly CPC-3) at activation temperature of 700 °C obtained via potassium permanganate modulation with optimal specific surface area and volume of pores 1612.86 m2 g−1 and 2.25 cm3 g−1, which exhibited the ultra-high capacitance of 691.05 F g−1 at a current density of 0.5 A g−1 with good rate capability. In addition, the electrode exhibits excellent capacitance retention of 109.7 % over 10000 charge-discharge cycles at a current density of 10 A g−1. Furthermore, the assembled symmetric supercapacitor using CPC-3 and PVA-KOH gel electrolyte delivered a high energy/power density of 16.47 Wh kg−1/15360 W kg−1, respectively. The as-prepared quasi-solid-state device also shows superior applicability and outstanding cycling stability over a wide temperature range of −25 to +60 °C. This work provides a fundamental understanding of the structure-property relationship of the biomass-derived hierarchical porous carbon and allows for the development of supercapacitors in harsh temperature conditions. Supercapacitors with a large specific capacitance, high energy density, and wide temperature range adaptability are constructed using hierarchically porous carbon derived from biomass waste by a facile one-step method to precisely regulate the pore structure. [Display omitted] [ABSTRACT FROM AUTHOR]

Electrode materials based on transition metal selenide have lately gained much favor in electrochemical supercapacitor owing to their outstanding capacitive performance, abundant availability and high electrical conductivity. In this study, we developed SmSe based reduced graphene oxide (rGO) nanocomposite via solvothermal technique. First, it is established that the SmSe/rGO nanoarray forms a porous microstructure in three dimensions. Various instrumental investigation was employed to examined the material microscopic and spectroscopic properties. The as-synthesized SmSe/rGO nanostructure possesses an outstanding specific capacitance (Cs) of 1226 F g−1 @ 1 A g−1 and remarkable long-cycle efficiency of 95.84% retention capacitance after 5000 cycles @ 1 A g−1. The incorporation of rGO into SmSe nanostructure is responsible for faster transfer of electron and providing high surface area having greater active sites which are responsible for the higher efficiency. [Display omitted] • The 2D-rGO based SmSe nanocomposite was developed via simple hydrothermal approach. • The electrode material suggests the specific capacitance of 1226 F g-1 @ 1 A g-1. • The nanohybrid display the smaller Rct of 1.28 Ω than the other materials. • The incorporation of rGO into SmSe facilitates faster transfer of electron. [ABSTRACT FROM AUTHOR]

We present experimental studies of alternating current (AC) electrowetting dominantly influenced by several unique characteristics of an ion gel dielectric in its capacitance. At a high-frequency region above 1 kHz, the droplet undergoes the contact angle modification. Due to its high-capacitance characteristic, the ion gel allows the contact angle change as large as Δθ = 26.4°, more than 2-fold improvement, compared to conventional dielectrics when f = 1 kHz. At the frequency range from 1 to 15 kHz, the capacitive response of the gel layer dominates and results in a nominal variation in the angle change as θ ≈ 90.9°. Above 15 kHz, such a capacitive response of the gel layer sharply decreases and leads to the drastic increase in the contact angle. At a low-frequency region below a few hundred Hz, the droplet’s oscillation relying on the AC frequency applied was mainly observed and oscillation performance was maximized at corresponding resonance frequencies. With the high-capacitance feature, the ion gel significantly enlarges the oscillation performance by 73.8% at the 1st resonance mode. The study herein on the ion gel dielectric will help for various AC electrowetting applications with the benefits of mixing enhancement, large contact angle modification, and frequency-independent control.

Abstract In this paper, hierarchical Co 3 O 4 -SnO@SnO 2 nanostructures flexible supercapacitor electrodes were fabricated by hydrothermal routine. Owing to the introduction of Co 3 O 4 as well as a cleverly PN junction hierarchically skeleton, the Co 3 O 4 -SnO@SnO 2 electrode presents a structure of nanospheres covered by nanoparticles, offering a low internal resistance (0.6 Ω) and high electrical conductivity. Without the use of a binder and complicated manufacturing process, the hierarchical nanostructures can be directly used as the working electrode in the three-electrode system. In addition, the electrode demonstrates a high specific capacitance (1.056 F cm−2 at 1 mA cm−2) and excellent stability (only 8.5% was lost in initial specific capacitance at 1 mA cm−2 after 2000 cycles). Therefore, the hierarchical Co 3 O 4 -SnO@SnO 2 nanostructures provide an opportunity for the coordinated development of novel energy density and power density of supercapacitor. Highlights • Metal oxides are introduced into the skeleton by a cleverly PN junction hierarchical nanostructure. • Built-in electric field in hierarchical nanostructure can reduce the electrode internal resistance to 0.6 Ω. • The hierarchical nanostructure electrode exhibits excellent discharge time, good cycle stability and higher capacitance. [ABSTRACT FROM AUTHOR]

Abstract Two-dimensional (2D) MXenes such as Ti 3 C 2 , Ti 2 C, Mo 2 C, and Mo 1.33 C have shown excellent electrochemical performances as supercapacitor electrodes, and the exploration of new and/or high-capacity MXene-based supercapacitor electrode materials is an active field. In this work, 2D multi-layered V 4 C 3 MXene has been synthesized by selectively etching Al from V 4 AlC 3 and it shows a high capacitance of 209 F g−1 at 2 mV s−1, good rate performance, and stable long cyclic performance with capacitance retention rate of 97.23% after 10000 cycles at 10 A g−1 in 1 M H 2 SO 4. Importantly, the pseudocapacitance (∼100.1 F g−1) accounts for about 37% of the total capacity (∼268.5 F g−1) for V 4 C 3 MXene electrode. Therefore, the high specific capacitance of V 4 C 3 MXene is not only due to their wide interlayer spacing (∼0.466 nm), large specific surface areas (∼31.35 m2 g−1) and pore volumes (∼0.047 cm3 g−1), and good hydrophilicity but also attributed to the abundant valence states of vanadium (+2, +3, and +4). The high rate performance and excellent cycling stability of V 4 C 3 MXene electrodes are mainly attributed to the high electronic conductivity (1137 S m−1 at 300 K). The present work provides another promising MXene-based supercapacitor electrode material. Graphical abstract Here we report on the synthesis of two-dimensional multi-layered V 4 C 3 MXene and its electrochemical performances as supercapacitor electrode. Large interlayer spacing and specific surface area as well as excellent hydrophilicity are obtained in as-prepared V 4 C 3 MXene. As a supercapacitor electrode, it shows high capacitance (∼209 F g−1 at 2 mV s−1), good rate performance, and stable long cyclic performance (capacitance retention rate is 97.23% after 10000 cycles at 10 A g−1) in 1 M H 2 SO 4 electrolyte. Image 1 Highlights • Two-dimensional multi-layered V 4 C 3 MXene is synthesized by etching Al from V 4 AlC 3. • V 4 C 3 possesses large interlayer spacing and specific surface as well as good hydrophilicity and electrical conductivity. • As supercapacitors electrode materials, V4C3 shows excellent electrochemical performance in 1 M H 2 SO 4. • V 4 C 3 MXene is a typical pseudocapacitive electrode material for supercapacitors. [ABSTRACT FROM AUTHOR]

• A bind-free MoTe 2 /rGO nanohybrid electrode was developed via a hydrothermal route. • A MoTe 2 nanoparticles are anchored on the rGO nanosheet investigated by scanning electron microscopy (SEM). • MoTe 2 /rGO nanohybrid display a remarkable specific capacitance of 1196.4 F g−1 as compared to pristine material. The rising prevalence of electronic devices necessitates the application of supercapacitors, which rely on electrochemically active materials with high capacitive performance. Two-dimensional (2D) molybdenum ditelluride (MoTe 2) nanoarrays have piqued great interest due to their wide-range applications including supercapacitor material, because of the inherent layered structure, low band gap and comparable conductivity. On the other hand, its self-aggregations decrease its chemical stability and activity, which remains a major barrier to its actual application. By combining with carbon-based reduced graphene oxide (rGO), self-aggregation and electrochemical activity can be improved significantly. In this research, MoTe 2 -supported rGO (MoTe 2 /rGO) was fabricated via a low-cost facile hydrothermal approach and characterised by fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), and energy dispersive X-ray spectroscopy (EDX) that is inclined with scanning electron microscope (SEM). Electrochemical assessments were also accomplished in an aqueous electrolytic solution of 2.0 M potassium hydroxide (KOH) for supercapacitor performance. The MoTe2/rGO shows exceptional specific capacitance (Cs) of 1196 F g−1, specific energy of 83.06 Wh kg−1- as well as 353.5 W kg−1 specific power at a current density of 1 A g−1 measured from galvanostatic charge/discharge (GCD) profile. On the other hand, the composite shows specific capacitance of 757.40 F g−1 measure via cyclic voltammetry (CV) at a scan rate of 5 mV s−1. Additionally, the nanohybrid shows a robust retention capacitance of 94.23% after 5000th successive cycles at 1 A g−1. The mechanical flexibility, intense cooperation and combined effects of MoTe 2 and rGO nanosheets are responsible for the exceptional performance of supercapacitor applications. Because of its enormous potential for green energy generation and its simplicity of manufacture in a single step, MoTe 2 /rGO nanocomposite can serve as an electrode for extraordinary supercapacitors. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Repeated in-situ depositions of polyaniline was performed on graphite-coated tape. • It adds mass load and affects physical and chemical structures of polyaniline. • It greatly increases energy-storage properties of polyaniline. • Tape electrodes are made into self-encapsulated flexible supercapacitors (FSCs). • The FSCs achieve thin, flexible, reliable and high-capacitance goals concurrently. Flexible supercapacitors (FSCs) are among the essential power suppliers of flexible electronics, while it is still challenging to achieve the high-performance, flexible, ultrathin and reliable targets concurrently. This work proposes the repeated in-situ chemical solution polymerizations (ICSPs) of polyaniline (PANI) on graphite-coated polyimide tape, and assembles the electrodes into self-encapsulated FSCs. Repeated ICSPs can increase the mass load of PANI and significantly influence its morphological, chemical and crystalline structures, as well as electronic and ionic transports, greatly increasing final energy-storage properties. The tape electrodes show maximum specific capacitances of 1955 mF cm−2 (1068F g−1) at 0.4 mA cm−2 and 1089 mF cm−2 (595F g−1) at 10 mA cm−2. Tape acts as substrates and packaging simultaneously. Consequently, the self-encapsulated FSCs show ultrathin thickness (∼200 μm), high areal and volumetric capacitances (481 mF cm−2 and 24F cm−3), durable flexibility (retaining a maximum of ∼ 97% after thousands of presses, bends, rolls, folds, twists, beats and even crumples for the FSC that was previously placed at open air over 2 months) and high device reliability. This work provides a prototype for reliable and advanced FSCs. [ABSTRACT FROM AUTHOR]

Abstract The N,S co-doped carbon nanospheres with/without hierarchical pores (N,S-HPCNs/N,S-CNs) are prepared by the pyrolysis of polypyrrole and (NH 4) 2 S 2 O 8 with/without F127 as the pore-foaming agent in flowing N 2. The results show that the combination of the hierarchical pores and N,S co-doping improves the electrochemical properties of carbon materials. As a result, the specific capacitance of N,S-HPCNs is as high as 416 F g−1 at a current density of 0.2 A g−1, which is much higher than that of N,S-CNs (138 F g−1). At a current density of 10 A g−1, the specific capacitance of 313 F g−1 for N,S-HPCNs is obtained, which keeps a capacitance retention of 75.2%, while the N,S-CNs has only the capacitance retention of 44.2%. After 5000 cycles, the retention ratio of N,S-HPCNs as high as 95.8% is obtained and the columbic efficiency of N,S-HPCNs is close to 100%. The symmetric supercapacitor device assembled using N,S-HPCNs exhibited a high energy density of 18.1 Wh kg−1 at a power density of 100 W kg−1. The exhibited excellent electrochemical performances of N,S-HPCNs are attributed to a high content of doped heteroatoms N and S and the hierarchical pore structure. Highlights • The N,S co-doped carbon nanospheres with hierarchical pores (N,S-HPCNs) are prepared. • The specific surface area of N,S-HPCNs reached 1830.8 m2 g−1. • The contents of N and S of N,S-HPCNs were 4.29% and 3.38%, respectively. • The specific capacitance of N,S-HPCNs reached 416 F g−1 at 0.2 A g−1. • The retention ratio of N,S-HPCNs was 95.8% after 5000 cycles. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Free-standing carbon materials can be fabricated by directly carbonizing waste dyed silk fabrics. • The carbonized dyed silk fabric shows excellent 3D hierarchical porosity and flexibility. • The carbon fabric electrode exhibits a high capacitance of 305.02 F g−1 at a scan rate of 2 mV s−1. Abstract An easy one-step pyrolysis method without any activation was employed to convert a waste dyed silk fabric into an interconnected hierarchically porous free-standing carbon fabric. As a result, nitrogen and oxygen co-doped carbonized dyed silk fabric with blue dye (CSF-B) exhibits a high specific capacitance of 305.02 F g−1 at a scan rate of 2 mV s−1 using 1 M Na 2 SO 4 electrolyte and a good cycling life stability with only 10% capacitance loss after 5000 cycles. Moreover,supercapacitor assembled by two CSF-B electrodes shows an energy density of 10.73 Wh kg−1 at a power density of 160.71 W kg−1. This exciting results display a green and low-cost design of self-supporting carbon electrode materials for supercapacitors with high performance. Interestingly, this concept can be readily extended to other waste fabrics such as cotton, wool and synthetic fiber dyed fabrics, which is beneficial to effectively utilize waste textile to create high value-added products. [ABSTRACT FROM AUTHOR]

Synthesis of mesoporous graphitic carbon nitride (MGCN) by soft template method is still challenging and its application as an electrode material for supercapacitor remains unexplored. Herein, we introduce MGCN as an electrode material for supercapacitors. MGCN is synthesized by facile direct carbonization of methylolated surfactant‐polymer composite and bulk graphitic carbon nitride (BGCN) is synthesized under similar condition but in the absence of surfactant. MGCN displays excellent capacitance properties in 1 M H2SO4 electrolyte with a specific capacitance as high as 279 F g−1 at a current density of 0.25 A g−1. It also exhibits good rate capability and outstanding cycling stability with excellent coulombic efficiency of 100% over 5000 cycles. This superior capacitive storage performance is attributed to the high surface area, easily accessible mesopores and high pyridinic nitrogen content. High surface area and uniform pores of MGCN provide more active sites for charge storage and reduce diffusion path length for ions while high pyridinic nitrogen enhanced the overall specific capacitance by surface Faradaic reaction. Mesoporous graphitic carbon nitride (MGCN) is unveiled as a promising electrode material for supercapacitors. MGCN displays excellent capacitance properties in 1 M H2SO4 electrolyte with a specific capacitance as high as 279 F g−1 at a current density of 0.25 A g−1. It retains 45% of its initial specific capacitance when the current density is increased from 0.25 to 20 A g−1 demonstrating excellent rate capability. It also exhibits outstanding cycling stability with excellent coulombic efficiency. [ABSTRACT FROM AUTHOR]

Design of sensors with improved parameters is still an extensive field of analytical research. A comparative study between seven types of all-solid-state ion-selective electrodes (ASS-ISEs) and coated disc ion-selective electrode (CD-ISE) was carried out. This work developed solid contact layers designed from molecular organic materials (MOMs): tetrathiafulvalene (TTF), its chloride salt (TTFCl) or tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) with or without the addition of carbon black (CB) acting as inner transducers. Intermediate layers were deposited by a solution casting on the top of glassy carbon disc electrodes and then were covered with a membrane containing tridodecylmethylammonium chloride, o-nitrophenyl octyl ether, and poly(vinyl chloride). Molecular organic conductive materials were compared with CB-MOM composites as materials responsible for transduction process in all-solid-state chloride-selective electrodes. The proposed solid contact layers were characterized by scanning electron microscopy and electrochemical methods. The intermediate layer effect on the electrodes was tested, and prepared sensors were investigated by potentiometric, chronopotentiometric and electrochemical impedance spectroscopy measurements. All the modified electrodes displayed a satisfactory performance and Nernstian electrode function for chloride in the concentration range from 10 −5  M to 10 −1  M, however the best sensitivity and detection limit were observed for the CB-TTFCl-contacted electrode. The obtained results showed that the electrodes with internal layer consisting of CB-MOM nanocomposite presented slightly more sensitive response to chloride, lower impedance and a higher capacitance than electrodes based only on various molecular organic materials. [ABSTRACT FROM AUTHOR]

A hybrid electrochemical capacitor in 1 mol L −1 Li 2 SO 4 + 0.2 mol L −1 KI aqueous solution (pH = 6.5, conductivity = 86 mS cm −1 at 24 °C) has been developed by implementing highly microporous carbon (KAC, average micropore size L 0  = 0.88 nm) as negative electrode and a micro-/mesoporous carbon (PAC, average micropore size L 0  = 1.01 nm) as positive electrode. Under negative polarization, KAC demonstrates a high electrical double-layer (EDL) capacitance (187 F g −1 ), owing to strictly microporous texture making it suitable as negative electrode in a hybrid cell. Besides, under positive polarization, a well-defined faradaic redox signature (in narrow potential range) related with the iodine/iodide system is observed with PAC, giving rise to much higher capacity (62 mAh g −1 ) than with KAC (37 mAh g −1 ) and making the former a good candidate to be implemented as positive electrode in a hybrid cell. As a result, the asymmetric (−)KAC/PAC(+) hybrid cell in aqueous Li 2 SO 4 +KI exhibits a high capacitance of 74 F g −1 (per total active mass of the two electrodes) compared to 66 F g −1 and 50 F g −1 for the (−)KAC/KAC(+) and (−)PAC/PAC(+) hybrid cells, respectively. Moreover, for the asymmetric (−)KAC/PAC(+) capacitor, the potential of the positive electrode is lower than the thermodynamic limit of water oxidation, and the potential of the negative electrode is higher than the kinetic limit of hydrogen evolution. Consequently, the asymmetric (−)KAC/PAC(+) hybrid cell demonstrates the lowest capacitance drop and resistance increase during floating. At 2.5 A g −1 , the (−)KAC/PAC(+) capacitor exhibits a high specific energy of 15.4 Wh kg −1 compared to 10.1 Wh kg −1 and 8.1 Wh kg −1 for the (−)KAC/KAC(+) and (−)PAC/PAC(+) capacitors, respectively. Raman spectra on the PAC positive electrode of the asymmetric (−)KAC/PAC(+) cell demonstrate upshifting of D and G bands by 12 cm −1 and 8 cm −1 , respectively, suggesting a charge transfer between carbon and polyiodides confined in the porosity. [ABSTRACT FROM AUTHOR]

The introduction of novel materials into industrial demonstrators is an essential step in developing unique commercial energy storage devices. However, this step is rarely considered in literature. In this study, we report on the introduction of innovative materials for high energy density electrical double-layer capacitors (EDLCs), namely the carbide-derived carbon (CDC) "Curved Graphene" with a specific and an aerial capacitance of 114 F g−1 and 82 F cm−3, polysaccharide binders, and electrolyte based on acetonitrile (ACN) and pyrrolidinium-based salt, into a demonstrator. We show that by utilizing this innovative cell chemistry it is possible to realize an industrial demonstrator exhibiting a nominal capacitance of 5000 F, with a specific energy and energy density of up to 8.4 Wh kg−1 and 12.2 Wh L−1 as well as a remarkable lifetime with a capacitance retention of 77% after floating for almost 1400 h at 2.85 V and 65 °C. These results prove that the novel materials considered in this work can indeed be utilized for the realization of commercially available devices with improved cell performance with respect to the state-of-the-art. • Introducing novel materials into industrial demonstrators. • Demonstrator with nominal capacitance of 5000 F and energy density of 12.2 Wh L−1. • Capacitance retention of 77% after 1400 h of float at 2.85 V and 65 °C. [ABSTRACT FROM AUTHOR]