Good Capacitance Research Articles

Ti3C2Tx MXene/Alginic Acid-Derived Mesoporous Carbon Nanocomposite as a Potential Electrode Material for Coin-Cell Asymmetric Supercapacitor

In this study, we demonstrate a MXene (Ti₃C₂Tₓ)-based coin-cell asymmetric supercapacitor (coin-cell ASC) exhibiting high energy density and high power density along with good capacitance. We synthesized mesoporous carbon (MC)...

Mild chemical-activated hydrothermal porous carbon derived from durian peel biomass for an electrochemical supercapacitor

The durian peels with ball/nanosheet structure presents good specific capacitance (267 F g−1 at 1 A g−1) in the three-electrode system. The Na2SO4-based symmetric supercapacitor shows the maximum energy density of 14.45 W h kg−1 at 225 W kg−1.

Structural and Electrical Studies of Chitosan: Polyvinyl Alcohol with Blend Polymer Electrolyte Doped with Potassium Iodide

The technique of solution casting was employed to produce a flexible and uniform blend polymer electrolyte film (BPE) comprising Chitosan (Cs): polyvinyl alcohol (PVA) doped with potassium iodide (KI) at varying concentrations (X= 0%, 10%, 20%, 30%). X-ray diffraction (XRD) was utilized to examine the structural characteristics of the BPE and assess their crystallinity and amorphous nature. Fourier-transform infrared spectroscopy (FTIR) was used to identify the functional groups and ensure the homogeneous mixing of PVA/CS/KI. The electrical properties of the BPE were assessed to determine the capacitance and potential window using cyclic voltammetry (CV). It was observed that the BPE doped with 20% KI (sample PCK20) exhibited a highly crystalline nature and demonstrated the highest capacitance of BPE 449.1 pF. The potential window for the BPE ranged from 1.45 V to 2 V. These BPE materials show potential for use in environmentally friendly energy storage applications. The acquired results show good crystallinity, potential stability, and capacitance as evaluated by cyclic voltammetry (CV), and they could be beneficial for energy storage applications.

Implementation of phosphonium salt for high-performance supercapacitors from room to ultra-low temperature conditions

Conventional supercapacitors encounter limitations in operating voltage and performance at low temperatures due to poor ionic conductivity and diminished interfacial dynamics in electrolytes. In this study, we synthesized the phosphonium salt 5-phosphinaspiro[4.4] nonane tetrafluoroborate (PSNBF4) for the first time. We extensively characterized the physical and electrochemical properties of PSNBF4 in acetonitrile (AN) and propionitrile (PN) as electrolytes, assessing their performance in supercapacitors at room temperature and − 40 °C. The results demonstrate PSNBF4 electrolytes exhibit high solubility, outstanding ionic conductivity (1 M PSNBF4/AN: 49.8 mS cm−1; 1 M PSNBF4/PN: 27.5 mS cm−1), and high electrochemical stability, contributing to good capacitance retention after 500 h of floating tests at 25 °C. Supercapacitors using PSNBF4/AN retained 78 % of their capacitance at 3.1 V, whereas those with PSNBF4/PN maintained 68 % at 3.2 V. Impressively, these supercapacitors performed exceptionally well at −40 °C, displaying excellent cycle stability and high capacitance retention at elevated voltages. Supercapacitors with PSNBF4/AN retain 96.6 % of their capacitance at 3.2 V, while PSNBF4/PN retained 93.4 % of their capacitance at 3.4 V after floating for 500 h. These results demonstrate PSNBF4-based supercapacitors can operate effectively at high voltages in both room and extremely low temperatures, addressing a significant challenge in commercial supercapacitor applications.

Comprehensive analysis of the effect of weight percentage of V and Mn doping in NiCo MOFs for hybrid supercapacitors

The present work provides a critical exploration of the use of NiCo Metal organic frameworks (NC) as pseudocapacitor materials with different weight percentages of V & Mn (1, 5, 10, and 20 %, abbreviated as NCV1–20 & NCM1–20) in NC for hybrid supercapacitors. Physico-chemical properties of all MOFs were characterized by means of analytical techniques such as P-XRD, FT-IR, BET, TGA, ICP-OES, SEM-EDS, HR-TEM & SAED. The MOFs NCV1 and NCM1 showed a good specific capacitance (Cs) value of 1074 Fg−1 and 1389 Fg−1 at 2 mVs−1 with 503 Fg−1 and 783 Fg−1 at 1 Ag−1 respectively in 1 M KOH. The Cs values of NCV1 and NCM1 were lesser compared to pure NC (1862 Fg−1 at 2 mVs−1 and 811 Fg−1 at 2.5 Ag−1). At each of their respective OCP windows, the estimated Cs values of NC, NCV1, and NCM1 were found to be 512, 371, and 383 Fg−1. All the MOFs were stable for 20,000 cycles at a current density of 20 Ag−1 with good Cs retention values for NCV1 and NCM1. This statistical analysis of the values acquired from the electrochemical studies of all the MOFs, indicated the negative effect (with respect to electrochemical performance) of V and Mn doping in NCs and hence hinged on other physico-chemical properties.Asymmetric coin cells NCV1//CA and NCM1//CA (charcoal activated carbon) were fabricated in 1 M KOH solution. Out of which, NCM1//CA exhibited a Cs of 140.3 Fg−1 at 2 mVs−1 (0-2 V) and 65.4 Fg−1 at 1 Ag−1 in an operating potential window of 1.7 V. The cell also indicated maximum Energy density (ED) and Power density (PD) of 26.2 Whkg−1 and 17 k Wkg−1 respectively. Further, cycles stability test indicated 67.6 % of Cs retention with coulombic efficiency of 100 % at the end of 75,000 cycles. To check the practical application, two such designed cells were charged to 3 V at 2.5 Ag−1 connected in series and utilized to power six LEDs for three minutes.

APullulan polysaccharide-based flame-retardant polyelectrolyte hydrogel for high-safety flexible zinc ion capacitors

Potential safety hazards such as leakage, flammability and thermal runaway of liquid electrolytes in conventional energy storage devices have seriously hindered their further development. In this work, a flame-retardant polyacrylamide/pullulan/phytic acid (PAM/PUL/PA) hydrogel electrolyte is prepared by using PA as flame-retardant additive, PAM as main polymer chain by one-step radical polymerization method. The PAM/PUL/PA hydrogel shows good flame-retardant properties with limiting oxygen index of up to 58 %, high mechanical performance with stretch up to 1535 % and 92 kPa tensile stress. Zinc ion capacitor (ZIC) assembled with the PAM/PUL/PA hydrogel as electrolyte and separator exhibits high ionic conductivity of 22.54 mS cm−1, high specific capacity of 111.5 mAh g−1 at 0.1 A g−1 and energy density of 97.57 Wh kg−1 at a power density of 49.99 W kg−1, as well as good capacitance retention of 74.6 % even after 10,000 cycles. Furthermore, the ZIC has outstanding flexibility, the capacitance retention rate almost unchanged even after 1000 consecutive bending of deformations. These excellent properties are attributed to the hydrogen bonds easily formed by polar functional groups in hydrogels and the electrostatic interactions with metal ions. This work presented a simple and general pathway to prepare high-safety flexible energy storage devices with multifunctional properties.

CeO2/MnFe2O4 nanocomposite: Structural, magnetic, electrochemical and cytotoxicity properties

The synthesis and characterization of CeO2/MnFe2O4 nanocomposite is significant due to its potential uses in various sectors, including environment and energy storage. This nanocomposite, created through calcination at 600 °C, has received a lot of interest. However, worries about potential cytotoxicity have encouraged studies into its safe use in biological systems. This study investigates the material’s cytotoxic properties to determine its impact on cell health. Electrochemical testing revealed good capacitance performance within the 0–0.5 V potential window, with a specific capacitance (Cs) of 76 F/g at a current density of 0.25 A/g, making it a prospective candidate for supercapacitor (SC) development. Despite the higher current density of 5 A/g, the electrode maintained 81.28 % of its capacitance retention. These findings highlight the nanocomposite’s potential in SC applications. Furthermore, cell viability studies with normal mouse muscle fibroblasts (BLO-11) and murine colorectal cancer cells (CT-26) demonstrated high biocompatibility, with cell survival rates exceeding 82 %. These findings highlight the need to assess nanocomposite safety for potential biological applications.

Materials Science Aspects and Performance of High Power Magnetically Ordered Pseudocapacitors

This investigation was motivated by increasing interest in magnetically ordered pseudocapacitor (MOPC) materials for applications in high-power pseudocapacitors and water purification devices. MOPCs exhibit capacitance enhancement due to the magnetohydrodynamic effect and interesting magnetocapacitive effects, which result in influence of charge/magnetization on magnetic/pseudocapacitive properties.Advanced magnetic materials, such as ferrimagnetic spinels, ferrimagnetic hexagonal ferrites and ferromagnetic lanthanum strontium manganates (LSM) were studied. Electrodes with active mass loadings of 40 mg cm-2 were tested in Na2SO4 electrolytes. Chemical precipitation methods, hydrothermal synthesis and high energy ball milling techniques were used for the synthesis of nanoparticles. Capping agents, such as caffeic acid, gallic acid and murexide, were used for synthesis. The chelating groups of the capping agents facilitated their adsorption on particles and the adsorbed capping agents limited particle growth. The use of multifunctional organic capping agents-alkalizers influenced the morphology and phase content of the synthesized materials and facilitated the fabrication of electrodes with enhanced capacitance. In another approach, enhanced capacitance was achieved using redox active dispersants, such as gallocyanine and Celestine Blue, which acted as charge transfer mediators and facilitated charge transfer.Electrochemical testing was performed using cyclic voltammetry, galvanostatic charge-discharge and impedance spectroscopy. Ferrimagnetic spinels, such as CuFe2O4, Fe3O4, γ-Fe2O3, MnFe2O4 showed capacitances of 2.76, 5.82, 3.78 and 2.67 F cm-2, respectively. The high active mass electrodes showed low resistance, which was below 1 Ohm. The large voltage window, high capacitance and low resistance of the electrodes facilitated the fabrication of devices with enhanced power-energy characteristics. The electrodes were used for the fabrication of asymmetric and symmetric devices. A symmetric device, containing two ferrimagnetic MnFe2O4 electrodes showed a capacitance of 0.92 F cm-2. Asymmetric devices showed capacitances in the range of 2.4-3.2 F cm-2 in a voltage window of 1.6V.Ferrimagnetic SrFe12O19 and BaFe12O19 showed capacitances of 1.2 and 1.34 F cm-2, respectively. Good capacitive behavior was linked to beneficial effect of high energy ball milling and the use of efficient dispersant, which also acted as a charge transfer mediator. A remarkably high capacitance of 4.59 F cm-2 was achieved at a low resistance for ferromagnetic LSM electrodes. The electrodes showed good capacitance retention at fast charge-discharge rates and excellent cyclic stability.Magnetic properties of the ferrimagnetic and ferromagnetic materials were analyzed. The charging mechanisms in positive and negative potential ranges were studied. The effect of hard and soft magnetic properties on capacitive behavior was analyzed. The high active mass MOPC electrodes showed good capacitance retention at fast charge-discharge rates and enhanced power-energy characteristics.The MOFC electrodes tested in this work combine advanced charge storage properties, high spontaneous magnetization, low resistance, giant magnetoresistance and other functional properties. The obtained electrodes are promising for energy storage in supercapacitors with enhanced power-energy characteristics for operation at fast charge-discharge rates, capacitive deionization of water devices and novel applications based on magnetocapacitive effects.

Intercalation of Polyacrylonitrile Nanoparticles in Ti3C2Tx MXene Layers for Improved Supercapacitance.

We report the intercalation of polyacrylonitrile nanoparticles in Ti3C2Tx MXene layers through simple sonication. The use of polyacrylonitrile, which was synthesized via radical polymerization, offered dual benefits: (1) It increased the interlayer spacing of MXene, thereby exposing more surface area and enhancing ion transport channels during charge and discharge cycles, and (2) Integrating MXene with polyacrylonitrile enables the creation of a composite with conductive properties, following percolation principle. X-ray diffraction analysis showed an increase in the c-lattice parameter, indicative of the interlayer spacing, from 22.31 Å for the pristine MXene to 37.73 Å for the MXene-polyacrylonitrile composite. The intercalated polyacrylonitrile nanoparticles facilitated the delamination by weakening the interlayer interactions, especially during sonication. Electrochemical assessments revealed significant improvement in the properties of the MXene-polyacrylonitrile composite compared to the pristine MXene. The assembled asymmetric device achieved a good specific capacitance of 32.1 F/g, an energy density of 11.42 W h/kg, and 82.2% capacitance retention after 10,000 cycles, highlighting the practical potential of the MXene-polyacrylonitrile composite.

Honeycomb-like N, S dual-doped porous carbons derived from pomelo peel by effective exogenous doping strategy for supercapacitor electrodes

Biomass has emerged as a pivotal precursor to synthesize supercapacitor electrode materials owing to its low-cost and plentiful resources. The optimization of heteroatoms and porous structures is believed to be a viable method to enhance the electrochemical properties of biomass-generated carbons. Herein, pomelo peel as a precursor using KOH as an activator and heteroatom dopants (urea and sodium sulfide) was successfully converted into N, S dual-doped porous carbons under the high temperature. The effective exogenous doping strategy realizes a high abundance of N/S heteroatoms, and KOH chemical activation promotes the development of nanopores and interconnected porosities. The resultant carbon CNS-800 with a high specific surface area of 1823.8 m2 g−1 and rich heteroatoms of N (2.51 wt%) and S (1.36 wt%) anticipately exhibits the outstanding electrochemical properties, including the excellent specific capacitance of 329.2 F g−1 at 1 A g−1 in a three-electrode (3E) system and the superb capacitance retention rate of 74.12 %. The fabricated CNS-800-based symmetric two-electrode (2E) supercapacitor demonstrates a good capacitance of 243.7 F g−1 and excellent cycling stability, as well as a superb energy density of 14.3 Wh kg−1. This work provides a compelling and cost-effective approach to transform biomass waste like pomelo peels into high-performance electrodes for supercapacitors.

A Study of the Effect of Temperature on the Capacitance Characteristics of a Metal-μhemisphere Resonant Gyroscope.

Metal-μhemispherical resonant gyros (M-μHRGs) are widely used in highly dynamic navigation systems in extreme environments due to their high accuracy and structural stability. However, the effect of temperature variations on the capacitance characteristics of M-μHRGs has not been fully investigated, which is crucial for optimizing the performance of the gyro. This study aims to systematically analyze the effect of temperature on the static and dynamic capacitances of M-μHRGs. In this study, an M-μHRG structure based on a 16-tooth metal oscillator is designed, and conducted simulation experiments using non-contact capacitance measurement method and COMSOL Multiphysics 6.2 finite element simulation software in the temperature range of 233.15 K to 343.15 K. The modeling analysis of the static capacitance takes into account the thermal expansion effect, and the results show that static capacitance remains stable across the measured temperature range, with minimal effect from temperature. The dynamic capacitance exhibits significant nonlinear variations under different temperature conditions, especially in the two end temperature intervals (below 273.15 K and above 313.15 K), where the capacitance values show local extremes and fluctuations. In order to capture this nonlinear behavior, the experimental data were smoothed and fitted using the LOESS method, revealing a complex trend of the capacitance variation with temperature. The results show that the M-μHRG has good capacitance stability in the mid-temperature range, but its dynamic performance is significantly affected at extreme temperatures. This study provides a theoretical reference for the optimal design of M-μHRGs in high- and low-temperature environments.

Acid‐doped polyaniline‐based asymmetric supercapacitors with high energy density by electrochemical polymerization

AbstractIn this article, conductive polyaniline (PANI) was prepared by electrochemical polymerization on the FTO surface doping different protonic acids (H2SO4, HCl and H3PO4), named the rod‐like PANI‐S, dogtail‐like PANI‐Cl and burr‐like PANI‐P, respectively. The three‐type PANIs possess stable structure, novel morphology and low charge transfer resistance after careful investigation. Among them, the obtained rod‐like PANI‐S has the best specific capacitance of 542.8 F g−1. Also, biomass activated carbon AC with good specific capacitance was successfully prepared by chemical activation of green tea. Interestingly, the asymmetric supercapacitor (ASC) device was assembled with PANI‐S in PVA‐H2SO4 as the positive electrode and AC3:1 in PVA‐KOH as the negative electrode and the obtained ASC device has voltage window of 1.6 V and energy density of 29 Wh kg−1. Electrochemical evaluation in the PANI‐based ASC devices improves the potential applications in energy storage fields.

Nanorod-based smart windows with solid-gel electrolyte: An integrated electrochromic and pseudocapacitive technology for energy-saving and conversion

We fabricated two emerging nanorod-based smart windows with WO3 and NiO nanorods grown on the ITO/glass and ITO/muscovite mica (MM) substrates, respectively. The WO3/ITO/glass and WO3/ITO/MM substrates are excellent working electrodes, while the NiO/ITO/glass and NiO/ITO/MM substrates are exceptional counter electrodes. The nanorod-based WO3/Li+(s)/NiO@glass smart window consists of a WO3/ITO/glass working electrode, a NiO/ITO/glass counter electrode, and a solid-gel LiClO4 electrolyte (labeled as Li+(s)), respectively. The other nanorod-based WO3/Li+(s)/NiO@MM is comprised of a WO3/ITO/MM working electrode, a NiO/ITO/MM counter electrode, and a solid-gel LiClO4 electrolyte, respectively. Both the nanorod-based WO3/Li+(s)/NiO@glass and WO3/Li+(s)/NiO@MM smart windows have brilliant dual-band (red and near-infrared lights) electrochromic behaviors, such as large transmittance differences (ΔT), fast response times (bleaching time, tb, and coloration time, tc) at red (680 nm) and near infrared (1000 nm) lights and great electrochromic retention (4000 cycles), and outstanding pseudocapacitive performances like good specific capacitances of ∼18.4 F/g and ∼7.6 F/g, intensive power densities of ∼1779 W/kg and ∼2100 W/kg with corresponding energy densities of ∼5.4 Wh/kg and ∼2.2 Wh/kg, enormous pseudocapacitive retention (10,000 cycles), and so on. Therefore, the brilliant dual-band electrochromic behaviors and outstanding pseudocapacitive performances make the nanorod-based WO3/Li+(s)/NiO@glass and WO3/Li+(s)/NiO@MM smart windows tremendous for use in multifunctional energy-saving-conversion devices.

Titanate nanorod/reduced graphene oxide-filled poly (vinylidene fluoride) fibers as piezoelectric nanogenerators

To investigate the influence of nanorod ceramic powders MTiO3 (M: Mg, Co, Ni) as fillers on the electrical performance, piezoelectric nanogenerators (PENG) device, were constructed using the electrospinning method with polyvinylidene fluoride (PVDF), reduced graphene oxide (RGO), and ceramic powders. The composite nanofibers were characterized using SEM, EDX, ATR-FTIR, EDS-mapping analysis, and XRD. Sensing capacity of the PVDF-RGO-MTiO3 nanofiber-based PENG were compared. Utilizing CoTiO3 (CT) in the PENG resulted in a voltage output of 17.03, which exhibited the best piezoelectric response. Observations revealed that mechanical stimulation could charge different capacitors, suggesting a viable platform for removing the requirement of an external power source for operating portable devices. With varying resistances in the circuit, the resistance of 104 Ω produced the maximum power density of 1.40 mW/cm2. When comparing the P-RGO-CT composite to pure PVDF, the differential scanning calorimetric analysis revealed that the thermal stability and crystallinity percentage increased. Tensile testing was used to evaluate the mechanical characteristics of P-RGO-CT PENG. The maximum stress and breaking strain that the nanofiber film can tolerate are 50 kPa and 33.9 %, respectively. EIS investigations obtained that the real intrinsic internal resistance of the P-RGO-CT PENG electrode is lower than PVDF, demonstrating the good conductivity of the synthesized PENG electrode. The impedance spectrum of the PENG electrode is almost parallel to the Zim axis, demonstrating good capacitance performance.

Nanosized hyperbranched cobalt and metal-free phthalocyanine intercalated with Pd–C matrix using PVA-TEOS as binder for admirable supercapacitor properties

The expanding global economy resulted mainly from consuming fossil fuels, which are scarce and cause prodigious environmental harm. Mankind is shifting towards sustainable, efficient and clean energy sources known as green energy. The storage of green energy is an urge of time, to fulfil the energy requirements. Supercapacitors are gaining popularity in the field of energy storage due to their excellent safety, cost-effectiveness, and environmental friendliness. The forthright strategy of using a nitrogen-rich phthalocyanine macrocycle as a nanosized particle is to increase surface area resulting in a high specific capacitance. Herein, an innovative approach has been made by synthesising nanosized hyperbranched metal-free/Co-Phthalocyanine characterized by various analytical and spectroscopic techniques. The morphology of the composite was confirmed through physicochemical characterization like BET, SEM, XRD and electrochemical features were studied through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). The electrode modification was carried out using the binder Poly (vinyl alcohol)-Tetraethyl orthosilicate (PVA-TEOS) crosslinked hybrid solution. The intercalated nanosized palladium on carbon matrix with HBCoPc and HBPc at different ratios enhanced the performance of capacitance. Amongst all the ratios, HBCoPc: Pd–C with 30:70 ratio has demonstrated superior specific capacitance of 824.25 F g−1 at 0.5 A g−1. Additionally, the fabricated electrode of HBCoPc: Pd–C and HBPc: Pd–C has exhibited good capacitance retention of 84.03 % and 81.01 % over 5000 cycles, respectively. This work delivers a promising approach towards the development of high-performance supercapacitors using metal phthalocyanine/metal-carbon composites as a new way to manufacture devices for conversion and energy storage.

Fabrication of modified laser-induced graphene using activated carbon and polyamic acid coating for flexible and high-performance microsupercapacitors

In this study, we developed a method to combine polyamic acid (PAA) and activated carbon (AC), which were then coated on laser-induced graphene (LIG). The material was heated to facilitate the conversion of PAA–AC into polyimide (PI)–AC. Then, the resulting material was subjected to a second laser irradiation process to obtain AC–LIG composite materials. The resulting material features a robust and flexible electrode architecture with a high surface area, improved ion accessibility, and enhanced charge transfer kinetics. In tests conducted with a three-electrode setup, the AC–LIG configuration exhibited a considerably high specific capacitance, reaching 97.2 mF cm−2 at 0.2 mA cm−2, which is approximately fourteen times larger than that of pristine LIG (7.1 mF cm−2). When integrated into a flexible microsupercapacitor using a polyvinyl alcohol (PVA)–H2SO4 (sulfuric acid) gel-type electrolyte, AC–LIG exhibited a higher specific capacitance (68.4 mF cm−2 at 0.3 mA cm−2) than d-LIG (17.1 mF cm−2 at 0.3 mA cm−2). Furthermore, AC–LIG showed good Coulombic efficiency (98.5 %) and capacitance retention (90.0 %) after 10,000 cycles. These results highlight the potential of AC–LIG as a viable alternative for advanced supercapacitor (SC) applications, providing improved energy storage capacities and a reliable performance.

MgOMo2C/multiwalled carbon nanotube composite for high-performance supercapacitor applications

Magnesium molybdate (MgMoO4) nanostructure has been successfully prepared and employed as a catalyst for the production of multi-walled carbon nanotubes (CNTs) by the chemical vapor deposition method. The prepared nanostructure materials are characterized through XRD, TEM, FTIR, BET and Raman spectroscopy. The XRD results and TEM images confirm the formation of the plate-like MgMoO4 structure, as well as the existence of Mo2C and CNTs in the type of bundles structure (CNTBs). The high dispersion and stability of Mo nanoparticles in the composite of plate-like MgMoO4 is responsible for the formation of CNTBs with uniform diameters. Thus, the plate-like MgMoO4 nanoparticles and the MgOMo2C@CNTBs hybrid material are assessed as electrodes in a supercapacitor device for the first time. The produced hybrid supercapacitor MgOMo2C@CNTBs has a good specific capacitance (354 F g−1) and strong cycling stability (82 percent capacity retention over 2000 cycles)

Bimolecular Salt Strategy Enhances Heteroatom Doping and Porosity Optimization of Porous Carbon for Supercapacitors.

The incompatibility between electrolyte ions and electrode pore sizes, coupled with the extensive use of activators and dopants, significantly restricts the fabrication of porous carbon materials. Consequently, developing environmentally sustainable and efficient methodologies that exploit the intrinsic properties and pretreatment of materials to facilitate self-activation and self-doping becomes crucial. In this study, potassium histidine and magnesium histidine molecular salts were synthesized as precursors, enabling specific ion activation and bimetallic template-directed tunable porosity through a one-step carbonization process. Notably, the ratio of bimolecular salts significantly influenced the porous structure of carbon, the properties of heteroatoms, and the electrochemical performance. By optimizing the ratio, the porous carbon materials exhibited high accessibility to electrolyte ions and effective ion/electron transport channels. Consequently, the optimal sample (NOSPC-2) achieved a high specific capacitance of 318 F g-1 at 0.1 A g-1 and a good capacitance retention rate of 98.8% after 50,000 cycles at 5 A g-1. In addition, NOSPC-2 also boasted high energy density and power density, reaching 22 Wh kg-1 and 25 kW kg-1, respectively. This research represents a significant stride in advancing preparation technologies for small molecule derived porous carbon materials, providing valuable insights for the rational design of carbon electrode materials for capacitive energy storage.

A novel hybrid sodium ion capacitor based on Na [Ni0.60Mn0.35Co0.05] O2 battery type cathode and presodiated D-Ti3C2Tx pseudocapacitive anode

The combination of the high-power density of supercapacitors and the high energy density of batteries makes hybrid sodium-ion capacitors (HSICs) a promising device. HSICs can provide better performance characteristics by harnessing both ion adsorption/desorption in the capacitor-type electrode and sodium-ion intercalation in the battery-type electrode. Here, the synthesis of MXene (Ti3C2Tx), a two-dimensional (2D) carbide and nitride is reported. Delaminated MXene (D-Ti3C2Tx) is a promising candidate for anode material in HSIC due to its large surface area (∼ 42 m2/g) and good electronic conductivity. Electrochemical study indicates that D-Ti3C2Tx anode exhibits a high discharge capacity of ∼213 mAh/g at a current rate of 20 mA/g. Further the presodiated D-Ti3C2Tx anode is paired with Na [Ni0.60Mn0.35Co0.05] O2 (P2-NMC) cathode to obtain the configuration of HSIC. The HSIC exhibits good specific capacitance of ∼187 F/g and specific discharge capacity of ∼110 mAh/g at a current density of 10 mA/g, according to the electrochemical analysis. A notable improvement in specific energy density (∼ 256 Wh/kg) and specific power density (∼579 W/kg) is also demonstrated by the HSIC. With P2-NMC being used as the cathode material rather than traditional activated carbon, there has been a rise in specific energy density.

The impact of processing voltage of wire electric discharge machining on the performance of Mo doped V-VO0.2 based Archimedean micro-supercapacitors.

Vanadium oxide-based electrode materials have attracted increasing attention owing to their extraordinary capacitance and prolonged lifespan, excellent conductivity and outstanding electrochemical reversibility. However, the development of vanadium oxide-based integrated electrodes with outstanding capacitive performance is an enduring challenge. This research reports a facile method for structuring 3D Archimedean micro-supercapacitors (AMSCs) composed of Mo doped V-VO0.2 (Mo@V-VO0.2) based integrated electrodes with designable geometric shape, using computer-aided wire electric discharge machining (WEDM). The performance of Mo@V-VO0.2 based AMSCs manufactured by different processing voltages of 60 V, 80 V and 100 V were evaluated. It was found that 80 V is the optimal processing voltage for manufacturing Mo@V-VO0.2 based AMSCs with the best electrochemical performance. This device demonstrates superior capacitive behavior even at an ultra-high scan rate of 50, 000 mV s-1, and achieves a good capacitance retention rate of 94.4% after 2000 cycles. Additionally, the characteristics of electric field distribution were also simulated for optimizing the geometric structure of the microdevices. This WEDM fabrication technique, which is easy, secure, patternable, efficient, economical, eco-friendly, and does not require binders or conductive additives, enables the development of high-capacity 3D pseudocapacitive micro-supercapacitors and demonstrates the great potential for metal oxide synthesis and microdevice manufacturing.