Pseudocapacitive Characteristics Research Articles

Improved photocatalytic activity triggered by UV light, as well as electrochemical sensing characteristics of MgO nanoparticles

ABSTRACT The current study’s objective was to investigate the potential applications of synthesised magnesium oxide nanoparticles (MgO NPs) as green fuel through solution combustion with leaves of tulsi (holy basil). The end product was further calcined for 3 h at 800°C to produce a well-crystalline nanomaterial. Transmission electron microscopy (TEM) examinations indicated a typical crystallite size of approximately 52 nm, determined by applying Scherer’s formula. The results from the scanning electron microscope (SEM) revealed a morphology that is clumped, puffy, and porous. The energy band gap (Eg) values for MgO NPs were determined to be 4.31 eV using DRS data, verifying the semiconductor behaviour of the NPs. Degradation experiments were conducted on two dyes, Fast Blue (FB) and Fast Orange (FO), exposed to UV light for 90 minutes. Under UV light, the photocatalytic degradation of FO (80.35%) and FB (80.5%) reached their maximum. A graphite paste electrode was used for cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and sensor investigations. The cyclic CVs of the MgO NPs-modified graphite paste electrode in 0.1 M NaOH were scanned at 10 to 50 mV/s to determine the specific capacitance values of 250.3 Fg−1. Based on the acquired EIS data, the MgO NPs used as the electrode displayed pseudocapacitive capacitor characteristics. Further, the proposed sensor was employed to determine the Pb2+ and Li+ ions in water and showed sensitivity in the order of 0.005 and 0.006 A. Therefore, MgO NPs synthesised via green solution combustion may have excellent applications as photocatalysts and electrochemical sensors.

Deciphering heterojunction layered double hydroxide-polyaniline-carbon nanotubes for phosphorus capture in capacitive deionization

The capacitive deionization (CDI) has emerged as a robust technology due to its effective performance in removing and recovering phosphate in wastewater. However, there are still challenges in achieving fast charge transfer and high capacity phosphorus storage simultaneously. In this study, a layered double hydroxide-polyaniline-carbon nanotubes composite material (ZnFe-PANI/CNT) with heterojunction and pseudocapacitive characteristics was fabricated via a simple and effective precipitation strategy. The existence of heterojunction and pseudocapacitance of ZnFe-PANI/CNT was confirmed through material performance testing Moreover, with its fast charge transfer and high ion storage performance, it was achieved high phosphate adsorption efficiency (94 %) and sustainable electrode regeneration in low concentration phosphate wastewater. Ultraviolet photoelectron spectroscopy (UPS) and density functional theory revealed the ability to accelerate charge transfer, which was contributed by the heterojunction ZnFe-PANI/CNT. In addition, it was found that the synergies of electrostatic attraction, ligand exchange and surface complexation contributed to the high phosphate capture ability in the acidic environments. The binuclear bidentate or mononuclear bidentate structures dominated the surface configuration of phosphate adsorption at pH 4–9.

Fabrication of Na and K based MnO2 nanocomposites for supercapacitive applications

α-Na0.5Mn0.93O2@Na0.91MnO2 (NaMnO) and K0.48Mn1.94O5@Na0.91MnO2 (KNaMnO) nanocomposites have been synthesized using solid-state reaction method. FESEM results convey the formation of column-shaped morphology. FTIR exhibited a shift in the vibration frequency upon potassium loading. Cyclic voltammetric curves are scanned (0 V–0.8 V) at different scan rates (5 mV/s to 100 mV/s) in 1M KOH electrolyte. Galvanostatic charge-discharge characteristics, for different current densities, have shown non-linear or pseudocapacitive characteristics of the prepared electrodes. High specific capacitance of ∼361 F/g and ∼143 F/g, at a current density of 1A/g, has been achieved for KNaMnO and NaMnO samples, respectively. KNaMnO sample exhibited higher capacitive retention (116 %), up to 2000 cycles, and obeys lower series resistance, charge transfer resistance, and Warburg impedance parameters, thus, convey higher efficiency of this compound for supercapacitor applications.

Selective capacitive removal of Pb(II) ions from industrial wastewater using NF/Mn2CoO4@MoO2 electrodes

To achieve targeted removal of Pb2+ from industrial wastewater, a NF/Mn2CoO4@MoO2 composite electrode, synthesised using the hydrothermal method combined with electrodeposition technology, was employed to construct an asymmetric capacitive deionization (CDI) system to selectively electro-adsorb and desorb Pb2+ ions. The electrode exhibited pseudocapacitive characteristics in solutions containing Pb2+, facilitating rapid and reversible redox reactions. The asymmetric CDI system, utilising graphite paper as the positive electrode and NF/Mn2CoO4@MoO2 as the negative electrode, displayed exceptional adsorption performance at 1.4 V for 1 h, decreasing the Pb2+ concentration from 50 ppm to 4 ppb, achieving an adsorption capacity of 156.24 mg g−1, and displaying outstanding cyclic stability. Moreover, the electrode demonstrated preferential adsorption of Pb2+ in mixed solutions containing multiple heavy metal ions, with relative removal coefficients of 4.48 − 19.86 compared with other ions. Analysis of the adsorption mechanism indicated that during the adsorption process, Pb2+ was embedded between MoO2 layers, disrupting the electron cloud symmetry and triggering an oxidation reaction. Octahedral MoO2 then lost electrons and transformed into tetrahedral [MoO4]2-, forming PbMoO4 with embedded Pb2+ between the layers, and achieving effective removal of Pb2+ with high selectivity. Molecular dynamics simulations and density functional theory (DFT) calculations confirmed the high selectivity of the prepared electrode for Pb2+ ions based on stronger binding of Pb2+ to MoO2 than other ions. The electrode has application potential for the capacitive removal of Pb2+ from industrial effluent through CDI technology.

Synthesis of Template-Free CNTS Nanostructures by Hydrothermal Method: Investigating Structural, Photocatalytic, Antibacterial and Electrochemical Properties

In this study, nanoparticles of quaternary chalcogenide Cu2NiSnS4 (CNTS) were prepared by a hydrothermal method to evaluate their electrochemical, photocatalytic and antibacterial performances. The samples were synthesized using aqueous solution of thiourea as a sulfur source without any surfactant assistance. The XRD pattern of the synthesized samples exhibited pure phases of Cu2NiSnS4 nanoparticles corresponding to the cubic structure along the (111) plane. The average crystallite sizes decreased with increasing thiourea concentrations. FESEM analysis revealed that the optimized sample exhibited nanosheets with bundle-like structures. The oxidation states of quaternary chalcogenide nanoparticles, such as Cu2+, Ni2+ and Sn4+ were confirmed by XPS technique. The bandgap value of the synthesized sample was estimated at 1.35 eV. The cyclic voltammetry profiles exhibited pseudocapacitive characteristics, whereas the charge-discharge investigation of the CNTS-10 electrode yielded the highest capacitance value of 374 Fg-1 under a low scan rate. The degradation efficiency of two different dyes e.g. methylene blue (MB) and crystal violet (CV) was investigated by photocatalytic measurements and the optimized sample CNTS-10 exhibited the highest efficiencies of 88% and 82% respectively. The antibacterial activity results clearly showed that a maximum inhibition rate (22 mm for 100 µg/mL) was found for Vibrio parahaemolyticus against other pathogenic bacteria.

Co3 O4 Quantum Dots Intercalation Liquid-Crystal Ordered-Layered-Structure Optimizing the Performance of 3D-Printing Micro-Supercapacitors.

The effects of near surface or surface mechanisms on electrochemical performance (lower specific capacitance density) hinders the development of 3D printed micro supercapacitors (MSCs). The reasonable internal structural characteristics of printed electrodes and the appropriate intercalation material can effectively compensate for the effects of surface or near-surface mechanisms. In this study, a layered structure is constructed inside an electrode using an ink with liquid-crystal characteristics, and the pore structure and oxidation active sites of the layered electrode are optimized by controlling the amount of Co3 O4 -quantum dots (Co3 O4 QDs). The Co3 O4 QDs are distributed in the pores of the electrode surface, and the insertion of Co3 O4 QDs can effectively compensate for the limitations of surface or near-surface mechanisms, thus effectively improving the pseudocapacitive characteristics of the 3D-printed MSCs. The 3D printed MSC exhibits a high area capacitance (306.13 mF cm-2 ) and energy density (34.44 µWh cm-2 at a power density of 0.108mW cm-2 ). Therefore, selecting the appropriate materials to construct printable electrode structures and effectively adjusting material ratios for efficient 3D printing are expected to provide feasible solutions for the construction of various high-energy storage systems such as MSCs.

Vacancy and surface modulation engineering of CuxCo3-xO4 nanowires as an advanced cathode for zinc-ion hybrid supercapacitors

Zn-ion hybrid supercapacitors (ZHSCs) with high power and energy density have great potential in energy storage applications such as hybrid vehicles and renewable energy storage. However, the large radius of hydrated Zn2+-ions hampers their efficient storage in micropores with limited pore sizes, resulting in limited weight ratio capacitance and poor rate capability of ZHSCs. In this study, we developed the novel N-doped and oxygen vacancy-rich CCO nanowires (N-Ov-CCO@CC) architecture with the help of Chemical Vapor Deposition (CVD). Due to the guiding synergy of N-doping, defects, and surface engineering, N-Ov-CCO@CC exhibits significantly enhanced electrochemical performance. The N-Ov-CCO@CC single electrode exhibits excellent charge storage properties, including a high capacitance of 1480.7 F/g at 1 A/g, excellent rate-capability (88.4 % at 20 A/g), and excellent cycle stability of up to 90.1 % for 5000 cycles. The charge storage mechanism was analyzed by ex-situ XRD and XPS, and it reveals that the pseudocapacitive charge storage characteristics are dominant. Operating in the potential range of 1.2–2.0 V, the N-Ov-CCO@CC//Zn-ZHSC provides a high capacitance of 308.2 F/g at 1 A/g, excellent rate capability (86.9 % at 10 A/g), long lifetime (97 % after 10,000 cycles), and high specific energy/power (134.32 Wh/kg at 9507.6 W/kg). Density function theory (DFT) validations show that the N-Ov-CCO system possesses higher conductivities than Ov-CCO and pristine CCO. This work provides an effective strategy for constructing multifunctional electrochemical energy materials for ZHSCs.

Mixed-phase bismuth ferrite oxide (BiFeO3) nanocomposites by green approach as an efficient electrode material for supercapacitor application

The study presents bismuth ferrite nanomaterial (BiFeO3) prepared by the green method using Moringa oleifera natural extract as an anode material for supercapacitor application. Cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge discharge methods were employed to evaluate the electrochemical properties of the nanomaterial at the modified electrode relative to the unmodified electrode. The cyclic voltametric response revealed broad redox peaks and peak separations that clearly indicated the pseudo-capacitive characteristics derived from faradaic reactions. The EIS results indicated that the electrochemical reaction on the material electrode is kinetically and diffusionally controlled. The obtained GCE/BiFeO3 electrode has a specific capacitance of 105 F/g at 0,25 A g−1, an energy density of 90 Wh k/g, and a power density of 0,99 kW k/g. The electrochemical performance revealed an excellent electrochemical response, suggesting that BiFeO3 nanomaterial is an ideal electrode material for supercapacitance applications.Graphical abstract

Hierarchical NiMn-LDH Hollow Spheres as a Promising Pseudocapacitive Electrode for Supercapacitor Application.

Layered double hydroxides (LDH) are regarded as attractive pseudocapacitive materials due to their impressive capacitive qualities that may be adjustable to their morphological features. However, the layered structure of LDH renders them susceptible to structural aggregation, which inhibits effective electrolyte transport and limits their practical applicability after limited exposure to active areas. Herein, we propose a simple template-free strategy to synthesize hierarchical hollow sphere NiMn-LDH material with high surface area and exposed active as anode material for supercapacitor application. The template-free approach enables the natural nucleation of Ni-Mn ions resulting in thin sheets that self-assemble into a hollow sphere, offering expended interlayer spaces and abundant redox-active active sites. The optimal NiMn-LDH-12 achieved a specific capacitance of 1010.4 F g-1 at a current density of 0.2 A g-1 with capacitance retention of 70% at 5 A g-1 after 5000 cycles with lower charge transfer impedance. When configured into an asymmetric supercapacitors (ASC) device as NiMn-LDH//AC, the material realized a specific capacitance of 192.4 F g-1 at a current density of 0.2 A g-1 with a good energy density of 47.9 Wh kg-1 and a power density of 196.8 W kg-1. The proposed morphological-tuning route is promising for designing template-free NiMn-LDHs spheres with practical pseudocapacitive characteristics.

Synergistic effect of NaTi2(PO4)3 and MXene synthesized in situ for high-performance sodium-ion capacitors

The rapid growth of industries that use electrical energy requires novel energy storage systems that are low-cost, reliable, and have improved capacity and power. Sodium-ion capacitors (SICs) have attracted considerable attention as next-generation energy storage systems because they comprise sodium, which is a relatively inexpensive resource, and have high energy and power. Battery-type materials for SICs need to be studied due to their poor rate performance and lifespan. This study reports a NaTi2(PO4)3/MXene (NTP/MXene) composite as a battery-type anode material for high-performance SICs. The NTP/MXene composite is synthesized via the in situ growth of NTP, with poor electrical conductivity, on the surface of MXene, with a two-dimensional structure and high electrical conductivity. The in situ synthesized NTP/MXene composite exhibits better rate performance and cyclic stability than NTP or MXene. These improved electrochemical properties are attributed to the synergistic effect of the pseudocapacitive characteristics of MXene and the battery characteristics of NTP. An SIC assembled with the NTP/MXene composite and activated carbon affords a high energy density of 112.1 Wh kg−1 and a high power density of 9.5 kW kg−1. Furthermore, it exhibits excellent long-term capacity retention of 78 % even after 10,000 cycles.

Advanced Nb2O5 Anode towards Fast Pseudocapacitive Sodium Storage

Intercalation-type Nb2O5, based on its inherent structural advantages in energy storage, shows excellent energy storage characteristics in sodium-ion batteries (SIBs). The rapid pseudocapacitive Na-ion insertion/extraction dynamic mechanisms result in its outstanding rate performance. However, the inherent low electronic conductivity hinders its application and development in SIBs. Though various modification projects can effectively ameliorate these shortcomings, there are also some basic research problems that need to be clarified and solved. This review summarizes the latest research progress of Nb2O5 in SIBs. The structural advantages and pseudocapacitive characteristics of sodium storage are emphasized. The recent advanced modification strategies are summarized comprehensively, including carbon modification, structural optimization, defect engineering, increased mass loading, flexible electrodes, synergistic effect electrodes, etc. In addition, this review summarizes and prospects the key research strategies and future development directions of Nb2O5 in future practical applications.

Substantial Na-Ion Storage at High Current Rates: Redox-Pseudocapacitance through Sodium Oxide Formation.

Batteries and supercapacitors, both governed by electrochemical processes, operate by different electrochemical mechanisms which determine their characteristic energy and power densities. Battery materials store large amounts of energy by ion intercalation. Electrical double-layer capacitors store charge through surface-controlled ion adsorption which leads to high power and rapid charging, but much smaller amounts of energy stored. Pseudocapacitive materials offer the promise to combine these properties by storing charge through surface-controlled, battery-like redox reactions but at high rates approaching those of electrochemical double-layer capacitors. This work compares the pseudo-capacitive charge storage characteristics of self-organized titanium dioxide (TiO2-x) nanotubes (NTs) to flat TiO2-x surface films to further elucidate the proposed charge storage mechanism within the formed surface films. By comparing TiO2-x NTs to flat TiO2-x surface films, having distinctively different oxide mass and surface area ratios, it is shown that NaO2 and Na2O2 formation, which constitutes the active surface film material, is governed by the metal oxide bulk. Our results corroborate that oxygen diffusion from the lattice oxide is key to NaO2 and Na2O2 formation.

In-situ construction of binder-free MnO2/MnSe heterostructure membrane for high-performance energy storage in pseudocapacitors

Manganese (Mn)-based oxides are considered suitable positive electrode materials for supercapacitors (SCs). However, their cycle stability and specific capacitance are significantly hindered by key restrictions such as structural instability and low conductivity. Herein, we demonstrated a novel nanorod (NR)-shaped heterostructured manganese dioxide/manganese selenide membrane (MnO2/MnSe) on carbon cloth (CC) (denoted as MnO2/MnSe-NR@CC) with a high aspect ratio by a straightforward and facile hydrothermal process. Experiments have demonstrated that doping selenium atoms to oxygen sites reduce electronegativity, increasing the intrinsic electronic conductivity of MnO2, decreasing electrostatic interactions with electrolyte ions, and thus boosting the reaction kinetics. Further, the selenium doping results in an amorphous surface with extensive oxygen defects, which contributed to the emergence of additional charge storage sites with pseudocapacitive characteristics. As expected, novel heterostructured MnO2/MnSe-NR@CC as an electrode for SC exhibits a high capacitance of 740.63 F/g at a current density of 1.5 A/g, with excellent cycling performance (93% capacitance retention after 5000 cycles). The MnO2/MnSe-NR@CC exhibited outstanding charge storage capability, dominating capacitive charge storage (84.6% capacitive at 6 mV/s). To examine the practical applications of MnO2/MnSe-NR@CC-ASC as a positive electrode, MnO2/MnSe-NR@CC//AC device was fabricated. The MnO2/MnSe-NR@CC//AC-ASC device performed exceptionally well, with a maximum capacitance of 166.66 F/g at 2 A/g, with a capacitance retention of 94%, after 500 GCD cycles. Additionally, it delivers an energy density of 75.06 Wh/kg at a power density of 1805.1 W/kg and maintains 55.044 Wh/kg at a maximum power density of 18,159 W/kg. This research sheds fresh information on the anionic doping method and has the potential to be applied to the synthesis of positive electrode materials for energy storage applications.

Enhanced cyclic stability of Ga2O3@PDA-C nanospheres as pseudocapacitive anode materials for lithium-ion batteries

Ga2O3 is widely used as anode material for lithium-ion batteries owing to its high theoretical capacity. However, Ga2O3 has the disadvantages of limited electronic conductivity and severe volume expansion, which seriously restrict its application. Therefore, the Ga2O3 nanospheres were coated with carbon using dopamine hydrochloride as the carbon source, which could self-polymerize along the surface of the Ga2O3 particles, forming a uniform carbon coating layer, resulting in superior overall electrochemical performance. Moreover, this particular pomegranate-like morphology and carbon-coating treatment not only shorten the ion transmission path and improve the cycle stability but also provide abundant lithium-ion storage space inside the particle, which improves the pseudocapacitive storage characteristics. High capacitive contribution ratios were obtained for Ga2O3@PDA-C at different scan rates; these ratios were found to be much higher than those for Ga2O3 electrode at different scan rates; the pseudocapacitance of Ga2O3@PDA-C increased to 69% and the more enormous capacitance contribution indicates its high capacity. Under the synergistic effect of multiple effects, the Ga2O3@PDA-C composite electrode exhibited excellent performance, with an initial capacity of 1863.9 mAh/g and maintained 1059.7 mAh/g after 100 cycles.

Multi-Functional Materials Based on Cu-Doped TiO2 Ceramic Fibers with Enhanced Pseudocapacitive Performances and Their Dielectric Characteristics.

In this work, pure TiO2 and Cu (0.5, 1, 2%)-doped TiO2 composites prepared by electrospinning technique followed by calcination at 900 °C, and having high pseudocapacitive and dielectric characteristics were reported. These nanocomposites were characterized by scanning electron microscopy, X-ray diffraction, and dynamic water sorption vapor measurements. The structural characterization of these nanostructures highlighted good crystallinity including only the rutile phase. The electrochemical characteristics were investigated by cyclic voltammetry and galvanostatic charge-discharge measurements, which were performed in a KOH electrolyte solution. Among the Cu-doped TiO2 nanostructures that were prepared, the one containing 0.5% Cu exhibited superior electrochemical properties, including high specific gravimetric capacitance of 1183 F·g-1, specific capacitance of 664 F·g-1, energy density of 45.20 Wh·kg-1, high power density of 723.14 W·kg-1, and capacitance retention of about 94% after 100 cycles. The dielectric investigation shows good dielectric properties for all materials, where the dielectric constant and the dielectric loss decreased with the frequency increase. Thus, all the interconnected studies proved that these new materials show manifold ability and real applicative potential as pseudocapacitors and high-performance dielectrics. Future work and perspectives are anticipated for characterizing electrochemical and dielectric properties for materials including larger amounts of Cu dopant.

Effects of Methoxy Substituents in Contorted Polycyclic Aromatic Hydrocarbons for Pseudocapacitive Charge Storage

We investigate the potential of a methoxy-group-coordinated contorted hexabenzocoronene (OCH3-cHBC) derivative as a promising pseudocapacitive Li-ion hosting organic electrode. By inserting a polar methoxy group at the end of each peripheral aromatic ring of cHBC, the strong negative electrostatic potential near the oxygen atom enabled us to modulate the pseudocapacitive characteristics of the OCH3-cHBC electrode with enhanced specific capacity. Particularly, benefiting from the electron-donating group, a Li-ion capacitor (LIC) consisting of an OCH3-cHBC anode with a double-layer capacitor cathode could be readily fabricated. It exhibited reliable energy and power densities as well as an ultralong lifetime of over 13000 cycles without significant degradation. The promising electrochemical results enriched the strategic molecular approach of polycyclic aromatic hydrocarbons, altering the electrochemical energy storage systems and ensuring advanced LIC electrodes.

Analysis of impedance: The distribution of capacitance in halide ion treated supercapacitors

The micro- and mesoporous carbon electrode material has an enough pore width capacity to allow to adsorb the small-sized halide- and alkali ions, even to adsorb ionic liquid ions. • Ionic liquid mixtures containing halide or alkali ions are used to treat carbon electrodes. • The CV and EIS characteristics of carbon-based supercapacitors are studied. • The EIS modeling is applied to analyze the electrochemical characteristics. • The capacitive and pseudocapacitive characteristics of supercapacitors are analyzed. • Pseudocapacitance originates in the redox activity and specific adsorption of halide ions. A combination of two energy-stored modes, faradaic and electrostatic, has been applied to improve the energy density of supercapacitors with ionic liquid salt mixtures via impregnation of micro- and mesoporous carbon electrodes. An enhancement of capacitance was observed in the supercapacitors containing halide ion treated carbon electrodes, caused by the pseudocapacitive processes related to redox-active halide ions within and near the micro- and mesoporous carbon electrodes. To highlight the contribution of pseudocapacitance, an equivalent circuit model was applied to analyze the impedance spectra in detail. Significant pseudocapacitive behavior was only observed in the supercapacitors with halide ion treated carbon electrodes. A comparable result for both electrical double layer capacitance and pseudocapacitance values was obtained based on the direct current electrochemistry measurements as well as impedance fitting results. Meanwhile, according to the resistive behavior associated with the mass-transfer and faradaic processes, halide ion treated systems were more reactive compared with alkali ion treated systems. This article offers a brief and fundamental understanding with a focus on the contribution and distribution of both resistive and capacitive behavior analyzed by electrochemical impedance spectroscopy coupled with equivalent circuit modeling.

Fabrication of Zn-Cu-Ni Ternary Oxides in Nanoarrays for Photo-Enhanced Pseudocapacitive Charge Storage.

To meet the increasing demands of energy consumption, sustainable energy sources such as solar energy should be better employed to promote electrochemical energy storage. Herein, we fabricated a bifunctional photoelectrode composed of copper foam (CF)-supported zinc-nickel-copper ternary oxides in nanoarrays (CF@ZnCuNiOx NAs) to promote photo-enhanced pseudocapacitive charge storage. The as-fabricated CF@ZnCuNiOx NAs have shown both photosensitive and pseudocapacitive characteristics, demonstrating a synergistic effect on efficient solar energy harvest and conversion. As a result, a high areal specific capacitance of 2741 mF cm−2 (namely 418 μAh cm−2) under light illumination can be calculated at 5 mA cm−2, which delivered photo-enhancement of 38.3% compared to that obtained without light. In addition, the photoelectric and photothermal effects of the light energy on pseudocapacitive charge storage have been preliminarily studied and compared. This work may provide some evidence on the different mechanisms of photoelectric/thermal conversion for developing solar-driven energy storage devices.

Metal‐organic chemical vapor deposition of anatase titania on multiwalled carbon nanotubes for electrochemical capacitors

AbstractIn practice, the capacitance from the electrochemical double layer formation on porous carbon‐based electrodes is still below preferred values, limiting their use in electrochemical capacitors. The current drive is to innovate ways that generate additional capacitance in the electrochemical double layer capacitive nature of carbon nanomaterials towards both a high specific energy density (Es) and power density (Ps). Herein we report the use of metal‐organic chemical vapor deposition (MOCVD) to coat multiwalled carbon nanotubes (MWCNTs) with anatase titanium dioxide (TiO2) to induce pseudocapacitive charge storage characteristics on a carbon‐based electrode. The study shows that MWCNTs were coated in bundles, and targeted TiO2 loadings were successfully attained, though the TiO2 agglomerates also increased with TiO2 wt.%. The 10 wt.% TiO2 TiO2‐MWCNT material displayed the best capacitive behavior with associated specific discharge capacitance (Cd), Es, and Ps values of 907 F kg−1, 55.56 Wh kg−1, and 2.78 W kg−1 at 0.1 A g−1, respectively, due to the synergistic effect of the two components of the composite. Additionally, the integral capacitance (Cs) of the 20 wt.% TiO2 material was enhanced more than 5000‐fold relative to that of the 5 wt.% TiO2 TiO2‐MWCNT composite at higher scan speeds of 100 and 200 mV s−1. Electrochemical measurements further demonstrated the possible positive tuning of capacitive characteristics (charge/discharge rates, Cd and Cs) with TiO2 wt.% control. The MOCVD synthesis method imparted the TiO2‐MWCNT composites with suitable traits that showed high potential in improving physicochemical processes favorable in electrical energy storage.

Lithium Lanthanum Titanate derived from Lanthanum Oxalate as the Anode Active Material in Lithium-ion Batteries

Lithium-ion battery has been drawing attention from researchers due to its excellent properties in terms of electrochemical and structural stability, low cost, and high safety feature, leading to prospective applications in electric vehicles and other large-scale applications. However, lithium-ion batteries are still in charging time owing to its low conductivity, restricting its wide applications in large-scale applications. In this work, therefore, lithium lanthanum titanate (LLTO) was synthesized derived from lanthanum oxalate, as a lanthanum source, for an anode active material application in the lithium-ion batteries due its high electrochemical conductivity and pseudocapacitive characteristics. To the best our knowledge, our work is the first one to synthesize LLTO from lanthanum oxalate as the lanthanum source. Commercial lithium carbonate and commercial titanium oxide were used as the lithium and titanium sources, respectively. It was used low cost and simple solid-state reaction process to synthesize this material and performed a two-step calcination processs at 800 oC for 8 hours and 1050 oC for 12 hours under ambient atmosphere. The physical characteristics showed that LLTO possesses high purity (98.141%) and micro sized grains with abundant empty spaces between the grains. This, therefore, lead to improve electrochemical performances such as stable discharge capacity at low potential even near to zero (98.67 mAh), and a high conductivity of 2.45 × 10-2 S/cm at room temperature. This LLTO is interesting to be used as the anode active material in low potential lithium-ion battery applications.