High-performance Electrode Materials Research Articles

Salvia officinalis leaf extract-stabilized NiO NPs, ZnO NPs, and NiO@ZnO nanocomposite: Green hydrothermal synthesis, characterization and supercapacitor application

AbstractIn this study, NiO nanoparticles (NiO NPs) and NiO@ZnO nanocomposite were synthesized for the first time using a Salvia officinalis (S. officinalis) extract-assisted hydrothermal process. The S. officinalis leaf extract served as a natural reducing and capping agent. The synthesized NiO NPs, ZnO NPs, and NiO@ZnO nanocomposite were thoroughly characterized using various techniques, including Fourier-transform infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV–Vis), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), energy-dispersive spectrometry (EDS) mapping, vibrating sample magnetometer (VSM), and cyclic voltammetry (CV) analysis. The direct and indirect band gap energies of NiO NPs, ZnO NPs, and NiO@ZnO were found to be 3.00, 2.28, and 2.71 eV, and 2.63, 1.91, and 2.23 eV, respectively. The crystallite sizes were analyzed using PXRD spectra through Scherrer and Williamson–Hall (W–H) methods. TEM analysis revealed that the average particle sizes of NiO NPs, ZnO NPs, and NiO@ZnO were 16.0, 207.5, and 31.0 nm, respectively. The magnetic properties of all nanomaterials were assessed via the VSM technique. Specific capacitance (Cs) values, determined from CV voltammograms, were 196.8, 632.4, and 785 Fg-1 at a scan rate of 25 mVs-1 for NiO NPs, ZnO NPs, and NiO@ZnO, respectively. These findings suggest that the green-synthesized NiO@ZnO nanocomposite holds significant potential as a high-performance electrode material for supercapacitor applications.

High Capacity and Fast Kinetics Enabled by Metal-Doping in Prussian Blue Analogue Cathodes for Sodium-Ion Batteries.

Prussian blue analogues (PBAs) have gained tremendous attention as promising low-cost electrochemically-tunable electrode materials, which can accommodate large Na+ ions with attractive specific capacity and charge-discharge kinetics. However, poor cycling stability caused by lattice strain and volume change remains to be improved. Herein, metal-doping strategy has been demonstrated in FeNiHCF, Na1.40Fe0.90Ni0.10[Fe(CN)6]0.85 ⋅ 1.3H2O, delivering a capacity as high as 148 mAh g-1 at 10 mA g-1. At an exceptionally high rate of 25.6 A g-1, a reversible capacity of ~55 mAh g-1 still can be obtained with a very small capacity decay rate of 0.02 % per cycle for 1000 cycles, considered one of the best among all metal-doped PBAs. This exhibits the stabilizing effect of Ni doping which enhances structural stability and long-term cyclability. In situ synchrotron X-ray diffraction reveals an extremely small (~1 %) change in unit cell parameters. The Ni substitution is found to increase the electronic conductivity and redox activity, especially at the low-spin (LS) Fe center due to inductive effect. This larger capacity contribution from LS Fe2+C6/Fe3+C6 redox couple is responsible for stable high-rate capability of FeNiHCF. The insight gained in this work may pave the way for the design of other high-performance electrode materials for sustainable sodium-ion batteries.

Excellent capacitive storage performance of N-doped porous carbon derived from the orientation-guidance coupled with in-situ activation methodology

The orientation-guidance coupled with in-situ activation methodology is developed to synthesize the N-doped porous carbon (NPC) with well-developed porosity and high specific surface area, using coal pitch as a carbon precursor. The orientation-guidance and activation are dedicated to generating microporous and mesoporous channels, respectively. The in-situ N incorporation into the carbon skeleton is realized along with the formation of porous carbon (PC), ensuring the uniformity of N doping. As an electrode material of supercapacitor, benefiting from the robust hexagon-like building block decorated with micro-mesoporous channels and N doping, NPC electrode affords a significant improvement in capacitive energy-storage performance, achieving a specific capacitance of up to 333F g−1 at 1 A/g, which far exceeds those of PC and activated carbon. Notably, even under high mass loading of 10 mg cm−2, the NPC maintains a satisfactory capacitance of 258F g−1 at 1 A/g. When employed as the anode in Li-ion capacitor (LIC), apart from exhibiting enhanced anode behavior compared to graphite anode, NPC also delivers exceptional cyclability. Furthermore, density functional theory calculations have validated the enhanced electrical conductivity and Li storage ability contributed by N doping, providing a theoretical foundation for the observed improvements in electrochemical performance. A full LIC configured with NPC anode delivers extraordinary Ragone performance and outstanding cyclability. This work also proposes a feasible way to realize the oriented conversion of coal pitch into high-performance electrode materials for electrochemical energy-storage devices.

NiCoMn-LDH with core-shell heterostructures based on CoS nanotube arrays containing multiple ion diffusion channels for boosted supercapacitor applications

Nanostructure engineering and composition rationalization are crucial for materials to become candidates for high-performance supercapacitor. Herein, a novel core-shell heterostructured electrode, combining CoS hollow nanorods with NiCoMn-layered double hydroxides (LDH) ternary metal nanosheets, were prepared on carbon cloth by reasonably controlled vulcanization and electrodeposition. By optimizing electrodeposition conditions, the material's structure and properties can be fine-tuned. The enhanced capacitance of the optimized carbon cloth (CC)@CoS/NiCoMn-LDH-300 electrode (4256.0 F g−1) lies in the open space provided by CoS and the establishment of a new charge transfer channel across the interfaces of CC@CoS/NiCoMn-LDH-300 nanosheets. This is further demonstrated by Density functional theory (DFT) simulations based on OH− adsorption energy, which produces faster redox charge kinetics and significantly enhances the electrode's energy storage capacity. The hybrid supercapacitor, integrating the optimized CC@CoS/NiCoMn-LDH-300 electrode with active carbon, demonstrates the highest energy density of 86 Wh kg−1 (under the power density of 850 W kg−1) and the long cycle stability of 89.7%. This study aims to go beyond simple binary LDH by constructing a ternary LDH with a hierarchical core-shell heterostructure to provide an effective and feasible new concept for high-performance supercapacitor electrode materials via rational structure design.

Electrochemical insertion of Ni2+ to synthesize Ca-doped β-NiV3O8 films as electrodes for sodium-ion batteries

Sodium-ion batteries (SIBs) need to address inherent limitations such as low energy densities and poor cycle stability. In the paper, a novel yet safe electrochemical method has been employed to insert Ni2+ in pre-prepared films, culminating in the synthesis of Ca-doped β-NiV3O8. The high covalency of the Ni–O bond was expected to enhance the migration rate of Na+, and in turn exhibit a higher ionic conductivity. Various doping amounts of Ca2+ were applied to investigate the differences in the kinetic behavior of β-NiV3O8 film electrodes. Throughout the discharge process, the average DNa+ of Ca-doped β-NiV3O8 was calculated to be 10−13～10−12 cm2 s−1. In addition, high-resolution transmission electron microscopy (HRTEM) and ex-situ X-ray photoelectron spectroscopy (XPS) revealed the presence of oxygen defects, which assisted interfacial electron transfer. Ex-situ X-ray diffraction (XRD) revealed partial new phases (NaV3O8·xH2O and NaVO3·1.9H2O) generation alongside diverse mechanisms of sodium ion insertion/extraction. Under a lower current density with 1 M NaClO4/PC as the electrolyte, it exhibited an initial discharge capacity of 433.2 mA h m−2 at 167 mA m−2 and 96.3 % capacity retention after 100 cycles. This electrochemical method, applicable to treating film electrodes, provides a novel idea for the preparation of high-performance electrode materials for SIBs.

Phytic acid as an eco-friendly phosphorus source in the synthesis of phosphorus-doped NiCo2O4 for supercapacitor electrodes

This study explores the synthesis of nickel-cobalt bimetallic precursors using phytic acid (PA) as a phosphorus source and their application as supercapacitor electrodes. Through high-temperature annealing, these precursors were converted into phosphorus-doped nickel-cobalt bimetallic oxides (NCO) with certain defects. The morphologies and particle size of NCO can be easily adjusted by the amount of PA. Compared to the undoped nickel-cobalt bimetallic oxides, the phosphorus-doped materials exhibited significantly enhanced electrochemical activity and specific capacitance. The optimized electrode exhibits the highest specific capacitance of 1075 F·g−1 at a current density of 1 A·g−1. The asymmetric supercapacitor assembled together with activated carbon can deliver a relatively high energy density of 39.8 Wh·kg−1 at a power density of 696 W·kg−1. Additionally, this paper provides a detailed discussion on the impact of phosphorus doping on the performance of supercapacitor electrodes and the potential of PA as an eco-friendly phosphorus source in the synthesis of high-performance electrode materials.

Supercapacitors and triboelectric nanogenerators based on electrodes of greener iron nanoparticles/carbon nanotubes composites

The development of supporting materials based on carbon nanotubes (CNTs) impregnated with iron nanoparticles via a sustainable and green synthesis employing plant extract of Punica granatum L. leaves was carried out for the iron nanoparticle modification and the following impregnation into the carbon nanotubes composites (CNT-Fe) that were also coated with polypyrrole (CNT-Fe + PPy) for use as electrode for supercapacitor and triboelectric nanogenerators. The electrochemical characterization of the materials by cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) assays revealed that the CNT-Fe + PPy gave rise to better performance due to the association of double-layer capacitance behavior of carbon derivative in association with the pseudocapacitance contribution of PPy resulting in an areal capacitance value 202 mF/ cm2 for the overall composite. In terms of the application of electrodes in triboelectric nanogenerators, the best performance for the composite of CNT-Fe + PPy was 60 V for output voltage and power density of 6 μW/cm2. The integrated system showed that the supercapacitors can be charged directly by the nanogenerator from 0 to 42 mV in 300 s. The successful green synthesis of iron nanoparticles on CNT and further PPy coating provides a feasible method for the design and synthesis of high-performance SCs and TENGs electrode materials. This work provides a systematic approach that moves the research front forward by generating data that underpins further research in self-powered electronic devices.

Controllable synthesis of porous NiSe2 nanowires to boost energy storage performance for supercapacitors

Porous nanowires can improve energy storage performance due to their fascinating one-dimensional architecture, and large exposed surface areas. Developing high-performance porous electrode materials is essential for enhancing the energy storage performance of supercapacitors. In this study, porous NiSe2 nanowires (NWs) with abundant nanocavities were obtained by treating α-Ni(OH)2 NWs with Se powder under an Ar atmosphere. The amount of Se powder had a significant impact on the specific surface (SS) and capacitive performance. Compared to NiSe2–100 and NiSe2–300, NiSe2–200 exhibited the highest SS and pore volume of 83.8 m2 g−1 and 0.463 cm3 g−1, respectively. The NiSe2–200 electrode achieved a maximum specific capacity of 653.3 C g−1 at 0.25 A g−1, attributed to its highly accessible surface, abundant active sites, and short charge transfer path. Additionally, the assembled NiSe2–200//activated carbon hybrid supercapacitor (NiSe2–200//AC HSC) delivered high specific capacitance (88.3 F g−1 at 1.0 A g−1), remarkable specific energy (35.4 Wh kg−1 at 850 W kg−1), and robust cycling durability. Furthermore, a homemade NiSe2–200//AC HSC successfully powered a clock for about 8 min. This study not only provides a simple method for preparing porous NiSe2 NWs but also shows its promising application in HSCs.

Nickel-molybdenum bimetallic sulfide decorated biomass derived carbon support for high performance asymmetric supercapacitor application

Biomass - derived carbon electrode material with a porous structure is widely used in supercapacitor applications, which can improve electron transfer and shorter ion diffusion pathways. In this work, the garlic peel biomass carbon (GPBC), NiMo3S4(NMS) and garlic peel biomass carbon decorated with NiMo3S4 (GPBC/NMS) composite were prepared through a in situ two-step hydrothermal method. The synthesized materials were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), energy dispersive x-ray spectroscopy (EDS), Transmission electron microscopy techniques (TEM), Raman spectroscopy and Brunauer-Emmett-Teller (BET) techniques were used to analyze the structure, morphology and specific surface areas and X-ray photoelectron spectroscopy (XPS). The prepared bimetallic metal sulfide on a biomass - derived carbon namely the GPBC/NMS composite is used in supercapacitor application. The GPBC/NMS composite electrode exhibits good cycle performance with high specific capacity of 304C/g at current density of 1 A/g in a 3 M KOH electrolyte solution. The electrochemical performance of the GPBC/NMS//GPBC asymmetric supercapacitor device produces an excellent energy density 45.5 Wh kg−1 at a power density of 1125 W kg−1 in the 1.6 V operating potential window. The GPBC/NMS//GPBC also exhibits 93 % retention of its initial capacitance after the 10,000 GCD cycle performance. The above results demonstrate a new way of developing high performance electrode materials for energy storage applications.

A sustainable solution: Conversion of distillers' grains waste into high-performance supercapacitor electrode materials for energy storage applications

The development of cost-effective biomass-derived carbon with good electrochemical properties is crucial for advancing energy storage devices sustainably. One feasible approach to producing supercapacitor electrode materials is the conversion of heteroatom-rich biomass waste into heteroatom self-doped hierarchical porous carbons with favorable electrochemical properties. In this study, distillers' grains with abundant crude fiber and protein were utilized as precursors to prepare N, S self-doped hierarchical porous carbon, which presents a high specific surface area of 3642.87 m2 g−1. The N, S doping could improve the interfacial wettability of electrode materials and enhance the pseudocapacitive effect of the materials. In three-electrode system, the carbon delivered a high capacitance of 347 F g−1 at 1 A g−1. Symmetrical capacitors assembled with PVA/KOH gel electrolytes delivered an ultrahigh energy density of 11.29 Wh kg−1 at a power density of 250 W kg−1. This strategy provides a practical, low-cost, and renewable design approach of carbon electrode for high-performance supercapacitors.

Home-made chemical vapor deposition-based synthesis of binder-free nanostructured magnesium-molybdenum-sulfide electrode materials for supercapacitor application

Molybdenum disulfides (MoS2) is considered as promising electrode materials (E-M) for high electrochemical performance (ECP) of lithium-ion batteries and supercapacitors due to their layered nanostructures. Herein, MoS2, MgS and hetrostructure MgS/MoS2 E-Ms comprising of nano-particles/sheets/needles like structures are synthesized on Nickel foam (Ni–F) by a simple home-made chemical vapor deposition (CVD) technique. The XRD analysis confirmed the formation of MoS2, MgS and MgS/MoS2 polycrystalline E-Ms growing along different directions. The FESEM analysis is confirmed that the addition of MgS layer over the surface of MoS2 change the surafce morphology from nano-particles to nano-needles. The change in structural and microstructural features is indicated the appearance of defects, micro-strain and dislocations density which are fruitful for excellent ECP. The cyclic voltammetry analysis is indicated the pseudocapacitive nature of the synthesized E-Ms. The maximum specific capacitance values for MoS2/Ni–F, MgS/Ni–F and MgS/MoS2/Ni–F E-Ms are 1273, 1688 and 3934 F/g at 1 A/g respectively. Moreover, the addition of MgS layer over MoS2/Ni–F is revealed the excellent cyclic stability of 98.76 % at current density of 10 A/g after 4000 cycles, energy density values are ranged from 79 to 136 W h/kg with homologous power density of 250–2500 W/kg and very small charge transfer resistance. The simulations of Power's Law and Dunn's model is confirmed that the excellent ECP is due to both capacitive and diffusive controlled contributions of heterostructured MgS/MoS2/Ni–F E-Ms. Additionally, MgS/MoS2/Ni–F E-Ms have both battery and pseudocapacitive nature due to unique nano-needles like morphology. The excellent electrochemical properties of MgS/MoS2/Ni–F E-Ms substantiate their potential applications in portable energy storage devices.

Tuning the thermo-mechanical synergies effect of solid oxide fuel cells with negative thermal expansion NdMnO3 in La0.6Sr0.4Co0.2Fe0.8O3-δ-based symmetric electrode

Solid oxide fuel cells (SOFCs) are efficient and clean energy conversion devices, but one of the major challenges for their marketization is the instability of different component materials under high temperature operating conditions. The existence of a certain internal stress gradient between materials with different thermal expansion characteristics in the process of SOFCs from low temperature assembly to high temperature use is the main reason of this instability, leading to the inability of SOFCs to repeat start-stop and the rapid decay of long-term stability performance. To improve these problems, a creative concept of fuel cell interface overall regulation is proposed, simplifying the complex interface between different components of SOFCs into a unified and adjustable quasi-zero difference thermal expansion interface. The composite of high catalytic activity electrode material and high stability negative thermal expansion material is used for electrolyte support structure symmetrical cell, which makes the whole cell “sandwich” structure thermally and mechanically compatible. As a concept verification, the classic high catalytic performance electrode material La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF), Gd0.2Ce0.8O2-δ (GDC) and NdMnO3 (NM) negative thermal expansion material with high chemical stability and mechanical stability were composited in equal proportions to form LSCF@GDC&NM electrode as the symmetrical electrode. After equal proportion compositing, the thermal expansion curve of LSCF@GDC&NM material can highly coincide with the thermal expansion curve of GDC, making the single cell with LSCF@GDC&NM electrode can withstand 25 power thermal cycles without significant performance decay, achieving 442 mW cm−2 at 800 °C and maintaining stably for 140 h without any degradation. These results show that using negative thermal expansion material to regulate electrode strategy is expected to make a whole zero difference thermal fuel cell configuration.

Boosting interfacial reaction kinetics in yarn-shaped zinc-V2O5·nH2O batteries through carbon nanotube intermediate layer integration

Flexible yarn-shaped batteries are promising candidates for the wearable electronics owing to their good flexibility, tiny volume, compatibility with textiles. However, their practical applications are hindered by low capacity, active material mass loading, and energy density. Herein, we develop a coaxially wrapping strategy to fabricate an advanced yarn-shaped aqueous zinc-ion batteries (AZIBs) incorporating core-sheath carbon nanotube (CNT)/V2O5·nH2O composite yarns as cathodes and zinc wire as anodes. The as-wrapped CNT intermediate layer not only enhances the surface's conductivity, but the nano-array porous layer can also accelerate the mixing of ion concentration between the electrode surface and the electrolyte fluid through the turbulence effect, thereby improving the interfacial ion/electron kinetics. As a result, the energy storage mechanism of CNT/V2O5·nH2O yarn AZIBs transformed from capacitive-dominant to diffusion-controlled process, and the batteries demonstrate exceptional discharge capacity of 566.7 mAh g−1 at 0.1 A g−1, surpassing the state-of-art yarn-based AZIBs and approaching the theoretical zinc storage capacity (589 mAh g−1). In addition, they exhibit a high energy density of 471 Wh kg−1 at 25.5 W kg−1 and excellent cycling performance. This work opens a new and efficient avenue for the structure design of high-performance electrode materials for flexible yarn-based batteries.

Iodine intercalation-assisted alkali activation constructs coal-based porous carbon for high-performance supercapacitors

Supercapacitors have the advantages of fast charging and discharging speeds, high power density, long cycle life, and wide operating temperature range. They are widely used in portable electronic equipment, rail transit, industry, military, aerospace, and other fields. The design and preparation of low-cost, high-performance electrode materials still pose a bottleneck that hinders the development of supercapacitors. In this paper, coal was used as the raw material, and the coal-based porous carbon electrode material was constructed using the iodine intercalation-assisted activation method and used for supercapacitors. The CK-700 electrode exhibits excellent charge storage performance in a 6 M potassium hydroxide (KOH) electrolyte, with a maximum specific capacitance of 350 F/g at a current density of 0.5 A/g. In addition, it has an excellent rate performance (310 F/g at 1 A/g) and cycle stability (capacitance retention up to 91.7 % after 30000 cycles). This work provides a method for realizing high-quality, high-yield and low-cost preparation of coal-based porous carbon, and an idea for improving the performance of supercapacitors.

WITHDRAWN: Magnetic field-assisted electrodeposition of ZnCo2O4-rGo nanoelectrodes for enhanced supercapacitor performance

To investigate a convenient, rapid, and environmentally friendly method for the preparation of supercapacitor electrode materials to enhance supercapacitor performance, this study achieved the successful synthesis of ZnCo2O4-rGo (ZCG) nanomaterial electrodes on a nickel foam substrate. These electrodes were then assembled into supercapacitors using Magnetic field-assisted Electrodeposition (MFAED) technology. The surface morphology and structure characterization analysis revealed that the ZCG-4 material exhibited a mesoporous layered nanosheet structure. Moreover, they exhibited a significant specific active surface area of 155.7 m2/g and showed excellent adhesion to the nickel foam substrate. The electrochemical properties of the ZCG nanoelectrode material were studied in a 1 M KOH aqueous solution. The results revealed that the ZCG-4 nanoelectrode displayed low electrochemical impedance (Rs 0.23 Ω, Rct 1.36 Ω, and Zw 0.99 Ω) and a high specific capacitance of 2672 Fg−1. Furthermore, at a current density of 3 Ag−1, the electrode maintained good capacity retention (2672 Fg−1–2529 Fg−1, 94.6 %). Moreover, it retained a significantly high specific capacitance of 1339 Fg−1 even after 6000 cycles under a current density of 20 Ag−1. The supercapacitor assembled with ZCG-4 electrodes exhibits good electrochemical performance, possessing a high capacitance of 5.8F/cm2 at a current density of 1 mA/cm2. Moreover, the ZCG-4 supercapacitor demonstrates outstanding cyclic performance, maintaining 86 % capacity retention following 6000 charge–discharge cycles at a high current density of 30 mA/cm2. The mechanism of magnetic field electrodeposition for preparing ZCG has also been explained using magnetohydrodynamics theory. At a magnetic field strength of 6 T, the ion migration speed is 1.7 × 10−5 m/s, and the addition of the magnetic field effectively increases this speed. An effective magnetic field electrodeposition approach was thus proposed in this investigation to enable the synthesis of high-performance electrode materials and capacitors by combining metal oxide and rGo.

Synthesis of Co@CoO/C by micro-tube method and their electrochemical performances

Lithium-ion batteries (LIBs) are promising secondary batteries that are widely used in portable electronic devices, electric vehicles and smart grids. The design and synthesis of high-performance electrode materials play a crucial role in achieving lithium-ion batteries with high energy density, prolonged cycle life, and superior safety. CoO has attracted significant attention as a negative electrode material for lithium-ion batteries due to its high theoretical capacity and abundant resources. However, its limited conductivity and suboptimal cycling performance impede its potential applications. The study proposes a novel micro-tube reaction method for the synthesis of Co@CoO/C, utilizing Kapok fiber as a template with a special hollow structure. The microstructure and composition of the samples were characterized using X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). After conducting electrochemical performance tests, it was discovered that at a current density of 100 mA/g and within the range of 0.01–3.0 V for 50 charge and discharge cycles. Co@CoO/C composite negative electrode exhibits a reversible lithium insertion specific capacity of 499.8 mAh/g and keep a discharge capacity retention rate of 97.6 %. The greatly improved lithium storage and stability performance of Co@CoO/C composite anode is mainly attributed to the synergistic effect between Co@CoO nanoparticles and the kapok carbon microtubule structure.

Nitrogen-doped porous carbon derived from cross-cutting bamboo for high-performance supercapacitors by one-pot ball milling method

In this work, Nitrogen-doped cross-cut KOH-activated porous carbon (NCKC) was obtained through a simple and effective fabrication process. Cross-cut bamboo, KOH, and urea are mixed through a one-pot ball milling strategy. The obtained sample (NCKC) has a high specific capacitance in the three-electrode test (367 F·g−1 at 0.2 A· g−1), and maintains a satisfactory specific capacitance of 183 F·g−1 at a high current of 50 A·g−1. Moreover, an aqueous supercapacitor based on NCKC with 1 M Na2SO4 as the electrolyte can provide an outstanding specific energy of 31.1 W h kg−1 with a specific power of 200 W·kg−1, without any noticeable reduction in capacity even after 40,000 cycles. This is attributed to the fact that NCKC has an abundant hierarchical pore structure. The cross-cutting process can shorten natural pores origin from bamboo native structures, and facilitate hydrophilicity in the resulting porous carbon. The results reveal that the synergistic effect of cross-cutting process, ball milling, and N-doping in carbon enhanced the electrochemical performance of carbon remarkably. The results show such one-pot ball milling method simplifies the preparation process and is of great interest for the innovation and application of high-performance electrode materials.

Mn-doped V2O5@rGO towards high-performance electrode materials for aqueous zinc-ion supercapacitors

In order to address the diverse energy storage requirements, there is an urgent need to fabricate supercapacitors with high specific capacitance, long cycle life, high power density and high energy density. Among various transition metal oxide materials, vanadium pentoxide emerges as a promising candidate for cathode materials in supercapacitors. Herein, we report an ion intercalation strategy to synthesize Mn-doped V2O5 (MnVO) and recombine it with reduced graphene oxide (rGO) to form Mn-doped V2O5@rGO (MnVO@rGO) hybrids with special hierarchical structure. During the hydrothermal process, Mn2+ gradually inserts into the layer spacing of V2O5 to form nanobelts, which could be cross-linked with graphene nanosheets to form MnVO@rGO 3D skeleton network. This unique structure enables the MnVO@rGO electrode to exhibit excellent specific capacitance of 1120 F g−1 at 0.2 A g−1. Outstanding cycling performance is demonstrated by achieving a capacity retention rate of 91.5 % after 2000 cycle. The symmetrical supercapacitor device assembled with MnVO@rGO as both positive and negative electrodes exhibits an energy density of 150.75 and 77.5 W h Kg−1 at power density of 450 and 9000 W kg−1, respectively. Moreover, DFT calculations also have been employed to account for the improved electrochemical performances of MnVO@rGO. Besides, the excellent electrochemical performances of MnVO@rGO indicate that it has broad application prospects in future energy storage devices.

Novel Electrospun Sn-Based Composite Cathodes Exhibiting Extended Cycle Life for Hybrid Magnesium-Lithium Batteries.

In this study, we present a strategic approach for the structural design and composite modification of one-dimensional Sn-based nanocomposites to enhance the overall electrochemical performance of hybrid magnesium-lithium batteries (MLIBs), which are emerging as promising successors to lithium-ion batteries. By using electrospinning technology, we successfully synthesized NST-SnO2, NST-SnO2-NiO, Sn-CNF, and Ni3Sn2-CNF composite cathodes, as well as analyzed the synthesis mechanism of the four Sn-based cathodes. The 100-cycle testing at a current density of 500 mA·g-1 revealed that NST-SnO2 maintained a discharge specific capacity of 129.8 mA h·g-1 with a retention rate of 90.76%, while NST-SnO2-NiO achieved a higher capacity of 147.4 mA h·g-1 and an 88.05% retention rate. Notably, Sn-CNF and Ni3Sn2-CNF exhibited initial discharge capacities of 66.7 and 79.6 mA h·g-1, respectively, coupled with exceptional cycle stability, evidenced by retention rates of 104.19 and 102.38%. The remarkable cycling stability observed in these novel cathodes is attributed to their robust structural integrity, thus demonstrating the potential for an extended cycle life in MLIBs. This work provides significant advancement in the development of high-performance electrode materials for next-generation hybrid magnesium-lithium energy storage systems.

Hydrogels and Carbon Nanotubes: Composite Electrode Materials for Long-Term Electrocardiography Monitoring.

This paper presents methods for developing high-performance interface electrode materials designed to enhance signal collection efficacy during long-term (over 24 h) electrocardiography (ECG) monitoring. The electrode materials are fabricated by integrating commercial ECG liquid hydrogels with carbon nanotubes (CNTs), which are widely utilized in dry-electrode technologies and extensively discussed in the current scientific literature. The composite materials are either prepared by dispersing CNTs within the commercial liquid hydrogel matrix or by encasing the hydrogels in macroscopic CNT films. Both approaches ensure the optimal wetting of the epidermis via the hydrogels, while the CNTs reduce material impedance and stabilize the drying process. The resulting electrode materials maintain their softness, allowing for micro-conformal skin attachment, and are biocompatible. Empirical testing confirms that the ECG electrodes employing these hybrid hydrogels adhere to relevant standards for durations exceeding 24 h. These innovative hybrid solutions merge the benefits of both wet and dry ECG electrode technologies, potentially facilitating the extended monitoring of ECG signals and thus advancing the diagnosis and treatment of various cardiac conditions.