Superior Specific Capacitance Research Articles

Enhancing the Cycling and Rate Performance of Ni-Rich Cathodes for Lithium-Ion Batteries by Bulk-Phase Engineering and Surface Reconstruction.

The structural and interfacial instability of Ni-rich layered cathodes LiNi0.9Co0.05Mn0.05O2 (NCM9055) severely hinders their commercial application. In this work, straightforward high-temperature solid-state methods are utilized to successfully synthesize Nb-doped and Li3PO4-coated LiNi0.9Co0.05Mn0.05O2 by combining two niobium sources, NbOPO4·3H2O and Nb2O5, for the first time. Studies indicate that Nb doping enhanced the integrity of the layered structure, and the Li3PO4 coating reduced water absorption on the surface and considerably boosted the durability of the interface. The dual-modified cathode Li(Ni0.9Co0.05Mn0.05)0.985Nb0.015O2@Li3PO4 (NCM-2) exhibits remarkable cycling and rate performance. The initial discharge specific capacity of NCM-2 is 203.33 mAh g-1 at 0.1 C and 196.04 mAh g-1 at 1 C, while the capacity retention after 200 cycles is 91.38% at 1 C, which is much higher than that of pristine NCM9055 (49.96%). In addition, it also provides a superior discharge specific capacity of about 175.63 mAh g-1 even at 5 C. This study emphasizes a feasible approach to enhancing the stability of Ni-rich cathodes at the interfaces and bulk structures.

Molybdenum single-atoms decorated multi-channel carbon nanofibers for advanced lithium-selenium batteries

The cathode in lithium-selenium (Li-Se) batteries has garnered extensive attention owing to its superior specific capacity and enhanced conductivity compared to sulfur. Nonetheless, the adoption and advancement of Li-Se batteries face significant challenges due to selenium’s low reactivity, substantial volume fluctuations, and the shuttle effect associated with polyselenides. Single-atom catalysts (SACs) are under the spotlight for their outstanding catalytic efficiency and optimal atomic utilization. To address the challenges of selenium’s low chemical activity and volume expansion in Li-Se batteries, through electrospun, we have developed a lotus root-inspired carbon nanofiber (CNF) material, featured internal multi-channels and anchored with molybdenum (Mo) single atoms (Mo@CNFs). Mo single atoms significantly enhance the conversion kinetics of selenium (Se), facilitating rapid formation of Li2Se. The internally structured multi-channel CNF serves as an effective host matrix for Se, mitigating its volume expansion during the electrochemical process. The resulting cathode, Se/Mo@CNF composite, exhibits a high discharge specific capacity, superior rate performance, and impressive cycle stability in Li-Se batteries. After 500 cycles at a current density of 1 C, it maintains a capacity retention rate of 82% and nearly 100% coulombic efficiency (CE). This research offers a new avenue for the application of single-atom materials in enhancing advanced Li-Se battery performance.

Multi-Functional 2D Covalent Organic Frameworks with Diketopyrrolopyrrole as Electron Acceptor.

2D covalent organic framework (COF) materials with extended conjugated structure and periodic columnar π-arrays exhibit promising applications in organic optoelectronics. However, there is a scarcity of reports on optoelectronic COFs, mainly due to the lack of suitable π-skeletons. Here, two multi-functional optoelectronic 2D COFs DPP-TPP-COF and DPP-TBB-COF are constructed with diketopyrrolopyrrole as electron acceptor (A), and 1,3,6,8-tetraphenylpyrene and 1,3,5-triphenylbenzene as electron donor (D) through imine bonds. Both 2D COFs showed good crystallinities and AA stacking with a rhombic framework for DPP-TPP-COF and hexagonal one for DPP-TBB-COF, respectively. The electron D-A and ordered intermolecular packing structures endow the COFs with broad UV-vis absorptions and narrow bandgaps along with suitable HOMO/LUMO energy levels, resulting in multi-functional optoelectronic properties, including photothermal conversion, supercapacitor property, and ambipolar semiconducting behavior. Among them, DPP-TPP-COF exhibits a high photothermal conversion efficiency of 47% under 660nm laser irradiation, while DPP-TBB-COF exhibits superior specific capacitance of 384Fg-1. Moreover, P-type doping and N-type doping are achieved by iodine and tetrakis(dimethylamino)ethylene on a single host COF, resulting in ambipolar semiconducting behavior. These results provide a paradigm for the application of multi-functional optoelectronic COF materials.

Highly Stable Polyaniline-Based Cathode Material Enabled by Phosphorene for Zinc-Ion Batteries with Superior Specific Capacity and Cycle Life.

Aqueous zinc-ion batteries (ZIBs) are regarded as a type of promising energy-storage device because of their high safety and low cost, and polyaniline (PANI) is normally employed as a cathode material for ZIBs owing to its unique electrochemical properties and high environmental stability. However, a low specific capacity and a short cycle life limit the development and applications of PANI-based electrodes. Herein, we have developed a novel type of highly stable PANI-based cathode material enabled by phosphene (PR) for aqueous Zn-PANI batteries through in situ chemical oxidative polymerization. The introduction of PR nanoflakes not only inhibits the degradation of PANI and generates more active sites for Zn2+ storage but also enables a synergistic effect of the Zn2+ insertion/extraction and P-Zn alloying reaction. This promotes a high reversible specific capacity of 240.2 mAh g-1 at 0.2 A g-1 and excellent rate performance for the PR/PANI nanocomposite cathode material. Compared to the pristine PANI cathode material, the PR/PANI nanocomposite cathode material is more suitable for the Zn-PANI battery, thanks to its higher specific capacity and better cycle stability. This study provides an innovative approach for developing the next generation of reliable PR-based electrode materials for aqueous energy-storage devices.

Investigation of electrochemical and photoluminescence properties of Dy[formula omitted] doped SrO/BaO/Al2O3 nanocomposite for supercapacitor and display applications

The current study investigates the synthesis and characterization of dysprosium-doped strontium barium aluminum nanocomposites (SBAD NCs), aiming to enhance their suitability for display and supercapacitor applications. SBAD NCs are synthesized by Solution combustion synthesis using aloevera extract as a reducing agent. Multi-phase formation of NCs due to SrO, BaO, and γ-Al2O3 phases was confirmed by PXRD analysis, and crystallite size is found to be in the range of 26 nm to 36 nm. SEM analysis confirmed the surface morphology and the elemental composition was affirmed by the EDAX spectrum which confirmed the purity of the synthesis. The blue shift in the UV–visible absorption peak with increasing dopant concentration suggests a rise in the direct energy band gap from 4.07 eV to 4.11 eV. FTIR analysis confirmed functional groups and fingerprint region affirmed the presence of SrO, BaO, and AlO bonds. Photoluminescence analysis performed under excitation wavelength 276 nm revealed a prominent emission peak at 565 nm, and the CIE values fall in the yellow-green region of visible spectra. The CCT value was found to be 4490 K–4542 K which might find an application as a nanophosphor in cool light-emitting diodes. The tailored nanocomposites exhibit exceptional electrochemical performance characterized by superior specific capacitance, and improved charge–discharge kinetics, as evaluated through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The specific capacitance is found to be in the range of 103.26 F/g to 173.24 F/g at a scan rate of 10 mV/s with increasing Dy3+ dopant concentration from 1 mol% to 9 mol% respectively. The dysprosium-doped SBAD NCs emerge as promising candidates for high-performance energy storage systems and vibrant display technologies, offering a synergistic integration of efficient energy storage and vivid display functionalities.

PDDA-modified nanoflower-like BiOCl/MXene hybrid electrode for efficient capacitive deionization dichlorination

Currently, chloride ions in industrial water limits its reuse when extending the circulating water cycle. Therefore, it is necessary to remove Cl− to ensure its effective reuse. Considering the development of new materials for efficient electrochemical chloride removal is a key issue limiting the development of capacitive deionization technology for chlorine removal. In this study, BiOCl was grown in situ on the surface of V-MXene, and then a nanoflower-like BiOCl/MXene composite was synthesized by utilizing the properties of MXene as a structure-directing agent to modulate the morphology, which exhibits superior pore structure and specific capacitance. The poly (diallyl dimethylammonium) (PDDA) modification improved the materials’ specific capacitance and reduced energy consumption for dichlorination. The optimal BMP-10 exhibited superior performance for dichlorination, the maximum dichlorination capacity and rate were 161.64 mg g−1 and 2.20mg g−1 min−1. We found that MXene has excellent properties for exfoliation and morphology modulation of layered materials. Additionally, the electrical properties have an important influence on the electrochemical removal of chloride ions. Here we successfully synthesized an efficient electrode material with unique morphological structure for CDI dichlorination and provided ideas for structure-directing agents and electrical modulation in material design for electrochemical dichlorination.

Focus on lithiation kinetics of selenium-doped NiO@C electrodes with multistage pore structure

Nickel oxide (NiO) has received considerable attention as an anode for lithium-ion batteries (LIBs) due to its superior theoretical specific capacity and cycling stability. However, its low conductivity as a wide bandgap semiconductor and sluggish lithiation kinetics are still obstacles to its widespread commercial use. In this study, we have developed a Se-doped NiO@C microsphere with a multistage pore structure. The Se-doped NiO@C shows satisfactory specific capacity and cycling stability when used as an anode for LIBs. Specifically, it exhibits a specific capacity of 1622.2 mAh g-1 after 190 cycles at 0.1 A g-1, and a capacity retention of 79.3% after 1500 cycles at 2 A g-1. The Se-doped NiO@C exhibited improved lithiation reaction kinetics due to its hierarchical pore structure, as indicated by rate performance, pseudocapacitance contribution, and galvanostatic intermittent titration technique. Furthermore, DFT calculations revealed that the addition of selenium altered the band structure of NiO, resulting in a narrower forbidden band width and faster charge transfer. Meanwhile, the electrons provided by selenium enhance the density of states of elemental oxygen and improve the adsorption energy of lithium ions. This study provides insights into the structure and composition necessary for improving the hysteresis kinetics of oxide electrodes.

Hierarchical porous graphene nanosheets derived from moso bamboo with superior supercapacitor performance

Moso bamboo is regarded as a kind of biomass resource with abundant reserves in nature, and how to achieve its high-value utilization is one of the important research topics widely concerned by the academic community. In this work, hierarchical porous graphene nanosheets with wrinkled structures derived from the natural moso bamboo is obtained via a compact two-step processing method including pyrolysis and chemical activation. The as-prepared ABC-950 possess a large specific surface area of 1758 m2 g−1, pore volume of 1.55 cm3 g−1, mesopores ratio of 75.5 % and high graphitization degree with ID/IG as low as 0.43. With these merits, as the electrode material for supercapacitor, the ABC-950 exhibits a high specific capacitance of 459.4 F g−1 at 1 A g−1 and an excellent rate performance of 82.3 % in 6 M KOH electrolyte. Moreover, the ABC-950 based symmetric supercapacitor shows superior specific capacitance of 112.3 F g−1 at 0.5 A g−1 and an attractive energy density of 15.6 Wh·kg−1 at 250 W kg−1. Moreover, outstanding capacitance retention of about 102.1 % even after 30,000 charge-discharge cycles at a large current density of 10 A g−1. Our work offers a promising method to easily transform moso bamboo into porous graphene nanosheets for the electric energy storage.

The construction of a flexible solid-state asymmetric supercapacitor device using nickel-copper oxide nanoplates and carbon nanosphere serving as positive and negative electrode, respectively with excellent electrochemical capabilities

Here, nickel-copper oxide nanoplates (NCN) and carbon nanosphere (CNS) as positive and negative electrodes are synthesised via a hydrothermal protocol without adding any surfactant and binders. The NCN and CNS electrodes in KOH electrolyte exhibit superior specific capacitance of ∼ 2362.5 F g−1 and ∼ 246.11 F g−1 at 1 A g−1 respectively. The NCN and CNS retained 98.54 % and 97.88 % of the initial capacitance after 3000 galvanostatic charge–discharge (GCD) cycles, respectively. Additionally, an asymmetric supercapacitor (ASC) device NCN//CNS is constructed using NCN and CNS as positive and negative electrodes, utilizing poly(vinyl alcohol) PVA − KOH gel electrolyte separator. The ASC device demonstrates a maximum energy density of 50.4 Wh kg−1 (181.44 KJ kg−1) with a power density ∼ 750 W kg−1 at 1 A g−1, maintaining 90.4 % cyclic stability after 10,000 GCD cycles. The electrochemical outputs of the device present significant potential for the advancement of high-performance ASC devices in electronic applications.

Trigger a multi-electron reaction by tailoring electronic structure of VO2 toward more efficient aqueous zinc metal batteries

VO2 (B) is recognized as a promising cathode material for aqueous zinc metal batteries (AZMBs) owing to its remarkable specific capacity and its unique, expansive tunnel structure, which facilitates the reversible insertion and extraction of Zn2+. Nonetheless, challenges such as the inherent instability of the VO2 structure, poor ion/electron transport and a limited capacity due to the low redox potential of the V3+/V4+ couple have hindered its wider application. In this study, we present a strategy to replace vanadium ions by doping Al3+ in VO2. This approach activates the multi-electron reaction (V4+/V5+), to increase the specific capacity and improve the structural stability by forming robust V5+O and Al3+O bonds. It also induces a local electric field by altering the local electron arrangement, which significantly accelerates the ion/electron transport process. As a result, Al-doped VO2 exhibits superior specific capacity, improved cycling stability, and accelerated electronic transport kinetics compared to undoped VO2. The beneficial effects of heterogeneous atomic doping observed here may provide valuable insights into the improvement electrode materials in metal-ion battery systems other than those based on Zn.

Improvement in Electrochemical Performance of Waste Sugarcane Bagasse-Derived Carbon via Hybridization with SiO2 Nanospheres.

Sugar industries generate substantial quantities of waste biomass after the extraction of sugar water from sugarcane stems, while biomass-derived porous carbon has currently received huge research attention for its sustainable application in energy storage systems. Hence, we have investigated waste sugarcane bagasse (WSB) as a cheap and potential source of porous carbon for supercapacitors. The electrochemical capacitive performance of WSB-derived carbon was further enhanced through hybridization with silicon dioxide (SiO2) as a cost-effective pseudocapacitance material. Porous WSB-C/SiO2 nanocomposites were prepared via the in situ pyrolysis of tetraethyl orthosilicate (TEOS)-modified WSB biomass. The morphological analysis confirms the pyrolytic growth of SiO2 nanospheres on WSB-C. The electrochemical performance of WSB-C/SiO2 nanocomposites was optimized by varying the SiO2 content, using two different electrolytes. The capacitance of activated WSB-C was remarkably enhanced upon hybridization with SiO2, while the nanocomposite electrode demonstrated superior specific capacitance in 6 M KOH electrolyte compared to neutral Na2SO4 electrolyte. A maximum specific capacitance of 362.3 F/g at 0.25 A/g was achieved for the WSB-C/SiO2 105 nanocomposite. The capacitance retention was slightly lower in nanocomposite electrodes (91.7-86.9%) than in pure WSB-C (97.4%) but still satisfactory. A symmetric WSB-C/SiO2 105//WSB-C/SiO2 105 supercapacitor was fabricated and achieved an energy density of 50.3 Wh kg-1 at a power density of 250 W kg-1, which is substantially higher than the WSB-C//WSB-C supercapacitor (22.1 Wh kg-1).

Two-dimensional/three-dimensional hierarchical self-supporting potassium ammonium vanadate@MXene hybrid film for superior performance aqueous zinc ion batteries

Currently, aqueous zinc ion batteries (AZIBs) have grown to be a good choice for large-scale energy storage systems due to their high theoretical specific capacity, low redox potential, low cost, and non-toxicity of the aqueous electrolyte. However, it is still challenging to obtain high specific capacity and stability suitable cathodes. Herein, hierarchical self-supporting potassium ammonium vanadate@MXene (KNVO@MXene) hybrid films were prepared by vacuum filtration method. Due to the three-dimensional nanoflower structure of KNVO with dual ions intercalation, high conductivity of two-dimensional Ti3C2Tx MXene, and the hierarchical self-supporting structure, the AZIB based on the KNVO@MXene hybrid film cathode possessed superior specific capacity (481 mAh/g at 0.3 A/g) and cycling stability (retaining 125 mAh/g after 1000 cycles at a high current density of 10 A/g). In addition, the storage mechanism was revealed by various ex-situ characterizations. Hence, a new viewpoint for the preparation of AZIB self-supporting cathode materials is presented.

Pre‐Oxidating and Pre‐Carbonizing to Regulate the Composition and Structure of Coal Tar Pitch: The Fabrication of Porous Carbon for Supercapacitor Applications

AbstractThe capacitive properties of supercapacitors highly rely on the reasonable design of high‐performance electrode materials. Herein, a synergetic strategy of pre‐oxidation and pre‐carbonization is proposed to prepare coal tar pitch (CTP) based porous carbon. The formation mechanism of porous carbon is revealed. Pre‐oxidation increases the heteroatom content and promotes the decomposition of polycyclic aromatic hydrocarbons into small molecules, which is more conducive to improving the subsequent activation and enhancing the microporous specific surface area. Also, the autoclave pre‐carbonization promotes the polymerization of the precursors and increases the carbon yield. Benefiting from the synergistic effect of pre‐oxidation and pre‐carbonation, the obtained carbon exhibits a superior specific capacitance of 365 F g−1. Meanwhile, ZnCl2 is used as a hydrogen‐bonding acceptor to synthesize ZnCl2‐EG/PVA deep eutectic solvent (DES) gel, and it is applicable to acidic, neutral, and alkaline electrolytes. The capacitor assembled with the prepared porous carbon and DES gel electrolyte achieves a high energy density of 41.3 Wh kg−1 and works well in unconventional temperatures (−40–75 °C). This work confirms the effect of pre‐oxidation and pre‐carbonization on the fabrication of CTP‐based carbon material and expects to prepare porous carbon using other pre‐oxidation/carbonization agents.

Electron-interactive 1D porous vertical NiCo2O4 nanowire and 3D N-doped graphene aerogel enable high hydroxyl-ion adsorption capacity for superior energy storage

Supercapacitors are a kind of highly efficient energy-storage device with long cycle life and high power density, however, their specific capacitance is insufficient for further application and development. In this work, a novel composite with one-dimensional (1D) NiCo2O4 nanowire arrays (NiCo2O4-NWA) vertically supported on three-dimensional (3D) nitrogen-doped graphene aerogel (NGA) is designed and facilely realized by hydrothermal reaction and thermal treatment. The NiCo2O4 nanowires, with length of ∼1 μm and diameter of ∼25 nm, display a porous structure and are regularly arranged on both sides of the sheets in nitrogen-doped graphene aerogel. The aerogel-supporting NiCo2O4 nanowires demonstrate a remarkably high specific capacitance of 2742 F g−1 at 1 A g−1, and an outstanding cyclic stability with capacitance retention of 90% even after 10,000 cycles at 80 A g−1. The density functional theory calculation shows the narrow band gap (0.32 eV) and strong electronic interaction and hydroxyl-ion adsorption effect of NiCo2O4 supported on NGA, resulting in superior specific capacitance and energy storage performance. The 3D nitrogen-doped graphene aerogel supporting 1D nanowire arrays represent a promising high-performance electrode material for application in the supercapacitors and other electrochemical energy-conversion and storage equipment.

Energy Storage Performance of Electrode Materials Derived from Manganese Metal-Organic Frameworks.

Metal-organic frameworks (MOFs) are porous materials assembled using metal and organic linkers, showing a high specific surface area and a tunable pore size. Large portions of metal open sites in MOFs can be exposed to electrolyte ions, meaning they have high potential to be used as electrode materials in energy storage devices such as supercapacitors. Also, they can be easily converted into porous metal oxides by heat treatment. In this study, we obtained high energy storage performance by preparing electrode materials through applying heat treatment to manganese MOFs (Mn-MOFs) under air. The chemical and structural properties of synthesized and thermally treated Mn-MOFs were measured by Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The surface area and porosity were investigated by nitrogen adsorption/desorption isotherms. The electrochemical properties were studied by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) using a three-electrode cell. It was found that Mn-MOF electrodes that underwent heat treatment at 400 °C under air consisted of Mn2O3 with high specific surface area and porosity. They also showed a superior specific capacitance of 214.0 F g-1 and an energy density value of 29.7 Wh kg-1 (at 0.1 A g-1) compared to non-treated Mn-MOFs.

Achieving new insights on rational design and application of double perovskite Y2CrMnO6 nanostructures as potential materials for electrochemical hydrogen storage performance

Fossil fuel consumption and environmental concerns have long motivated the use of electric vehicles around the world. To meet the global energy demand, hydrogen has been proposed as a clean energy carrier with carbon-free combustion. There is, however, a great need for high-performance electrode materials in hydrogen storage applications in order to achieve the desired goals of long life and superior specific capacity. The purpose of our study is to investigate how novel double perovskite Y2CrMnO6 (YCMO) nanostructures can be used as highly active electrocatalysts in hydrogen storage activity by kinetics of redox and physisorption mechanisms. For the first time, spherical-shaped YCMO nanoparticles were fabricated via sol-gel auto-combustion using grape juice as fuel and complexing agent. A series of physic-chemical and electrochemical techniques was used to analyze the electrochemical performance of resultant YCMO samples based on their uniformity, size, and phase purity, including X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Fourier-Transform Infrared Spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), Cyclic Voltammetry (CV), chronopotentiometry, electrochemical impedance spectroscopy (EIS), and Tafel polarization. At a constant current of 1 mA in a three electrode set-up, the 15th profile of hydrogen storage capacity of YCMO-15, synthesized with 15 mL of grape juice, reached a maximum value of 465 mAh g−1 at a constant current of 1 mA, which is higher than that of YCMO-5 (355 mAh g−1) and YCMO-10 (350 mAh g−1). The results presented here can also lead to a new plan for developing Cr–Mn-based double perovskite oxides with hydrogen storage properties.

Synthesis of submicron-sized LiNi0.5Co0.2Mn0.3O2 cathode particles via reverse microemulsion method: Tailoring size, interfacial properties, and enhanced electrochemical performance for lithium-ion battery

This study explores the impact of submicron-sized cathode materials on lithium-ion battery performance, an area with limited prior research due to synthetic challenges. Employing the reverse microemulsion method, LiNi0.5Co0.2Mn0.3O2 (NCM) cathode particles with tunable sizes (180 nm to 340 nm) were synthesized. Notably, NCM6.67-4.5, which prepared under the volume ratio of the oil phase to the water phase (i.e. 6.67) and applying 4.5 mL NH4OH as the complexing agent, obtained the largest particle size (340 nm). Further investigation revealed that NCM6.67-4.5 exhibited superior discharge specific capacity (177.54 mAh·g−1) and a high coulomb efficiency (99.5 %). The larger particle size in the submicron range facilitated heightened lithium-ion diffusion rates and reduced polarization. Focused Ion Beam-Scanning Electron Microscopy (FIB-SEM) confirmed that increased particle size diminishes specific surface area, mitigating interfacial side reactions during battery cycling. This research underscores the importance of controlling cathode particle size for optimizing electrochemical performance in lithium-ion batteries.

Space-confined intercalation expansion strategy for simple and rapid synthesis of kish-based expanded graphite for aluminum ion batteries

The practical application of graphite cathodes in aluminum ion batteries (AIBs) is hindered by poor cycle and rate performance of graphite, due to serious structural degradation. In this work, different types of kish-expanded graphite (KEG) with different expansion volumes were prepared simply and rapidly using low-cost solid waste kish graphite (KG) as precursor, and K2S2O8 and concentrated H2SO4 as oxide intercalation agents by space-confined intercalation expansion strategy. By adjusting the mass ratio of K2S2O8 to KG, the macrostructure and microstructure of KEG can be effectively controlled. Specifically, KEG6, synthesized with the mass ratio of K2S2O8 to KG of 6, exhibited a large expansion volume, graphene nanosheets with numerous graphite microcrystalline layer structures, and micro-nano interlayer pore structures resulting from the cross-linking of graphene nanosheets, along with abundant oxygen-containing functional groups. KEG6, as a cathode material for AIBs, exhibited outstanding electrochemical performance, including superior specific capacity (141.1 mA h/g at 50 mA/g), good rate capability (119.8 mA h/g at 1000 mA/g, 85.6 mA h/g at 2000 mA/g) and remarkable cycle stability (134.0 mA h/g with 99.1% Coulombic efficiency after 10,000 cycles at 1000 mA/g). This study provides a simple and rapid method for the large-scale synthesis of KEG as a potential candidate for AIBs.

Superior specific capacity and energy density simultaneously achieved by Sr/In co-deposition behavior of Mg-Sr-In ternary alloys as anodes for Mg-Air cells

In this work, the combined addition of strontium/indium (Sr/In) to the magnesium anode for Mg-Air Cells is investigated to improve discharge performance by modifying the anode/electrolyte interface. Indium exists as solid solution atoms in the α-Mg matrix without its second-phase generation, and at the same time facilitates grain refinement, dendritic segregation and Mg17Sr2-phases precipitation. During discharge operation, Sr modifies the film composition via its compounds and promoted the redeposition of In at the substrate/film interface; their co-deposition behavior on the anodic reaction surface enhances anode reaction kinetics, suppresses the negative difference effect (NDE) and mitigates the “chunk effect” (CE), which is contributed to uniform dissolution and low self-corrosion hydrogen evolution rate (HER). Therefore, Mg-Sr-xIn alloy anodes show excellent discharge performance, e.g., 0.5Sr-1.0In shows an average discharge voltage of 1.4234 V and a specific energy density of 1990.71 Wh kg−1 at 10 mA cm−2. Furthermore, the decisive factor (CE and self-discharge HE) for anodic efficiency are quantitively analyzed, the self-discharge is the main factor of cell efficiency loss. Surprisingly, all Mg-Sr-xIn anodes show anodic efficiency greater than 60% at high current density (≥10 mA cm−2), making them excellent candidate anodes for Mg-Air cells at high-power output.

Designing of high performance MoS2@VZnS//AC hybrid battery supercapacitor device for the electrochemical energy storage and glucose detection

Due to their high conductive properties and superior specific capacitance, metal sulfides exhibit remarkable electrical conductivity. Transition metal dichalcogenides (TMDs) are regarded ideal options for energy harvesting devices due to their unique 2D arrangement and remarkable electrochemical properties. In this work, the typical exfoliation method (tip sonication method) was used to synthesize the molybdenum disulfide (MoS2). By using the hydrothermal method, the vanadium zinc sulfide is synthesized. The composite was analyzed through SEM, XRD, and XPS techniques to investigate its morphological, structural, and compositional characteristics comprehensively. The MoS2@VZnS electrode achieved a specific capacity (Qs) of 1025 Cg−1 at 3 mVs−1 after being tested in 1 M KOH. In a two-electrode set-up, activated carbon is used as a negative electrode, and MoS2@VZnS is used as a positive electrode for the fabrication of a hybrid supercapacitor. The asymmetric device has demonstrated a Qs of 285.4 Cg−1 at 1.4 Ag−1. The fabricated asymmetric supercapacitor device has manifested an excellent energy density (Ed) of 39.5 Whkg−1 and power density (Pd) of 2462.35 Wkg−1. Furthermore, in the durability test of MoS2@VZnS//AC, it exhibited an impressive capacity retention of 91.32% after enduring 5,000 cycles. Besides this, an investigation was conducted on a glucose electrochemical sensor utilizing MoS2@VZnS, to enhance its performance. The device showed extraordinary performance and considerable sensitivity against glucose, even up to a very high value. The multifunctional MoS2@VZnS nanocomposite electrode material provides new opportunities to design hybrid devices in energy storage devices and biomedical applications.