LiOH Electrolyte Research Articles

Novel pseudocapacitive one-dimensional copper pyrophosphate (Cu2P2O7) nanofibers for asymmetric supercapacitor

The redox activity of a supercapacitor electrode can be significantly compromised by irregular, non-uniform, and agglomerated morphologies of the material. The preparation of a one-dimensional fibrous morphology not only ensures a consistent, continuous, and well-separated network of fibers but also results in an increased surface area compared to higher-dimensional structures. In this study, the fabrication of a continuous network of one-dimensional copper pyrophosphate (Cu2P2O7) nanofibers through a straightforward polymer-based electrospinning method followed by calcination at 900°C is reported. The resulting Cu2P2O7 monoclinic nanofibers exhibited an average diameter of 95 nm, highlighting the enhanced surface area of the material. By employing nickel foam (NF) as a current collector, the Cu2P2O7/NF electrode demonstrated a remarkable specific capacitance of 567.31 F g-1 (357.4 C g-1) at 2 A g-1 in 1 M LiOH electrolyte, surpassing performances in 1 M KOH and 1 M NaOH electrolytes. Furthermore, we designed an asymmetric supercapacitor (ASC) device configuration by incorporating carbon nanofibers (CNFs) as the negative electrode. Cu2P2O7//CNFs asymmetric supercapacitor showcases an exceptional specific capacitance, reaching 143.73 F g-1 (244.34 C g-1) at a current density of 0.4 A g-1. This remarkable performance is complemented by a notable energy density of 57.69 Wh kg-1 and power density of 1104.7 W kg-1. Furthermore, even at an elevated power density of 5132.25 W kg-1, the device maintained a considerable energy density of 22.81 Wh kg-1. These findings underscore the viability of Cu2P2O7 nanofibers as a compelling choice for energy storage devices.

Asymmetric lithium supercapacitors with solid-state hybrid electrolytes containing zeolite particle and water-soluble polymer

Here we demonstrate that high-performance solid-state hybrid electrolytes are prepared via environment-friendly water-based processes of zeolite Y (Zy) particle, branched-poly(ethylene imine) (bPEI), and lithium hydroxide (LiOH). The hybrid Zy:bPEI:LiOH electrolytes (ZyPL) were successfully applied to fabricate asymmetric-type lithium supercapacitors consisting of graphite-based active electrodes and indium-tin-oxide (ITO) counter electrodes. Results showed that the ion conductivity of electrolytes was greatly dependent on the Zy content and reached the highest value (ca. 0.28 mS/cm) at Zy = 30 wt% due to the formation of interfacial ion transport channels between Zy particles and bPEI chains. The galvanostatic charging/discharging (GCD) test revealed that the ZyPL supercapacitors could deliver the highest potential of 2.28 V at Zy = 30 wt% compared to 1.86 V at Zy = 0 wt%. In particular, the ZyPL supercapacitors, after charging at 0.1 mA/g, exhibited a long-lasting high-potential level of > 1.0 V at Zy = 30 wt% compared to 0.5 V at Zy = 0 wt%. The long-term GCD cycle test disclosed that the ZyPL supercapacitors could work stably with a capacitance retention of 91.7 % even after 3000 cycles. The series connection of six ZyPL supercapacitors delivered ca. 10.94 V with consistent charging/discharging characteristics.

High carbon containing biomaterial offering honeycomb morphology as a charge storing electrode in aqueous alkaline electrolytes

Research on unconventional carbon structures and morphologies obtainable from renewable sources are a way forward in realizing sustainable materials for the next-generation industry. Herein, renewable porous carbon from a biomass (coconut rachis) with high carbon content (∼81 %) and honeycomb morphology (inner diameter ∼60 μm and wall thickness ∼500 nm) is developed as an electrochemical capacitor electrode. The coconut rachis upon chemical activation yield a surface area ∼1,630 m2‧g−1 and desirable pore characteristics for storing aqueous cations. The electrochemical charge storability of the porous carbon electrodes in 1 M KOH, NaOH and LiOH electrolytes showed specific capacitances ∼320, ∼140 and ∼102 F‧g−1, respectively. Electrochemical impedance spectra validated the higher capacitance in the KOH electrolyte. Besides, symmetric supercapacitor full cells were fabricated using the present electrode in 1 M KOH electrolyte with desirable charge storage properties. Given the abundance of the precursor and desirable charge storage characteristics, the present work could be useful in developing the coconut rachis-resourced honeycomb-shaped porous carbon as a charge storing electrode.

Tracing the impact of CO2 on the electrochemical and charge–discharge behavior for Al–Mg alloy in KOH and LiOH electrolytes for battery applications

For the first time, it has been found that the electrochemical performance of the Al–Mg alloy as an anode in alkaline batteries has been markedly enhanced in the presence of CO2 and LiOH as an electrolyte. This work compares the electrochemical performance of an Al–Mg alloy used as an anode in Al-air batteries in KOH and LiOH solutions, both with and without CO2. Potentiodynamic polarization (Tafel), charging-discharging (galvanostatic) experiments, and electrochemical impedance spectroscopy (EIS) are used. X-ray diffraction spectroscopy (XRD) and a scanning electron microscope (SEM) outfitted with an energetic-dispersive X-ray spectroscope (EDX) were utilized for the investigation of the products on the corroded surface of the electrode. Findings revealed that the examined electrode’s density of corrosion current (icorr.) density in pure LiOH is significantly lower than in pure KOH (1 M). Nevertheless, in the two CO2-containing solutions investigated, icorr. significantly decreased. The corrosion rate of the examined alloy in the two studied basic solutions with and without CO2 drops in the following order: KOH > LiOH > KOH + CO2 > LiOH + CO2. The obtained results from galvanostatic charge–discharge measurements showed excellent performance of the battery in both LiOH and KOH containing CO2. The electrochemical findings and the XRD, SEM, and EDX results illustrations are in good accordance.

Cathode Material Designing and Characterization: Co3O4/N‐doped Porous Carbon for Asymmetric Supercapacitors

AbstractMesoporous Co3O4/N‐PC in powder form was synthesized via a wet‐chemical approach, and the resulting material was deposited onto nickel foam as a substrate without the use of a binder. Prior to device fabrication, a thorough analysis of suitable and cost‐effective aqueous alkaline and neutral electrolytes was conducted. Electrolyte optimization was performed using Co3O4/N‐PC/NF electrode with Na2SO4, NaOH, LiOH, and KOH electrolytes. The supercapacitor performance of the binder‐free deposited materials was found to be superior in KOH electrolyte compared to other aqueous electrolytes at equal concentrations. Further optimization of the KOH electrolyte concentration was carried out to achieve the best electrochemical performance for the Co3O4/N‐PC/NF electrode. Electrochemical results demonstrated that the Co3O4/N‐PC/NF electrode performed well in 1 M KOH electrolyte, surpassing its performance at other concentrations. Subsequently, a solid‐state asymmetric device was fabricated, utilizing Co3O4/N‐PC, activated carbon, and a KOH+PVA gel as the cathode, anode, and electrolyte, respectively. The assembled asymmetric Co3O4/N‐PC/NF‐AC/NF device exhibited an energy density of 12.08 Wh kg−1 and a power density of 2500 W kg−1 within a potential window of 1.5 V. Impressively, after nearly 3000 continuous GCD cycles, the device showed negligible initial specific capacitance decay. The device was also successfully tested for powering the LED.

Stabilizing poly(vinylidene fluoride) solid-state electrolytes/lithium metal interface by constructing an ultrathin interface layer to inhibit the electron transfer

Residual N, N-dimethylformamide (DMF) enhances the conductivity of poly(vinylidene fluoride) (PVDF) solid-state polymer electrolytes (SPEs), but adversely impacts the SPEs/Li interface through electron transfer between DMF and Li. Herein, we developed a novel LiOH and LiNH2 (LON) artificial solid electrolyte interface (SEI) layer with limited electronic conductivity to block such electron transfer. Unlike conventional SEI, which are unsuitable for integration with SPEs since their high thickness (1–30 μm) results in high interfacial resistance, the LON layer is ultrathin (∼30 nm), and more importantly, it facilitates the separation of Li ions from Li-DMF bound ions during Li plating, contributing to a notable reduction in interfacial impedance. As a result, the LON protected Li (Li@LON)-based symmetrical cell exhibits an ultra-long cycle life of 2100 h and survives even under 0.6 mAh cm−2 at 25 °C, in stark contrast to the Bare Li-based symmetrical cell, which only maintains stable cycles for 806 h at 0.2 mAh cm−2. Furthermore, the Li@LON//LiNi0.8Co0.1Mn0.1O2 (NCM811) cell stably cycles over 3000 times at 0.5 C and 25 °C, significantly outperforming the Li//NCM811 cell with 880 times. This work paves a novel strategy for stabilizing SPEs-Li interface by constructing an ultrathin artificial SEI with low electronic conductivity.

Regeneration of waste Zn-MnO2 batteries: Value-added transformation to regenerate essential materials for sustainable battery manufacturing

Zn-MnO2 batteries have a 3–5 year shelf life and make up 75 % of portable batteries. Disposing of spent batteries is a global issue and demand for MnO2 cathode material is growing 9.6 % annually, causing increased resource use and potential toxic metal leaching risk. Eco-efficient practices are needed to reduce environmental impact through recycling and reusing end-of-life products. Herein, electrolytic manganese dioxide (EMD) of spent Zn-MnO2 batteries was recycled using a thermochemical process where the structure of EMD was upgraded resulting in improving its electrochemical performance. The applicability of the recycled EMD as cathode into a new battery was explored by examining the discharge behaviour of the Zn-MnO2 cell made in KOH electrolyte and the results were compared with the performance of an original battery/EMD. In the recycled EMD cell, γ-MnO2 transformed to Zn2Mn7O8.H2O upon discharge (with a capacity of 213 mAh.g−1) and no Mn3O4 was observed, whereas in the original EMD, discharge resulted in the formation of mainly ZnMn5O4 and Mn3O4 (with a capacity of 175 mAh.g−1). The reversibility of the intercalation of cations into the structure of γ-MnO2 and their rechargeability was further examined via charge-discharge cycles using LiOH electrolyte where the recycled EMD exhibited enhanced behaviour. This indicates that in the recycled EMD, ZnMnO2 was able to revert to the original γ-MnO2, whereas in the original EMD, the formed Mn3O4 seemed to be irreversible resulting in the poor rechargeability behaviour of such batteries. Conclusively, the proposed method is a more efficient solution for reducing environmental impacts in value-added manufacturing due to its fewer steps compared to conventional techniques.

Molten salt-shielded synthesis of Ti3AlC2 as a precursor for large-scale preparation of Ti3C2Tx MXene binder-free film electrode supercapacitors.

MXenes are a group of two-dimensional materials that are promising for many applications, including as film electrode supercapacitors. When synthesizing such materials, special attention is paid to the conditions for obtaining the MAX phase, the chemical, morphological and structural features of which determine the functional properties of the final product. In this study, the Ti3AlC2 precursor is proposed to be obtained using a technologically simple and accessible method of synthesis in molten salt. This method allows reducing the reaction temperature and creating an antioxidant atmosphere. Ti3C2Tx MXene electrode films are produced by the easily scalable blade coating method without a binder. The synthesized materials were studied by X-ray phase analysis and scanning electron microscopy. Electrochemical testing of Ti3C2Tx film electrodes was carried out in a three-electrode configuration in aqueous solutions of 1M H2SO4, 6M KOH, 1M LiOH and 1M Na2SO4 electrolytes. The maximum specific capacity value for Ti3C2Tx MXene binder-free film electrode supercapacitors is obtained in 1M H2SO4 electrolyte (480 F g-1 at a scan rate of 1 mV s-1). The simple, low-cost and scalable production technology and promising electrochemical characteristics of the Ti3C2Tx MXene binder-free film electrode make it an excellent candidate for new-generation supercapacitors.

Lithium supercapacitors with environmentally-friend water-processable solid-state hybrid electrolytes of zinc oxide/polymer/lithium hydroxide

Environment-friendly and safe solid-state electrolytes are of utmost importance for energy storage devices, but no study has been reported on water-processable hybrid electrolytes that take advantage of both organic and inorganic components. Here, for the first time, we demonstrate that novel water-processable hybrid films, consisting of zinc oxide (ZnO) nanoparticle, lithium hydroxide (LiOH), and branched-poly(ethylene imine) (bPEI), act as efficient solid-state electrolytes for lithium supercapacitors. The ZnO:bPEI:LiOH (ZPL) hybrid solutions were prepared using water by varying ZnO molar ratios up to 60 mol% to the repeating unit of bPEI. The enhanced ionic conductivity (∼1.36 mS/cm), which is higher than that of bPEI:LiOH electrolytes, was achieved at ZnO = 30 mol%. The best ZPL supercapacitors, exhibiting high performances of peak potential (2.0 V) and energy density (3.38 mWh/kg) upon charging at 0.4 mA/g only, could be stably operated over 1000 charging/discharging cycles. Series connection of multiple ZPL supercapacitors delivered increased output potentials (∼4.5 V from three devices in series) with reproducible charging/discharging performances. The experimental result supports that the present ZPL hybrid electrolyte technology paves the way for eco-friendly processes of next-generation solid-state electrolytes that can be a key in safe energy storage devices for applications to electrical vehicles etc.

Electrolyte dependence for the electrochemical decarboxylation of medium-chain fatty acids (n-octanoic acid) into fuel on Pt electrode

The deoxygenation of organic acids, important biomass feedstocks and derivatives, to synthesize hydrocarbon products under mild electrochemical conditions, holds significant importance for the production of carbon-neutral biofuels. There is still limited research on the influential factors of the electrochemical decarboxylation reaction of medium-chain fatty acids. In this study, n-octanoic acid (OA) was chosen as the research subject to investigate the electrochemical decarboxylation behavior of OA on a platinum electrode, focusing on the influence of different alkali metal cations (Li+, Na+, K+), common anions (SO42−, Cl−), and electrolyte pH. It was found that KOH as an electrolyte exhibited the best performance for OA. Possibly, the larger size of K+ increased the alkalinity of the electrode surface, facilitating OA deprotonation. LiOH electrolyte reduced the solubility of OA, thereby inhibiting the decarboxylation reaction. SO42− exhibited a weak promoting effect on the decarboxylation reaction of OA, while Cl− showed no adverse effect although Cl− may adsorb on the electrode surface. Furthermore, unlike short-chain fatty acids, medium-chain OA can only achieve efficient decarboxylation under alkaline conditions due to its solubility properties. This study provides references and foundations for future efforts to enhance the efficiency of electrochemical decarboxylation synthesis of hydrocarbon biofuels from medium-chain fatty acids.

Bifunctional rGO incorporated NiSe2 nanocomposite as a photocatalyst and an electrode in supercapacitor

The rGO incorporated NiSe2 nanocomposite (NC) has been synthesized by hydrothermal method and the photocatalytic and electrochemical performance were reported. From the VSM analysis, the magnetic properties such as coercivity, magnetic retentivity and saturation of the synthesized NC have been calculated. Since the synthesized NC has a high surface-to-volume ratio, the specific capacitance as well as absorption capability of dyes from the wastewater are enhanced. The rGO incorporated NiSe2 NC exhibits 98.8% degradation of Rhodamine B after 120 min. The synthesized NC shows superior photocatalytic performance and it can also be recovered after degradation by applying an external magnetic field. The rGO incorporated NiSe2 NC shows a high specific capacitance of 510 Fg−1 at 5 mV/sec with an ideal capacitive behavior using LiOH electrolyte. The synthesized NC retains 59% of its initial capacitance at the high current density of 10 Ag−1 indicating good charging and discharging capability. Results revealed that rGO incorporated NiSe2 NC is a promising material to be used in dye degradation and as an electrode material for supercapacitors.

Role of the intercalated ions on the high capacitance behavior of Ti 3 C 2 Tx MXene nanohybrids

T i 3 C 2 T x (MXene) is prone to surface oxidation because of the presence of oxygen surface terminals in its surfaces. In this work, the effect of oxygen surface terminals has been reduced by replacing it with other surface terminals or thin layers of heteroatom at the interlayers. These resulted in increasing the interlayer spacing from 9.3 Å up to 12.5 Å with better flexibility properties, thereby facilitating electron/mass transports by exposing enough active surface areas. The carbon nanoplated MXene showed enhanced specific capacitance of 110 F/g at 2 mV/s in LiOH electrolytes for superior supercapacitor applications.

Studies on dielectric, thermal and electrochemical characteristics of rGO incorporated CoSe2 nanocomposite for energy storage application

A hydrothermal process was employed to synthesize rGO incorporated CoSe2 nanocomposite. Powder X-ray diffraction and FTIR analyses were used to identify the prepared nanocomposite. The synthesized nanocomposite is found to have an average crystallite size of 18.63 nm. The presence of incorporation of poly-dispersed agglomerated spherical shape of CoSe2 over the surface of rGO was confirmed by FESEM and HRTEM analyses. The presence of elements such as cobalt, selenide, carbon and oxygen in the synthesized nanocomposite were verified using EDAX and XPS analysis. TG/DTA was used to investigate the thermal properties of the prepared nanocomposite. A detailed study about the process underlying the variation of dielectric constant and dielectric loss in rGO incorporated CoSe2 nanocomposite due to several parameters such as nanoparticle size, operating frequency and temperature is reported. Electrical conduction was found to be dependent on both frequency and temperature in an AC electrical conductivity investigation. The activation energy of the rGO incorporated CoSe2 nanocomposite was found to be 0.0369 KJ/mol. This lower value of activation energy will help the prepared nanocomposite to attain quick regeneration of rGO-CoSe2 bonds and will not experience partial reduction of charge capacity during energy storage. The electrochemical properties of rGO incorporated CoSe2 nanocomposite exhibits specific capacitance of 202 F g−1 at scan rate of 5 mV/ sec in 3 M LiOH electrolyte. The prepared nanocomposite has an ideal capacitor behaviour and smaller charge transfer resistance between the electrode and electrolyte due to the conductivity of rGO present in it. These findings suggest that the prepared nanocomposite is expected to pave the way for creative electronic applications.

Investigating the effect of electrolyte and its concentration dependence on WO3 nanosheet as an efficient electrode for supercapacitors: Effect of Redox Additive

This research aimed to synthesize non-uniform nanosheet-like tungstate oxide (WO3) using a simple hydrothermal process, which would result in an effective and environment-friendly material for use in supercapacitors (SCs). The resulting materials are thoroughly examined using physio-chemical techniques. The supercapacitive properties of the WO3–Ni-Foam (NF) were examined using 1 M KOH, NaOH, and LiOH electrolytes and further, the electrochemical performance of the WO3–NF electrode was assessed by changing the concentration of KOH electrolytes from 1 to 4 M respectively. The WO3–NF electrode demonstrated the highest specific capacity (Csp) of 70 mAh/g and capacitance (Cs) of 563 F/g with a high energy density of 16 Wh/kg, and power density of 281 W/kg in 2 M KOH electrolyte respectively. Additionally, the WO3–NF electrode showed excellent Columbic efficiency of 98% and long-term capacitive retention of 88% over 5000 cycles in 2 M KOH electrolyte. Additionally, the effect of redox additive (0.01 M of potassium ferrocyanide) improves the electrochemical performance of WO3–NF; the Csp and Cs values were 137 mAh/g, 618 F/g and 100 mAh/g, 800 F/g at 5 mV/s and 5 mA/cm2, respectively. Furthermore, the WO3–NF electrode exhibits good stability retention of 94% over the 2000 cycles. The electrochemical performance of WO3 nanosheets for energy storage applications was improved by this straightforward hydrothermal method and evaluating the effect of redox additive electrolyte.

Exploration of aqueous electrolyte on the interconnected petal-like structure of Co-MOFs for high-performance paper-soaked supercapacitors

The electrolyte is a crucial component in supercapacitors (SCs), along with the electrode material, which can affect the electrochemical parameters, such as specific capacitances (Cs), energy density (ED), cyclic stability, and potential window. Therefore, the present work explores the effect of different electrolytes on the performance of Co-MOFs/FSS electrodes for SCs. The Co-MOFs/FSS electrode was synthesized on a flexible stainless-steel (FSS) substrate using the reaction-diffusion framework method, and its structural, morphological, and compositional characteristics were analyzed. The SCs performance of Co-MOF/FSS was examined across multiple electrolytes (1M KOH, 1M LiOH, and 1M NaOH). The SCs performance of Co-MOFs/FSS increased in the following sequence: 1M LiOH > 1M NaOH > 1M KOH. Furthermore, the dependence of concentration variation of LiOH electrolyte on Co-MOFs/FSS for SCs was studied. In 2M LiOH electrolyte, the Co-MOFs/FSS demonstrated a maximum Cs of 650 F g− 1 and specific capacity (Csp) of 262 C g− 1 at 5 mV s− 1. Furthermore, it exhibited a favourable retention rate of 71 % over 5000 GCD cycles at 10 mA cm−2. It also possessed higher ED and Power Density (PD) of 14.10 Wh kg−1 and 666 W kg−1 at 1 mA cm−2 respectively. Further, a flexible symmetric paper-soaked Co-MOFs/FSS//Co-MOFs/FSS device was fabricated, and its electrochemical performance was assessed. The fabricated device exhibited a higher Cs of 122 F g− 1 and Csp of 171 C g− 1 at 10 mV s− 1. Additionally, it showed good retentivity of 46 % after the 3000th cycle at 15 mA; and exhibited higher ED of 6.78 Wh kg−1 and PD of 1500 W kg−1 at 6 mA. This study highlights the importance of selecting the appropriate electrolyte for enhancing the electrochemical performance of Co-MOFs/FSS electrode material.

Highly Stable Hybrid Electrolyte Lithium-Air Batteries Based on Weakly Acidic Lithium Bromide Catholyte

Hybrid lithium-air battery (HLAB) have garnered significant attention from researchers due to their relatively low overpotential, stable cyclability, and reversibility. In this paper, we investigate an HLAB system that uses a catholyte of lithium bromide solution in a weak acid state to enhance the stability of Li1−xAlxGe2−x(PO4)3 (LAGP) and improve its cycle life. The electrochemical performance of the optimized LiBr electrolyte exhibited stability after 443 cycles (1772 h) in ambient air (RH = 15%). Additionally, an improvement of >20% in coulombic efficiency was observed at a discharge specific capacity of 10736 mAh·g−1 compared to HLABs using LiOH electrolyte. This study provides insights into the protection of LAGP membranes in HLAB and the inhibition of reaction product precipitation.

Effect of Electrolyte Concentration on the Electrochemical Performance of Spray Deposited LiFePO4.

LiFePO4 is a common electrode cathode material that still needs some improvements regarding its electronic conductivity and the synthesis process in order to be easily scalable. In this work, a simple, multiple-pass deposition technique was utilized in which the spray-gun was moved across the substrate creating a "wet film", in which-after thermal annealing at very mild temperatures (i.e., 65 °C)-a LiFePO4 cathode was formed on graphite. The growth of the LiFePO4 layer was confirmed via X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy. The layer was thick, consisting of agglomerated non-uniform flake-like particles with an average diameter of 1.5 to 3 μm. The cathode was tested in different LiOH concentrations of 0.5 M, 1 M, and 2 M, indicating an quasi-rectangular and nearly symmetric shape ascribed to non-faradaic charging processes, with the highest ion transfer for 2 M LiOH (i.e., 6.2 × 10-9 cm2/cm). Nevertheless, the 1 M aqueous LiOH electrolyte presented both satisfactory ion storage and stability. In particular, the diffusion coefficient was estimated to be 5.46 × 10-9 cm2/s, with 12 mAh/g and a 99% capacity retention rate after 100 cycles.

Ion dynamics into different pore size distributions in supercapacitors under compression

Compressing supercapacitor (SCs) electrode is essential for improving the energy storage characteristics and minimizing ions’ distance travel, faradaic reactions, and overall ohmic resistance. Studies comprising the ion dynamics in SC electrodes under compression are still rare. So, the ionic dynamics of five aqueous electrolytes in electrodes under compression were studied in this work for tracking electrochemical and structural changes under mechanical stress. A superionic state is formed when the electrode is compressed until the micropores match the dimensions with the electrolyte’s hydrated ion sizes, which increases the capacitance. If excessive compression is applied, the accessible pore regions decrease, and the capacitance drops. Hence, as the studied hydrated ions have different dimensions, the match between ion/pore sizes differs. To the LiOH and NaClO4 electrolytes, increasing the pressure from 60 to 120 and 100 PSI raised the capacitance from 13.5 to 35.2 F g−1 and 30.9 to 39.0 F g−1, respectively. So, the KOH electrolyte with the lowest and LiCl with the biggest combination of hydrated ion size have their point of maximum capacitance (39.5 and 36.7F g−1) achieved at 140 and 80 PSI, respectively. To LiCl and KCl electrolytes, overcompression causes a drop in capacitance higher than 23%.

Core-shell structured hierarchical Ni nanowires and NiS/Co3S4 microflowers arrays as a high-performance supercapacitor electrode

To develop new positive electrode materials with high electrochemical performance for practical applications in energy storage, the design of new complex morphologies with a core-shell structure based on MS sulfide materials with M = Ni, Co, Fe or Mn and nanomaterials metallic is a very essential technique. In this study, an asymmetric supercapacitor (ASC) with high energy density was fabricated by combining a NiS/Co3S4@h-Ni NWs battery-like electrode with α-MnO2 as a pseudo-capacitive electrode. Firstly, hierarchical Nickel Nanowires, h-Ni NWs, were prepared by the reduction of Ni2+ ions by hydrazine, and then the h-Ni NWs are coated with NiS/Co3S4 by the hydrothermal method to form a core-shell structure with good electrical conductivity. The electrochemical performance of the NiS/Co3S4@h-Ni NWs electrode was evaluated in the 4 M LiOH electrolyte. The results showed that the NiS/Co3S4@h-Ni NWs electrode had a specific capacity of 1893 C/g at a current density of 1 A/g and an excellent retention of 98.63 % of its initial specific capacity after 10,000 charge-discharge cycles at 20 A/g due to the synergistic interaction between the nickel nanowires and (Ni/Co) sulfides in the developed core-shell structure. Furthermore, the fabricated ASC device provided a high energy density of 101.05 Wh/kg at a power density of 850 W/kg. At a maximum power density of 17 kW/kg, the device provided an energy density of 57.13 Wh/kg along with excellent capacity retention (83.56 %) after 10,000 charge-discharge cycles at 20 A/g.

HKUST-1/LaNiO3 hybrid composite as superior material for symmetrical pseudocapacitors

Perovskite phase metal oxides are extensively explored due to their structural and compositional flexibility and excellent electrocatalytic activity. Its composite with the porous and conductive materials has potential application for the energy storage devices due to its additional conductive pathways for enhancing the charge kinetics. In the present work synthesis of highly porous Cu-MOF(HKUST-1)/LaNiO3 heterostructure composite is explored as pseudocapacitive electrode in three electrode system using KOH as well as LiOH electrolytes. The prepared HKUST-1/LaNiO3 composite electrode has shown a high specific capacitance of 424.30 F/g, 786.0 F/g in LiOH and KOH electrolytes respectively at 1 A/g current density. The obtained value is significantly better than the pristine LaNiO3 perovskite electrode (170 F/g and 273 F/g in LiOH and KOH respectively). The symmetrical supercapacitor using HKUST-1/LaNiO3 electrodes have displayed the energy densities of 28.24 Wh/kg and 28.15 Wh/kg and power densities of 775 W/kg, 836 W/kg in KOH and LiOH electrolytes respectively.