Charge-discharge Curves Research Articles

MnO2 nanowires modified reduced graphene oxide thick film cathode for aqueous zinc-ion prismatic battery

Aqueous zinc-ion batteries are an excellent alternative to lithium-ion batteries that can meet the energy requirements while also being safe and eco-friendly. However, developing a suitable cathode material with good energy density and high-rate capability is challenging. In this study, we developed an aqueous zinc-ion battery with a high surface area MnO2 nanowires modified reduced graphene oxide nanocomposite screen printed interdigitated array electrodes and a distinctive aqueous electrolyte comprising 1 M each of ZnSO4 and Na2SO4, 0.1 M MnSO4, and 0.8 mM sodium dodecyl sulfate. The charge-discharge curves reveal that the cathode material exhibits a high reversible storage capacity of 164 mAh g−1 at a current density of 50 mA g−1. The battery retained 99.59% of its Coulombic efficiency after 300 cycles when cycled at a high current rate of 300 mA g−1. The prismatic battery realized exhibited a calculated energy density of 505.5 Wh kg−1 which is higher than previously reported works. On account of the large energy density and high rate capability coupled with non-toxic components, low cost and facile fabrication method, the Zn||MnO2/rGO battery shows good promise for energy storage application.

Design and fabrication OF Cu2O@MoS2/r-Go dendrite binary electrode for quasi – Symmetric capacitor- sustainable approach

Modified hummers method to synthesise GO from powdered graphite and sodium molybdate, then green synthesised Cu2O/MoS2/rGO nanostructure prepared by economical microwave approach. XRD analysis proved that Cu2O and MoS2/rGO were present in the sample. FTIR spectra revealed a Cu2O group at around 620 cm−1, whilst EDAX analysis revealed Mo, Cu, S, O, and C characteristic bands. rGO material resembles the SEM image of Cu2O/MoS2-rGo in appearance, with dendritic morphologies of Cu2O and MoS2 sheets on its exterior. When applied to nearby r-GO sheet formations, MoS2 thins down the layers. Incorporating rGO, a conductive material, into the MoS2/rGO composite greatly enhanced its capacity to store charges. Improved storage properties of the composite led to charge-discharge curves that were more symmetrical than those of pure MoS2. The significant heterostructure of 2D materials is responsible for their remarkable cyclic stability. Supercapacitors with a Cu2O/MoS2/r-GO nanostructure as manufactured are safe for use with batteries. Building 2D and 3D heterostructures to improve energy storage systems of the future is the goal of this endeavor.

A study on the evolution of hydrothermally synthesized MoS2 on thermal annealing and development of novel MoS2-MoO3 hybrid nanostructure for supercapacitor applications

The electrochemical capacitor also known as supercapacitor is a high-performance energy storage device with exceptional properties. We report the evolution of structural, morphological, optical, and thermal properties of MoS2 on thermal annealing along with its supercapacitor study. The pristine MoS2 is synthesized via the hydrothermal method at 200°C and the material is annealed in the presence of air at 250°C, 300°C, and 350°C. The 300°C annealed sample has shown a hybrid MoO3-xMoS2-y phase characterized by morphology of mixed flower-like and nano brick-like structures, marking the first time report of this novel formation. The evolution of the novel MoO3-xMoS2-y phase can be attributed to the intervention of lattice and interstitial oxygen species during synthesis. Electrochemical analysis is employed to study the supercapacitor nature of the materials. The electrochemical study revealed that the hybrid structure has a higher charge storage capacity than MoS2 or MoO3. The calculated specific capacitance from the galvanostatic charge-discharge curve of MoO3-xMoS2-y in 0.1M NaOH is observed to be 1.71mF/cm2, five times greater than other samples. Furthermore, the capacitor behavior of MoO3-xMoS2-y is studied in different electrolytes such as KOH, NaOH, and Na2SO4 at a concentration of 3M. The intercalation-assisted faradaic process is observed to be the major charge storage mechanism of the hybrid structure. Developing novel nanostructures with distinct properties is crucial for advancing supercapacitors to achieve optimal performance.

LaMnO3-Mn3O4 nanocomposite: Synergetic effect towards high electrochemical performance

Metal oxides have been a focus of research for energy storage devices. Herein, xLaMnO3 – (100-x) Mn3O4 (LMO-MO) composites (xwt%: 100, 90, 70, and 50) were prepared via one-pot synthesis to elucidate the synergistic effect of the composite constituents on composite’s electrochemical performance. The X-ray diffraction analysis confirmed the presence of individual compounds in the desired ratio and phase. The X-ray photoelectron spectroscopy confirmed the presence of Mn2+ and Mn3+ oxidation states, indicating the presence of both LaMnO3 (LMO) and Mn3O4 (MO) in the composite. The electrochemical performance of composite electrodes prepared using nickel foam was assessed in 1 and 6 M KOH solutions. High specific capacitance measured via cyclic voltammetry of ∼ 770 Fg−1 at a scan rate of 1 mVs−1 was recorded for the composite of LMO-MO (70 %: 30 %) in 6 M KOH. At the same time, charge-discharge curves revealed a maximum specific capacitance of around 405 Fg−1 for an x =70 % sample at a current density of 0.5 Ag−1. The EIS studies show a reduction in the internal resistance of the composite due to the interconnected structure and reversible faradic process at the interface with a high degree of Coulombic efficiency. A higher overall electrochemical performance of the electrode was recorded in a 6 M KOH electrolyte. The enhanced electrochemical performance of the composite is attributed to efficient charge transfer kinetics through the electrode-electrolyte interface via easy electron hopping pathways between LMO and MO in the composite. These findings suggest that the studied LMO-MO composites could be a potential material for pseudocapacitor energy devices.

Synthesis and electrochemical performance of CeO2/NiS nanocomposite for enhanced asymmetric supercapacitor device applications

A novel CeO2/NiS nanocomposite, combining the advantageous properties of transition metal sulfides (high conductivity) and rare-earth metal oxides (excellent stability), was successfully synthesized using a simple hydrothermal method. This composite leverage synergistic effects to potentially achieve superior electrochemical performance in supercapacitor applications. To evaluate its suitability for supercapacitors, the electrochemical performance of the CeO2/NiS electrode was comprehensively investigated using a series of techniques, including cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) curves, electrochemical impedance spectroscopy (EIS), and cyclic stability analysis. The results demonstrate that the as-prepared CeO2/NiS electrode exhibits significantly improved supercapacitor performance compared to the bare CeO2 electrode. The CV curves of the CeO2/NiS electrode reveal a high specific capacitance of 825.53 F/g at a low scan rate of 5 mV/s, indicating good charge storage capability. Further insights into the charge storage mechanism were obtained using the Trasatti method. This analysis revealed that the total stored capacitance of the CeO₂/NiS electrode is 1250 F/g, with contributions from both outer surface capacitance (94 F/g) and inner diffusion capacitance (1156 F/g). Notably, the dominant contribution (92.5 %) originates from capacitive processes, highlighting the efficient charge storage at the electrode surface. The CeO2/NiS electrode also demonstrates exceptional rate capability, delivering a specific capacitance (Csp) of 710 F/g at a high current density of 1 A/g. Additionally, it exhibits impressive cycling stability, retaining approximately 96.56 % of its initial capacitance even after undergoing 3000 continuous GCD cycles at a high current density of 10 A/g. These results suggest that the CeO2/NiS composite can maintain its performance during extended charge-discharge cycles, a crucial characteristic for practical supercapacitor applications. Finally, an asymmetric supercapacitor device was fabricated using the CeO2/NiS nanocomposite. This device achieved a specific capacitance of 157 F/g, demonstrating the potential of the CeO2/NiS composite for practical energy storage applications.

Date Seed-Derived Supercapacitor Electrodes in Aqueous Electrolyte: Unveiling High Capacity and Coulombic Efficiency

Date seeds, often considered byproducts of date fruit processing, represent a significant bio-waste stream. Despite their abundance, these seeds are underutilized and typically regarded as agricultural waste. Rich in carbon content, date seeds have the inherent potential to serve as precursors for hard carbon electrodes in supercapacitors. Free-standing electrodes were fabricated to enhance cyclic stability and improve Coulombic efficiency, showcasing superior electrochemical performance. The activation process with a 1:3 KOH-to-bio-char ratio yielded a specific capacitance of 204 F/g at 0.2A/g for the symmetric cell with an energy density of 6.5 Wh/kg and a power density of 47.70 W/kg, highlighting the effectiveness of this approach in advancing both structural integrity and electrochemical attributes. To elucidate the electrochemical performance of KOH-activated hard carbon, BET analysis, Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), and Raman Spectroscopy were employed. BET analyses revealed a higher surface area for the hard carbon activated with a 1:3 KOH ratio. This enhancement in structural integrity was further corroborated by cyclic voltammetry (CV) and charge-discharge curves, emphasizing the favorable electrochemical attributes of the proposed method. While previous investigations into date seed supercapacitors revealed promising results, achieving near 100% Coulombic efficiency remained challenging. In this study, the implementation of free-standing electrodes marked a significant advancement, resulting in a remarkable Coulombic efficiency of 99.97%. This nuanced approach underscores the effectiveness of our methodology in addressing and improving the Coulombic efficiency of date seed-derived supercapacitors.

(Digital Presentation) Experimental Techniques for Parameterization of a Commercial 21700 Lithium-Ion Cell for Multiscale Battery Models

Lithium-ion batteries have gained huge attention in the past few decades. Since its commercialization, a steady improvement in cost, and performance over the last 25 years has surfaced many new applications such as EV, HEV, etc., and growing popularity for military and aerospace applications [1, 2]. However, developing a safer, longer life, high energy, power-dense, and cheaper Lithium-ion battery requires a concerted research effort from various disciplines. For a long time, research was focused on developing the chemistry, but in the recent past, the improvement in the battery performance has been realized by reengineering the manufacturing processes and model innovation that help to understand the battery performance during the charging-discharging process. Battery models employed to optimize and predict battery performance are useful tools to design and manage batteries to ensure safe and efficient utilization. To understand the underlying physical, chemical, and electrochemical properties and precisely capture the cell dynamics in EVs application, the model should be based on fundamental governing equations of diffusion and migration processes as well as the kinetics of species intercalation.The physicochemical model requires precisely evaluated model parameters for the materials under consideration. Accurately measured kinetics and transport parameters will hold the key to deriving reliable conclusions about the internal state of a Lithium-ion battery. Parameter’s quantification is a challenging and time-consuming process that requires a range of characterization and analytical methods as shown in Figure. The battery modelling community usually borrowed the parameters list from the literature, with their origins not essentially being traced [3]. In literature, parameterizations have been reported for both high-energy and high-power cells for a physicochemical model [4-7]. This work employed several characterization techniques to parametrize a commercial Lithium-ion cell model. Also, various analytical methods were employed to determine the geometrical, chemical, and electrode microstructure as suggested in Figure. To determine the thermodynamic, kinetics, and transport properties of the extracted electrode materials different electrochemical tests, e.g., galvanostatic intermittent titration technique (GITT), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), constant current constant voltage (CC-CV) charge and constant current (CC) discharge were employed. The parameter’s accuracy would be investigated by validating the mathematical modelling simulation results with the experimental charge-discharge curves at different currents of the commercial 21700 cell at room temperature.

Evaluation of the effect of hydrogen evolution reaction on the performance of all-vanadium redox flow batteries

The exceptional advantages of vanadium redox flow batteries (VRFBs) have garnered significant attention, establishing them as the preferred choice for large-scale and long-term energy storage solutions. However, side reactions such as hydrogen evolution reaction (HER) lead to suboptimal performance of VRFB parameters, resulting in an overall decrease in VRFB performance. Therefore, it is imperative to investigate the mechanism by which HER affects VRFB performance and identify effective methods to mitigate its impact. In light of this, critical parameters such as charge-discharge curve, internal resistance, pressure-drop, pump power consumption, efficiency, and capacity retention rate are selected to evaluate the impact of HER on VRFB performance. Experimental results demonstrate that HER causes an increases in voltage during charging and a decrease during discharging stages leading to voltage loss; additionally, bubble generation significantly increases pressure drop and pump power consumption; furthermore, blockage of flow channels and electrodes due to bubbles leads to an increase in ohmic resistance. Finally, HER has a substantial impact on efficiency and capacity with an average energy efficiency of 2.92 %. After 60 cycles, the capacity retention rate decreased by nearly 7.69 %.

Synthesis of Poly‐Pyrrole Nanotubes/Chromium Vanadate Composite as Wired Interlocks to Achieve an Asymmetric Supercapacitor Device with Scaled Electrochemical Energy Parameters

AbstractHerein, a novel combination with a focused morphology is designed after synthesizing CrVO4 (CV) nanoparticles and poly‐pyrrole nanotubes (PNT or P) to prepare the interlocks of the composites of PNT and CrVO4 as 1PCV1, 1PCV2, 2PCV1, and 2PCV2 to study the supercapacitor application. Structural and spectral characterizations are perpetuated to confirm the synthesis of the samples. Results furnishing best energy storage are obtained for the intercalated composite 2PCV1 examined for three‐probe and two‐probe set‐up. The excel values for specific capacitance (Cs) for 2PCV1 concerning the Cyclic voltammetry (CV) cycle and Galvanostatic Charge Discharge (GCD) curve are 1745.60 F g−1 at 10 mV s−1 rate and 1545.62 F g−1 at 0.625 A g−1 current density studied along with interface controlled and transport‐controlled Cs with a contribution of 55.13% interface part and 44.87% transport part at 5 mV s−1 scan rate. Electrochemical Impedance Spectroscopy (EIS) study has provided 0.86 n‐factor with solution resistance Rs of 1.48 Ω, and a charge transfer resistance of 0.166 Ω. The respective specific power and specific energy values obtained through the two‐probe set‐up are also interestingly high 416.68 W kg−1 and 45.14 Wh kg−1 at 0.83 A g−1 current density. Also, the retention % in Cs values is studied by running 5000 continuous voltammetric cycles with 96.23% retention in supercapacitor device.

Novel promising aqueous electrolytes for manganese dioxide/stainless steel pseudocapacitor electrode

Manganese dioxide (MnO2) films are developed by potentiostatic electrodeposition on a stainless steel sheet as a current collector using manganese acetate tetrahydrate solution at a concentration of 0.25 mol L−1. The deposited sample layer is found to be amorphous as confirmed by the scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses. The capacitive property of the prepared electrodes is characterized by charging/discharging, cyclic voltammetry, and electrochemical impedance spectroscopy techniques in four different aqueous solutions; sodium sulfate, magnesium acetate, nickel acetate, and a mixture of sodium chloride + sodium bicarbonate + borax. Charge–discharge curves reveal higher specific capacitance (Cs) of 1580 F g−1 at 0.5 mA cm−2 for the investigated MnO2 film which is characterized in Ni acetate aqueous solution. The structural, morphological, and electrochemical properties of the electrodeposited manganese oxide films are also studied. The results indicate that the specific capacitance of the deposited samples showed a strong dependency on the electrolyte aqueous solutions, resulting in developing new electrolytes which is a top priority effort in comparison to seeking new electrode materials. It is found that the matching between the pore size structure of the electrode and the ion size of the electrolyte is of great importance for the improved capacity of prepared capacitors.

Synthesis and characterization of C@CdS core-shell structures for high-performance capacitors

The present study investigates the synthesis and characterization of carbon@cadium sulphide (C@CdS) core-shell nanostructures for their potential application in electrochemical double-layer (ECDL) capacitors. Two distinct synthesis methods, hydrothermal route and co-precipitation method, were employed to fabricate C@CdS materials, each resulting in unique morphology and growth mechanisms. Detailed microstructural analyses, including high-resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD), revealed nanosheets in co-precipitated sample (CCSP) and core-shell structures in hydrothermally synthesized sample (CCSA). Optical investigations using UV-Vis spectroscopy provided insights into the absorbance properties of the synthesized materials. Electrical characterization, including frequency response testing and impedance analysis, demonstrated distinct capacitive behaviours for CCSP and CCSA, highlighting their potential for use in energy storage applications. Electrical characterization, including frequency response testing, impedance analysis, and galvanostatic charge-discharge (GCD) curve analysis, demonstrated distinct capacitive behaviours for CCSP and CCSA, highlighting their potential for use in energy storage applications. The integration of optical, structural, and electrical analyses provides a comprehensive understanding of the synthesized C@CdS core-shell nanostructures, offering insights into their potential application for ECDL capacitor technology and other emerging energy storage applications. Further optimization of synthesis parameters and exploration of scalable production methods are suggested for future research endeavors.

Poly(ethylene‐thiosuccinate)/carbon allotrope/cubic nickel‐cobalt hexacyanoferrate nanoparticles nanocomposites as supercapacitor materials

AbstractThis paper reports the synthesis of poly(ethylene‐thiosuccinate) (PETS) using succinic anhydride and 1,2‐ethanedithiol monomers and investigates its electrochemical behavior as supercapacitor electrode material. The synthesized polymer's structure is designed so that to contain sulfur atoms in the main chain of polymer, as the sulfur containing polymers are among the interesting active compounds for fabricating of novel devices for energy storage with wider voltage window and increase the energy density. The cyclic voltammetry (CV) graphs show the supercapacitor behavior of the materials with the faradic charge storage mechanism. The triangular shape of the charge–discharge curves indicate the reversible performance of the PETS as an electrode material. To enhance the supercapacitive action of PETS, its nanocomposites including PETS/Norit (1:1), PETS/MWCNT (1:1) and PTES/MWCNT (1:1)/(1.5%, 3% and 5%) Ni2CoHCF (nickel‐cobalt hexacyanoferrate) is prepared. The results indicate that the PETS/MWCNT/0.15% Ni2CoHCF nanocomposite exhibits a specific capacity which is 7 times higher than that of the PETS/MWCNT (1:1) nanocomposite, when the current density is 0.05 mA.cm−2. Also, according to the Nyquist diagrams, by incorporating of 1.5% of Ni2CoHCF in the PETS/MWCNT (1:1) nanocomposite, its electrical resistance decreases significantly by about two times.Highlights Poly(ethylene‐thiosuccinate) (PETS) made by succinic anhydride & ethanedithiol PETS/Norit or MWCNT/cubic Ni2CoHCF nanoparticles composites are prepared PETS/MWCNT composites as supercapacitor materials by Faradic storage mechanism PETS/1.5% Ni2CoHCF showed 0.0449 mF.cm−2 specific capacity at 0.01 mA.cm−2

The capacity degradation path prediction for the prismatic lithium-ion batteries based on the multi-features extraction with SGPR

Accurate capacity degradation path estimation of lithium-ion batteries plays a crucial role in ensuring the safety and reliability of electric vehicles. In recent years, the evolution of the status of health (SOH) prediction with machine learning techniques has become a research hotspot because of its powerful computing power and robustness. Thus, this study employes the sparse gaussian process regression (SGPR) data-driven approach with multi-features extracted from the battery cycling processes to project the potential degradation patterns of the lithium-ion batteries. Firstly, a battery life test platform was built. The accelerated life aging tests of batteries at different temperatures (25 °C, or 60 °C) and different discharge rates (1C, or 2C) were conducted to establish the dataset for the multi-features extraction and training of the SGPR algorithm. Secondly, different battery characteristic features were extracted based on the battery cycle charge-discharge curves. Various order-reduction treatments, i.e., the filter-based, embedding-based, and fusion-based selection algorithms, were performed to suppress the over-fitting and improve the estimate's accuracy. Finally, using the extracted features as inputs, SGPR models are constructed to estimate the degradation path of the battery. With the 50 % training data, the SGPR has a higher estimation accuracy than the regular GPR, and the average maximum absolute errors for the batteries are 2.80 %, 1.22 %, 3.57 %, and 1.83 %, respectively.

Lattice engineering of high-entropy olivine-type lithium metal phosphate as high-voltage cathodes

Engineering of high-entropy cathode materials for lithium-ion batteries has been actively pursued owing to the outstanding conductivity of high-entropy materials benefited from the maximum entropy and unique antisite disordering structure. Olivine lithium metal phosphates such as LiMnPO4 and LiNiPO4 feature high working voltages but low capacities due to their insulation nature. In this work, the synthesis of the high-entropy lithium metal phosphate materials (HELMPs) is realized by combining mechanochemistry with a calcination method. By regulating lattice of HELMPs, the high-entropy Li(Mn0.35Fe0.35Co0.1Mg0.1Ca0.1)PO4 reveals three typical high-voltage plateaus in charge–discharge curves corresponding to the redox of Fe, Mn, and Co in the voltage range of 2.0–4.9 V vs Li+/Li, and a much higher initial capacity than LiMnPO4 (104 vs 15 mAh g−1).

Lithium-Ion Battery Capacity Prediction Method Based on Improved Extreme Learning Machine

Abstract Currently, research and applications in the field of capacity prediction mainly focus on the use and recycling of batteries, encompassing topics such as SOH estimation, RUL prediction, and echelon use. However, there is scant research and application based on capacity prediction in the battery manufacturing process. Measuring capacity in the grading process is an important step in battery production. The traditional capacity acquisition method consumes considerable time and energy. To address the above issues, this study establishes an improved extreme learning machine (ELM) model for predicting battery capacity in the manufacturing process, which can save approximately 45% of energy and time in the grading process. The study involves the extraction of features from the battery charge–discharge curve that can reflect battery capacity performance and subsequent calculation of the grey correlation between these features and capacity. The feature set comprises features with a high correlation with capacity, which are used as inputs for the ELM model. Kernel functions are used to adjust the ELM model, and Bayesian optimization methods are employed to automatically optimize the hyperparameters to improve the capacity prediction performance of the model. The study uses lithium-ion battery data from an actual manufacturing process to test the predictive effect of the model. The mean absolute percentage error of the capacity prediction results is less than 0.2%, and the root-mean-square error is less than 0.3 Ah.

Zn2+ doped Ni3(NO3)2(OH)4 nanoflower spheres for electrochemical applications

In this present work, Ni3(NO3)2(OH)4 doped with Zn2+ ions are prepared by a solvothermal method using Ni(NO3)2·6H2O, Zn(NO3)2·6H2O, C16H33(CH3)3NBr (CTAB) and C2H5OH as raw materials. Characterization methods such as X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) are used to analyze the materials. Cyclic voltammetry (CV) and galvanostatic charge–discharge curves (GCD) are employed to compare the electrochemical performance of materials with different doping amounts. The electrochemical test results show that doping with Zn2+ significantly enhances the poor electrical conductivity of Ni3(NO3)2(OH)4. Electrochemical tests reveal that the doping amount of 0.4 mmol has the best electrochemical performance with a mass-specific capacitance of 1832 F·g−1 at a current density of 1 A·g−1 in the three-electrode system which is much higher than that of undoping sample (771 F·g−1). Additionally, the assembled NiZn-0.4//AC asymmetric supercapacitor device (ASC) has an energy density of 61.9 Wh·kg−1 at a power density of 747.8 W·kg−1. The Coulombic efficiency retention of the ASC device remains at 98 % after 2000 galvanostatic charge–discharge circles, and the specific capacitance retention is 91 % of the initial value. The doping of Zn2+ provides a valuable approach for enhancing the conductivity and specific capacitance of nickel-based supercapacitor electrode materials.

Enhancing the electrochemical and mechanical performance of LiFePO4 cathode material by ternary doping of Mn, Ti, and N

This study employs a first-principles approach based on density functional theory to analyze the electrochemical and mechanical properties of LiFePO4 system with Mn, Ti, and N ternary doping. Computational findings reveal a formation energy of −1.98 eV, affirming excellent stability. Doping generates impurity bands, reducing the bandgap to 1.21 eV and enhancing conductivity. Doping significantly improves Li-ion diffusion, increasing the coefficient by 6 orders of magnitude and reducing the energy barrier by 0.35 eV. Moreover, Ti doping induces favorable local structural changes and enhances Li-ion diffusion. Mechanical performance calculations indicate improved stability, toughness, and isotropy. Ternary doping raises de-lithiation voltage, optimizing charge–discharge curves without compromising the capacity of LiFePO4, enhancing electrochemical performance.

Cobalt sulfide flower-like derived from metal organic frameworks on nickel foam as an electrode for fabrication of asymmetric supercapacitors

Metal–organic frameworks, as a kind of advanced nanoporous materials with metal centers and organic linkers, have been applied as promising electrode materials in energy storage devices. In this study, we are successfully prepared cobalt sulfide nanosheets (CoS) derived from the metal–organic framework on nickel foam (NF). The prepared electrodes are characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller and Barrett-Joyner-Halenda and electrochemical methods like voltammetry, galvanostatic charge–discharge curve and electrochemical impedance spectroscopy. The CoS/NF electrode demonstrates a high specific capacity of 377.5 mA h g−1 (1359 C g−1) at the current density of 2 A g−1, considerable rate performance and excellent durability (89.4% after 4000 cycles). A hybrid supercapacitor is assembled using CoS/NF as the positive electrode and activated carbon as the negative electrode, it shows a high energy density of 57.4 W h kg−1 at a power density of 405.2 W kg−1. The electrochemical results suggest that the CoS nanosheet arrays would possess excellent potential for applications in energy storage devices.

A novel approach for facile synthesis of cost-optimal catalyst for high-performance lithium-air battery

We have developed a novel and efficient cathode for advanced lithium-air batteries by employing a new approach and facile strategy. In this method, we prepared core-shell structured ZIF-8@ZIF-67 crystals with epitaxial growth using a hydrothermal technique. By subjecting these crystals to carbonization at a temperature 200 °C higher than the degradation initiation temperature (i.e. 600 °C according to thermogravimetric results), we successfully obtained functionalized nanoporous hybrid carbon materials. These hybrid carbon materials consist of hierarchical nitrogen-doped carbon @ cobalt anchored/nitrogen doped carbon (NC@CNC), where the nitrogen-doped carbon (NC) serves as the core and the cobalt anchored/nitrogen doped carbon (CNC) forms the shell. It is worth noting that electrochemical characterization data strongly support the superior performance of this nanoporous hybrid carbon material. It combines the advantageous properties of individual mesopores of nitrogen-doped carbon and the catalytic activity of cobalt‑nitrogen doped carbon. In particular, the cathode material, i.e. NC@CNC, exhibits a remarkable specific capacitance of 10,000 mAh·g−1, as calculated from the galvanostatic charge-discharge curves obtained at a current density of 50 mA·g−1. This impressive performance highlights the potential of our developed material in enhancing the efficiency and overall performance of lithium-air batteries.

Capacitive tendency concept alongside supervised machine-learning toward classifying electrochemical behavior of battery and pseudocapacitor materials

In recent decades, more than 100,000 scientific articles have been devoted to the development of electrode materials for supercapacitors and batteries. However, there is still intense debate surrounding the criteria for determining the electrochemical behavior involved in Faradaic reactions, as the issue is often complicated by the electrochemical signals produced by various electrode materials and their different physicochemical properties. The difficulty lies in the inability to determine which electrode type (battery vs. pseudocapacitor) these materials belong to via simple binary classification. To overcome this difficulty, we apply supervised machine learning for image classification to electrochemical shape analysis (over 5500 Cyclic Voltammetry curves and 2900 Galvanostatic Charge-Discharge curves), with the predicted confidence percentage reflecting the shape trend of the curve and thus defined as a manufacturer. It’s called “capacitive tendency”. This predictor not only transcends the limitations of human-based classification but also provides statistical trends regarding electrochemical behavior. Of note, and of particular importance to the electrochemical energy storage community, which publishes over a hundred articles per week, we have created an online tool to easily categorize their data.