Effect of Initial Reactants and Reaction Temperature on Molten Salt Synthesis of CuCo₂O₄ and Its Sustainable Energy Storage Properties

We have prepared CuCo₂O₄ using 0.5 M NaNO₃ and 0.5 M LiNO₃ molten salts at different temperatures (410 and 610 °C) in the air. This was later used as an anode material for LIBs. The morphology, structure, and electrochemical properties of the products were observed using various techniques such as scanning electron microscopy, X-ray diffraction (XRD), Brunauer–Emmett–Teller surface and density method, cyclic voltammetry, and galvanostatic cycling tests. The XRD patterns showed a minor CuO phase in addition to the major CuCo₂O₄ phase in most of the reactant and salt combination. CuCo₂O₄ prepared using copper sulfate and cobalt sulfate at 610 °C and copper sulfate and cobalt acetate at 410 °C showed the best performance with capacities of 848 mAh g^–1 and 882 mAh g^–1 and capacity retentions of 93% and 94%, respectively

Energy Storage Studies on InVO₄ as High Performance Anode Material for Li-Ion Batteries

InVO₄ has attracted much attention as an anode material due to its high theoretical capacity. However, the effect of preparation methods and conditions on morphology and energy storage characteristic has not been extensively investigated and will be explored in this project. InVO₄ anode material was prepared using five different preparation methods: solid state, urea combustion, precipitation, ball-milling, and polymer precursor methods. Morphology and physical properties of InVO₄ were then analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM), and Brunauer–Emmett–Teller (BET) surface area method. XRD patterns showed that orthorhombic phased InVO₄ was synthesized. Small amounts of impurities were observed in methods II, III, and V using XRD patterns. BET surface area ranged from 0.49 to 9.28 m² g^–1. SEM images showed slight differences in the InVO₄ nanosized crystalline structures with respect to preparation methods and conditions. Energy storage studies showed that, among all the preparation methods, the urea combustion method produced the best electrochemical results, with negligible capacity fading between the 2nd and 50th cycles and high capacity of 1241 mA h g^–1 at the end of the 20th cycle, close to the theoretical capacity value. Precipitation method also showed good performance, with capacity fading (14%) and capacity of 1002 mA h g^–1 at the 20th cycle. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) was then used to determine the reaction mechanisms of InVO₄

Maghemite Nanoparticles on Electrospun CNFs Template as Prospective Lithium-Ion Battery Anode

In this work, maghemite (γ-Fe₂O₃) nanoparticles were uniformly coated on carbon nanofibers (CNFs) by a hybrid synthesis procedure combining an electrospinning technique and hydrothermal method. Polyacrylonitrile nanofibers fabricated by the electrospinning technique serve as a robust support for iron oxide precursors during the hydrothermal process and successfully limit the aggregation of nanoparticles at the following carbonization step. The best materials were optimized under a carbonization condition of 600 °C for 12 h. X-ray diffraction and electron microscopy studies confirm the formation of a maghemite structure standing on the surface of CNFs. The average size of γ-Fe₂O₃ nanoparticles is below 100 nm, whereas CNFs are ∼150 nm in diameter. In comparison with aggregated bare iron oxide nanoparticles, the as-prepared carbon–maghemite nanofibers exhibit a higher surface area and greatly improved electrochemical performance (>830 mAh g^–1 at 50 mA g^–1 for 40 cycles and high rate capacity up to 5 A g^–1 in the voltage range of 0.005–3 V vs Li). The greatly enhanced electrochemical performance is attributed to the unique one-dimensional nanostructure and the limited aggregation of nanoparticles

Template Free Facile Molten Synthesis and Energy Storage Studies on MCo₂O₄ (M = Mg, Mn) as Anode for Li-Ion Batteries

Spinel MCo₂O₄ (M = Mg, Mn) materials were synthesized using a template free molten salt method with various precursor salts. Powder X-ray diffraction, Brunauer–Emmett–Teller (BET) surface area analysis, scanning electron microscopy, and transmission electron microscopy were carried out to characterize the phase, structure, and morphology of the compounds. Electrochemical cycling was carried out between voltages 0.005 and 3.0 V was carried out on button cells. At the end of cycling using 60 mA g^–1, MgCo₂O₄ showed reversible capacity of 816 (±5) mAh g^–1 after 50 cycles and MnCo₂O₄ showed a capacity fading of only 4% after 45 cycles retaining a capacity of 863 (±5) mAh g^–1. In addition, cyclic voltammetry and electrochemical impedance spectroscopy were carried out on select cycles to study the electrode kinetics

Li-Cycling Properties of Molten Salt Method Prepared Nano/Submicrometer and Micrometer-Sized CuO for Lithium Batteries

We report the synthesis of CuO material by molten salt method at a temperature range, 280 to 950 °C for 3 h in air. This report includes studies on the effect of morphology, crystal structure and electrochemical properties of CuO prepared at different temperatures. Obtained CuO was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) surface area methods. Samples prepared at ≥410 °C showed a single-phase material with a lattice parameter value of <i>a</i> = 4.69 Å, <i>b</i> = 3.43 Å, <i>c</i> = 5.13 Å and surface area values are in the range 1.0–17.0 m² g^–1. Electrochemical properties were evaluated via cyclic voltammetry (CV) and galvanostatic cycling studies. CV studies showed a minor difference in the peak potentials depending on preparation temperature and all compounds exhibit a main anodic peak at ∼2.45 V and cathodic peaks at ∼0.85 V and ∼1.25 V vs Li. CuO prepared at 750 °C showed high and stable capacity of ∼620 mA h g^–1 at the end of 40th cycle

Impact of Electrical Conductivity on the Electrochemical Performances of Layered Structure Lithium Trivanadate (LiV_3–<i>x</i>M_<i>x</i>O₈, M= Zn/Co/Fe/Sn/Ti/Zr/Nb/Mo, <i>x</i> = 0.01–0.1) as Cathode Materials for Energy Storage

Pristine trivanadate (LiV₃O₈) and doped lithium trivanadate (LiV_3–<i>x</i>M_<i>x</i>O₈, M = Zn/Co/Fe/Sn/Ti/Zr/Nb/Mo, <i>x</i> = 0.01/0.05/0.1 M) compounds were prepared by a simple reflux method in the presence of the polymer, Pluronic P123, as the chelating agent. For comparison, pristine LiV₃O₈ alone was also prepared in the absence of the chelating agent. The Rietveld-refined X-ray diffraction patterns shows all compounds to exist in the layered monoclinic LiV₃O₈ phase belonging to the space group of <i>P</i>2₁/<i>m</i>. Scanning electron microscopy analysis shows the particles to exhibit layers of submicron-sized particles. The electrochemical performances of the coin cells were compared at a current density of 30 mA/g in the voltage window of 2–4 V. The cells made with compounds LiV_2.99Zr_0.01O₈ and LiV_2.95Sn_0.05O₈ show a high discharge capacity of 245 ± 5 mA h/g, with an excellent stability of 98% at the end of the 50th cycle. The second cycle discharge capacity of 398 mA h/g was obtained for the compound LiV_2.99Fe_0.01O₈, and its capacity retention was found to be 58% after 50 cycles. The electrochemical performances of the cells were correlated with the electrical properties and the changes in the structural parameters of the compounds

Mixed Oxides, (Ni_1–<i>x</i>Zn_<i>x</i>)Fe₂O₄ (<i>x</i> = 0, 0.25, 0.5, 0.75, 1): Molten Salt Synthesis, Characterization and Its Lithium-Storage Performance for Lithium Ion Batteries

We prepared solid solutions based on Ni, Zn, and Fe oxides to be used as nanomaterials for anodes of Li-ion batteries. The materials were synthesized using molten salt method with KCl as the molten salt. The prepared nanomaterials (Ni_1–<i>x</i>Zn_<i>x</i>)­Fe₂O₄ (<i>x</i> = 0, 0.25, 0.5, 0.75, 1) were subsequently characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), the Brunauer–Emmett–Teller surface and density methods. Cyclic voltammetry (CV) and galvanostatic cycling tests were then conducted to understand the lithium storage performance of the electrodes. Electrochemical impedance spectroscopy (EIS) was also performed to analyze the kinetics of our electrodes and other characteristics of the battery cell. The electrochemical properties of prepared compounds showed reversible capacities (mAh/g) of 706, 819, 603, 781, 637 for <i>x</i> = 0, 0.25, 0.5, 0.75, and 1 at the end of the 50th cycle

Sustainable Graphenothermal Reduction Chemistry to Obtain MnO Nanonetwork Supported Exfoliated Graphene Oxide Composite and its Electrochemical Characteristics

Exfoliated graphene oxide (EG)/manganese­(II) oxide (MnO) composite powder is synthesized by simple solid state graphenothermal reduction process. Structural, chemical, and morphological studies confirm the formation of EG/MnO composite in which cubic MnO crystallites are found to anchor onto EG surfaces. The as-synthesized EG/MnO composite is constituted with 65 and 35 wt % of MnO and EG, respectively. The EG/MnO composite exhibits a specific surface area of ∼82 m² g^–1 and an average pore size of ∼12 nm. As an anode in lithium-ion batteries, the EG/MnO composite shows a high reversible capacity of 936 mAh g^–1 at a current rate of 75 mA g^–1. Capacity retention of ∼84% (784 mAh g^–1) is observed even at the 100th cycle which corresponds to a Coulombic efficiency of ∼99%. Cyclic voltammetry studies on the composite show that Li storage is owing to reversible conversion reactions of MnO and electrochemical absorption/desorption by EG. Electrochemical impedance spectroscopy studies clearly show easy lithiation kinetics. Owing to the electrochemical performance of EG/MnO composite and its easy, reproducible, and scalable synthesis procedure, it is an excellent addition to this class of similar materials

Electrochemical Analysis of the Carbon-Encapsulated Lithium Iron Phosphate Nanochains and Their High-Temperature Conductivity Profiles

Carbon-encapsulated LiFePO₄ (LFP) nanochains were prepared as a cathode material for lithium batteries by sol–gel method using citric acid as the carbon source. The prepared LFP/C material is characterized by structural, morphological, and electrochemical characterization. LFP/C shows an orthorhombic olivine structure with “<i>Pnma</i>” space group having an average particle size of 50 nm. The uniform distribution of LFP particles coated by the carbon matrix as a nanochain array has been analyzed by scanning electron microscopy and transmission electron microscopy analysis of the sample. The electrochemical performance of the LFP/C nanochain has been analyzed using galvanostatic cycling, cyclic voltammetry, and impedance analysis of the assembled batteries. The sol–gel-derived LFP/C nanochain exhibits better capacity and electrochemical reversibility in line with the literature results. The high-temperature conductivity profile of the sample has been recorded from room temperature to 473 K using impedance analysis of the sample. The transport dynamics have been analyzed using the dielectric and modulus spectra of the sample. A maximum conductivity up to 6.74 × 10^–4 S cm^–1 has been obtained for the samples at higher temperature (448 K). The nucleation and growth at higher temperature act as factors to facilitate the intermediate phase existence in the LiFePO₄ sample in which the phase change that occurs above 400 K gives irreversible electrochemical changes in the LFP/C samples

RGO/Stibnite Nanocomposite as a Dual Anode for Lithium and Sodium Ion Batteries

RGO/Sb₂S₃ nanocomposite has been investigated in this study as a dual anode material for Li- and Na-ion battery applications. The stibnite phase of Sb₂S₃, and its rGO composite have been obtained from a molecular complex, Sb­(SCOPh)₃ or its rGO mixture by solid state decomposition or hydrothermal treatment. The pristine sample consists of micron sized particles with rod-like morphology while the rGO composite is made of nanoparticles of Sb₂S₃ embedded in rGO sheets. Electrochemical lithium and sodium storage properties of the prepared materials have been investigated using galvanostatic cycling, cyclic voltammetry, and electrochemical impedance spectroscopy studies. The rGO composite demonstrates better lithium storage capacity than the pristine sample owing to enhanced conductivity. In addition, the rGO sheets act as a buffer for volume change during lithium/sodium cycling resulting in a better energy storage