Cathode Material For Secondary Batteries Research Articles

Microstructure regulation of WxV1-xO2(B) nanorods with improved electrochemical properties

VO2(B) is regarded as a highly promising cathode material for secondary batteries due to its outstanding theoretical specific capacity and unique expansion tunnel structure, which facilitates reversible insertion and extraction of metal ions. Nonetheless, inherent structural instability, suboptimal ion/electron transport, and constrained capacity resulting from low redox potentials pose challenges to its wider adoption. Hence, in this paper, we proposed a strategy for synthesizing gradient concentration-doped WxV1-xO2(B) nanorods via a one-step hydrothermal method to solve the above problems. The experimental results demonstrated that as the W ion content increased, all fabricated WxV1-xO2(B) nanorods exhibited a monoclinic crystal phase along with noticeable lattice distortion. The positron annihilation lifetime spectra indicated that vacancy clusters were the predominant defect types in WxV1-xO2(B) nanorods. The synergistic effects of grain sizes and vacancy defects contributed to the superior electrochemical performance observed in the W0.01V0.99O2(B) sample. The capacitor retention reached 88.76 % at 0.10 A/g after 1000 charge/discharge cycles. These results had provided experimental foundation for improving electrochemical properties of WxV1-xO2(B) in metal ion secondary batteries.

Facile Preparation of Three-Dimensional Cubic MnSe2/CNTs and Their Application in Aqueous Copper Ion Batteries.

Transition metal sulfide compounds with high theoretical specific capacity and excellent electronic conductivity that can be used as cathode materials for secondary batteries attract great research interest in the field of electrochemical energy storage. Among these materials, MnSe2 garners significant interest from researchers due to its unique three-dimensional cubic structure and inherent stability. However, according to the relevant literature, the performance and cycle life of MnSe2 are not yet satisfactory. To address this issue, we synthesize MnSe2/CNTs composites via a straightforward hydrothermal method. MnSO4·H2O, Se, and N2H4·H2O are used as reactants, and CNTs are incorporated during the stirring process. The experimental outcomes indicate that the fabricated electrode demonstrates an initial discharge specific capacity that reaches 621 mAh g-1 at a current density of 0.1 A g-1. Moreover, it exhibits excellent rate capability, delivering a discharge specific capacity of 476 mAh g-1 at 10 A g-1. The electrode is able to maintain a high discharge specific capacity of 545 mAh g-1 after cycling for 1000 times at a current density of 2 A g-1. The exceptional electrochemical performance of the MnSe2/CNTs composites can be ascribed to their three-dimensional cubic architecture and the 3D CNT network. This research aids in the progression of aqueous Cu-ion cathode materials with significant potential, offering a viable route for their advancement.

A general methodology for the in situ construction of MxSy@N,S-C composites from L-cysteine for sodium-ion battery applications

High-capacity metal sulfides have been extensively investigated as cathode materials for secondary batteries. Despite their high capacity, the redox potential of metal sulfides is limited to 2.7 V. Therefore, researchers explored its application as a negative electrode material and discovered its exceptional electrochemical performance. However, the conventional methods for synthesizing transition metal sulfides (TMS) inevitably require an external source of sulfur for secondary sulfidation, resulting in energy dissipation. In this study, L-cystine was adopted as a polydentate ligand for the synthesis of MxSy@N, SC metal-organic frameworks, which can confine the desired carbon, nitrogen, and sulfur sources within the framework. This approach facilitates one-step sintering to obtain nitrogen-doped transition metal sulfides. The structure composition and electrochemical reaction mechanism of FeS@N,S-C as the negative electrode in Na-ion batteries were studied through scanning electron microscopy (SEM)/transmission electron microscopy (TEM) and X-ray diffraction (XRD)/X-ray photoelectron spectroscopy (XPS) analysis. The electrochemical properties of FeS@N,S-C materials were test as an example. The FeS@N, SC composite exhibited a reversible Na+ storage capacity of 724.4 mAh g−1 at a current density of 200 mA g−1, and still maintained a reversible capacity of 600.7 mAh g−1 at a current density of 2000 mA g−1, demonstrating excellent rate performance. After 200 cycles, the material was still able to retain 97.3 % of the discharge specific capacity, demonstrating fine cycle performance. It shows that the FeS@N, SC composite has rapid electron conduction ability and high sodium ion diffusion coefficient. At the same time, a rapidly charge-discharge process can be achieved with a large capacitive contribution, indicating the great potential of this material as a sodium-ion battery.

Pd quantum dots supported on rhombic dodecahedral porous carbons connected by CNTs as multifunctional electrocatalysts for Li–S batteries

Lithium sulfide (Li2S) is considered as one of the promising cathode materials for secondary batteries owing to its high lithium storage capacity and low–cost advantage of sulfur. However, the commercial application of Li2S is hindered by the sluggish reaction kinetics of electrochemical conversion from Li2S to S and the shuttle effect of their soluble lithium polysulfides (LiPSs). Herein, we report a multifunctional electrocatalyst composed of 5.9 wt% Pd quantum dots supported on rhombic dodecahedral porous carbons connected by CNTs (Pd@RDPC–CNT) to improve the electrochemical reaction kinetics of Li2S and to alleviate the shuttle effect of LiPSs. The Pd@RDPC–CNT/Li2S nanocomposite exhibits a low first activation barrier of 2.56 V and fast reaction kinetics with a high reversible capacity of 1119 mAh g−1 at 0.2 A g−1, very close to the theoretical capacity of 1166 mAh g−1. The superior electrochemical performance including high reversible capacity, good rate capability and long–term cycling stability over 1000 cycles can be attributed to the multifunctional electrocatalyst of Pd@RDPC–CNT with high catalytic activation, strong LiPSs adsorption and high electronic/ionic conductivity, which is demonstrated by our experimental results and DFT calculation results. This study provides a way to apply Li2S to secondary batteries by using multifunctional electrocatalysts.

Research progress in cathode materials of secondary batteries with high specific energy based on anionic charge compensation mechanism

Research progress in cathode materials of secondary batteries with high specific energy based on anionic charge compensation mechanism

The State of Affairs of ‘Rare Metal Industry’ in Korea

This paper provides an in-depth exploration of the rare metal industry in Korea, examining its definition, classification, supply and demand dynamics, international trade conflicts, and the government's strategic initiatives. The research underscores the global significance of rare metals, the challenges posed by their uneven distribution, and the imperative for countries, including Korea, to address these challenges strategically. The paper also delves into Korea's recent legal and policy frameworks, emphasizing the role of the Korea Institute of Industrial Technology (KITECH) in fostering the rare metal industry. Furthermore, it discusses the current state of Korea's rare metal industry, highlighting key areas such as rare earth metals for electric vehicles, refractory metals for semiconductors/displays, and cathode materials for secondary batteries. The concluding section emphasizes the need for technological advancements, recycling, and refining to establish a circular rare metal industrial economy.

Photocatalytic and Cathode Active Abilities of Ni-Substituted α-FeOOH Nanoparticles.

The present study investigates the relationship between the local structure, photocatalytic ability, and cathode performances in sodium-ion batteries (SIBs) and lithium-ion batteries (LIBs) using Ni-substituted goethite nanoparticles (NixFe1-xOOH NPs) with a range of 'x' values from 0 to 0.5. The structural characterization was performed applying various techniques, including X-ray diffractometry (XRD); thermogravimetry differential thermal analysis (TG-DTA); Fourier transform infrared spectroscopy (FT-IR); X-ray absorption spectroscopy (XANES/EXAFS), both measured at room temperature (RT); 57Fe Mössbauer spectroscopy recorded at RT and low temperatures (LT) from 20 K to 300 K; Brunauer-Emmett-Teller surface area measurement (BET), and diffuse reflectance spectroscopy (DRS). In addition, the electrical properties of NixFe1-xOOH NPs were evaluated by solid-state impedance spectroscopy (SS-IS). XRD showed the presence of goethite as the only crystalline phase in prepared samples with x ≤ 0.20, and goethite and α-Ni(OH)2 in the samples with x > 0.20. The sample with x = 0.10 (Ni10) showed the highest photo-Fenton ability with a first-order rate constant value (k) of 15.8 × 10-3 min-1. The 57Fe Mössbauer spectrum of Ni0, measured at RT, displayed a sextet corresponding to goethite, with an isomer shift (δ) of 0.36 mm s-1 and a hyperfine magnetic distribution (Bhf) of 32.95 T. Moreover, the DC conductivity decreased from 5.52 × 10-10 to 5.30 × 10-12 (Ω cm)-1 with 'x' increasing from 0.10 to 0.50. Ni20 showed the highest initial discharge capacity of 223 mAh g-1, attributed to its largest specific surface area of 174.0 m2 g-1. In conclusion, NixFe1-xOOH NPs can be effectively utilized as visible-light-activated catalysts and active cathode materials in secondary batteries.

Effect of Potassium Carbonate Additives on the Properties of Copper Foils Electroplated at High Current Density

The amount and kind of additives in electrolytes play a very important role on the electroplating of Cu foil, which is used as a cathode materials for secondary batteries. As the use of Cu foil increased, various studies on the electroplated Cu foil are urgently needed. We studied surface characteristics and changes in structural properties due to the addition of inhibitors under electroplating conditions with high current density. The surface layer was observed, to analyze the effect of the amount of potassium carbonate as an inhibitor. When the potassium carbonate was added at 5~25 ppm without any other additives, the initial plating voltage was observed to decrease. To uniformly distribute crystals without agglomeration at the initial stage of electroplating, it is reasonable to add potassium carbonate within the range of 20~25 ppm. There was no significant difference in surface roughness and specific resistance due to the amount of potassium carbonate, when the additives were added complexly. There was an increase in the relative strength of the preferred growth orientation of (220) in a group with 20 ppm potassium carbonate, compared to the group with 10 ppm potassium carbonate. The grain size decreased with the amount of potassium carbonate added with other additives. However, there was no significant difference in tensile strength and elongation (p-value: 0.000). To ensure uniform properties with a combination of 4 kinds of additives it is reasonable to add potassium carbonate in the range of 10~20 ppm.

Impact of Structural Flexibility of Amine Moieties as Bridges for Redox-Active Sites on Secondary Battery Performance.

Although environmentally benign organic cathode materials for secondary batteries are in demand, their high solubility in electrolyte solvents hinders broad applicability. In this study, a bridging fragment to link redox-active sites is incorporated into organic complexes with the aim of preventing dissolution in electrolyte systems with no significant performance loss. Evaluation of these complexes using an advanced computational approach reveals that the type of redox-active site (i. e., dicyanide, quinone, or dithione) is a key parameter for determining the intrinsic redox activity of the complexes, with the redox activity decreasing in the order of dithione>quinone>dicyanide. In contrast, the structural integrity is strongly reliant on the bridging style (i. e., amine-based single linkage or diamine-based double linkage). In particular, owing to their rigid anchoring effect, diamine-based double linkages incorporated at dithione sites allow structural integrity to be maintained with no significant decrease in the high thermodynamic performance of dithione sites. These findings provide insights into design directions for insoluble organic cathode materials that can sustain high performance and structural durability during repeated cycling.

Effects of Nickel/Manganese Variation on Na2Mn3–zNizO7 for Sodium-Ion Battery Cathodes

This paper discusses the process of determining the energy density and electronic properties of sodium-ion batteries with nickel doping and the manganese–oxygen combination (Na2Mn3–zNizO7) using the density-functional theory calculation in Quantum Espresso software. These materials were chosen due to their abundance in nature as an alternative to overcome the limitations of lithium materials. Moreover, Na2Mn3–zNizO7 has a similar structure to lithium-based batteries that have been widely used. The Na transfer process and activation energy were simulated, and the voltage and the electronic properties of the material were analyzed using first-principles calculation. This research shows that the material (Na2Mn3–zNizO7) has the potential to be implemented as a cathode material in secondary batteries.

A layered lithium nickel manganese oxide as environmentally friendly cathode material for secondary batteries

<p>Cobalt-free cathode material development is considered necessity to assure the sustainability of Li-ion batteries. Cobalt is always considered expensive and unsafe for both human and environment. LiNi<sub>0.5</sub>Mn<sub>0.5</sub>O<sub>2</sub> (LNMO) is a layer structured cathode material that has similar feature to LiCoO<sub>2</sub> (LCO). A simple and fast processing of LNMO is proposed. A precipitation of nickel manganese oxalate was obtained in a batch reactor under atmospheric condition. The as-obtained homogenous oxalate precursor was converted to LNMO via high temperature lithiation. Based on the XRD result, a crystalline product with layer structure is successfully obtained. The presence of impurities such as residual Li can be detected from the FTIR spectra. SEM Images confirmed quasi-spherical particles with grain size of less than 10 micrometer. The charge-discharge analysis of LNMO containing cell deliver a capacity of 42 mAh/g. In spite of its promising report, continuous improvement is necessary to obtain cell with better electrochemical performance.</p>

Precisely quantifying bulk transition metal valence evolution in conventional battery electrode by inverse partial fluorescence yield

Precisely quantifying transition metal (TM) redox in bulk is a key to understand the fundamental of optimizing cathode materials in secondary batteries. At present, the commonly used methods to probe TM redox are hard X-ray absorption spectroscopy (hXAS) and soft X-ray absorption spectroscopy (sXAS). However, they are both facing challenges to precisely quantify the valence states of some transition metals such as Mn. In this paper, Mn-L iPFY (inverse partial fluorescence yield) spectra extracted from Mn-L mRIXS (mapping of resonant inelastic X-ray scattering) is adopted to quantify Mn valence states. Mn-L iPFY spectra has been considered as a bulk-sensitive, non-distorted probe of TM valence states. However, the exact precision of this method is still unclear in quantifying practical battery electrodes. Herein, a series of LiMn2O4 electrodes with different charge and discharge states are prepared. Based on their electrochemical capacity (generally considered to be very precise), the precision of Mn iPFY in quantifying bulk Mn valence state is confirmed, and the error range is unraveled. Mn-L mRIXS iPFY thus is identified as one of the best methods to quantify the bulk Mn valence state comparing with hXAS and sXAS.

Recent Progress and Prospects of Layered Cathode Materials for Potassium‐ion Batteries

Layered materials with two‐dimensional ion diffusion channels and fast kinetics are attractive as cathode materials for secondary batteries. However, one main challenge in potassium‐ion batteries is the large ion size of K+, along with the strong K+−K+ electrostatic repulsion. This strong interaction results in initial K deficiency, greater voltage slope, and lower specific capacity between set voltage ranges for layered transition metal oxides. In this review, a comprehensive review of the latest advancements in layered cathode materials for potassium‐ion batteries is presented. Except for layered transition metal oxides, some polyanionic compounds, chalcogenides, and organic materials with the layered structure are introduced separately. Furthermore, summary and personal perspectives on future optimization and structural design of layered cathode materials are constructively discussed. We strongly appeal to the further exploration of layered polyanionic compounds and have demonstrated a series of novel layered structures including layered K3V2(PO4)3.

Realizing Ultralong-Term Cyclicability of 5 Volt-Cathode-Material Graphite Flakes by Uniformly Comodified TiO2/Carbon Layer Inducing Stable Cathode-Electrolyte Interphase.

A common issue the high-voltage cathode materials of secondary batteries suffered from is oxidative electrolyte decomposition inducing rapid capacity fading with discharge/charge cycling. Herein, a highly efficient strategy realizing stable cathode-electrolyte interphase (CEI) and ultralong-term cyclicability of 5 volt-cathode-material graphite flakes (GFs) for dual-ion batteries is demonstrated. The TiO2/carbon-comodified GF (TO/GF) cathode material with uniform distribution and tight bonding of the nanosized TiO2/carbon layer on the GF surface is synthesized, in which the GF surface is partitioned into nanodomains by the uniformly distributed TiO2 nanoparticles. Meanwhile, the amorphous carbon layer acts as a gummed tape bonding tightly the TiO2 nanoparticles on the graphite flake surface. Serial electrochemical impedance spectroscopy and structural/chemical analyses demonstrate that these unique structural characteristics of the TiO2/carbon comodification endow the TO/GF cathode material with a stable CEI layer coupled with much reduced electrolyte decomposition. Consequently, extremely high cyclicability of 10,000 stable discharge/charge cycles with an extremely low capacity fading rate of 0.0021% for anion PF6- storage is realized. This efficient strategy has a potential to be extended to other high-voltage cathode materials and further scaled to the industrial level.

Synthesis, Structure, and Electrochemical Properties of Some Cobalt Oxalates.

Transition-metal oxalates have wide applications in magnetics, photoemission, electrochemistry, etc. Herein, using hydrothermal reactions, five cobalt(II) oxalates, Na2Co2(C2O4)3·2H2O (I), Na2Co(C2O4)2·8H2O (II), KLi3Co(C2O4)3 (III), Li4Co(C2O4)3 (IV), and (NH4)2Co2(C2O4)F4 (V) have been synthesized, and their structures are determined from single-crystal X-ray diffraction or Rietveld refinement of powder X-ray diffraction data. Notably, IV and V are identified for the first time. The structures of these cobalt oxalates are versatile, covering 0D, 1D, 2D, and 3D frameworks, while the coordination environments of Co2+ centers are uniquely distorted octahedra. As representative examples, I and III are investigated as cathode materials for secondary batteries. Both exhibited electrochemical activity despite large cell polarization. The present study enriches the transition-metal oxalate family and provides new options for energy storage materials.

Effects of sodium nitrate and heat treatment atmosphere on the synthesis of α–NaFeO2 layered oxide

α-NaFeO2 type layered oxides shows reversible intercalation/de-intercalation of sodium ions between the oxide layers, which is suitable as regenerable CO2 absorber and cathode material for secondary batteries. This paper reports a critical effect of heating atmosphere to synthesize pure α-NaFeO2 from equimolar sodium nitrate and iron oxide. Reaction of NaNO3 with γ-Fe2O3 was much faster in nitrogen than oxygen atmosphere and high-purity α-NaFeO2 was yielded in a few hours of heat treatment in nitrogen while in oxygen atmosphere the reaction was sluggish, resulting in partially sodiated γ-Fe2O3. Inert atmosphere thermodynamically enhances nitrate decomposition, which controls the reaction rate of NaNO3 with γ-Fe2O3, and increases the solubility of γ-Fe2O3 in molten NaNO3 to promote topotactic phase transformation to α-NaFeO2. Molten NaNO3 works as a solvent for ferric ions and a redox buffer for maintaining the lattice oxygen structure and oxidation state of γ-Fe2O3. Larger iron oxide crystal was found to be suitable for production of high-purity α-NaFeO2 in a wide temperature range.

Highly reversible electrochemical reaction of insoluble 3D nanoporous polyquinoneimines with stable cycle and rate performance

Carbonyl compounds have potential for use as cathode materials of secondary batteries because of their large specific capacities, stable redox active centers, high efficiencies and ability to regenerate, however their intrinsic solubilities and low electrical conductivities present challenges to hinder their practical utilization. Here, three-dimensional nanoporous polyquinoneimines (PQ) were synthesized by hydrothermal polymerization reactions, and examined as electrode materials in lithium-ion batteries to solve these problems of solubility and electronic conductivity. The large specific surface area (116.95 m2 g−1) and abundant pore structure (0.2428 cm3 g−1) of the PQ, which were formed by the anisotropic growth of nanosized rose flakes, shortened the lithium-ion diffusion path and reduced lithium solubility. The capacities of the PQ electrodes of 1 mg cm−2 were 228 (1st cycle; theoretical capacity of PQ with 4 electron reaction is 228 mAh g−1) and 103 (1000th) mAh g−1 at 50 mA g−1, and the declined rate per cycle at 200 mA g−1 was only 0.05% (0.077 mAh g−1 per cycle) within the first 1000 cycles. The capacity of the 500th cycle with a high load of 3 mg cm−2 was 123 mAh g−1, exhibiting a coulombic efficiency of 99%. The molecular structure during lithiation was calculated with density functional theory and showed that the robust bridge bond formed and promoted the electrochemical activity of the charge/discharge process.

Recent Approaches for the Direct Use of Elemental Sulfur in the Synthesis and Processing of Advanced Materials

Elemental sulfur is an abundant and inexpensive material obtained as a by-product of natural-gas and petroleum refining operations. Recently, the need for the development of new energy-storage systems brought into light the potential of sulfur as a high-capacity cathode material in secondary batteries. Sulfur-containing materials were also shown to have useful IR optical properties. These developments coupled with growing environmental concerns related to the global production of excess elemental sulfur have led to a keen interest in its utilization as a feedstock in materials applications. This Minireview focuses on the recent developments on physical and chemical methods for directly processing elemental sulfur to produce functional composites and polymers.

Thermal hydrolysis synthesis and characterization of monoclinic metahewettite CaV6O16·3H2O

Monoclinic metahewettite CaV6O16·3H2O has been fabricated via thermal hydrolysis of calcium vanadate (Ca10V6O25). High purity calcium vanadate precipitate, featuring column structure with surface area of 8.61 m2/g, can be obtained by reacting sodium orthovanadate (Na3VO4) with calcium oxide at 90 °C for 2 h. By acidification of calcium vanadate in hot water at pH of 1.0–3.0, the monoclinic metahewettite crystals with uniform particle distribution, layered structure and nonporous structure can be fabricated. With the well crystallized layered structure, CaV6O16·3H2O may be a potential cathode material for secondary batteries as well as super capacitor materials.

Enhancement of Electric Conductivity in Transparent Glass–Ceramic Nanocomposites of Bi2O3–BaTiO3 Glasses

The frequency and temperature dependent electrical conductivity measurements for heat-treated binary glass system with composition of (100–x)Bi2O3–xBaTiO3 (x = 20, 30, 40 and 50, in mol%) were carried out. The glass was prepared by melt quenching technique and their corresponding glass–ceramic nanocomposites were obtained by suitable heat treatment. Nanostructured behavior and electrical properties of these glasses and their corresponding glass–ceramic nanocomposites were studied. X-ray diffraction (XRD) and differential scanning calorimetry confirmed the amorphous nature of the glasses. Moreover, XRD patterns of the samples indicate nanocrystallites embedded in the glass matrix. The Fourier transform infrared spectroscopy (FT-IR) spectral analysis showed that the band positions of glass system are within the wave number range of BiO6, BiO3 and TiO6 structural units. It is observed that the electrical conductivity is enhanced by 102–103 times in the transparent glass–ceramic nanocomposite phase. With further heat treatment, the conductivity decreased considerably in the stage of glass–ceramic nanocomposite phase as compared with the glassy phase sample. Therefore, partially devitrified phase is more suitable as cathode material in secondary batteries compared to its vitreous or fully crystalline counterpart. The conduction mechanism was confirmed to obey the adiabatic small polaron hopping (SPH). AC conductivity measurements were performed as a function of temperature and frequency, showing a very slow increasing rate at low temperatures and then a fast rate at higher temperatures.