Cathode Material For Batteries Research Articles

Sustainable Sulfur-Carbon Hybrids for Efficient Sulfur Redox Conversions in Nanoconfined Spaces.

Nanoconfinement is a promising strategy in chemistry enabling increased reaction rates, enhanced selectivity, and stabilized reactive species. Sulfur's abundance and highly reversible two-electron transfer mechanism have fueled research on sulfur-based electrochemical energy storage. However, the formation of soluble polysulfides, poor reaction kinetics, and low sulfur utilization are current bottlenecks for broader practical application. Herein, a novel strategy is proposed to confine sulfur species in a nanostructured hybrid sulfur-carbon material. A microporous sulfur-rich carbon is produced from sustainable natural precursors via inverse vulcanization and condensation. The material exhibits a unique structure with sulfur anchored to the conductive carbon matrix and physically confined in ultra-micropores. The structure promotes Na+ ion transport through micropores and electron transport through the carbon matrix, while effectively immobilizing sulfur species in the nanoconfined environment, fostering a quasi-solid-state redox reaction with sodium. This translates to ≈99% utilization of the 2e- reduction of sulfur and the highest reported capacity for a room temperature Na-S electrochemical system, with high rate capability, coulombic efficiency, and long-term stability. This study offers an innovative approach toward understanding the key physicochemical properties of sulfurcarbon nanohybrid materials, enabling the development of high-performance cathode materials for room-temperature Na-S batteries with efficient sulfur utilization.

A phase transition coordinated monoclinic Fe-based Prussian blue for high-performance sodium-ion battery cathode

Prussian blue analogs (PBAs) are ideal cathode materials for sodium-ion batteries (SIBs) owing to their cost-effectiveness, good low-temperature performance, and facile synthesis process. Nevertheless, their actual capacity and cycling stability limit practical application. Herein, a new chelating agent, sodium tartrate, is proposed to synthesize high-quality Fe-based Prussian blue (HQ-NFF) with enhanced Na content and a stable structure through chelation effect-assisted co-precipitation. The crystal structure of HQ-NFF undergoes a phase transition to a Na-rich monoclinic phase after full discharge, leading to improved capacity and cycling stability. The HQ-NFF cathode exhibits an ultra-high capacity of 160.8 mAh g−1 and a capacity of 146.1 mAh g−1 at 2 C, with a capacity retention of 75.3 % after 150 cycles. Moreover, a 3D-printed HQ-NFF cathode with an areal loading of 7.88 mg cm−2, delivers a high areal capacity of 0.969 mAh cm−2 and good rate capability.

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.

Ab initio investigation of ZnV2O4, ZnV2S4, and ZnV2Se4 as cathode materials for aqueous zinc-ion batteries

Zinc-ion batteries (ZIBs) employing aqueous electrolytes have emerged as one of the most promising alternatives to lithium-ion batteries (LIBs). Nonetheless, the development of ZIBs is hindered by the scarcity of cathode materials with suitable electrochemical properties. In this work, we investigate the unique properties of zinc vanadate oxide (ZnV2O4, ZVO) and zinc vanadate sulfide (ZnV2S4, ZVS) compounds as cathode materials, focusing on their crystal structures, electrochemical performance, spectroscopic features and potential applications in ZIBs. Additionally, we investigate a new cathode material, zinc vanadate selenide (ZnV2Se4, ZVSe), constructed by replacing sulfur with selenium in the ZVS cubic structure. Our findings reveal that these compounds exhibit distinct electronic and electrochemical properties, although they have similar magnetic properties due to the fact that vanadium has the same oxidation state in all three compounds. On average, ZVS stands out as the most promising candidate for ZIBs cathodes, followed by ZVO. ZVSe, shows lower electrochemical performance and also has the obvious drawback of being more costly than the sulfur- and oxygen-based compounds. Our theoretical results align closely with available experimental data, both for electrochemical properties as well as x-ray and photoelectron spectroscopy, where a comparison can be made.

Sulfur-doped enhanced ZnMn2O4 spinel for high-capacity zinc-ion batteries: Facilitating charge transfer

ZnMn2O4 spinel is considered a promising cathode material for zinc-ion batteries due to its superior Zn2+ storage capability. However, the widespread utilization of ZnMn2O4 spinel as a high-capacity cathode material is impeded by its insufficient electrical conductivity. To tackle this limitation, we have employed a sulfur doping approach by substituting sulfur for oxygen atoms within the ZnMn2O4 lattice structure. After theoretical calculation, the charge exchange between metal Zn/Mn and surrounding coordinated atoms is enhanced after sulfur doping. The sulfur-doped ZnMn2O4 spinel effectively enhances the electrical conductivity, improving its electrochemical discharge capacity. Furthermore, the results reveals that a doping level of 20 % provided the greatest enhancement in capacitance, achieving a specific capacity of 220.1 mAh/g. This work improves the disadvantages of ZnMn2O4 at the atomic level and can provide ideas for the optimization and modification of spinel cathode materials.

Entropy-Stabilized Multication Fluorides as a Conversion-Type Cathode for Li-Ion Batteries-Impact of Element Selection.

Metal fluorides (e.g., FeF2 and FeF3) have received attention as conversion-type cathode materials for Li-ion batteries due to their higher theoretical capacity compared to that of common intercalation materials. However, their practical use has been hindered by low round-trip efficiency, voltage hysteresis, and capacity fading. Cation substitution has been proposed to address these challenges, and recent advancements in battery performance involve the introduction of entropy stabilization in an attempt to facilitate reversible conversion reactions by increasing configurational entropy. Building on this concept, high entropy fluorides with five cations were synthesized by using a simple mechanochemical route. In order to examine the impact of element selection, Co0.2Cu0.2Ni0.2Zn0.2Fe0.2F2 (HEF-Fe) was compared with Co0.2Cu0.2Ni0.2Zn0.2Mg0.2F2 (HEF-Mg), replacing electrochemically inactive Mg with Fe as an active participant in the conversion reaction. Combining electrochemical measurements with first-principles calculations, high-resolution electron microscopy, and synchrotron X-ray analysis, HEFs' battery performances and conversion reaction mechanisms were investigated in detail. The results highlighted that replacement of Mg with Fe was beneficial, with enhanced capacity, rate capability, and surface stability. In addition, it was found that HEF-Fe showed similar cycle stability without an electrochemically inactive element. These findings provide valuable insights for the design of high entropy multielement fluorides for improved Li-ion battery performance.

A facile self-saturation process enabling the stable cycling of a small molecule menaquinone cathode in aqueous zinc batteries.

Small quinone molecules are promising cathode materials for aqueous zinc batteries. However, they experience fast capacity decay due to dissolution in electrolytes. Herein, we introduce a simple methyl group to a naphthoquinone (NQ) cathode and demonstrate a facile self-saturation strategy. The methyl group exhibits hydrophobic properties together with light weight and a weak electron-donation effect, which allows a good balance among cycling stability, capacity and voltage for cathode materials. The resulting menadione (Me-NQ) presents around one-third solubility of NQ. The former thus rapidly reaches saturation in the electrolyte during cycling, which suppresses subsequent dissolution. Thanks to this process, the Me-NQ cathode preserves 146 mA h g-1 capacity after 3500 cycles at 5 A g-1, far exceeding 88 mA h g-1 for NQ. Me-NQ also delivers a stabilized capacity of 316 mA h g-1 at 0.1 A g-1 with only 0.05 V lower average redox voltage than NQ. The co-storage of Zn2+ and H+ with the redox reactions on the carbonyl sites of Me-NQ is revealed.

Pr6O11 modification effectively enhancing sodium storage for Na3V2(PO4)3 batteries

Na3V2(PO4)3 (NVP) is one of the most promising cathode materials for sodium-ion batteries (SIBs) due to its robust three-dimensional framework, high tunability, and relatively high Na+ intercalation potentials. However, its utility is generally constrained by low conductivity, inefficient charge transfer, and subpar interface kinetics. This work presents an efficient and simple method to address these issues. We innovatively modified the NVP surface with Pr6O11 nanoparticles, a negative temperature coefficient (NTC) thermosensitive material, to enhance interface compatibility with electrolytes and improve conductivity. This modification significantly enhances the overall sodium-ion storage performance. Specifically, the optimized NVP-2 %Pr6O11 electrode exhibits excellent electrochemical properties with the aid of an optimized conductivity network compared to the unmodified NVP. Cycled at an 8C current density, the NVP-2 %Pr6O11 electrode achieves high specific capacities of 102.6 mAh·g−1 at 27 °C and 95.6 mAh·g−1 at 45 °C. After 1000 cycles, the capacity retention rates are 81.18 % and 78.97 %, respectively, significantly higher than the 20.59 % and 14.99 % of pure NVP. In coin full-battery testing, the NVP-2 %Pr6O11 electrode retains 89.76 % capacity after 500 cycles at 8C. In addition, the assembled The NVP-2 %Pr6O11//HC pouch full battery exhibits better sodium-ion storage and thermal safety performance compared to the NVP-SP//HC battery. This simple modification strategy provides an effective insight into the application of NVP electrodes in energy storage.

Fabrication of Phthalocyanine Polymers with Abundant Nitrogen Active Sites as the Cathode Materials for Aqueous Zinc-Organic Batteries

Fabrication of Phthalocyanine Polymers with Abundant Nitrogen Active Sites as the Cathode Materials for Aqueous Zinc-Organic Batteries

Improving the Performance of the Layered Nickel Manganese Oxide Cathode of Sodium-Ion Batteries by Direct Coating with Sodium Niobium Oxide.

This research highlights the efficacy of NaNbO3 as a coating for P2-Na2/3Ni1/3Mn2/3O2 cathodes in sodium-ion batteries. The coating enhances the kinetic behavior and cyclability of the electrochemical cells, as shown by electrochemical measurements. XRD analysis indicates that Nb does not incorporate into the cathode structure, implying a physical interaction between the coating and the cathode material. XRF analysis and EDX mapping confirm the actual composition and uniform dispersion of elements throughout the sample, while the electron micrographs evidence the occurrence of NaNbO3 particles modifying the surface of the layered oxide. The Ni4+/Ni3+ and Ni3+/Ni2+ redox pairs, along with the partially reversible oxidation of oxide to peroxide anions, contribute significantly to cell capacity, as revealed by XPS spectra. This last effect and the appearance of a co-intercalated phase at high voltage are positive factors to provide fast kinetics. Cyclic voltammograms show that samples coated with 2-3% NaNbO3 have superior rate capability, with high capacitive response and apparent diffusion coefficients. These samples also have low impedance at the electrode-electrolyte interface, which helps deliver a high capacity at 5C. Further cycling at 1C shows improved cyclability in the bare and 3% coated samples, due to their higher diffusion coefficients on charging. Notably, the 3% NaNbO3-coated sample exhibits excellent cyclability below 0 °C, making it a promising cathode material for sodium-ion batteries.

Electronic Confinement-Restrained Anti-Site Defects in Sodium-Rich Phosphates Toward Multi-Electron Transfer and High Energy Efficiency.

Sodium (Na) super-ionic conductor structured Na3MnTi(PO4)3 (NMTP) cathodes have garnered interest owing to their cost-effectiveness and high operating voltages. However, the voltage hysteresis phenomenon triggered by anti-site defects ( -ASD), namely, the occupation of Mn2+ in the Na2 vacancies in NMTP, leads to sluggish diffusion kinetics and low energy efficiency. This study employs an innovative electronic confinement-restrained strategy to achieve the regulation of -ASD. Partial replacement of titanium (Ti) with electron-rich vanadium (V) favors strong electronic interactions with Mn2+, restraining Mn2+ migration. The results suggest that this strategy can significantly increase the vacancy formation energy and migration energy barrier of manganese (Mn), thus inhibiting -ASD formation. As proof of this concept, an Na-rich Na3.5MnTi0.5V0.5(PO4)3 (NMTVP) material is designed, wherein the electronic interaction enhanced the redox activity and achieved more Na+ storage under high-voltage. The NMTVP cathode delivered a reversible specific capacity of up to 182.7 mAh g-1 and output an excellent specific energy of 513.8Wh kg-1, corresponding to ≈3.2 electron transfer processes, wherein the energy efficiency increased by 35.5% at 30C. Through the confinement effect of electron interactions, this strategy provides novel perspectives for the exploitation and breakthrough of high-energy-density cathode materials in Na-ion batteries.

Cracking Mechanism and Inhibition Strategies of Polycrystalline NCM Electrode Particles.

Developing a high-energy-density cathode material (LiNi1-x-yCoxMnyO2, NCM) for lithium-ion batteries is crucial to the electric vehicle and energy storage industries. However, the continuous insertion/extraction of Li+ generates diffusion-induced stress, causing NCM particles to crack or even pulverize, leading to battery capacity loss and limiting its wider commercial application. Current experimental studies are primarily postmortem examinations, and it is difficult to capture the particle cracking evolution. Simulation studies frequently ignore or simplify anisotropic volume contraction, demonstrating an insufficient understanding of the cracking mechanism of NCM polycrystalline particles, and cracking prevention strategies still need improvement. Therefore, we develop an anisotropic polycrystalline fracture phase-field model (AP-FPFM) that focuses on the anisotropic volume contraction of primary particles and precisely generates grain boundary distribution, coupling with Li+ diffusion, mechanical stress, and particle cracking. We employ AP-FPFM to demonstrate the behavior and mechanism of NCM polycrystalline particle cracking and illustrate the necessity and importance of anisotropic volume contraction to understand particle cracking. Furthermore, we explore the effects of average primary particle size, secondary particle size, and core-shell structure modulation on crack initiation and propagation and propose strategies to inhibit or migrate NCM polycrystalline particle cracking. This work provides theoretical support for revealing the cracking mechanism of anisotropic polycrystalline NCM particles and supplying optimization strategies to suppress particle cracking and improve the mechanical stability.

Boosting the synergistic activation of δ-MnO2 as cathode for aqueous zinc-ion batteries through Ni, Co co-doping

Layered δ-MnO2 is regarded as a promising cathode material for high-performance aqueous zinc-ion batteries (AZIBs) due to the sufficient interlayer spacing for the accommodation and migration of charge carriers. However, the sluggish activation process limits the reversible capacity, thus prevent their application. In this study, Ni-Co co-doped layered δ-MnO2 was designed to enhance ion diffusion capability and cycling stability. The influencing mechanism of Ni and Co on the long activation process are proposed by a comparative analysis between single doping and co-doping approaches. Specifically, the optimized co-doped δ-MnO2 maintained a high specific capacity of 200.2 mAh·g−1 with a capacity retention of 97.40 % after 700 cycles at 1 A·g−1. The co-doping approach exhibited a synergistic effect in suppressing Mn dissolution and enhancing ion diffusion capability. These findings provide new directions on boosting the synergistic activation process of manganese oxide and shed lights on the rational design of low-cost and high-safe batteries.

Modification study of Mg/W-doped LiNi0.9Mn0.1O2 layered oxide cathode materials for lithium-ion batteries

Modification study of Mg/W-doped LiNi0.9Mn0.1O2 layered oxide cathode materials for lithium-ion batteries

Stable electrochemical properties of trace titanium doping layered P3-type K0.5Mn0.92Ti0.08O2 cathode material for potassium ion batteries

The wide application of potassium ion batteries (PIBs) urgently requires the development of ideal cathode materials with low cost, good reaction kinetics and structural stability. Here, a titanium-doped K0.5Mn0.92Ti0.08O2 cathode material for potassium ion batteries is developed by doping modification strategy using a high-temperature solid-state method. The structure and performance structure-activity relationship of binary K0.5Mn1-xTixO2 cathode materials doped with non-electrochemically active element Ti4+ are studied experimentally and theoretically. With the introduction of Ti4+, when the doping amount is <10 mol%, the doped solid solution is hexagonal P3 phase, and the transition metal layer spacing increases. The non-equivalent doping affects the relative content of Mn3+/Mn4+, smoothes the redox peak in the electrochemical process, reduces the doping formation energy, and improves the structural stability. The ex-situ XRD fine structure study of the electrochemical process shows that the structural change of the material during the discharge process is suppressed after doping. The best Ti-doped cathode material K0.5Mn0.92Ti0.08O2 has an initial discharge capacity of 126.9 mAh·g−1 at a current density of 20 mA·g−1, and the capacity retention rate is 53.7 % after 100 cycles. This work provides a feasible strategy for the construction of stable electrode materials for PIBs.

Modified structure of vanadium oxide via cadmium doping and in-situ activation for high-performance aqueous zinc ion storage

Vanadium oxides are promising cathode materials for aqueous zinc-ion batteries, but they suffer from severe crystal collapse and poor electrical/ionic conductivity. Herein, we successfully synthesized the designed cadmium-doped, carbon-coated vanadium oxide precursor with abundant oxygen vacancies (Cd0.015V2O3-x@C) using a straightforward one-pot thermal reduction method, followed by in-situ activation to form a high-performance cathode material, Cd0.004V2O5-y·nH2O@C. We find that the interlayered water dramatically reduces the electrostatic force between zinc ions and V2O5-y layers, meanwhile, abundant oxygen vacancies and cadmium doping alter the material’s band structure, resulting in enhanced electronic and ionic conductivities. Leveraging these advantages, the phase transitioned Cd0.004V2O5-y·nH2O@C cathode delivers a remarkably high capacity of 420 mAh/g (0.2 A/g), an excellent rate capability of 198 mAh/g (20.0 A/g), and an outstanding capacity retention of 78.5 % after 3500 cycles (20 A/g). This synergistic structure modification strategy of elemental doping and in-situ activation offers a novel approach to design high-performance vanadium oxide-based cathodes for advanced aqueous batteries.

Enhancing the efficiency of two-electron zinc-manganese batteries enabled by Glycine complexation of manganese ions and compatibility with zinc anodes

Aqueous Zn//MnO2 batteries, leveraging the Mn2+/MnO2 conversion reaction, are gaining significant interest for their high redox potential and cost-effectiveness. However, they typically require a highly acidic environment to initiate this redox process. Herein, Glycine (Gly), a gentle and safe amino acid, is employed to enhance the effectiveness of depositing and dissolving Mn2+/MnO2. On one hand, Gly can complex with Mn2+, reducing its concentration and releasing H+. This not only promotes the dissolution of MnO2 but also increases the electrode potential. On the other hand, the Gly attaches to the Zn metal anode’s surface, shielding it from unwanted reactions. Hence, the assembled aqueous Zn//MnO2 battery exhibits an elevated output voltage during the discharge of 1.5 V with high coulombic efficiency (0.5 mAh cm−2 capacity), a long cycling life and excellent rate. This work showcases an efficient approach to enable the two-electron process of MnO2 cathode materials in aqueous zinc batteries.

Development of new cathode materials for all-iron redox flow batteries using hard carbon-based composites containing niobium pentoxide

We report in this study new cathodes for all-Fe RFBs synthesized using carbon flakes dispersed in plasticizing and hardening agents to obtain hard and dense carbon (HC) materials in the absence and presence (HC-Nb) of niobium pentoxide (Nb2O5). These cathode materials exhibited excellent resistance to wear in acidic solutions and larger potential intervals for water stability (e.g., 1200–1300 mV) compared to conventional graphite (e.g., 800 mV). These characteristics decreased the parasitic occurrence of hydrogen evolution reaction (HER) using a laboratory-made battery cell during the charging process. The latter was based on the Fe0/Fe2+ and Fe2+/Fe3+ redox couples present in the anode and cathode compartments, respectively. The different ex-situ and in-situ characterization studies evidenced that the presence of Nb2O5 in HCs substantially changed their physicochemical properties. The highest heterogenous kinetic rate constant (k0) representing the electrocatalytic activity for electron transfer was verified for the cathode containing 10 wt.% Nb2O5. An electromotive force (EMF) of 1.053 V was verified for the fully charged all-Fe RFB. Galvanostatic charge–discharge (GCD) studies revealed excellent coulombic efficiency (> 88 %) after 300 cycles. A pH control by acid addition as a function of the battery operation is necessary to avoid iron hydroxide formation on the anode’s surface.

Revealing the Role of Ruthenium on the Performance of P2-Type Na0.67Mn1-xRuxO2 Cathodes for Na-Ion Full-Cells.

Herein, P2-type layered manganese and ruthenium oxide is synthesized as an outstanding intercalation cathode material for high-energy density Na-ion batteries (NIBs). P2-type sodium deficient transition metal oxide structure, Na0.67Mn1-xRuxO2 cathodes where x varied between 0.05 and 0.5 are fabricated. The partially substituted main phase where x = 0.4 exhibits the best electrochemical performance with a discharge capacity of ≈170mAhg-1. The in situ X-ray Absorption Spectroscopy (XAS) and time-resolved X-ray Diffraction (TR-XRD) measurements are performed to elucidate the neighborhood of the local structure and lattice parameters during cycling. X-ray photoelectron spectroscopy (XPS) revealed the oxygen-rich structure when Ru is introduced. Density of States (DOS) calculations revealed the Fermi-Level bandgap increases when Ru is doped, which enhances the electronic conductivity of the cathode. Furthermore, magnetization calculations revealed the presence of stronger Ru─O bonds and the stabilizing effect of Ru-doping on MnO6 octahedra. The results of Time-of-flight secondary-ion mass spectroscopy (TOF-SIMS) revealed that the Ru-doped sample has more sodium and oxygenated-based species on the surface, while the inner layers mainly contain Ru-O and Mn-O species. The full cell study demonstrated the outstanding capacity retention where the cell maintained 70% of its initial capacity at 1C-rate after 500 cycles.

Fluorinated aggregated nanocarbon with high discharge voltage as cathode materials for alkali-metal primary batteries.

Due to its exceptionally high theoretical energy density, fluorinated carbon has been recognized as a strong contender for the cathode material in lithium primary batteries particularly valued in aerospace and related industries. However, CF x cathode with high F/C ratio, which enables higher energy density, often suffer from inadequate rate capability and are unable to satisfy escalating demand. Furthermore, their intrinsic low discharge voltage imposes constraints on their applicability. In this study, a novel and high F/C ratio fluorinated carbon nanomaterials (FNC) enriched with semi-ionic C-F bonds is synthesized at a lower fluorination temperature, using aggregated nanocarbon as the precursor. The increased presence semi-ionic C-F bonds of the FNC enhances conductivity, thereby ameliorating ohmic polarization effects during initial discharge. In addition, the spherical shape and aggregated configuration of FNC facilitate the diffusion of Li+ to abundant active sites through continuous paths. Consequently, the FNC exhibits high discharge voltage of 3.15V at 0.01C and superior rate capability in lithium primary batteries. At a high rate of 20C, power density of 33,694Wkg-1 and energy density of 1,250Wh kg-1 are achieved. Moreover, FNC also demonstrates notable electrochemical performance in sodium/potassium-CF x primary batteries. This new-type alkali-metal/CF x primary batteries exhibit outstanding rate capability, rendering them with vast potential in high-power applications.