Cathode Material For Sodium-ion Batteries Research Articles

A 3.5 V-class organic sodium-ion battery using a croconate cathode

Sodium-ion batteries (SIBs) based on organic cathode materials have received considerable attention owing to high theoretical capacities, cost-effectiveness, and raw material abundance. However, high-voltage organic cathodes have been rarely investigated for SIBs mainly due to their electrical insulation and dissolution in electrolytes. In this study, sodium croconate (C5O5Na2) is utilized as a high-voltage cathode material for SIBs, designing an interface using a functionalized multi-walled carbon nanotube (MWCNT). The composite C5O5Na2 cathode with carboxylic-acid-functionalized-(COOH–) MWCNT exhibits a 3.5 V-class high-voltage redox activity with a cycle performance higher than that of non-functionalized MWCNT/C5O5Na2 composite cathodes; the capacity retention ratio is improved from 0 % to 34 % after 30 cycles at 0.1C. Raman, X-ray photoelectron spectroscopy, and solid-state nuclear magnetic resonance reveal the formation of hydrogen bonding between COOH groups on MWCNT and carbonyl groups in C5O5Na2 molecules; leading to suppression of organic molecules and improvement on the cycle performance. A full cell assembled with the C5O5Na2/COOH–MWCNT cathode and a hard carbon anode also shows a high-voltage redox plateau at around 3.5 V and a 1st discharge capacity of 123 mAh g−1 at 1C. These results suggest the feasibility of developing a high-energy-density storage system using completely common-metal components.

Zero-Strain Na3 V2 (PO4 )2 F3 @Rgo/CNT Composite as a Wide-Temperature-Tolerance Cathode for Na-Ion Batteries with Ultrahigh-Rate Performance.

Sodium-ion batteries (SIBs) are widely considered a hopeful alternative to lithium-ion battery technology. However, they still face challenges, such as low rate capability, unsatisfactory cycling stability, and inferior variable-temperature performance. In this study, a hierarchical Na3 V2 (PO4 )2 F3 (NVPF) @reduced graphene oxide (rGO)/carbon nanotube(CNT) composite (NVPF@rGO/CNT) is successfully constructed. This composite features 0D Na3 V2 (PO4 )2 F3 nanoparticles are coated by a cross-linked 3D conductive network composed of 2D rGO and 1D CNT. Furthermore, the intrinsic Na+ storage mechanism of NVPF@rGO/CNT through comprehensive characterizations is unveiled. The synthesized NVPF@rGO/CNT exhibits fast ionic/electronic transport and excellent structural stability within wide working temperatures (-40-50 °C), owing to the zero-strain NVPF and the coated rGO/CNT conductive network that reduces diffusion distance for ions and electrons. Moreover, the stable integration between NVPF and rGO/CNT enables outstanding structural stability to alleviate strain and stress induced during the cycle. Additionally, a practice full cell is assembled employing a hard carbon anode paired with an NVPF@rGO/CNT cathode, which provides a decent capacity of 105.2 mAh g-1 at 0.2 C, thereby attaining an ideal energy density of 242.7Wh kg-1 . This work provides valuable insights into developing high-energy and power-density cathode materials for SIBs.

Recent progress of manganese-based Prussian blue analogue cathode materials for sodium-ion batteries

Recent progress of manganese-based Prussian blue analogue cathode materials for sodium-ion batteries

Using Highly Electronegative Zn to Regulate the Superlattice Structure for the Na-Ion Layered Oxide Cathode with Superior Electrochemical Performance.

The introduction of a superlattice structure into layered oxide cathode materials is a novel strategy to improve the structural stability of sodium-ion batteries (SIBs). However, the superlattice structure gradually disappears during cycling, which shortens the long life of SIBs. Here, the highly electronegative Zn is introduced into a P2-type layered oxide to regulate the superlattice structure. The obtained P2-Na0.80Li0.13Ni0.20Zn0.03Mn0.64O2 exhibits excellent cycling performance (the capacity retention is 96.7% after 100 cycles at 0.5C) and rate capability (95.8 mAh g-1 at 5C). Zn effectively inhibits the Li migration and the Mn dissolution, which ensures the integrity of the Li/Mn superlattice structure during long cycling, thus achieving an ultralong cycling life of SIBs. The introduction of Zn dramatically increases the length of the c-axis, leading to a faster de-embedding rate of Na+ and a better diffusion kinetics. Meanwhile, the larger pristine volume can withstand more stress/strain due to the sharp increase in the level of O-O repulsion during the desodiation process. In addition, Raman test results show that Zn can inhibit the Na+/vacancy ordering transition and improve the structural stability. This study confirms the feasibility of a Zn-regulated superlattice structure. It provides inspiration for the construction of stable layered oxide cathode materials for SIBs.

Copper ferricyanide particles modify Prussian blue and its analogues on the surface as cathode for high-performance sodium-ion batteries

Prussian blue and its analogs are currently attracting widespread attention as cathode materials for sodium-ion batteries due to their accomplished performance and low price. However, the unavoidable disruption of the structure and the dissolution of the surface layer of the material during sodium ion de-embedding affects its stability. In this work, using a simple method, we synthesize a composite material with uniformly grown Copper Ferricyanide particles on the surface of ferric ferricyanide. The material has a high specific capacity of more than 122.57mAhg−1 at 0.2 C (1 C=100mAg−1) and an initial Coulombic efficiency of 99.9 %. It can maintain over 92 % capacity retention after 800 cycles at 1 C. It also has excellent rate performance with a specific capacity of 103.4mAg−1 at 20 C. With its simple method and low cost, this surface modification strategy is of interest in the large-scale production of cathode materials for sodium-ion batteries.

Activating three electron reaction in sodium vanadium ferric phosphate toward high energy density for Na-ion batteries

Na3V2(PO4)3 (NVP) with a robust sodium superionic conductor (NASICON) structure and high voltage platform has been regarded as one of the most prospective cathode materials for sodium-ion batteries (SIBs). Nevertheless, the increasing demand for energy density encourages us to activate multielectron reactions in NVP-based materials to achieve higher voltage/capacity to meet the challenge of commercialization of SIBs. Herein, NASICON-structured Na3V2−xFex(PO4)3 [NVP-Fe(x)] has been developed through a solid state reaction. The introduction of Fe3+ successfully activates high-voltage-platform redox couple of V4+/V5+ in Na3V2−xFex(PO4)3 and thus achieves three-electron redox reactions, resulting in significantly enhanced energy density (417.3 Wh kg−1) and superhigh initial capacity (166.4 mA h g−1 at 1 C). This work excites the generation of three-electron redox reactions in Fe3+-doped NVP for the first time, providing an important guidance for designing high-energy-density polyanionic materials for sodium storage by inducing multielectron redox reactions.

Promising Cathode Materials for Sodium-Ion Batteries from Lab to Application.

Sodium-ion batteries (SIBs) are seen as an emerging force for future large-scale energy storage due to their cost-effective nature and high safety. Compared with lithium-ion batteries (LIBs), the energy density of SIBs is insufficient at present. Thus, the development of high-energy SIBs for realizing large-scale energy storage is extremely vital. The key factor determining the energy density in SIBs is the selection of cathodic materials, and the mainstream cathodic materials nowadays include transition metal oxides, polyanionic compounds, and Prussian blue analogs (PBAs). The cathodic materials would greatly improve after targeted modulations that eliminate their shortcomings and step from the laboratory to practical applications. Before that, some remaining challenges in the application of cathode materials for large-scale energy storage SIBs need to be addressed, which are summarized at the end of this Outlook.

Resolving Deactivation of Low-Spin Fe Sites by Redistributing Electron Density toward High-Energy Sodium Storage.

Prussian blue (PB) has been an emerging class of cathode material for sodium-ion batteries due to its low cost and high theoretical capacity. However, their working voltage and capacity are substantially restricted due to the deactivation of low-spin Fe sites. Herein, we demonstrate a universal strategy to activate the low-spin Fe sites of PB by hybridizing them with the π-π conjugated electronic conductors. The redistribution of electron density between π-π conjugated conductors and PB effectively promotes the participation of low-spin Fe sites in sodium storage. Consequently, the low-spin Fe-induced plateau is greatly aroused, resulting in a high specific capacity of 148.4 mAh g-1 and remarkable energy density of 444.2 Wh kg-1. In addition, the excellent structural stability enables superior cycling stability over 2500 cycles and outstanding rate performance. The work will provide fundamental insight into activating the low-spin Fe sites of PB for advanced battery technologies.

Nanotechnology based on anode and cathode materials of sodium-ion battery

With the urgent need for carbon neutrality and the new energy vehicle industry's quick development around the world, the market demand for batteries is growing rapidly. At present, the batteries in the market are mainly lithium-ion batteries. However, the shortage and uneven distribution of lithium deposits worldwide result in high production costs. In recent years, sodium-ion batteries have developed rapidly for the sake of their similar principles and easy access to sodium resources, and are regarded as being able to replace lithium-ion batteries in the future. Nanotechnology is widely used in sodium-ion batteries to overcome the issue of extracting/inserting during charging/discharging due to the sodium ions large radius. This paper reviewed the application of nanotechnology in both anode and cathode materials of sodium-ion batteries. This paper covers widely used cathode materials such as layered transition metal oxides, polyanion compounds, and Prussian blue. Nanotechnologies employed in anode materials such as carbon-based materials and titanium-embedded materials are also introduced. It has turned out that sodium-ion batteries can improve the sodium storage capacity, energy density, and cycle performance efficiently via the application of nanomaterials.

Effect of Zr4+ doping on the electrochemical properties of Na3MnTi(PO4)3/C cathode materials

NASICON structural materials have the advantages of structural stability, high ion conductivity, and high working potential, which have attracted widespread attention as cathode for sodium-ion batteries. Although the three-electron reaction in the NASICON structure Na3MnTi(PO4)3 increases the specific capacity of the material, poor electronic conductivity remains a key factor restricting its practical application. Herein, Na3Mn1-xZrxTi(PO4)3/C (x = 0, 0.01, 0.03, 0.05, 0.07 and 0.1), a typical three-dimensional NASICON structure cathode material for sodium-ion batteries, was synthesized by the sol-gel method. Through powder X-ray diffraction, the Zr4+ doping in the Na3MnTi(PO4)3 (NMTP) structure was verified. It was found that doping trace amounts of Zr at the Mn site can not only reduce the Jahn-Teller effect caused by Mn3+, but also strengthen the Zr-O bond compared to the Mn-O bond, making the crystal structure more stable by reducing the proportion of Mn. According to the findings of the EIS test, a suitable amount of Zr doping can enhance the electronic conductivity and Na ion diffusion coefficient of NMTP/C electrode materials, weaken polarization phenomena, increase electrode reaction rate, and significantly improve the rate performance and cycling performance of Na3Mn1-xZrxTi(PO4)3 material. The Na3Mn1-xZrxTi(PO4)3/C sample prepared has high initial capacity of 124mAh/g, a capacity retention rate of 86 % after 200 cycles at 0.2C, and a capacity retention rate of 84 % after 500 cycles at 1C. This proves that the material still exhibits excellent cycling stability and structural stability after high current cycling. More importantly, the Na3Mn0.95Zr0.05Ti(PO4)3 (Zr5-NMTP)//Hard carbon full battery also exhibits ideal electrochemical performance.

SnO2 coating to stabilize Mn-based layered oxide cathode materials for sodium-ion batteries

Thanks to high theoretical capacity and good ionic conductivity, Mn-based layered metal oxides are considered to be promising cathode materials for sodium-ion batteries (SIBs). However, the irreversible structural change and oxygen loss during sodiation/desodiation processes lead to rapid capacity attenuation. Herein, SnO2 surface coating was adopted for the first time to improve the Na-storage performance of Na0.6[Li0.2Mn0.8]O2 (NLMO) through solid-phase heat treatment with a subsequent liquid-phase method. The optimized 1 wt% SnO2 coated NLMO demonstrated a capacity of 103 mAh/g at a high rate of 1C (1C = 176 mA/g) and 88 mAh/g after 40 cycles with a capacity retention of 85.4%. The SnO2 coating layer endows the NLMO structure with stable ion transport interface to facilitate sodium-ion transfer and an isolated shielding layer to inhibit oxygen loss, thus contributing to stable cycling performance and high capacity even at a high rate. This surface-coating strategy is expected to be applicable to other layered metal oxides as cathode materials to achieve good cycling stability and high-rate capacity. This work is significant for the electrochemical performance improvement of layered metal oxides applied in SIBs.

Effects of the Mn/Ni ratio on the battery performance of layered Na-Ni-Mn oxide cathode materials in sodium-ion batteries

Effects of the Mn/Ni ratio on the battery performance of layered Na-Ni-Mn oxide cathode materials in sodium-ion batteries

Reduced graphene oxide (rGO)-induced preparation of flake-shaped Na3V2(PO4)3@C as a superior cathode material for sodium-ion batteries in e-vehicles applications

Reduced graphene oxide (rGO)-induced preparation of flake-shaped Na3V2(PO4)3@C as a superior cathode material for sodium-ion batteries in e-vehicles applications

Mitigating the P2–O2 phase transition of Ni–Co–Mn based layered oxide for improved sodium-ion batteries via interlayered structural modulation

Mn-based layered oxides are promising cathode materials for sodium-ion batteries owing to their high reversible capacities. However, P2–O2 phase transition and Jahn–Teller distortion of Mn3+ frequently occur at the end of the discharging process, resulting in low cycling stability and severe capacity degradation during the cycling processes. In this study, we proposed an effective strategy to inhibit the harmful phase transition and suppress the Jahn–Teller distortion using Al substitution. The proposed method was validated via in situ and ex situ X-ray diffraction. Furthermore, the Al-substituted P2-Na0.7Ni0.2Co0.2Mn0.58Al0.02O2(NCMA2) electrode exhibited only a topotactic phase transition from P2 to OP4 and excellent cycling stability (80% retention of the initial capacity at 170 mAh/g after 50 cycles at 0.1 C within 1.50–4.50 V). X-ray photoelectron spectroscopy analysis showed that the Mn4+ content of the Al-substituted electrode was higher than the bare NCM (Na0.7Ni0.2Co0.2Mn0.6O2) electrode in both the charge and discharge states. This confirms that Al substitution can improve the electrochemical performance by mitigating the irreversible P2–O2 phase transition and suppressing Jahn–Teller distortion. This study provides a new perspective for effectively mitigating the P2–O2 phase transition in Mn-based layered oxide cathodes via interlayered structural modulation.

Synthesis and design of NaNi1/3Fe1/3Mn1/3O2 cathode materials for long-life sodium-ion batteries

To enable the widespread adoption of residential energy storage, sustainable, low-cost, long-life, and energy-dense battery technologies are required. Sodium-ion offers many of these characteristics, however often the system is tailored for energy rather than cycle life. In this work, the effect of synthesis conditions upon the primary and agglomerated secondary particle size and shape of the sodium-ion cathode material NaNi1/3Fe1/3Mn1/3O2 was investigated for optimization of energy and cycle life. A two-level full factorial experimental design was utilized to examine how the synthesis parameters (pH, molar ratio of ammonia/metal precursor salt, and stirring speed) affect the physical and electrochemical properties. This approach enabled a comprehensive investigation of the main effects and interactions of these parameters. The data from multiple synthesis runs were analyzed using statistical methods and regression analysis. This experimental design provided valuable insights into the relationship between synthesis parameters and material properties. Statistical analysis indicates that both physical and electrochemical properties are mainly controlled through pH and NH4OH, while the effects of stirring speed are less pronounced. The optimal synthetic conditions producing the highest cycling performance were extrapolated from the statistical analysis. A validation experiment showed that particles synthesized with optimum parameters displayed a threefold increase in cycling performance together with uniformly distributed particle size and a high tap density.

Nickel pre-intercalated bilayer vanadium pentoxide hydrate for reversible structural evolution in Na-ion battery cathode

Layered vanadium oxides, due to their high specific capacity and the multiple oxidation states of vanadium, are attractive candidates as cathode materials for sodium-ion batteries (SIBs). To meet the requirements of increasing interlayer spacing and significantly improving structural stability, herein, nickel pre-intercalated bilayer vanadium pentoxide hydrate, Ni0.28V2O5∙0.62 H2O (referred to as NVO) is synthesized successfully. The interlayer water molecules significantly increase the interlayer distance of the bilayer vanadium pentoxide. At the same, by forming a stable interlayer NiO6 octahedron, the intercalated Ni atoms effectively relieve the big change of volume during the Na ions insertion/extraction process and effectively inhibit the interlayered water molecules escape in charge/discharge process. Due to the big interlayer distance and excellent structural stability, the NVO electrode exhibits an excellent electrochemical performance. Except for the first few cycles, a high reversible capacity of about 260 mAh g−1 is obtained and the mean fade is only 0.5% per cycle. In addition, the excellent Na storage mechanism of the NVO electrode is also explored in detail by in situ XRD.

Lattice regulation strategy for constructing high-rate performance Na0.44Mn0.895Ti0.1Mg0.005O2 sodium-ion batteries cathode materials

Na0.44MnO2 has received much interest as a potential cathode material for Sodium-ion batteries (SIBs) because of its unique tunnel structure and the ease of Na+ insertion/extraction. Therefore, the size and stability of the tunnel structure are critical factors in solving its low-rate performance and cycle stability. Herein, a lattice regulation strategy to enlarge the size in favor of Na+ insertion/extraction and to maintain the stability of the tunnel structure of Na0.44MnO2 by Ti and trace Mg co-doping is reported for the first time. Subsequently, the Na0.44Mn0.895Ti0.1Mg0.005O2 (NMO-TM) material is synthesized with Ti/Mg co-doping. The structure and phase composition of the as-synthesized samples are investigated through X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The results indicate that Ti/Mg has been effectively doped into the crystal structure of Na0.44MnO2 while it maintains the stability of the tunnel structure. The material was used as cathode materials of rechargeable sodium-ion batteries. As a result, at a 1 C rate, the NMO-TM sample exhibits a considerable capacity of 110 mAh g−1, with retention rates of up to 93.6 % after 200 cycles. Even at a higher cycle rate of 20 C, the NMO-TM sample maintains a specific capacity of 80.0 mAh g−1, with a retention rate of 67 % after 2000 cycles. This work provides a facile strategy for regulating the tunnel structure to get stable and high-rate performance of cathode materials.

Reusing the steel slag to design a gradient-doped high-entropy oxide for high-performance sodium ion batteries

Herein, a high-entropy layered oxide (HEO) is proposed as an outstanding cathode material for long-life sodium-ion batteries. Based on the self-segregation of elements from surface to bulk phase, a multi-element gradient doped high-entropy cathode material is prepared by doping steel slag with available elements (Mg, Al, Si, Fe, Ca). The surface high-entropy region vastly improves the air stability of materials and reduces surface impurities and side reactions. The Na-O-Mg configuration of near-surface high-entropy region continuously stimulates the anionic redox activity, and the DEMS shows the high-strength Al-O bonding achieves zero oxygen release. Therefore, the LNSM-0.01 reveals a stable capacity of ∼24 mA h g−1 in the range of 4.0–4.5 V. The Ca2+ in bulk phase high-entropy region disrupts the Na+/vacancy ordering transition and enhances the kinetic performance (90 mA h g−1 at 1000 mA g−1), while Fe2+/3+ provides a large amount number of charge compensation. Further, DFT calculations prove that the entropy stability based on synergistic effect immeasurably reinforce the layered oxide configuration, building a more robust structural framework during cycling. This work deepens the understanding on multi-element gradient doping to prepare HEOs, and provides a novel pathway for resource utilization of solid waste.

Preparation of Low-Defect Manganese-Based Prussian Blue Cathode Materials with Cubic Structure for Sodium-Ion Batteries via Coprecipitation Method.

Sodium-ion batteries have important application prospects in large-scale energy storage due to their advantages, such as safety, affordability, and abundant resources. Prussian blue analogs (PBAs) have a stable and open framework structure, making them a very promising cathode material. However, high-performance manganese-based Prussian blue cathode materials for sodium-ion batteries still suffer from significant challenges due to several key issues, such as a high number of vacancy defects and a high crystal water content. This article investigates the effects of the Fe-Mn molar ratio, Mn ion concentration, and reaction time on the electrochemical performance of MnHCF during the coprecipitation process. When Fe:Mn = 1:2, c(Mn2+) = 0.02 mol/L, and the reaction time is 12 h, the content of interstitial water molecules in the sample is low, and the Fe(CN)6 defects are few. At 0.1 C, the prepared electrode has a high initial discharge specific capacity (121.9 mAh g-1), and after 100 cycles at 0.2 C, the capacity retention rate is 65% (~76.2 mAh g-1). Meanwhile, the sample electrode exhibits excellent reversibility. The discharge capacity can still be maintained at around 75% when the magnification is restored from 5 C to 0.1 C. The improvement in performance is mainly attributed to two aspects: On the one hand, reducing the Fe(CN)6 defects and crystal water content is conducive to the diffusion and stable structure of N. On the other hand, reducing the reaction rate can significantly delay the crystallization of materials and optimize the nucleation process.

Amorphous Aluminum Oxide-Coated NaFe0.33Ni0.33Mn0.33O2 Cathode Materials: Enhancing Interface Charge Transfer for High-Performance Sodium-Ion Batteries.

Layered cathode materials for sodium-ion batteries (SIBs) have gained considerable attention as promising candidates owing to their high capacity and potential for industrial scalability. Nonetheless, challenges arise from stress and structural degradation resulting from the deposition of larger ion radius species, leading to diminished cyclic stability and rate performance. In this study, we present a novel and straightforward strategy that combines the synergistic effects of an amorphous aluminum oxide coating and aluminum ion doping. This approach effectively addresses the issues of grain cracking and expands the interlayer spacing of alkali metal ions in SIB materials, thereby enhancing their overall performance. Consequently, it optimizes the diffusion of charge carriers and facilitates interfacial charge transfer, leading to remarkable improvements in the performance of the NaNi0.33Mn0.33Fe0.33O2 material with 0.4 wt % amorphous aluminum oxide coating (NNMF-0.4A), which exhibits reversible capacities of 135.7, 114.3, 106.8, 99.9, 89.5, and 77.1 mAh g-1 at 0.1, 0.5, 1, 2, 5, and 10 C, respectively. Furthermore, the NNMF-0.4A material maintains a capacity of 76.7 mA g-1 after 500 cycles at a current density of 800 mA g-1 (10 C), with a capacity retention rate of 98.2%. Our findings present a groundbreaking pathway for modifying high-power sodium-ion battery cathode materials, contributing to the advancement of sustainable energy storage technologies.