Application In Sodium-ion Batteries Research Articles

Interface stabilization strategy realizing low-temperature sodium storage in Sb anode prepared by ball milling method

Antimony (Sb) is an attractive anode material for sodium-ion batteries (SIBs) owing to its low operating potential, low cost, and high theoretical capacity. However, the large volume expansion of Sb during the Na alloying/dealloying process, which greatly limits its application in SIBs. Simultaneously, as the temperature decreases, the formation of a poor coating on the anode surface significantly increase the difficulty of Na+ transmission. Herein, Sb-graphite-NaF (SCF) ternary composites were prepared by an easy to operate and low-cost ball milling method, which significantly improved the cycling stability and extended to the operation temperature of Sb-base SIBs. A small amount of NaF induces the formation of an inorganic-dominated NaF-rich stable solid electrolyte interphase (SEI) on the Sb anode surface, which can cooperate with graphite to inhibit volume expansion of the Sb particles during sodium storage, enhance conductivity and accelerate Na+ diffusion at room and low temperatures. As a result, the SCF electrode with propylene carbonate-base electrolyte delivered a discharge capacity of 458.4 mAh g−1 after 160 cycles at 500 mA g−1 at 20 °C. When matched with diethylcarbonate-based electrolyte at −20 °C, it had a specific capacity of 299.8 mAh g−1 after 120 cycles and a capacity retention rate of 86.2 %. This study shows that the interface stabilization strategy with a suitable electrolyte can improve the cycling stability of anode materials, provide a new idea for constructing NaF-rich SEI, and a new approach for applying Sb-based materials in low-temperature SIBs.

Nanodiamond-Assisted High-Performance Sodium-Ion Batteries with Weakly Solvated Ether Electrolyte at -40°C.

Realizing high performances of sodium-ion batteries (SIBs) working at low temperatures is a pressing need for the commercial applications of SIBs. In this work, nanodiamonds (NDs) are introduced in diglyme electrolytes (ND-Diglyme) to significantly improve the low-temperature performances of SIBs. The corresponding SIB achieves an initial reversible specific capacity of 324mA h g-1 at -40°C (slightly decreased from 357mA h g-1 at 25°C) and shows a capacity retention ratio of ≈82% after 100 cycles at 0.1 A g-1. Moreover, it shows a capacity as high as 40mA h g-1 at 1 A g-1, nearly five times the date of the pure Diglyme electrolyte. Experimentally reveals that introducing NDs is helpful in inhibiting dendrite growth and improving the cyclic stability of anode at LT, because the ND with strong adsorption to sodium ions can not only assist in forming an effective solid electrolyte interface rich with NaF and Na2CO3 but also effectively reduce the activation energy (decreased from 426.68 to 370.51 meV) during the charge transfer processes. Hence, the proposed ND-assisted weakly ether electrolyte in this study presents a viable electrolyte additive solution to fulfill the rising low-temperature demands of SIBs.

Synergetic benefits of zinc antimony oxide/reduced graphene oxide hybrid anode for enhanced sodium-ion storage

Organic-inorganic hybrid nanocomposites are rapidly evolving as a new generation of materials with attractive properties for electrochemical energy storage. Unfortunately, their practical applications in sodium-ion batteries (SIBs) still require further research due to the unsatisfactory cycling stability and rate performance. This work explores using zinc antimony oxide/reduced graphene oxide (ZSO/rGO) hybrid nanocomposite as an anode material in SIBs. After 150 cycles at 0.05 A g-1, the ZSO/rGO electrode delivers a specific capacity of 357.21 mAh g-1 with a coulombic efficiency of 99.3%, which is almost 2.5-fold higher than the specific capacity of the pristine ZSO electrode. An in-situ Raman spectroscopy study demonstrates that the sodiation/desodiation mechanism in the ZSO/rGO electrode involves the conversion and alloying reactions in the ZSO nanoparticles. Further electrochemistry analysis reveals that the nanocomposite anode shows synergistic effects by coupling diffusion and surface contribution, in which the latter plays an important role.

3D MoS2/graphene oxide integrated composite as anode for high-performance sodium-ion batteries

Sodium-ion batteries (SIBs) are emerging as a promising alternative to conventional lithium-ion technology, due to the abundance of sodium resources. The major drawbacks for the commercial application of SIBs lie in the slow kinetic processes and poor energy density of the devices. Molybdenum sulfide (MoS2), a graphene-like material, is becoming a promising anode material for SIBs, because of its high theoretical capacity (670 mAh g–1) and layered structure that suitable for Na+ intercalation/extraction. However, the intrinsic properties of MoS2, such as low conductivity, slow Na+ diffusion kinetics and large volume change during charging/discharging, restrict its rate capability and cycle stability. Here, molybdenum disulfide and graphene oxide (3D MoS2/GO) with excellent conductivity were fabricated through layer-by-layer method using amino-functionalized SiO2 nanospheres as templates. The 3D MoS2/GO composite demonstrates excellent cycling stability and capacity of 525 mA h g–1 at 500 mA g–1 after 100 cycles, which mainly due to the integrated MoS2/GO components and unique 3D macroporous structure, facilitating the material conductivity and Na+ diffusion rate, while tolerating the volume expansion of MoS2 during the charge/discharge processes.

Preparation and application of high-performance sodium-ion batteries cathode material Na3.6Fe2.6(PO4)1.6P2O7 with optimized sodium-iron ratio

Na4Fe3(PO4)2P2O7 (NFPP) has been developed as the most promising polyanion cathode for sodium-ion batteries due to its excellent electrochemical performance, high safety properties, and environmental friendliness. However, the electrochemically inactive impurity (m-NaFePO4) will inevitably generate during synthesis process, which decreases the practical capacity of NFPP significantly. In this paper, a novel Na3.6Fe2.6(PO4)1.6P2O7 cathode material with excellent performance is successfully exploited by optimizing sodium-iron ratio to reduce the formation of impurity phases. In a series of as-prepared materials with sodium-iron ratio between 1.33–1.50, Na3.6Fe2.6(PO4)1.6P2O7 exhibits the highest discharge specific capacity (110.3 mAh g−1 at 0.1C), best rate capability (84.4 mAh g−1 at 30 C) and cycle performance (78.2 % capacity retention after 3000 cycles at 20 C). Furthermore, 20 Kg of the Na3.6Fe2.6(PO4)1.6P2O7 cathode material is prepared by spray drying method, which has been successfully applied in sodium-ion pouch cells (12 Ah) with a commercial hard carbon as the anode materials. The assembled pouch cells display excellent cycle performance (82.4 % capacity retention after 2000 cycles at 1 C), rate capability (88 % capacity retention at 30 C) and low-temperature performance (74 % capacity retention at −40 °C).

Molecular Dynamics Simulation Investigation of Freezing Point Depression in NaClO4 Electrolyte Solution by CaCl2.

The development of inorganic antifreeze electrolytes is of paramount importance for the application of sodium-ion batteries under low-temperature conditions. However, there is little reported about their molecular mechanism for lowering the freezing point of electrolytes. Therefore, this study explores the mechanism by which CaCl2 lowers the freezing point of the NaClO4 electrolyte. Hexagonal ice (ice Ih) was used as the ice seed, and CaCl2 was selected as the antifreeze agent. The coexistence system of ice and solution was constructed to simulate the freezing process. It was found that there is ion rejection at the ice layer, with ions predominantly distributed in the solution. Over time, ions form an ion adsorption layer at the ice-solution interface. The radial distribution function (RDF) and spatial distribution function (SDF) of Na+, ClO4-, Ca2+, and Cl- revealed that ions form the first solvation shells with water molecules. The interaction energy between ions and water molecules is greater than that between ice nuclei and water. Therefore, ions are better able to maintain the stability of their solvation shells and inhibit the growth of ice Ih through a mechanism of competition for water molecules. Furthermore, the dissolution free energy of Na+ and Ca2+ in the aqueous phase was studied. The results indicated that Ca2+ has a stronger affinity for water molecules than Na+, making it more competitive in competing for water with ice Ih. Therefore, CaCl2 in NaClO4 solution can reduce the freezing point. This work provides a molecular-level understanding of how CaCl2 reduces the freezing point of NaClO4 solution, which is beneficial for designing strategies for low-temperature electrolytes.

Ce-substituted P2-type layered cathode with interfacial/ bulk stability for sodium ion batteries

Addressing a changing energy environment, sodium-ion batteries (SIBs) have emerged as one of the most potentially applicable energy resources in the world. Nevertheless, its further application is hindered owing to high degree of interfacial degradation and structural changes, which caused rapid capacity fading. Herein, a novel Ce modified P2-type layered structure cathode material Na0.67Mn0.8Co0.17Ce0.03O2 @ CeO2 is introduced, the stability of cell is improved by simultaneous bulk doping and surface coating in one scalable step. The doping of Ce4+ increases sodium ion transport rate by shrinking transition metal layer ions and expanding Na layer spacing. Irreversible phase transition can be mitigated from the stronger the bond energy between TM and O, which is conducive to the decrease in the Mn3+/Mn4+ ratio, and suppression of the Jahn−Teller distortion. Besides, the doping of larger radius Ce4+ extends the internal paths of crystal structure, which decreases the barrier of Na+, correspondingly, the Na+ diffusion rate was increased. Meanwhile, the CeO2 coating layer effectively inhibits parasitic reactions on the surface and improves the stability of the interface. which display excellent capacity with a remarkable retention of 86.9% after 100 cycles at 0.5 C and outstanding discharge rate performance of 87 mA h g−1 at 20 C. This study provides a simple process to concurrently stabilize the bulk structure and interface for the future application for sodium-ion batteries.

Comprehensive evaluation of the impact of ionic liquid incorporation on the optical properties, Urbach energy, thin film morphology, and surface roughness of poly(vinyl chloride) based on ionic materials

Abstract A newly synthesis composite thin films of poly(vinyl chloride) has been refinement with ionic liquid, where PVC dissolved in THF with various concentrations of IL by casting method to form the composite thin films, without any reaction and IL dangles within PVC matrix. The thin films were examined by the diffusive reflectance device under the wavelength range (238–1300 nm). The XRD, EDX, and AFM techniques were utilized to discover the structure of the PVC matrix after additive IL. The XRD analysis illustrated the amorphous structure of the films, while the EDS analysis illustrated the main composition of pure PVC and composite PVC/IL. The optical properties and optical parameters were studied. The reflectance, extinction factor, transmittance, and imaginary dielectric constant declined, the absorption value was between (80–89 %), and the refractive index, real dielectric constant, and optical conductivity were increased. The indirect energy gap declined from 4.2 eV to 2.2 eV and the direct energy gap declined from 3.7 eV to 2.6 eV. The Urbach energy was increased from 2.09 eV to 15.45 eV revealing an increase in the disorders of electrons. The E d increased from 23.42 eV to 70.68 eV and E o increased from 7.00 eV to 10.88 eV. AFM analysis illustrated the roughness of the films increased after additive IL to the PVC Matrix from 1.08 nm to 4.45 nm and the root mean square of the particles ranged from 1.57 nm to 5.56 nm. The PVC composite thin films are utilized in solar cell and sodium-ion battery applications.

Polyaniline-Coated Na3V2(PO4)2F3 Cathode Enables Fast Sodium Ion Diffusion and Structural Stability in Rechargeable Batteries.

Na3V2(PO4)2F3 (NVPF), a typical sodium superionic conductor (NASICON) type structure, has attracted much interest as a potential positive electrode in sodium-ion battery. However, the inherently poor electronic conductivity of phosphates compromises the electrochemical properties of this material. Here, we develop a general strategy to improve the electrochemical performance by preparing a new composite material "polyaniline (PANI)@NVPF" using a Pickering emulsion method. The X-ray diffraction and Raman results indicated a successful PANI coating without affecting the NASICON-type structure of NVPF, and they enhanced the interfacial bonding between the two components. Also, thermogravimetric analysis and scanning electron microscopy analyses revealed that the PANI content influenced the thermal stability and morphology of the nanocomposites. As a result, the sodium test cells exhibited multielectron reactions and a better rate performance for PANI@NVPF nanocomposites as compared to NVPF. Specifically, 2%PANI@NVPF maintained 70% of its initial capacity at 5C. Ex-situ electron paramagnetic resonance revealed the existence of mixed valence states of vanadium (V4+/V3+) in both discharge and charge processes. Consequently, the successful PANI coating into the sodium superionic conductor framework improved the sodium diffusion channels with a measurable increase of diffusion coefficients with cycling (ca. 3.25 × 10-11 cm2 s-1). Therefore, PANI@NVPF nanocomposites are promising cathode candidates for high-rate sodium-ion battery applications.

Engineering multiple heterogeneous Co/CoSe/MoSe2 embedded in carbon nanofibers with Co/Mo–Se–C bonding towards high performance sodium ion capacitors

MoSe2, as a representative two-dimensional transition selenide with a broad interlayer distance of 0.65 nm and a high theoretical capacity of 422 mAh g−1, is considered an optimal anode material for sodium-ion batteries (SIBs). However, its unsatisfactory electrical conduction and structural instability often lead to severe capacity decay during cycling, hindering its large-scale application in SIBs. To overcome these challenges, coupling heterostructures has been identified as an effective solution. The establishment of multiple heterointerfaces can minimize interface diffusion resistance, significantly enhancing ion and electron delivery dynamics compared to a single component. In this work, multiple heterogeneous Co/CoSe/MoSe2 uniformly distributed in carbon nanofibers (CNF) via Co/Mo–Se–C bonding are successfully synthesized using electrospinning and subsequent calcination. Importantly, the Co/CoSe and Co/MoSe2 heterointerfaces can greatly accelerate charge transfer and improve Na + adsorption capability compared to the CoSe/MoSe2 heterostructure, as corroborated by theoretical calculations. Given the high rate performance of Co/CoSe/MoSe2@CNF as an anode in SIBs (267.9 mAh g−1 at 5 A g−1), a rocking-chair sodium-ion capacitor (SIC) incorporating a Co/CoSe/MoSe2@CNF anode and a Na3V2(PO4)3 cathode is proposed, delivering high energy densities of 199.1 Wh kg−1 at 180 W kg−1 and 126.8 Wh kg−1 at 3280 W kg−1.

Liquid bath-assisted combustion activation preparation of nitrogen/sulfur-doped porous carbon for sodium-ion battery applications

A liquid-bath-assisted salt-template combustion activation method has been developed to overcome the shortcomings of the conventional template method, including elaborate processes and environmental pollution. Herein, N/S double-doped porous carbon material (ECSK-15) with high specific surface area (1148.60 m2 g-1) is synthesized through it for sodium-ion batteries (SIBs). Benefitting from this approach, the number of ion diffusion channels and the ion exchange rate of the product are significantly increased. When using ether-based electrolyte, after 1000 cycles at a large current density of 2 A g−1, the reversible capacity could still be maintained at 135.60 mA h g−1. The assembled full cell exhibits a high reversible capacity of 480.49 mAh g-1 at a current rate of 0.5 A g-1. The energy density is calculated to be 204.11 Wh kg-1 at a power density of 160.71 W kg-1. This work provides a porous carbon anode material with good sodium-ion storage capacity and multiplicity performance for application in SIBs, as well as a new pathway for the green synthetic utilization of the molten salt template method in the field of energy storage.

Colloidally synthesized Cu3VS4 nanocrystals as a long cycling anode material for sodium-ion batteries

We report on the colloidal synthesis of Cu3VS4 nanocrystals as an earth abundant anode material for sodium-ion battery applications. The nanocrystals were structurally characterized prior to testing in half-cells, where they displayed excellent cycling stability up to 1000 cycles, demonstrating the potential of colloidally synthesised materials for sustainable battery applications.

Tailoring Stepped Layered Titanates for Sodium-Ion Battery Applications

Tailoring Stepped Layered Titanates for Sodium-Ion Battery Applications

Upscaling Brønsted acid intercalation and exfoliation of graphite into graphene by polyoxometalate clusters for sodium-ion battery application

Non-oxidative intercalation of graphite avoids damage to graphene lattices and is a suitable method to produce high-quality graphene. However, the yield of exfoliated graphene is low in this process due to the poor delamination efficiency of guest species. In this study, a Brønsted acid intercalation protocol is developed involving polyoxometalate (POM) clusters (H6P2W18O62) as guests and intercalation of graphite is realized at the sub-nanometer scale. Theoretical simulation based on DFT elucidates the stepwise intercalation mechanism of Brønsted acid molecules and clusters. Unlike common molecules/ionic guests, intercalation of POM clusters induces large expansion and extensive donor–acceptor interactions among graphite interlayers. This significantly weakens the van der Waals forces and promotes exfoliation efficiency of graphene layers. The exfoliated graphene possesses outstanding features of large lateral size, thin thickness, and high purity, and shows excellent performance as the anode for high power sodium-ion batteries. This work proffers a new pathway toward non-oxidative intercalation of graphite for large-scale production of graphene.

First-Principles Study of High-Entropy Sulfides and their Alkali Metal-Doped Modification as Cathode Material for Sodium-Ion Batteries.

High-entropy materials (HEMs) have been explored as high-capacity cathode materials for sodium-ion batteries (SIBs) due to their excellent structural stability and abundant metal redox sites. Among them, high-entropy sulfides (HESs) have greater potential and more extensive research than high-entropy oxides, as they exhibit higher charging voltage and theoretical capacity as cathodes. Furthermore, alkali metal doping of HESs can further enhance their performance and broaden their application fields. Inspired by the cocktail effect of HEMs, we performed the first theoretical calculation of the properties of Na(MnFeCoNi)1/2S and its Li-doped derivative, Na7/8Li1/8(MnFeCoNi)1/2S, to understand their potential as SIB cathode materials. Using density functional theory based on first principles, we investigated the structure and electronic characteristics of Na(MnFeCoNi)1/2S and Na7/8Li1/8(MnFeCoNi)1/2S, and calculated their theoretical voltage and capacity, respectively. Compared with Na(MnFeCoNi)1/2S, Na7/8Li1/8(MnFeCoNi)1/2S showed better electronic performance in reducing the band gap and increasing the density of states, ultimately providing a specific capacity of 160.3 mAh ⋅ g-1 and a charging voltage of 4.85 V in sodium-ion storage. Moreover, Na7/8Li1/8(MnFeCoNi)1/2S exhibited remarkable structural stability throughout the sodium-ion deintercalation process, thus it can be reasonably concluded that Na7/8Li1/8(MnFeCoNi)1/2S can serve as an excellent cathode material for future SIB applications.

Off-Stoichiometry of Sodium Iron Pyrophosphate as Cathode Materials for Sodium-Ion Batteries with Superior Cycling Stability.

As one of the important devices for large-scale electrochemical energy storage, sodium-ion batteries have received much attention due to the abundant resources of raw materials. However, whether it is a base station power source, an energy storage power station, or a start-stop power supply, long energy cycle life (more than 5000 cycles), high stability, and safety performance are application prerequisites. Regrettably, currently, few sodium-ion batteries can meet this requirement, mainly due to shortcomings in positive electrode performance. We report a sufficiently stable sodium-ion battery cathode material, Na2Fe0.95P2O7, that retains 97.5% capacity after 5000 charge/discharge cycles. The use of nonstoichiometry in the lattice enables simultaneous modification of the crystal and electronic structure, promoting Na2Fe0.95P2O7 to be extremely stable while still being able to achieve a capacity of 92 mAh g-1 and stable cycling at high temperatures up to 60 °C. Our results confirm the positive effect of nonstoichiometric ratios on the performance of Na2Fe0.95P2O7 and provide a reliable idea to promote the practical application of sodium-ion batteries.

ICE optimization strategies of hard carbon anode for sodium-ion batteries: from the perspective of material synthesis

Abstract With the continuous exploration of researchers in the field of sodium-ion batteries, the performance of sodium-ion batteries has been greatly improved, and it has a wide range of application prospects in large-scale energy storage, traffic power and other fields. Hard carbon is the most important anode material for sodium-ion batteries. Although it has the advantages of low cost, stable structure and performance, it still has the problems of low initial coulomb efficiency (ICE) and poor rate performance in application. In order to solve the problem of low ICE of hard carbon anode of sodium-ion battery, literatures about hard carbon anode of sodium-ion battery in recent years are comprehensively reviewed. Based on the microstructure of hard carbon material, the causes of low ICE of hard carbon are analyzed. At the same time, from the point of view of material structure design and regulation, the current optimization strategies of hard carbon anode ICE are summarized, including the following aspects: optimization and improvement of carbonization process, precursor screening and design, surface coating strategy, micro-pore structure control and catalytic carbonization strategy. It is hoped that this review can provide reference for further optimization of hard carbon properties and its large-scale application in sodium-ion batteries.

Ti─O─C Bonding at 2D Heterointerfaces of 3D Composites for Fast Sodium Ion Storage at High Mass Loading Level.

3D composite electrodes have shown extraordinary promise as high mass loading electrode materials for sodium ion batteries (SIBs). However, they usually show poor rate performance due to the sluggish Na+ kinetics at the heterointerfaces of the composites. Here, a 3D MXene-reduced holey graphene oxide (MXene-RHGO) composite electrode with Ti─O─C bonding at 2D heterointerfaces of MXene and RHGO is developed. Density functional theory (DFT) calculations reveal the built-in electric fields (BIEFs) are enhanced by the formation of bridged interfacial Ti─O─C bonding, that lead to not only faster diffusion of Na+ at the heterointerfaces but also faster adsorption and migration of Na+ on the MXene surfaces. As a result, the 3D composite electrodes show impressive properties for fast Na+ storage. Under high current density of 10mAcm-2, the 3D MXene-RHGO composite electrodes with high mass loading of 10mgcm-2 achieve a strikingly high and stable areal capacity of 3mAhcm-2, which is same as commercial LIBs and greatly exceeds that of most reported SIBs electrode materials. The work shows that rationally designed bonding at the heterointerfaces represents an effective strategy for promoting high mass loading 3D composites electrode materials forward toward practical SIBs applications.

Synthesis and properties optimization of Na3(VOPO4)2F cathode material for sodium-ion batteries by co-precipitation method

Na3(VOPO4)2F (NVOPF) has become one of the most promising cathodes of the large-scale application of sodium-ion batteries (SIBs) owning to its high working voltage and high discharging specific capacities properties. However, the immature synthetic routes, the tedious preparation process as well as high preparation cost restrict its promotion and application to some extent. In this work, the pure NVPOF was successfully prepared by liquid phase coordination chemistry combined with co-precipitation method based on theoretical speculation. The sodium storage performances are optimized by adjusting the key process parameters such as the pH value of solutions, the catalogue of pH regulators and the solution concentrations. When pH value of the solution is 4.50, oxovanadium sulfate solution concentration lies at c[v] = 1.5 mol L−1, the as-prepared NVPOF outperforms the optimal performances. The NVPOF cathode material synthesized under the optimized conditions boasts a perfect NASICON sodium-storage structure, spherical or quasi spherical morphology. In detail, the specific capacity is 110 mAh g−1 at 0.1 C and the discharging voltage is 3.86 V. The first coulombic efficiency is 91.4 %, and the specific capacity decay from 97 mAh g−1 to 87 mAh g−1 with 91.3 % capacity retention after 300 cycles in the half-cell system. This large-scale co-precipitation synthesis of NVOPF will provide new guidance for the development and application of cathode materials for SIBs.

Ultrafast synthesis of hard carbon for high-rate and low-temperature sodium-ion storage through flash Joule heating

Developing effective strategies to promote the sodium-ion storage performance of hard carbon anodes is essential for its practical application in sodium-ion batteries. The carbonization process plays a crucial role in regulating the microstructure of hard carbon. Conventional carbonization methods of slow-heating have hit a bottleneck in structural controls of hard carbon materials. Herein, hard carbon with high-rate and low-temperature sodium storage capability is ultrafast synthesized by flash Joule heating. Compared to the hard carbon synthesized by conventional slow-heating, the hard carbon synthesized by flash Joule heating has smaller particle size, larger interlayer spacing, and larger closed-pores leading to superior performance. This work provides a simple and effective method of boosting sodium-ion storage performance for hard carbon materials.