High-performance Sodium-ion Batteries Research Articles

The Distance Between Phosphate-Based Polyanionic Compounds and Their Practical Application For Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) are a viable alternative to meet the requirements of future large-scale energy storage systems due to the uniform distribution and abundant sodium resources. Among the various cathode materials for SIBs, phosphate-based polyanionic compounds exhibit excellent sodium-storage properties, such as high operation voltage, remarkable structural stability, and superior safety. However, their undesirable electronic conductivities and specific capacities limit their application in large-scale energy storage systems. Herein, the development history and recent progress of phosphate-based polyanionic cathodes are first overviewed. Subsequently, the effective modification strategies of phosphate-based polyanionic cathodes are summarized toward high-performance SIBs, including surface coating, morphological control, ion doping, and electrolyte optimization. Besides, the electrochemical performance, cost, and industrialization analysis of phosphate-based polyanionic cathodes for SIBs are discussed for accelerating commercialization development. Finally, the future directions of phosphate-based polyanionic cathodes are comprehensively concluded. It is believed that this review can provide instructive insight into developing practical phosphate-based polyanionic cathodes for SIBs.

Vacancy defect MoSeTe embedded in N and F co-doped carbon skeleton for high performance sodium ion batteries and hybrid capacitors

Sodium-ion batteries (SIBs) and hybrid capacitors (SIHCs) have garnered significant attention in energy storage due to their inherent advantages, including high energy density, cost-effectiveness, and enhanced safety. However, developing high-performance anode materials to improve sodium storage performance still remains a major challenge. Here, a facile one-pot method has been developed to fabricate a hybrid of MoSeTe nanosheets implanted within the N,F co-doped honeycomb carbon skeleton (MoSeTe/N,F@C). Experimental results demonstrate that the incorporation of large-sized Te atoms into MoSeTe nanosheets enlarges the layer spacing and creates abundant anion vacancies, which effectively facilitate the insertion/extraction of Na+ and provide numerous ion adsorption sites for rapid surface capacitive behavior. Additionally, the heteroatoms N,F co-doped honeycomb carbon skeleton with a highly conductive network can restrain the volume expansion and boost reaction kinetics within the electrode. As anticipated, the MoSeTe/N,F@C anode exhibits high reversible capacities along with exceptional cycle stability. When coupled with Na3V2(PO4)3@C (NVPF@C) to form SIB full cells, the anode delivers a reversible specific capacity of 126 mA h g−1 after 100 cycles at 0.1 A g−1. Furthermore, when combined with AC to form SIHC full cells, the anode demonstrates excellent cycling stability with a reversible specific capacity of 50 mA h g−1 keeping over 3700 cycles at 1.0 A g−1. In situ XRD, ex situ TEM characterization, and theoretical calculations (DFT) further confirm the reversibility of sodium storage in MoSeTe/N,F@C anode materials during electrochemical reactions, highlighting their potential for widespread practical application. This work provides new insights into the promising utilization of advanced transition metal dichalcogenides as anode materials for Na+-based energy storage devices.

Breaking Mass Transport Limitations by Iodized Polyacrylonitrile Anodes for Extremely Fast-Charging Lithium-Ion Batteries.

The fast-charging capability of rechargeable batteries is greatly limited by the sluggish ion transport kinetics in anode materials. Here we develop an iodized polyacrylonitrile (I-PAN) anode that can boost the bulk/interphase lithium (Li)-ion diffusion kinetics and accelerate Li-ion desolvation process to realize high-performance fast-charging Li-ion batteries. The iodine immobilized in I-PAN framework expands ion transport channels, compresses the electric double layer, and changes the inner Helmholtz plane to form LiF/LiI-rich solid electrolyte interphase layer. The dissolved iodine ions in the electrolyte self-induced by the interfacial nucleophilic substitution of PF6 - not only promote the Li-ion desolvation process, but also reuse the plated/dead Li formed on the anode under fast-charging conditions. Consequently, the I-PAN anode exhibits a high capacity of 228.5 mAh g-1 (39 % of capacity at 0.5 A g-1 delivered in 18 seconds) and negligible capacity decay for 10000 cycles at 20 A g-1 . The I-PAN||LiNi0.8 Co0.1 Mn0.1 O2 full cell shows excellent fast-charging performance with attractive capacities and negligible capacity decay for 1000 cycles at extremely high rates of 5 C and 10 C (1 C=180 mA g-1 ). We also demonstrate high-performance fast-charging sodium-ion batteries using I-PAN anodes.

Constructing Abundant Oxygen-Containing Functional Groups in Hard Carbon Derived from Anthracite for High-Performance Sodium-Ion Batteries

Hard carbon is regarded as one of the greatest potential anode materials for sodium-ion batteries (SIBs) because of its affordable price and large layer spacing. However, its poor initial coulombic efficiency (ICE) and low specific capacity severely restrict its practical commercialization in SIBs. In this work, we successfully constructed abundant oxygen-containing functional groups in hard carbon by using pre-oxidation anthracite as the precursor combined with controlling the carbonization temperature. The oxygen-containing functional groups in hard carbon can increase the reversible Na+ adsorption in the slope region, and the closed micropores can be conducive to Na+ storage in the low-voltage platform region. As a result, the optimal sample exhibits a high initial reversible sodium storage capacity of 304 mAh g−1 at 0.03 A g−1, with an ICE of 67.29% and high capacitance retention of 95.17% after 100 cycles. This synergistic strategy can provide ideas for the design of high-performance SIB anode materials with the intent to regulate the oxygen content in the precursor.

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.

Fe0.6Co0.3Ni0.1S2@NC core-shell nanoboxes as anodes for ultrafast sodium-ion batteries

Developing sodium storage anode materials with high capacity and high rate capability is the primary challenge for high-performance sodium-ion batteries. This study presents sulfide nanoboxes with nitrogen-doped carbon encapsulation, specifically Fe0.6Co0.3Ni0.1S2@NC, as a promising anode material for sodium-ion batteries due to its high electrical conductivity. The Fe0.6Co0.3Ni0.1S2@NC is manufactured using polydopamine-coated Prussian blue analogues as the precursor in a sulfidation-in-nanobox strategy. Experimental analysis suggests that the Fe0.6Co0.3Ni0.1S2 nanoparticles with conformal carbon layers are uniformly embedded in a three-dimensional, high-conductivity carbon shell to form Fe0.6Co0.3Ni0.1S2@NC. The anode material demonstrates a high capacity of up to 1000 mAh g−1 at 0.1 A g−1 and delivers 390 mAh g−1 even at a high rate of 10 A g−1.

Constructing P2/O3 biphasic structure of Fe/Mn-based layered oxide cathode for high-performance sodium-ion batteries

Fe/Mn-based layered oxide cathode is regarded as a competitive candidate for sodium-ion batteries (SIBs) because of its high theoretical capacity, earth abundance and low cost. However, its poor cycling stability still remains a major bottleneck. Herein, P2/O3 biphasic Na0.67Fe0.425Mn0.425Cu0.15O2 layered oxide is successfully synthesized via a sol–gel method. It is observed that Cu substitution can facilitate the conversion of P2 to O3 phase, and the P2/O3 composite structure can be obtained with an appropriate amount of Cu. Meanwhile, in-situ XRD reveals that constructing P2/O3 composite structure can realize the highly reversible phase transition process of P2/O3–P2/P3–OP4/OP2 and decrease the lattice mismatch during Na+ insertion/extraction. Consequently, the biphasic P2/O3-Na0.67Fe0.425Mn0.425Cu0.15O2 electrode exhibits 87.1 % capacity retention after 100 cycles at 1C, while the single phase P2-Na0.67Fe0.5Mn0.5O2 electrode has only 36.4 %. Therefore, the constructing biphasic structure is proved to be an effective strategy for designing high-performance Fe/Mn-based layered oxide cathodes.

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.

Insights into unrevealing the effects of the monovalent cation substituted tunnel-type cathode for high-performance sodium-ion batteries

Tunnel-type Na0.44MnO2 (NMO) has attracted extensive concern as a prospective cathode for sodium-ion batteries due to the advantages of facile synthesis and cost-effectiveness. Nonetheless, the low capacity, unsatisfactory rate performance, and sluggish kinetics of NMO impede its further development for commercial application. Herein, a series of Li-substituted Na0.44Mn1-xLixO2 samples are synthesized to address the abovementioned issues. Results demonstrate that Li substitution can not only stabilize the crystal structure but also facilitate the Na+ diffusion behavior during the charging/discharging process. Density functional theory (DFT) calculations reveal that Li introduction can effectively strengthen the metallicity of NMO, which is conducive to electron transferability. Accordingly, the optimized Na0.44Mn0.94Li0.06O2 (NMOL0.06) can exhibit an improved reversible capacity of 106.1mAh g−1 at 5C, accompanying extraordinary cycling durability with 80.6 % capacity retention after 700 cycles at 10C. More importantly, the full cell combined with the NMOL0.06 cathode and the commercial hard carbon anode displays a high energy density of 257.2Wh kg−1, and superior capacity retention of 83.6 % after 300 cycles at 1C, demonstrating its great potential for practical applications. This work not only provides some insights into the influence of Li substitution on tunnel-type materials but also elucidates the construction of ultra-stable and high-performance cathodes for sodium-ion batteries.

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.

High-Capacity and High-Rate sodium storage of CoS2/NiS2@C anode material enabled by interfacial C-S covalent bond and Mott–Schottky heterojunction

In this paper, carbon-matrix-embedded Mott–Schottky (MS) heterojunction of CoS2/NiS2 (CoS2/NiS2@C) is prepared. The obtained CoS2/NiS2@C offers superior sodium storage performance such as large specific capacity (861.0 mAh/g at 2 A/g), extraordinary rate capability (649.2 mAh/g at 10 A/g, 371.4 mAh/g at 40 A/g) and excellent cycling stability (380.5 mAh/g after 3000 cycles at 10 A/g, and 298.5 mAh/g after 2000 cycles at 40 A/g). Electrochemical measurements and density functional theory (DFT) calculations as well as in/ex-situ characterization techniques are employed to reveal the underlying mechanisms. It is found that the outperforming sodium storage properties of CoS2/NiS2@C can be mainly attributed to the C-S bond and the MS heterojunction. The C-S bond formed at the interface between CoS2/NiS2 and the carbon matrix promotes the migration of the sodium ions in the carbon matrix to the embedded CoS2/NiS2, while the MS heterojunction accelerates the electrochemical reaction kinetics of CoS2/NiS2. Moreover, full-cell is assembled with CoS2/NiS2@C and Na3V2(PO4)3/C to validate the practical application of CoS2/NiS2@C. The full-cell achieves both high specific capacity and outstanding rate performance, demonstrating the great application potential of such CoS2/NiS2@C anode in high-performance sodium-ion batteries.

Boosted Redox Kinetics Enabling Na3V2(PO4)3 with Excellent Performance at Low Temperature through Cation Substitution and Multiwalled Carbon Nanotube Cross-Linking.

The open NASICON framework and high reversible capacity enable Na3V2(PO4)3 (NVP) to be a highly promising cathode candidate for sodium-ion batteries (SIBs). Nevertheless, the unsatisfied cyclic stability and degraded rate capability at low temperatures due to sluggish ionic migration and poor conductivity become the main challenges. Herein, excellent sodium storage performance for the NVP cathode can be received by partial potassium (K) substitution and multiwalled carbon nanotube (MWCNT) cross-linking to modify the ionic diffusion and electronic conductivity. Consequently, the as-fabricated Na3-xKxV2(PO4)3@C/MWCNT can maintain a capacity retention of 79.4% after 2000 cycles at 20 C. Moreover, the electrochemical tests at -20 °C manifest that the designed electrode can deliver 89.7, 73.5, and 64.8% charge of states, respectively, at 1, 2, and 3 C, accompanied with a capacity retention of 84.3% after 500 cycles at 20 C. Generally, the improved electronic conductivity and modified ionic diffusion kinetics resulting from K doping and MWCNT interconnecting endows the resultant Na3-xKxV2(PO4)3@C/MWCNT with modified electrochemical polarization and improved redox reversibility, contributing to superior performance at low temperatures. Generally, this study highlights the potential of alien substitution and carbon hybridization to improve the NASICON-type cathodes toward high-performance SIBs, especially at low temperatures.

Simultaneous modification of dual-substitution with CeO2 coating boosting high performance sodium ion batteries

Na3V2(PO4)3 (NVP) is highly valued based on the stable construction among the polyanionic compounds. Nevertheless, the drawback of low intrinsic conductivity has been impeded its further application. In this paper, the internal channels of the crystal structure are extended by the introduction of larger radius Ce3+, which increases the transport rate of Na+. The introduction of Mo6+ replacing the V site leads to a beneficial n-type doping effect and facilitates the transportation of electrons. Besides, CeO2 cladding is introduced to further enhance the electronic conductivity of NVP system. Initially, CeO2 serves as an n-type semiconductor and functions as a conductive additive to significantly enhance the electronic conductivity of the electrode, thereby improving the electrochemical characteristics. Moreover, CeO2 functions as an oxygen buffer, aiding in the maintenance of active metal dispersion during operation and enabling efficient electron transfer between CeO2 and [VO6] octahedra in NVP, thus fostering outstanding electrical connectivity between the oxides. CeO2 cladding can be effectively integrated with the carbon layer to stabilize the NVP system. Comprehensively, the modified Na3V1.79Ce0.07Mo0.07(PO4)3/C@8wt.%CeO2 (CeMo0.07@8wt.%CeO2) composite exhibits excellent rate and cycling properties. It delivers a capacity of 113.4 mAh/g at 1C with a capacity retention rate of 80.3 % after 150 cycles. Even at 10C and 40C, it also submits high capacities of 84.7 mAh/g and 76 mAh/g, respectively. Furthermore, the CHC//CeMo0.07@8wt.%CeO2 asymmetric full cell possesses excellent sodium storage property, indicating its prospective application potentials.

The ultralong Mo4O11 nanoribbons: Ultrasonic synthesis and topotactic transformation toward high-performance sodium-ion batteries

The design and synthesis of two-dimensional layered transitional metal oxides (TMOs) have been of great interest for their potential application in sodium-ion batteries (SIBs), due to the advantages such as multivalent ions and tunable interlayer spacing. However, achieving a well-defined crystal structural topology and geometric morphology in TMOs still remains a significant challenge, particularly in tailoring their polyhedral structures. Herein, the ultralong Mo4O11 nanoribbons (Mo4O11-NR) were prepared by a simple aniline-assisted sonochemical method for the first time. The resulting nanoribbons possess a unique tunnel structure and exhibit topologically frustrated arrangements of MoO6 octahedra and MoO4 tetrahedra. When used as anodes for SIBs, multielectron redox reactions of Mo4O11-NR allow for high-capacity energy storage. The buffered volume expansion of the nanoribbons accommodates the strain that occurs during cycling, thereby boosting cycling stability. The topologically frustrated arrangements of the polyhedra further contribute to the efficient storage and transfer of ions and electrons. As a result, Mo4O11-NR anode achieves a reversible specific capacity of 101 mA h g−1 after 2,000 cycles, when subjected to a high current density of 5 A g−1. This exceptional performance highlights the potential of Mo4O11-NR material as an advanced anode material for high-power devices.

Anion-derived cathode interface engineering enables ether-based electrolytes for sodium-ion batteries

High-performance sodium-ion batteries (SIBs) require not only non-aqueous electrolytes with high ion conductivity but also high interfacial compatibility with both electrodes. Ether-based electrolytes are considered one of the most promising electrolyte systems for SIBs due to the advantages of high reduction stability and weakly desolvating power. However, conventional ether-based electrolytes are easy to decompose and deteriorate on the cathode/electrolyte interface under high voltage, which greatly restricts their practical application in SIBs. Herein, a novel and effective interfacial stabilization strategy is proposed and systemically investigated. A homogeneous and compact cathode electrolyte interphase (CEI) film rich in fluorides and borides can be successfully constructed on the cathode surface by pre-cycling of NVP@C cathode in the NaODFB-DEGDME electrolyte. The ODFB anion-derived CEI film can effectively inhibit the continuous oxidation decomposition of NaPF6-DEGDME electrolytes. As a result, the Na||NVP@C half-cell can stably cycle for 1500 cycles with high average Coulombic efficiency (CE, >99.7 %) at 5C. This work illustrates the significance of the composition and structure of CEI film for improving the interfacial stability of high-voltage SIBs with ether-based electrolytes.

Construction of Three-Dimensional Hierarchical CoSe2 Microflowers Assembled by Thin Nanosheets for High-Performance Sodium-Ion Batteries

Transition metal selenides are considered as promising anode materials for sodium-ion batteries (SIBs) due to their high capacity and low cost. However, they suffer from large volume change, serious polyselenide dissolution and sluggish reaction kinetics during charge/discharge process, resulting in poor cycling stability and low rate performance for SIBs, which further restrict their widespread application. Here, we developed carbon-free three-dimensional (3D) hierarchical microflower-shaped CoSe2 with a diameter size of approximately 2[Formula: see text][Formula: see text]m, composed of nanosheets through a one-step solvothermal method. The thin nanosheets are conducive to shortening the Na[Formula: see text] diffusion channels and relieving the volume expansion, and the 3D hierarchical microflower architecture could effectively prevent the agglomeration of nanosheets; accordingly, the resulting CoSe2 microflowers deliver a high specific capacity of 451.94[Formula: see text]mA[Formula: see text]h[Formula: see text]g[Formula: see text] even at 0.5[Formula: see text]A[Formula: see text]g[Formula: see text] after 100 cycles, compared with CoSe2 nanoparticles. This work offers an approach for designing metal selenides with high capacities and rate capability for SIBs.

Heteroatom screening and microcrystal regulation of coal-derived hard carbon promises high-performance sodium-ion batteries

Coal is a cost-effective and high-yield precursor for the carbon anode of sodium-ion batteries (SIBs). To enhance Na+ storage behavior, it is crucial to prevent long-range graphitization of microcrystals within the coal structure during high-temperature carbonization. Herein, we present a strategy to inhibit graphitized microcrystals of anthracite-derived carbon, which reveals the correlations between the initial Coulombic efficiency (CE) and heteroatom/defects. By introducing NH3 during the carbonization process of anthracite, it is possible to effectively remove the heteroatoms (O, S, etc.) in anthracite, while also expanding the spacing of carbon layers derived from anthracite. This results in obtaining high capacity and high initial CE. Using Nitrogen-doped anthracite hard carbon (N-AC-1200) as an anode material for SIBs, a high reversible capacity of 220 mA h g−1 at 0.1 A g−1 is achieved. Furthermore, a full cell assembled by Na2/3Ni1/3Mn2/3O2 (NNMO) cathode and N-AC-1200 anode delivers a high capacity of 76 mA h g−1 at 5C. The insights provided by this work will help guide the design of heteroatom-controlled hard carbon microcrystalline environment and provide new ideas for practical hard carbon electrode design principles.

Single-Crystal Growth of P2-Type Layered Oxides with Increased Exposure of {010} Planes for High-Performance Sodium-Ion Batteries.

An increase in the size of single-crystal particles can effectively reduce the interfacial side reactions of layered oxides for sodium-ion batteries at high voltages but may result in sluggish Na+ transport. Herein, single-crystal Na0.66Ni0.26Zn0.07Mn0.67O2 with increased proportions of {010} planes is synthesized by adding low-cost NaCl as the molten salt. With the assistance of a NaCl molten salt, the median diameter (D50) of single-crystal Na0.66Ni0.26Zn0.07Mn0.67O2 increases to 10.46 μm relative to that of the comparison sample without NaCl (6.57 μm). Electrolyte decomposition on the surface of single-crystal Na0.66Ni0.26Zn0.07Mn0.67O2 is considerably suppressed, owing to a decrease in the specific surface area. Moreover, the increased exposure of {010} planes is favorable for improving the Na+ transport kinetics of single-crystal particles. Therefore, at 100 mA g-1, single-crystal Na0.66Ni0.26Zn0.07Mn0.67O2 exhibits a high-capacity retention of 96.6% after 100 cycles, which is considerably greater than that of the comparison sample (86.8%). Moreover, the rate performance of single-crystal Na0.66Ni0.26Zn0.07Mn0.67O2 (average discharge capacity of 81.2 mAh g-1) is superior to that of the comparison sample (average discharge capacity of 61.2 mAh g-1) at 2000 mA g-1. This work provides a new approach for promoting the single-crystal growth of layered oxides for highly stable interfaces at high voltages without compromising Na+ transport kinetics.

Honeycomb-Structured MoSe2 /rGO Composites as High-Performance Anode Materials for Sodium-Ion Batteries.

Sodium-ion batteries are a promising substitute for lithium batteries due to the abundant resources and low cost of sodium. Herein, honeycomb-shaped MoSe2 /reduced graphene oxide (rGO) composite materials are synthesized from graphene oxide (GO) and MoSe2 through a one-step solvothermal process. Experiments show that the 3D honeycomb structure provides excellent electrolyte penetration while alleviating the volume change during electrochemical cycling. An anode prepared with MoSe2 /rGO composites exhibits significantly improved sodium-ion storage properties, where a large reversible capacity of 215mAhg-1 is obtained after 2700 cycles at the current density of 30.0Ag-1 or after 5900 cycles at 8.0Ag-1 . When such an anode is paired with Na3 V2 (PO4 )3 to form a full cell, a reversible specific capacity of 107.5mAhg-1 can be retained after 1000 cycles at the current of 1.0Ag-1 . Transmission electron microscopy, X-ray photoelectron spectroscopy and in situ X-ray diffraction (XRD) characterization reveal the reversible storage reaction of Na ions in the MoSe2 /rGO composites. The significantly enhanced sodium storage capacity is attributed to the unique honeycomb microstructure and the use of ether-based electrolytes. This study illustrates that combining rGO with ether-based electrolytes has tremendous potential in constructing high-performance sodium-ion batteries.

Sb/SnO@C composite prepared by electrospinning for high performance sodium ion battery anodes

The development of high-performance anode material for sodium-ion batteries remains a challenge because of their low capacity, which limits their commercial application. Compared with carbon-based materials, metallic Sb and SnO-based anodes have received extensive attention because of their high theoretical specific capacity and safe working potential. The main problem faced is the serious volume expansion during charging and discharging, leading to irreversible loss of capacity and poor cycle life. In this paper, Sb/SnO@C composite material with adjustable ratio of Sb/SnO was prepared via electrospinning by encapsulating Sb and SnO particles in lantern-like carbon nanocages which connected through the nanofibers. The unique structure can not only effectively mitigate the volume changes during the cycle, but also provide multiple effective paths for ion and electron transport. The kinetic analysis is further performed with the assist of CV and EIS. The results show that the prepared composite can provide impressive Na+ ions storage and transport performance, and can still deliver a reversible charging capacity of 413mAhg−1 after 200 cycles at a current density of 50mAg−1, with a capacity retention ratio of 84%. This work provides a new strategy for the development of sodium ion batteries with high capacity and stable cycle performance.