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A novel oxidized ZIF-8/polyacrylonitrile fiber interlayer with excellent lithophilicity and uniform microporous structure could regulate Li-ion flux to obtain high performance of Li metal batteries.

Anthraquinone (AQ) and its derivatives have been attracting more attention as promising electrode materials for lithium storage because of their high specific capacity, structural diversity, and environmental friendliness. The dissolution and poor electrical conductivity of AQ, however, limit its practical application. Here, a novel metal-organic coordination polymer with a one-dimensional (1D) chain ([C

Plastic wastes are converted into two-dimensional carbon nanosheets with a graphitic-like structure and interlayer channels for improved solar evaporation performance.

CoSe-SC@NC as an advanced anode for SIBs have been reported in this work, it exhibits excellent electrochemical performance. Meanwhile, the improved sodium storage mechanism is further analyzed by in situ XRD and ex situ HRTEM.

A new metal-organic framework {(Me2NH2)2[Co3(μ3-O)(btb)2(py)(H2O)]·(DMF)2(H2O)2}n (Cobtbpy) was solvothermal synthesized (H3btb = 1,3,5-tri(4-carboxylphenyl)benzene, py = pyridine, DMF = N,N-dimethylformamide). Cobtbpy shows a (3,6)-connected rtl 3D network with a point symbol of (4·62)2(42·610·83) based on the [Co3(μ3-O)] clusters. The obtained Cobtbpy has stable, accessible, dense active sites and can be applied in the potassium- and sodium-ion batteries. Through mixing with single-walled carbon nanotubes, the prepared composite anode material Cobtbpy-0.9 achieved a high reversible capability, delivering 416 mAh/g in the potassium-ion batteries and 379 mAh/g in the sodium-ion batteries at 0.05 A/g. The outstanding properties of Cobtbpy-0.9 in the batteries demonstrated that this MOFs-based carbon composite is a highly desirable electrode material candidate for high-performance potassium- and sodium-ion batteries.

In recent years, rechargeable aqueous zinc-ion batteries (ZIBs) have shown extraordinary potential due to their safety, nontoxicity, sustainable zinc resources, and low price. However, the lack of suitable cathode materials hinders the development of ZIBs. Recently, layered phosphates have been widely used as cathode materials. As one typical phosphate cathode, vanadium oxyphosphate (VOPO

Due to the widespread employment of carbon materials in novel dual-ion batteries (DIBs) with high energy density, they possess the potential for large-scale energy storage and are inexpensive and environmentally friendly. However, drawbacks such as Al current collector corrosion and significant self-weight, as well as lithium metal abuse and poor deposition reversibility, impair the energy density and cycle performance of lithium-graphite DIBs (Li-G DIBs), severely limiting their application potential. Therefore, an integrated electrode structure design was proposed. That is, the flexible graphite and single-walled carbon nanotubes (SWCNTs) composite cathode (GSC), which is light-weight and self-supporting, and the self-supporting lithium metal anode, which is loaded on the flexible carbon cloth (CC) derived from waste mask (Li@CC), were prepared. Not only were the impacts of current collector corrosion and active material exfoliation avoided on the electrochemical performance, but the areal loading of Li metal was also regulated and its reversibility of deposition enhanced. At a current density of 200 mA g

Flexible power sources featuring high-performance, prominent flexibility and raised safety have received mounting attention in the area of wearable electronic devices. However, many great challenges remain to be overcome, notably the design and fabrication of flexible electrodes with excellent electrochemical performance and matching them with safe and reliable electrolytes. Herein, a facile approach for preparing flexible electrodes, which employs carbon cloth derived from commercial cotton cloth as the substrate of cathode and a flexible anode, is proposed and investigated. The promising cathode (NVPOF@FCC) with high conductivity and outstanding flexibility is prepared by efficiently coating Na3V2(PO4)2O2F (NVPOF) on flexible carbon cloth (FCC), which exhibits remarkable electrochemical performance and the significantly improved reaction kinetics. More importantly, a novel flexible quasi-solid-state sodium-ion full battery (QSFB) is feasibly assembled by sandwiching a P(VDF-HFP)-NaClO4 gel-polymer electrolyte film between the advanced NVPOF@FCC cathode and FCC anode. And the QSFBs are further evaluated in flexible pouch cells, which not only demonstrates excellent energy-storage performance in aspect of great cycling stability and high-rate capability, but also impressive flexibility and safety. This work offers a feasible and effective strategy for the design of flexible electrodes, paving the way for the progression of practical and sustainable flexible batteries.

The development of next-generation lithium metal batteries (LMBs) has been chronically hindered by uncontrollable dendrite growth and infinite dimension change of metal Li. Even though the porous carbon skeletons have been deemed as effective hosting materials to prepare low-stress Li metal anode (LMA), the lithiophobic feature and poor spatial regulation for Li nucleation/growth of carbon skeletons render the achievement of high-stable LMA to be challenging. Herein, vertical-aligned SnS2 nanosheet arrays (SnS2 NSA) with intrinsic lithiophilic nature, endowed by in situ formed Li13Sn5 via the alloying reaction of SnS2, are uniformly decorated on highly flexible carbon foam (SnS2 NSA@CF) to overcome the encountered issues of ordinary carbon skeletons. The vertical-aligned SnS2 nanosheet offers enriched lithiophilic surface area, thereby guiding the thin Li-nuclei layer uniformly deposited on nanosheet. Moreover, the continuous Li growth is proceeded on the initial Li-nuclei layer and spatially confined into the nanochannels of nanoarray to eliminate the volume change of LMA. The well-defined nanochannel effectively reduces the local current density and provides open spacing for quick charge transfer kinetics. Accordingly, the sustainable Li utilization with high Coulombic efficiency and highly stable Li plating/stripping with low polarization is achieved, shedding light on the feasibility of SnS2 NSA for dendrite-free LMA.

With the rapid development of sodium-ion batteries (SIBs), it is urgent to exploit the cathode materials with good rate capability, attractive high energy density and considerable long cycle performance. Na3V2(PO4)3 (NVP), as a NASICON-type electrode material, is one of the cathode materials with great potential for application because of its good thermal stability and stable. However, NVP has the inherent problem of low electronic conductivity, and various strategies are proposed to improve it, moreover, nanotechnology or nanostructure are involved in these strategies, the construction of nanostructured active particles and nanocomposites with conductive carbon networks have been shown to be effective in improving the electrical conductivity of NVP. Herein, we review the research progress of NVP performance improvement strategies from the perspective of nanostructures and classifies the prepared nanomaterials according to their different nano-dimension. In addition, NVP nanocomposites are reviewed in terms of both preparation methods and promotion effects, and examples of NVP nanocomposites at different nano-dimension are given. Finally, some personal views are presented to provide reasonable guidance for the research and design of high-performance polyanionic cathode materials of SIBs.

Sodium-ion batteries (SIBs) are prominently used for stationary energy storage due to the abundant resources and low cost of Na. The development of high-performance cathodes for SIBs will be a favorable choice for competing with the market-dominant lithium-ion batteries. Among the various cathodes, Na3V2(PO4)2O2−2xF1+2x (0 ≤ x ≤ 1) materials have become a preferred choice due to their superior structural stability, fast ion transport and high operating potential. Herein, a series of materials with various ratios of F− and O2− (F/O) are prepared via a high temperature solid-state method, and the tuning mechanism of different F/O ratios is studied in detail by analyzing the structural evolution, electrochemical performance and reaction kinetics of materials. The optimal F/O ratio material Na3V2(PO4)2O0.6F2.4 (x = 0.7) exhibits a favorable rate and cycling performance. The capacity at 20C is equivalent to that of the x = 0 material at 5C, and each cycle decay is 0.040% after 200 cycles at 0.5C. Moreover, the optimized F/O ratio material (x = 0.7) also demonstrates excellent reaction kinetics, and the Na apparent diffusion coefficient (Dapp,Na) for the high potential region is about 10−10–10−12 cm2 s−1. A systematic research of dual anion substitution in phosphates will be useful for the structural design and performance improvement of other cathode materials in SIBs.

Preparation of a material with excellent rate performance and high capacity contribution is significant for sodium-ion hybrid capacitors (SIHCs). TiO2 has been extensively studied due to its outstanding chemical stability, but the low specific capacity greatly hinders its practical application. Herein, TiO2 with a foveolate-shape is prepared via a precisely controlled Ostwald maturation procedure. Benefiting from the unique structure, foveolate TiO2 possesses satisfactory electrochemical performance. When used as the anode for SIHCs, a high reversible specific capacity of 290 mA h g−1 is obtained with an ultrahigh initial coulombic efficiency of 96% at 100 mA g−1. Even if the current density increases to 1000 mA g−1, the specific discharge capacity can still be maintained at 158 mA h g−1 after 1500 cycles. To further improve its capacity, the TiO2@MoSe2 composite electrode is synthesized by using foveolate TiO2 as the skeleton for the successful growth of MoSe2 nanosheets. A higher reversible specific capacity of 551 mA h g−1 is achieved at 100 mA g−1. Moreover, a reversible specific capacity of 164 mA h g−1 is maintained after 500 cycles at 5000 mA g−1. The foveolate TiO2 preparation method developed in this work provides new ideas for the development of both substrate materials and active materials in the field of energy storage.

Development of efficient and robust electrode materials is significant for sodium-ion batteries (SIBs). Metallic selenides have been widely investigated as a promising anode material based on their relatively high theoretical capacity. However, rapid capacity fading and huge volume changes greatly hinder their practical application. Herein, for the first time, uniform yolk-shell Fe7Se8@C/N nanoboxes (Fe7Se8@C/N NBs) with the Fe7Se8 cores completely embedded by a thin and robust carbon shell are prepared using a strategy of facile etching method combined with selenization for advanced anode materials for SIBs. Benefiting from the unique structural merits, the Fe7Se8@C/N NBs electrodes for Na-ion half cells exhibit high Na-ion storage capacity (385.5 mAh g−1 at 0.1 A g−1) and superior rate performance (316.0 mAh g−1 at 5 A g−1) as well as impressive cyclability with no capacity decay over 1000 cycles. The sodium storage mechanism of Fe7Se8@C/N NBs electrode is systematically studied with the aid of ex-situ X-ray diffraction and transmission electron microscopy. Finally, the assembled full cells coupled with the lab-made high-voltage Na3V2(PO4)2O2F cathode and Fe7Se8@C/N NBs anode materials show superior energy-storage performance.

N-doped hierarchically structured carbon pellicles (CZIF-8/PAN) were prepared from the carbonization of zeolitic imidazolate framework (ZIF-8)/polyacrylonitrile (PAN) composite fibers which were fabricated by electrospinning technique. The resultant free-standing nanofiberic pellicles can be cut into membrane disks and directly used as anode materials without any binder and additive. As an anode for sodium-ion batteries (SIBs), the CZIF-8/PAN nanofiberic carbon pellicles showed superior reversible capacities of 186.2 mAh g−1 at high current density of 1.0 A g−1 and an excellent cyclic stability (93.5% remaining after 600 cycles) compared to other similar reported carbonaceous anode materials for SIBs. The improved electrochemical performance of CZIF-8/PAN carbon pellicles is mainly attributed to the hierarchical porous structures produced by introducing large ZIF-8 particles as a template, which greatly promotes the large sodium cation transportation and electron transfer rates due to the enlarged pores and increased contact area between the electrode and electrolyte. In addition, the enhanced electrochemical performance of CZIF-8/PAN nanofiberic anodes also benefits from the doping of nitrogen atoms which enhance the conductivity and increase the active sites.

Polyanion-type compounds, used as promising cathode materials for sodium-ion batteries (SIBs), have attracted great attention because of their suitable operating voltage, stable framework and good thermal stability. However, they suffer from inherent low conductivity, poor high-rate capability and unsatisfactory cycle stability. Herein, in order to overcome these deficiencies, a feasible strategy, which integrates high conductivity reduced graphene oxide (rGO) with the representative vanadium-based fluorophosphates to form a 3D carbon network constructed in NaVPO4F, is proposed and investigated. Based on microstructural and morphological characterization, the NaVPO4F nanoparticles are successfully synthesized and uniformly embedded in a robust rGO carbon network. Ascribed to the multifunctional structure design, the reaction kinetics of NaVPO4F were significantly improved, as demonstrated by the electrochemical impedance spectroscopy, cyclic voltammetry at varied scan rates and galvanostatic intermittent titration technique. Moreover, the hard carbon (HC) and the NaVPO4F@rGO composite are employed as the anode and the cathode, respectively, to fabricate a sodium-ion full battery, which exhibits an excellent high-rate capability (75.1 mA h g−1 at 15C) and an outstanding cycling stability (0.0115% capacity decay per cycle over 1500 cycles at 5C rate). This study provides a feasible and effective method to develop high-performance polyanion-type electrode materials for SIBs.

Achieving fast-charging/discharging (FCD) performance for sodium-ion batteries (SIBs) has always been a great challenge, because of their slow reaction kinetics and the difficulty in ensuring the stability of the electrode during sodiation/desodiation. In this study, a hypoxic graphene (HG) is rationally designed and prepared using a simple high temperature treatment process. It is confirmed that the hypoxic surface is more conducive to the rapid conduction of electrons and forming a high quality SEI film in the first cycle to avoid irreversible side reactions. Furthermore, a versatile electrolyte suitable for improving the FCD performance of different carbon materials is screened and used in this system. As a result, the best sample of HG-1300 shows almost full pseudocapacitive behavior as an anode material for SIBs, and exhibits a super FCD performance (110 mA h g−1 at an ultrahigh current density of 200 A g−1, only 4 seconds per cycle) and ultralong lifespan (90.7% capacity retention over 100 000 cycles at 20 A g−1), even surpassing supercapacitors.

Impossible voltage plateau regulation for the cathode materials with fixed active elemental center is a pressing issue hindering the development of Na-superionic-conductor (NASICON)-type Na

Electrolyte additive is an effective strategy to inhibit the uncontrolled growth of Li dendrites for lithium metal batteries (LMBs). However, most of the additives are complex synthesis and prone to decompose in cycling. Herein, in order to guide the homogeneous deposition of Li

Constructing potential anodes for sodium-ion batteries (SIBs) with a wide temperature property has captured enormous interests in recent years. Fe1−xS, a zero-band gap material confirmed by density states calculation, is an ideal electrode for fast energy storage on account of its low cost and high theoretical capacity. Herein, Fe1−xS nanosheet wrapped by nitrogen-doped carbon (Fe1−xS@NC) is engineered through a post-sulfidation strategy using Fe-based metal-organic framework (Fe-MOF) as the precursor. The obtained Fe1−xS@NC agaric-like structure can well shorten the charge diffusion pathway, and significantly enhance the ionic/electronic conductivities and the reaction kinetics. As expected, the Fe1−xS@NC electrode, as a prospective SIB anode, delivers a desirable capacity up to 510.2 mA h g−1 at a high rate of 8000 mA g−1. Additionally, even operated at low temperatures of 0 and −25°C, high reversible capacities of 387.1 and 223.4 mA h g−1 can still be obtained at 2000 mA g−1, respectively, indicating its huge potential use at harsh temperatures. More noticeably, the full battery made by the Fe1−xS@NC anode and Na3V2(PO4)2O2F cathode achieves a remarkable rate capacity (186.8 mA h g−1 at 2000 mA g−1) and an impressive cycle performance (183.6 mA h g−1 after 100 cycles at 700 mA g−1) between 0.3 and 3.8 V. Such excellent electrochemical performance is mainly contributed by its pseudocapacitive dominated behavior, which brings fast electrode kinetics and robust structural stability to the whole electrode.

The intrinsic charge-transfer property bears the primary responsibility for the sluggish redox kinetics of the common electrode materials, especially operated at low temperatures. Herein, we report...

Na super ionic conductor (NASICON)-structured materials have evolved to play many critical roles in battery systems because of their three-dimensional framework structures. Here, by coupling NASICON-structured Na3V2(PO4)2O2F cathodes and Na3V2(PO4)3 anodes, an asymmetric Na-ion-based full cell exhibits two flat voltage plateaus at about 2.3 and 1.9 V and a high capacity of 101 mA h/g. Moreover, an all-solid-state Na-ion battery has been further enabled by the concept of using all NASICON-structured materials, including cathodes, anodes, and electrolytes (Na5YSi4O12), which delivers a high output voltage. Importantly, the full cell displays high safety without using a flammable organic liquid electrolyte and superior structure stability with all NASICON-structured materials.

Sodium ion batteries are in great need of electrode materials with high specificity and rate capability being developed. The sluggish reaction kinetics of SnO2-based materials has impeded their applications as anodes of SIBs. Designing electrode materials with high pseudocapacitive contribution can increase the near-surface faradaic reaction, which helps to improve their kinetics and achieve high rate capability. Here, we designed a high-pseudocapacitance sodium storage anode SnO2/N-rGO by downsizing the particle size of SnO2 and constructing an N-doped graphene wrapped structure. The ultrafine structure of SnO2 ensures the high faradaic near-surface reaction, while the N-doped graphene matrix guarantees the superior electron and Na+ diffusion. Meanwhile, the wrapped N-doped graphene acts as a buffer layer to alleviate the volumetric changes of the active SnO2. The obtained ultrafine SnO2/N-graphene composite exhibits a high capacity of 607.6 mA h g-1 at 50 mA g-1 with an impressive rate capability (261.8 mA h g-1 at 2 A g-1) in Na+ half-cells. Furthermore, a good performance with a capacity of 133.3 mA h g-1 at 2.4 A g-1 in Na+ full-cells can also be achieved, which makes it a promising anode material for SIBs.

Metallic sodium (Na) has been regarded as one of the most attractive anodes for Na-based rechargeable batteries due to its high specific capacity, low working potential, and high natural abundance. However, several important issues hinder the practical application of the metallic Na anode, including its high reactivity with electrolytes, uncontrolled dendrite growth, and poor processability. Metal nitrates are common electrolyte additives used to stabilize the solid electrolyte interphase (SEI) on Na anodes, though they typically suffer from poor solubility in electrolyte solvents. To address these issues, a Na/NaNO3 composite foil electrode was fabricated through a mechanical kneading approach, which featured uniform embedment of NaNO3 in a metallic Na matrix. During the battery cycling, NaNO3 was reduced by metallic Na sustainably, which addressed the issue of low solubility of an SEI stabilizer. Due to the supplemental effect of NaNO3, a stable SEI with NaNxOy and Na3N species was produced, which allowed fast ion transport. As a result, stable electrochemical performance for 600 h was achieved for Na/NaNO3||Na/NaNO3 symmetric cells at a current density of 0.5 mA cm-2 and an areal capacity of 0.5 mAh cm-2. A Na/NaNO3||Na3V2(PO4)2O2F cell with active metallic Na of ∼5 mAh cm-2 at the anode showed stable cycling for 180 cycles. In contrast, a Na||Na3V2(PO4)2O2F cell only displayed less than 80 cycles under the same conditions. Moreover, the processability of the Na/NaNO3 composite foil was also significantly improved due to the introduction of NaNO3, in contrast to the soft and sticky pure metallic Na. Mechanical kneading of soft alkali metals and their corresponding nitrates provides a new strategy for the utilization of anode stabilizers (besides direct addition into electrolytes) to improve their electrochemical performance.

All-purpose electrode materials (APEMs), which can be effectively available on not only alkali-ion batteries but also emerging Li metal batteries, are urgently pursued to open up cost-efficient tactics for practical application of energy storage systems (ESSs), but still remain challenging. Herein, the hierarchical porous carbon nanotubes network (NOPCT) with well-tailored nanoarchitecture and high N/O-co-doping content (20.6 at%) is developed to present large-span application on ESSs. As for Li/Na-ion batteries, the NOPCT delivered excellent cycle stability and robust rate performance in a conventional ester-based electrolyte. Moreover, NOPCT also serving as a metal Li host can effectively guide smooth and uniform Li nucleation/growth to enhance the cycle stability of hybrid Li metal anodes. In addition, the NOPCT played an important role in the sustainability of sulfur electrodes, promising the feasibility of shared NOPCT for practical Li-S batteries. First-principle calculations demonstrate that graphitic-N and CO function groups favor for improving electron conductivity while the pyridinic-N and CO function group make sense for improved Li/Na adsorption and affinity through Lewis acid-base interaction, enlightening the interplay between various doped categories on improved electrochemical performance of NOPCT. This work provides profound theoretical and experimental insight into the design and development of APEMs for advanced ESSs.

Sodium-ion batteries (SIBs) are heralded as promising candidates for grid-scale energy storage systems due to their low cost and abundant sodium resources. Excellent rate capacity and outstanding cycling stability are always the goals for SIBs. Up to now, nearly all attention has been focused on the control of morphology and structure of electrode materials, but the influence of binders on their performance is neglected, especially in cathode materials. Herein, using Na3V2(PO4)2O2F (NVPOF) as a cathode material, the influence of four different binders (sodium alginate, SA; carboxymethylcellulose sodium, CMC; poly(vinylidene fluoride), PVDF; and poly(acrylic latex), LA133) on its electrochemical performance is studied. As a result, when using SA as the binder, the electrochemical performance of the NVPOF electrode is improved significantly, which is mainly because of the high water solubility, rich carboxyl and hydroxyl groups, and high adhesive and cohesive properties of the SA binder, leading to the uniform distribution of active materials NVPOF and carbon black in electrodes, good integrity, low polarization, and superior kinetic properties of the NVPOF electrodes, as demonstrated by scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic intermittent titration technique. More importantly, when coupled with a hard carbon anode, the fabricated sodium-ion full cells also exhibit excellent rate performance, thus providing a preview of their practical application. This work shows that the battery performance can be improved by matching suitable binder systems, which is believed to have great importance for the further optimization of the electrochemical performance of SIBs.

Rational structure and morphology design are of great significance to realize excellent Na storage for advanced electrode materials in sodium-ion batteries (SIBs). Herein, a cube-like core/shell composite of single MnS nanocubes (≈50 nm) encapsulated in N, S co-doped carbon (MnS@NSC) with strong CSMn bond interactions is successfully prepared as outstanding anode material for SIBs. The carbon shell significantly restricts the expansion of the MnS volume in successive sodiation/desodiation processes, as demonstrated by in situ transmission electron microscopy (TEM) of one single MnS@NSC nanocube. Moreover, the in situ generated CSMn bonds between the MnS core and carbon shell play a significant role in improving the Na-storage stability and reversibility of MnS@NSC, as revealed by in situ Raman and TEM. As a result, MnS@NSC exhibits a high reversible specific capacity of 594.2 mAh g-1 at a current density of 100 mA g-1 and an excellent rate performance. It also achieves a remarkable cycling stability of 329.1 mAh g-1 after 3000 charge/discharge cycles at 1 A g-1 corresponding to a low capacity attenuation rate of 0.0068% per cycle, which is superior to that of pristine MnS and most of the reported Mn-based anode materials in SIBs.

In this communication, in order to develop superior electrode materials for advanced energy storage devices, a new strategy is proposed and then verified by the (Si@MnO)@C/RGO anode material for lithium ion batteries. The core idea of this strategy is the use of a positive cycling trend (gradually increasing Li-storage capacities of the MnO-based constituent during cycling) to compensate the negative one (gradually decreasing capacities of the Si anode) to achieve ultralong cycling stability. As demonstrated in both half and full cells, the as-prepared (Si@MnO)@C/RGO nanocomposite exhibits superior Li-storage properties in terms of ultralong cycling stability (no obvious increase or decrease of capacity when cycled at 3 A g−1 after 1500 cycles) and excellent high-rate capabilities (delivering a capacity of ca. 540 mA h g−1 at a high current density of 8 A g−1) as well as a good full-cell performance. In addition, the structure of the electrodes is stable after 200 cycles. Such a strategy provides a new idea to develop superior electrode materials for next-generation energy storage devices with ultralong cycling stabilities.

Due to the Earth’s scarcity of lithium, replacing lithium with earth-abundant and low-cost sodium for sodium-ion batteries (SIBs) has recently become a promising substitute for lithium-ion batterie...

As a promising cathode material of sodium-ion battery, P2-type Na2/3Ni1/3Mn2/3O2 (NNMO) possesses a theoretically high capacity and working voltage to realize high energy storage density. However, it still suffers from poor cycling stability mainly incurred by the undesirable P2–O2 phase transition. Herein, the electrochemically active Fe3+ ions are introduced into the lattice of NNMO, forming Na2/3Ni1/3Mn2/3–xFexO2 (x = 0, 1/24, 1/12, 1/8, 1/6) to effectively stabilize the P2-type crystalline structure. In such Fe-substituted materials, both Ni2+/Ni4+ and Fe3+/Fe4+ couples take part in the redox reactions, and the P2–O2 phase transition is well restrained during cycling, as verified by ex situ X-ray diffraction. As a result, the optimized Na2/3Ni1/3Mn7/12Fe1/12O2 (1/12-NNMF) has a long-term cycling stability with the fading rate of 0.05% per cycle over 300 cycles at 5 C. Furthermore, the 1/12-NNMF delivers excellent rate capabilities (65 mA h g–1 at 25 C) and superior low-temperature performance (the cap...

Polyanion-type phosphate materials are highly promising cathode candidates for next-generation batteries due to their excellent structural stability during cycling; however, their poor conductivity has impeded their development. Isostructural and multivalent anion substitution combined with carbon coating is proposed to greatly improve the electrochemical properties of phosphate cathode in sodium-ion batteries (SIBs). Specifically, multivalent tetrahedral SiO44- substitute for PO43- in Na3 V2 (PO4 )3 (NVP) lattice, preparing the optimal Na3.1 V2 (PO4 )2.9 (SiO4 )0.1 with high-rate capability (delivering a high capacity of 82.5 mAh g-1 even at 20 C) and outstanding cyclic stability (≈98% capacity retention after 500 cycles at 1 C). Theoretical calculation and experimental analyses reveal that the anion-substituted Na3.1 V2 (PO4 )2.9 (SiO4 )0.1 reduces the bandgap of NVP lattice and enhanced its structural stability, Na+ -diffusion kinetics and electronic conductivity. This strategy of multivalent and isostructural anion substitution chemistry provides a new insight to develop advanced phosphate cathodes.

As important anodes in lithium-ion batteries, graphene is always faced with the aggregation problem that makes most of the active sites lose their function at high current densities, resulting in low Li-ion intercalation capacity and poor rate performance. To address this issue, a layered g-C3N4@reduced graphene oxide composite (g-C3N4@RGO) was prepared via a scalable and easy strategy. The resultant g-C3N4@RGO composite possesses large interlayer distances, rich N-active sites, and a microporous structure, which largely improves Li storage performance. It shows excellent cycle stability (899.3 mA h g–1 after 350 cycles under 500 mA g–1) and remarkable rate performance (595.1 mA h g–1 after 1000 cycles under 1000 mA g–1). Moreover, the g-C3N4@RGO electrode exhibits desired capacity retention and relatively high initial Coulombic efficiency of 58.8%. Impressively, this result is better than that of RGO (29.1%) and most of RGO-based anode materials reported in the literature. Especially, the g-C3N4@RGO-base...

Developing a high-performance, low-cost, and safer rechargeable battery is a primary challenge in next-generation electrochemical energy storage. In this work, a quasi-solid-state (QSS) sodium-ion full battery (SIFB) is designed and fabricated. Hard carbon cloth derived from cotton cloth and Na3V2(PO4)2O2F (NVPOF) are employed as the anode and the cathode, respectively, and a sodium ion-conducting gel-polymer membrane is used as both the QSS electrolyte and separator, accomplishing the high energy and power densities in the QSS sodium-ion batteries. The energy density can reach 460 W h kg–1 according to the mass of the cathode materials. Moreover, the fabricated QSS SIFB also exhibits an excellent rate performance (e.g., about 78.1 mA h g–1 specific capacity at 10 C) and a superior cycle performance (e.g., ∼90% capacity retention after 500 cycles at 10 C). These results show that the developed QSS SIFB is a hopeful candidate for large-scale energy storage.

A novel core–shell Fe3O4@FeS composed of Fe3O4 core and FeS shell with the morphology of regular octahedra has been prepared via a facile and scalable strategy via employing commercial Fe3O4 as the precursor. When used as anode material for sodium-ion batteries (SIBs), the prepared Fe3O4@FeS combines the merits of FeS and Fe3O4 with high Na-storage capacity and superior cycling stability, respectively. The optimized Fe3O4@FeS electrode shows ultralong cycle life and outstanding rate capability. For instance, it remains a capacity retention of 90.8% with a reversible capacity of 169 mAh g–1 after 750 cycles at 0.2 A g–1 and 151 mAh g–1 at a high current density of 2 A g–1, which is about 7.5 times in comparison to the Na-storage capacity of commercial Fe3O4. More importantly, the prepared Fe3O4@FeS also exhibits excellent full-cell performance. The assembled Fe3O4@FeS//Na3V2(PO4)2O2F sodium-ion full battery gives a reversible capacity of 157 mAh g–1 after 50 cycles at 0.5 A g–1 with a capacity retention of...

A three-dimensional hierarchical Ni3Se2 nanorod array (NA) grown in situ on foam Ni is the first to act as a carbon/binder-free electrode of SIBs via a one-step reversible conversion reaction. By a special decomposition–fusion process, the morphology and composition of the NA are regulated to obtain ultrahigh areal capacity, which is three times greater than that reported for other metal selenides.

In this article, an effective strategy (viz., constructing multiple heterointerfaces) is proposed to develop superior electrode materials for sodium-ion battery (SIB), which is the most promising alternative to market-dominant lithium-ion battery for stationary energy storage. In the as-prepared heterogeneous-SnO2/Se/graphene (h-SSG) composite, there exists multiple phase interfaces, including heterointerfaces between tetragonal and orthorhombic SnO2 (t-/o-SnO2) in the heterogeneous SnO2 nanojunctions and two phase interfaces between t/o-SnO2 and amorphous Se. These multiple phase interfaces promise the much improved Na storage properties of h-SSG when compared to four controls without such multiple heterointerfaces because the multiple built-in electric fields at the heterointerfaces can significantly boost the surface reaction kinetics and facilitate charge transport as demonstrated by kinetics analyses, theoretical calculations and contrastive electrochemical tests. Moreover, h-SSG also exhibits superior Na-ion full cell performance when coupled with a high-voltage Na3V2(PO4)2O2F cathode. In view of the universality of the heterointerface-based enhancement effect on surface reaction and charge transport kinetics and the facile preparation procedures, the present strategy should be universal to develop other superior electrode materials for high-performance SIBs and other batteries for future energy storage applications.

Coaxial nanotubes are a significant class of nanoscale building blocks for advanced electrodes of secondary batteries. Herein, one-dimensional (1D) coaxial double nanotubes (DNTs) consisting of α-MnSe inner tubes and N-doped carbon (N–C) outer tubes (abbreviated as α-MnSe@N–C DNTs) are successfully prepared and are demonstrated to be promising anode material for Li-ion and Na-ion batteries (LIBs/NIBs). When used in LIBs, it was revealed by ex situ XRD/HRTEM studies and electrode kinetics that a new electrochemical α → β phase transition plays a crucial role in improving the cycling stability. As a result, the α-MnSe@N–C DNTs electrode delivers a high Li-storage capacity (800 mA h g−1 at 50 mA g−1), excellent rate capability (405 mA h g−1 at 14 A g−1) and ultra-long cycling stability (a high capacity retention of 87.2% even after 9000 cycles at 2 A g−1) with retained 1D morphology. In addition, the outer N–C nanotube can effectively protect the active α-MnSe inner nanotube to realize such outstanding electrochemical properties owing to the high electrical conductivity and particular 1D coaxial nanoarchitecture of the inner nanotube. Moreover, α-MnSe@N–C DNTs also exhibit excellent Li/Na-storage properties and full-cell performances when coupled with commercial LiFePO4 and LiNi0.6Co0.2Mn0.2O2 cathodes in LIBs as well as with the Na3V2(PO4)2O2F cathode in NIBs.

Simple yet efficient design of an outstanding multifunctional electrocatalyst is crucial for advanced energy conversion and storage devices. Herein, we report the synthesis of an N-enriched hierarchically porous carbon electrocatalyst, which demonstrated excellent overall oxygen electrode activity (ΔE = EOER,10 − EORR,1/2 of 0.770 V) and impressive durability in 0.1 M KOH. The activity of our material integrates a high BET surface area (1547.13 m2 g−1), accessible N dopant and suitable porous architectures. The material is formed by mixing cicada sloughs with ZnCl2, as the inorganic pore-fabricating agent, with ball milling followed by annealing treatment. Unexpectedly, the nitrogen reduction reaction (NRR) with excellent production yield (NH3: 15.7 μg h−1 mg−1 cat., faradaic efficiency: 1.45%) and selectivity is achieved at −0.2 V vs. RHE under ambient conditions. The present trifunctional catalytic activities are markedly better than leading results reported in recent literature. These results highlight the significance of deliberate structural engineering in the preparation of multifunctional electrocatalysts for versatile electrochemical reactions.

F-Doped MnWO4 nano-particles were synthesized by a one-pot hydrothermal reaction. When evaluated as an electrode material for a Li ion battery, the F-doped nano-MnWO4 delivers a theoretical capacity of 708 mA h g−1 and a long cycle life, as demonstrated by more than 85% capacity retention when cycled for 150 cycles.

Supercapacitors with high energy density and long cycle life without decay in the consecutive bending operation are urgently required for the next generation of wearable electronic devices. Here, we report a high-voltage flexible supercapacitor with enhanced energy density, which can be attributed to the tailored hierarchical carbon (HC) electrode materials and organic gel electrolyte. HC derived from MOF@graphene is synthesized via a facile and environmentally friendly process, where MOF derived porous carbon polyhedra are in situ anchored on the graphene surface to form a hierarchical nano-architecture. The HC shows a synergistic effect of porous nanocarbon and graphene, and possesses a large surface area (2837 m2 g−1), desired meso-/micropore distribution and superior conductivity. A 3.5 V solid-state flexible supercapacitor is constructed by employing HC electrodes and EMIMBF4/PVDF-HFP gel electrolyte, and it demonstrates a superior specific capacitance (201 F g−1) and good cycle life. The energy and power densities are significantly promoted (86 W h kg−1 at 438 W kg−1 and 61 W h kg−1 at 17 500 W kg−1). Meanwhile, the flexible supercapacitor shows excellent mechanical bending performance, exhibiting negligible capacitance decay under various bending states and repeated bending cycles, representing its promising potential for application in wearable electronics.