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Quasi‐solid sodium batteries, employing quasi‐solid polymer electrolytes (QSPEs) renowned for their high energy density and cost‐effective fabrication, are promising candidates for next‐generation energy storage systems. However, their practical application has encountered impediments such as insufficient ion transport and uneven sodium plating/stripping attributed to suboptimal interfacial compatibility. In this work, an innovative QSPE is developed by incorporating functional additives, specifically fluoroethylene carbonate (FEC) and tin trifluoromethanesulfonate (Sn(OTf)2), into the poly(vinylidenefluoride‐co‐hexafluoropropylene) (PVDF‐HFP)/propylene carbonate (PC) polymer electrolyte. Sn(OTf)2 catalyzes a ring‐opening reaction in PC, thereby reducing transmission barriers and augmenting the transport of sodium ions. Consequently, the resulting HFP‐PC‐FEC‐Sn QSPE demonstrates remarkable ionic conductivity (0.42 mS cm─1) and ion transference number (0.58). Furthermore, it forms a dense and smooth interphase enriched with NaF and metallic Sn, significantly enhancing the long‐term cycling stability of Na symmetric cells, which endure over 3000 h at 0.2 mA cm─2, and effectively suppressing the formation of sodium dendrites. This outstanding electrochemical performance extends to Na3V2(PO4)3/Na full coin and pouch cells across a wide temperature range. This work introduces an innovative approach for designing high‐performance QSPEs suitable for wide‐temperature quasi‐solid sodium batteries. [ABSTRACT FROM AUTHOR]

Prussian blue analogues (PBAs) have been widely applied in many fields, especially as cathode materials of sodium‐ion batteries on account of their low cost and open framework for fast ions transport. However, the capacity of reported PBAs has a great distance from its theoretical value. Herein, we proposed that [Fe(CN)6] vacancies are crucial point for the high specific capacity for the first time. The [Fe(CN)6] vacancies may create net electrons and reduce obstacles to ionic transport, which is conducive to rate performance of PBAs by increasing electronic and ionic conductivity to some extent. As a proof of concept, a series of PBAs have been prepared by co‐precipitation method. And then, a novel precipitation conversion method has been designed, by which unique PBAs with a specific quantity of [Fe(CN)6] vacancies was successfully synthesized. Remarkably, the as‐prepared PBAs possessing hierarchical hollow morphology have reached a unprecedent level of high capacity (168 mAh g−1 at 25 mA g−1, close to PBAs' theoretical capacity 170 mAh g−1), high rate performance (90 mAh g−1 at 5 A g−1), and high energy density (over 500 Wh kg−1). [ABSTRACT FROM AUTHOR]

Biomass‐based hard carbon has the advantages of a balanced cost and electrochemical performance, making it the most promising anode material for sodium‐ion batteries. However, due to the structural limitations of biomass (such as macropores and impurities), it still faces the problems of low specific capacity and initial Coulombic efficiency (ICE). Herein, an integrated strategy of biomass liquefaction and oxidation treatment is proposed to fabricate hard carbon with low ash content and sp2‐rich closed pores. Specifically, liquefaction treatment can break through the inherent constraints of biomass, while oxidation treatment with O‐targeted effect can directionally convert C─C/C─O bonds into C═O/O═C─O bonds, which would promote the formation of closed pores and the rearrangement into sp2‐carbon within the graphene layer. Moreover, it is well demonstrated that the hard carbon interface rich in sp2 hybridization can induce the generation of an inorganic‐rich solid electrolyte interface, contributing to fast ion migration and excellent interfacial stability. As a result, the optimized hard carbon with maximum closed pore volume and sp2/sp3 ratio can exhibit a high capacity of 347.3 mAh g−1 at 20 mA g−1 with the ICE of 90.5%, and a capacity of 110.4 mAh g−1 at 5.0 A g−1 after 10 000 cycles. [ABSTRACT FROM AUTHOR]

Porous hard carbon with good cycling durability attracts much attention in the application of sodium ions batteries as anode material, but the commonly used alkali metal ion-activation strategy with complex processes still renders its development. Herein, a simple and scalable method is proposed to synthesize hierarchical porous hard carbon. Benefitting from the efficient self-activation strategy, the hierarchical micro–mesoporous hard carbon (MMHC) with large interlayer distance possesses high specific surface area of 704.1 m2 g−1, which can provide shorter ionic diffusion path and much more accessible electrochemical active sites in the carbonaceous structure and then lead to fast sodium ion diffusivity kinetics (3.5 × 10–9 cm2 s−1). In consequence, MMHC electrode delivers high specific capacity of 214.3 mAh g−1 at 50 mA g−1, 118.3 mAh g−1 at 500 mA g−1 after 1000 cycles and 47.4 mAh g−1 even at 4000 mA g−1. Notably, the capacity contribution ratio from low-voltage range is enhanced with engineering micro–mesoporous structure (from 28.5% for HC to 37.7% for MMHC). Promisingly, the hierarchical micro–mesoporous hard carbon holds great potential in commercial sodium ions batteries. [ABSTRACT FROM AUTHOR]

Iron sulfide (FeS) has been extensively studied as sodium‐ion battery anodes due to its high theoretical capacity (609 mAh g−1), but its large volume expansion and low electrical conductivity result in unsatisfactory cycling life and poor rate performance. Moreover, the sodium ion storage mechanism of FeS at a voltage range of 0.01–1 V involving conversion reactions and subsequent ion storage process is unclear yet. Here, the study proposes a vapor‐pressure induced synthesis route to fabricate FeS/C yolk‐shell structure that ultrathin carbon layers coat on the surface of FeS nanosheets, which can accommodate volume expansion of FeS during sodiation observed via in situ transmission electron microscope and improve its electrical conductivity. Remarkably, an in situ magnetometry reveals that vast spin‐polarized electrons can be injected into superparamagnetic Fe nanoparticles (≈3 nm) formed during conversion reaction to induce evolution of electrode magnetization between 0.01 and 1 V, during which spin‐polarized surface capacitance effect occurs at Fe/Na2S interfaces to increase extra ion storage and boost ion transport stably. Consequently, the FeS/C yolk‐shell nanosheets deliver a high reversible capacity of 664.9 mAh g−1 at 0.1 A g−1, and 300.4 mAh g−1 after 10 000 cycles at 10 A g−1 with a capacity retention of 81.1%. [ABSTRACT FROM AUTHOR]

Designing innovative anode materials that exhibit excellent ion diffusion kinetics, enhanced structural stability, and superior electrical conductivity is imperative for advancing the rapid charge–discharge performance and widespread application of sodium-ion batteries. Hollow-structured materials have received significant attention in electrode design due to their rapid ion diffusion kinetics. Building upon this, we present a high-performance, free-standing MoO2@hollow carbon nanofiber (MoO2@HCNF) electrode, fabricated through facile coaxial electrospinning and subsequent heat treatment. In comparison to MoO2@carbon nanofibers (MoO2@CNFs), the MoO2@HCNF electrode demonstrates superior rate capability, attributed to its larger specific surface area, its higher pseudocapacitance contribution, and the enhanced diffusion kinetics of sodium ions. The discharge capacities of the MoO2@HCNF (MoO2@CNF) electrode at current densities of 0.1, 0.2, 0.5, 1.0, 2.0 and 5.0 A g−1 are 195.55 (155.49), 180.98 (135.20), 163.81 (109.71), 144.05 (90.46), 121.16 (71.21) and 88.90 (44.68) mAh g−1, respectively. Additionally, the diffusion coefficients of sodium ions in the MoO2@HCNFs are 8.74 × 10−12 to 1.37 × 10−12 cm2 s−1, which surpass those of the MoO2@CNFs (6.49 × 10−12 to 9.30 × 10−13 cm2 s−1) during the discharging process. In addition, these prepared electrode materials exhibit outstanding flexibility, which is crucial to the power storage industry and smart wearable devices. [ABSTRACT FROM AUTHOR]

The practical application of sodium (Na) metal anode has been seriously hindered by the uncontrolled Na dendrite growth and severe volume expansion inducing short battery lifespan and safety concerns. Here, highly sodiophilic and ultrafine ZnS‐modified carbon fibers have been rationally constructed as a scaffold to obviate these drawbacks. The in situ generated Na2S‐reinforced fast ion transport interphase and the effective space confinement synergistically facilitate the fast sodium ion interfacial transfer and the homogeneous and dendrite‐free Na deposition, thus enabling high‐rate and dendrite‐free Na metal anode. The modified Na metal demonstrates ultrahigh rate capability (15 mA cm−2) and ultralong cycling life (5300 cycles). Moreover, the Na|Na3V2(PO4)3 (NVP) cell delivers ultrahigh rate capability (80 C) and extraordinarily ultralong lifespan cycling durability (2980 cycles). The Na|NVP pouch cell also exhibits an extraordinarily ultralong‐term cycle life of over 1070 cycles with an extremely low capacity decay rate of 0.0088% per cycle at 10 C. This work provides a facile and efficient strategy to propel the Na metal anode towards practicability. [ABSTRACT FROM AUTHOR]

The utilization of pristine graphene as an anode material in sodium-ion batteries (SIBs) is limited by its inherent chemical inertness toward Na-ions. To address this issue, we propose a two-dimensional carbon allotrope (named as TD-graphene) by assembling tricyclo[4.4.1.11,6]dodecane (C12H20) skeleton. The topological non-hexagonal feature of C12H20 increases the degree of local carbon-ring disorder and introduces additional electron-deficient regions on the surface, thus enhancing the adsorption capability of Na. TD-graphene demonstrates exceptional stability across the energetic, thermodynamic, dynamic, and mechanical aspects. As a promising anode for SIBs, it exhibits an intrinsic metallicity, an ultra-high storage capacity (1487.58 mA h g−1), a low diffusion barrier (0.20 eV), a low average open-circuit voltage (0.33 V), and a small lattice expansion (0.6%). The presence of solvents with high dielectric constants improves the adsorption and migration capability of Na. Furthermore, taking into account the limitation of single-layer materials in practical applications, we employ h-BN as a promising substrate for TD-graphene, which can boost the Na adsorption and diffusion performance. These results render TD-graphene as a promising high-performance anode material for SIBs. [ABSTRACT FROM AUTHOR]

Highlights: A molecular-sieving electrode coating towards low-concentrated aqueous sodium-ion batteries is constructed by applying a composite of NaX zeolite and NaOH-neutralized Nafion. Resulting from a molecular sieving effect of zeolite channels and size-shrunken ionic domains in Nafion, the as-prepared coating layer reject hydrated Na+ ions and allow fast dehydrated Na+ permeance. 200 cycles of Na2MnFe(CN)6//NaTi2(PO4)3 full cells can be achieved in a practically feasible 2 m aqueous electrolyte. Aqueous sodium-ion batteries are known for poor rechargeability because of the competitive water decomposition reactions and the high electrode solubility. Improvements have been reported by salt-concentrated and organic-hybridized electrolyte designs, however, at the expense of cost and safety. Here, we report the prolonged cycling of ASIBs in routine dilute electrolytes by employing artificial electrode coatings consisting of NaX zeolite and NaOH-neutralized perfluorinated sulfonic polymer. The as-formed composite interphase exhibits a molecular-sieving effect jointly played by zeolite channels and size-shrunken ionic domains in the polymer matrix, which enables high rejection of hydrated Na+ ions while allowing fast dehydrated Na+ permeance. Applying this coating to electrode surfaces expands the electrochemical window of a practically feasible 2 mol kg–1 sodium trifluoromethanesulfonate aqueous electrolyte to 2.70 V and affords Na2MnFe(CN)6//NaTi2(PO4)3 full cells with an unprecedented cycling stability of 94.9% capacity retention after 200 cycles at 1 C. Combined with emerging electrolyte modifications, this molecular-sieving interphase brings amplified benefits in long-term operation of ASIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hard carbon in the PC/EC-based electrolyte can achieve excellent cycle performance and rate performance for sodium-ion batteries. • For the first time, the differences of the ion solvation/desolvation behavior in the electrolytes are proposed to uncover the underlying mechanisms of the distinct electrochemical performance of HC in the PC/EC-based electrolyte and the PC-based electrolyte. • A SEI film with a higher percentage of organic composition is formed in the PC/EC-based electrolyte. • The PC/EC-based electrolyte exhibits a faster ion desolvation process compared to the PC-based electrolyte. Although hard carbon in propylene carbonate / ethylene carbonate (PC/EC)–based electrolytes possesses favorable electrochemical characteristics in rechargeable sodium–ion batteries, the underlying mechanism is still vague. Numerous hypotheses have been proposed to solve the puzzle, but none of them have satisfactorily unraveled the reason at the molecular–level. In this study, we firstly attempted to address this mystery through a profound insight into the disparity of the ion solvation/desolvation behavior in electrolyte. Combining the results of density functional theory (DFT) calculations and experiments, the work explains that compared to the sole PC–based electrolyte, Na+–EC 4 molecules in the PC/EC–based electrolyte preferentially undergo reduction and contribute to the emergence of a more stable protective film on the surface of hard carbon, leading to the preferable durability and rate capability of the cell. Nevertheless, applying the ion solvation/desolvation model, it also reveals that Na+–(solvent) n molecules in the PC/EC–based electrolyte can achieve faster Na+ desolvation processes than in the PC–based electrolyte alone, contributing to the enhancement of charge transfer kinetics. This research holds great importance in uncovering the possible mechanism of the remarkable electrochemical– properties of hard carbon in PC/EC–based electrolytes, and advancing its practical utilization in future sodium–ion batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] Development of multitudinous heteroatoms co-doped carbon nanomaterials with pleasurable electrochemical behavior for sodium ion batteries is still an enormous challenge. Herein, high dispersion cobalt nanodots encapsulating into N, P, S tri-doped hexapod carbon (H-Co@NPSC) have been victoriously synthesized via H-ZIF67@polymer template strategy with using poly (hexachlorocyclophos-phazene and 4,4′-sulfonyldiphenol) as both carbon source and N, P, S multiple heteroatom doping sources. The uniform distribution of cobalt nanodots and the Co-N bonds are conducive to form a high conductive network, which synergistically increase a lot adsorption sites and lessens the diffusion energy barrier, thereby improving the fast Na+ ions diffusion kinetics. Consequently, H-Co@NPSC delivers the reversible capacity of 311.1 mAh g−1 at 1 A g−1 after 450 cycles with 70% capacity storage rate, while obtains the capacity of 237.1 mAh g- 1 after 200 cycles at the elevated current densities of 5 A g−1 as an excellent anode material for SIBs. These interesting results pave a generous avenue for the exploitation of promising carbon anode materials for Na+ storage. [ABSTRACT FROM AUTHOR]

Pre‐intercalating ions between VO layers is considered to be an effective strategy to modulate the interlayer spacing of 2D vanadium oxides. However, the rigid pre‐intercalated ions hardly keep stable during repeated charging/discharging process and their sizes limit the extent of interlayer spacing expansion, which inevitably lead to poor rate capability and cycle stability. In this work, aliphatic diamines are adopted as pre‐intercalated guests to elastically modulate the interlayer spacing of VO layers by tuning the chain length of the organic diamine molecules. Benefiting from the strong interaction between the terminal doubly protonated amine and the polar negative oxygen bridge of the VO layers, the aliphatic diamine molecules can act as a structural stabilizer between the layers and boost fast Na ion diffusion (10−8 to 10−10 cm2 s−1). The sodium ion battery based on the first synthesized 1,6‐hexanediamine pre‐intercalated vanadium oxide supported on nickel foam hybrid cathode achieves a large specific capacity of 597 mAh g−1 at 0.09 A g−1, as well as superior rate performance and cycling stability. This work provides a strategy to elastically modulate 2D layered materials with tunable interlayer spacing for batteries based on large‐size‐ions. [ABSTRACT FROM AUTHOR]

Nanocarbons play a significant role in the development of alternative, clean and sustainable energy technologies. The utility of low‐dimensional nanostructured carbons (one‐, two‐ and three‐dimensional) in the new generation of batteries have shown great potential due to their physicochemical and electrochemical properties as well as high safety. The electrodes made from nanostructured carbon materials with different dimensions, size and structures offer enhanced ionic transport and electronic conductivity as compared to conventional batteries. They also enable the occupation of all intercalation sites available in the particle which leads to high specific capacities, fast ion diffusion, superior rate capability and long‐term cyclability. The carbonaceous nanosized active materials are important to enhance the electrical conductivity of the electrode materials and buffer the structural change and strain during sodium insertion and extraction. Application potentialities of different low‐dimensional nanostructured carbons in sodium‐ion batteries (SIBs) are discussed in this part II. It also deals with the modifications made on the carbonaceous material by doping with heteroatoms, expressing diversified morphologies with porous materials or compositing with organic or inorganic species. [ABSTRACT FROM AUTHOR]

[Display omitted] Nickel-based sulfides are considered promising materials for sodium-ion batteries (SIBs) anodes due to their abundant resources and attractive theoretical capacity. However, their application is limited by slow diffusion kinetics and severe volume changes during cycling. Herein, we demonstrate a facile strategy for the synthesis of nitrogen-doped reduced graphene oxide (N -rGO) wrapped Ni 3 S 2 nanocrystals composites (Ni 3 S 2 - N -rGO-700 °C) through the cubic NiS 2 precursor under high temperature (700 ℃). Benefitting from the variation in crystal phase structure and robust coupling effect between the Ni 3 S 2 nanocrystals and N -rGO matrix, the Ni 3 S 2 - N -rGO-700 °C exhibits enhanced conductivity, fast ion diffusion kinetics and outstanding structural stability. As a result, the Ni 3 S 2 - N -rGO-700 °C delivers excellent rate capability (345.17 mAh g−1 at a high current density of 5 A g−1) and long-term cyclic stability over 400 cycles at 2 A g−1 with a high reversible capacity of 377 mAh g−1 when evaluated as anodes for SIBs. This study open a promising avenue to realize advanced metal sulfide materials with desirable electrochemical activity and stability for energy storage applications. [ABSTRACT FROM AUTHOR]

The VO 2 nanobelts with oxygen vacancies that were dispersed on interconnected nitrogen doped carbon nanosheets were fabricated (VO 2-x /NC), which exhibits impressive performance in sodium ion battery and sodium ion hybrid capacitors. [Display omitted] • The VO 2 nanobelts with oxygen vacancies are dispersed on interconnected ultrathin NC nanosheets (VO 2-x /NC). • VO 2-x /NC exhibits comprehensive performance including high storage capacity, fast ion/electron diffusion kinetics and ultralong cycle life in SIBs. • DFT indicates that the incorporating of oxygen vacancies provides extra surface capacitance and electronic conductivity, thus favoring fast kinetics. • SIHCs exhibits high energy/power density with ultralong lifespan and practical applications. Developing anode materials with high reversible capacity, fast redox kinetics, and stable cycling life for Na+ storage remains a great challenge. Herein, the VO 2 nanobelts with oxygen vacancies supported on nitrogen-doped carbon nanosheets (VO 2-x /NC) were developed. Benefitting from the enhanced electrical conductivity, the accelerated kinetics, the increased active sites as well as the constructed 2D heterostructure, the VO 2-x /NC delivered extraordinary Na+ storage performance in half/full battery. Theoretical calculations (DFT) demonstrated that oxygen vacancies could regulate the adsorption ability for Na+, enhance electronic conductivity, as well as achieve rapid and reversible Na+ adsorption/desorption. The VO 2-x /NC exhibited high Na+ storage capacity of 270 mAh g−1 at 0.2 A g−1, and impressive cyclic stability with 258 mAh g−1 after 1800 cycles at 10 A g−1. The assembled sodium-ion hybrid capacitors (SIHCs) could achieve maximum energy density/power output of 122 Wh kg−1/9985 W kg−1, ultralong cycling life with 88.4% capacity retention after 25,000 cycles at 2 A g−1, and practical applications (55 LEDs could be actuated for 10 min), promising to be utilized in a practicable Na+ storage. [ABSTRACT FROM AUTHOR]

Hard carbon, as the most promising commercial anode materials of sodium‐ion batteries (SIBs), has suffered from the coupling limitations on initial Coulombic efficiency (ICE), capacity, and rate capability. Herein, to break such coupling limitations, sulfur‐rich nitrogen‐doped carbon nanomaterials (S‐NC) were synthesized by a synergistic modification strategy, including structure/morphology regulation and dual heteroatom doping. The small specific surface area of S‐NC is beneficial for inhibiting excessive growth of solid electrolyte interphase (SEI) film and irreversible interfacial reaction. The covalent S can serve as active electrochemical sites by Faradaic reactions and provide extra capacity. Benefit by N, S co‐doping, S‐NC shows large interlayer spacing, high defects, good electronic conductivity, strong ion adsorption performance, and fast Na+ ion transport, which combined with a more significant pore volume result in speedier reaction kinetics. Hence, S‐NC possesses a high reversible specific capacity of 464.7 mAh g−1 at 0.1 A g−1 with a high ICE of 50.7%, excellent rate capability (209.8 mAh g−1 at 10.0 A g−1), and superb long‐cycle capability delivering a capacity of 229.0 mAh g−1 (85% retention) after 1800 cycles at 5.0 A g−1. [ABSTRACT FROM AUTHOR]

Alloying‐type bismuth with high volumetric capacity has emerged as a promising anode for sodium‐ion batteries but suffers from large volume expansion and continuous pulverization. Herein, a coordination constraint strategy is proposed, that is, chemically confining atomic Bi in an intercalation host framework via reconstruction‐favorable linear coordination bonds, enabling a novel quasi‐topological intercalation mechanism. Specifically, micron‐sized Bi0.67NbS2 is synthesized, in which the Bi atom is linearly coordinated with two S atoms in the interlayer of NbS2. The robust Nb−S host framework provides fast ion/electron diffusion channels and buffers the volume expansion of Na+ insertion, endowing Bi0.67NbS2 with a lower energy barrier (0.141 vs. 0.504 eV of Bi). In situ and ex situ characterizations reveal that Bi atom alloys with Na+ via a solid‐solution process and is constrained by the reconstructed Bi−S bonds after dealloying, realizing complete recovery of crystalline Bi0.67NbS2 phase to avoid the migration and aggregation of atomic Bi. Accordingly, the Bi0.67NbS2 anode delivers a reversible capacity of 325 mAh g−1 at 1 C and an extraordinary ultrahigh‐rate stability of 226 mAh g−1 at 100 C over 25 000 cycles. The proposed quasi‐topological intercalation mechanism induced by coordinated mode modulation is expected to be be conducive to the practical electrode design for fast‐charging batteries. [ABSTRACT FROM AUTHOR]

Sodium ion capacitors (SICs) show high energy/power densities owing to the special dual‐ion energy storage mechanism with cation intercalation and anion adsorption. However, the strong ion‐solvent interactions make it difficult for interfacial ion desolvation, which not only limits the ion transport kinetics, but also results in the solvent co‐intercalation into electrode materials. Here, an advanced zwitterionic gel polymer electrolyte (GPE) is developed to weaken the ion‐solvent interactions. The 3‐(1‐vinyl‐3‐imidazolio) propanesulfonate (VIPS) zwitterions help to lower the desolvation barriers, enabling fast ion transfer kinetics for constructing stable quasi‐solid‐state SICs. Furthermore, the decomposition of VIPS contributes to the formation of S‐ and N‐based inorganic interphase on the surface of hard carbon anode, which reduces the Na+ ion diffusion barriers and improves electrochemical compatibility. The designed Zwitterionic GPE can stabilize 4.0 V hard carbon//activated carbon SICs with 95.3% capacity retention after 9000 cycles, showing a high energy density of 140.2 Wh kg−1. This study highlights the regulation of ion‐solvent chemistry and provides a guiding principle in electrolyte design for advanced hybrid ion capacitors. [ABSTRACT FROM AUTHOR]

An interfacial covalent bonding strategy is proposed for the synthesis of the MXene-stabilized Sb2Se3 nanotube hybrid. As an anode material, the prepared Sb2Se3@NC/MXene exhibits an enhanced sodium-ion battery performance in half/full batteries in terms of a high specific and cycling stability. [ABSTRACT FROM AUTHOR]

Antiperovskite structure compounds (X3AB, where X is an alkali cation and A and B are anions) have the potential for highly correlated motion between the cation and a cluster anion on the A or B site. This so‐called "paddle‐wheel" mechanism may be the basis for enhanced cation mobility in solid electrolytes. Through combined experiments and modeling, the first instance of a double paddle‐wheel mechanism, leading to fast sodium ion conduction in the antiperovskite Na3−xO1−x(NH2)x(BH4), is shown. As the concentration of amide (NH2−) cluster anions is increased, large positive deviations in ionic conductivity above that predicted from a vacancy diffusion model are observed. Using electrochemical impedance spectroscopy, powder X‐ray diffraction, synchrotron X‐ray diffraction, neutron diffraction, ab initio molecular dynamics simulations, and NMR, the cluster anion rotational dynamics are characterized and it is found that cation mobility is influenced by the rotation of both NH2− and BH4− species, resulting in sodium ion conductivity a factor of 102 higher at x = 1 than expected for the vacancy mechanism alone. Generalization of this phenomenon to other compounds could accelerate fast ion conductor exploration and design. [ABSTRACT FROM AUTHOR]

The fast‐growing development for high‐capacity anodes is undermined by their unsatisfactory rate performance and cycling stability stemming from sluggish ion‐migration speed, poor electronic conductivity, and mechanical degradation induced by the stress accumulation, which greatly hamper practical applications of Na‐ion batteries. Here, a combined experimental and theoretical study on atomic‐thickness (0.6 nm) Co(OH)2 nanosheet with surface defects (2D‐Co(OH)2@D NSs) and large interplanar spacing (0.465 nm) is presented, in which fast ion/electron transport is permitted to boost battery reactions. The mechanical degradation on cycling can be well buffered via tailoring mesopores across the Co(OH)2 nanosheet and an elastic solid–electrolyte interface is established by modulating the electronic structure of the Co(OH)2 surface. The 2D‐Co(OH)2@D NSs exhibit high rate‐capacity (>228 mAh g−1 at 20 A g−1) and superior cyclic stability with negligible decay during 1300 cycles. This study will shed light on the development of electrode materials at atomic‐level design for high‐power and long‐lived performance. [ABSTRACT FROM AUTHOR]

Novel K 0.45 Rb 0.05 Mn 0.85 Mg 0.15 O 2 (KRMMO) cathode encapsulated by bisphosphate K 3 PO 4 /Mn 3 PO 4 shell layer is delicately designed for boosting potassium/sodium storage. Benefiting from the bisphosphate layer, the volume expansion of KRMMO is effectively inhibited, K 3 PO 4 /MnPO 4 double-coated K 0.45 Rb 0.05 Mn 0.85 Mg 0.15 O 2 (D-KRMMO) has a high electronic conductivity and fast ionic diffusivity, which can stimulate potassium/sodium storage. Meanwhile, bisphosphate K 3 PO 4 /Mn 3 PO 4 shell directly isolates the cathode from the electrolyte to alleviate side reactions occurring between the electrolyte and the material, thus the dissolution of Mn in KRMMO host can be inhibited during the cycling process. In potassium ion batteries (PIBs), the discharge specific capacity of D-KRMMO is 105.9 mAh g−1 at a current density of 20 mA g−1 compared with pure KRMMO (94 mAh g−1 at 20 mA g−1). A highly reversible discharge specific capacity of 112.8 mAh g−1 at 100 mA g−1 is shown in the sodium-ion batteries (SIBs). And acceptable C-rate performances of 112.8 mAh g−1 and 44.8 mAh g−1 are exhibited at 100 mA g−1 and 2 A g−1, respectively. EIS and GITT measurements have shown that D-KRMMO cathode has faster ion mobility and electron mobility, as well as higher pseudocapacitance contribution. [Display omitted] • D-KRMMO can be used as the cathode for both PIBs and SIBs. • D-KRMMO has excellent electrochemical properties. • XPS during cycling reveals changes in valence state of Mn ions. • The bisphosphate layer inhibits volume expansion and Mn dissolution. [ABSTRACT FROM AUTHOR]

• NaZn(BH₄)₃ is synthesized via mixing in THF, avoiding NaCl by-products from ball milling and lowering energy use. • A new solid-state electrolyte, NaZn(BH 4) 3 · x THF (x = 0.4, 1.3), enhances sodium ion conductivity via Na-O bond formation. • The material exhibits the highest sodium ion conductivity reported for sodium-based bimetallic borohydride solid electrolytes. Developing high-performance solid-state batteries requires solid electrolytes with high ionic conductivity and excellent electrode compatibility. This study focuses on bimetallic borohydride NaZn(BH 4) 3 · x THF, revealing a room temperature sodium conductivity of 1.89 × 10−5 S cm−1 due to the formation of Na-O bonds. This THF-involved NaZn(BH 4) 3 was synthesized in a THF solution without ball milling. Our investigation highlights the key role of THF in determining the crystal structure of NaZn(BH 4) 3 · x THF, which adopts a space group of P 2/ m. In-situ X-ray diffraction reveals that removing THF from NaZn(BH 4) 3 under dynamic vacuum conditions leads to a gradual transformation of the crystal structure from space group P 2/ m to P 2 1 / c. X-ray Absorption Fine Structure (XAFS), Pair Distribution Function (PDF), and Far-Infrared analysis illustrate the coordination of THF to NaZn(BH 4) 3 in the form of Na-O bonds. The DSC results suggest that dynamic desorption and adsorption of THF play an active role in Na+ migration, with the movement of THF creates sodium defects/vacancies that promote Na+ migration. This outstanding property offers attractive prospects for designing bimetallic borohydrides as novel solid-state sodium ion conductors. [ABSTRACT FROM AUTHOR]

P2-type manganese-rich layered oxide have attracted much attention as cathodes of sodium-ion batteries owing to the low cost, high capacity and fast sodium ion diffusion kinetics. However, the Jahn-Teller effect of Mn3+, P2-O2 phase transition and anionic redox on charging to the high-voltage, resulted in a severe capacity delay. Herein, an effective Li substitution strategy is proposed to suppress the Jahn-Teller effect of Mn3+, the harmful phase transition of P2-O2 and the anionic redox. As a result, the as-prepared sample Na 0.67 (Ni 0.25 Mn 0.75) 0.9 Li 0.1 O 2 (67L10) displays a discharge specific capacity of 168.6 mA h g−1 at 0.1 C, enhanced average working voltage, and improved cycling stability at 1 C after 200 cycles within 1.5–4.5 V voltage window (capacity retention of 83.3 %, specific capacity of 106.8 mA h g−1) compared with that of pristine Na 0.67 Ni 0.25 Mn 0.75 O 2 (capacity retention of 34.2 %, specific capacity of 51.3 mA h g−1). This work demonstrates the favorable effect of Li doping in P2-type layered materials to suppress the phase transition and inhibit the redox activity of Mn and O ions, and it provides an effective approach for the development of cathodes for sodium-ion batteries with high specific energy and long life. [Display omitted] • A series of P2-type cathodes Na 0.75 (Ni 0.25 Mn 0.75) 1-x Li x O 2 (x=0, 0.1, 0.2) are prepared by high-temperature solid phase method. • The Na 0.67 [Ni 0.25 Mn 0.75 ] 0.9 Li 0.1 O 2 cathode shows excellent cycling performance in a wide voltage window of 1.5-4.5 V. • Li substitution can effectively suppress the Mn redox and the harmful phase transition of P2-O2. [ABSTRACT FROM AUTHOR]

The rapid growth in electronic and portable devices demands safe, durable, light weight, low cost, high energy, and power density electrode materials for rechargeable batteries. In this context, biomass‐based materials and their hybrids are extensively used for energy generation research, which is primarily due to their properties such as large specific surface area, fast ion/electron kinetics, restricted volume expansion, and restrained shuttle effect. In this review, the key advancements in the preparation of biomass derived porous carbons using different synthesis strategies and their modifications with species such as heteroatoms, metal oxides, metal sulfides, silicon, and other carbon forms are discussed. The electrochemical performances of these materials and the ion storage mechanisms in different batteries including lithium‐ion, lithium–sulfur, sodium‐ion, and potassium‐ion batteries are discussed. Special attention will be paid to the challenges in using porous biomass‐derived carbons and the current strategies employed for maximizing the specific capacity and lifetime for battery applications. Finally, the drawbacks in current technology and endeavors for the future research and development in the field to catapult the performances of the biomass derived materials in order to equip them to meet the demands of commercialization are highlighted. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries (SIBs) based on solid‐state electrolytes (SSEs), although safe for high temperatures, are less capable of transferring ions at ambient temperatures, let alone at low temperatures. This work offers a simple and scalable technique to construct a nanofiber matrix composite electrolyte with boosting Na+ transport and interfacial compatibility for SIBs. Benefitting from the salt dissociation and selective cation conduction synergistic effect of the acylamino, carbonyl, and ester groups in the low‐cost copolymer synthesized from 2‐(methacryloyloxy)ethyl acetoacetate and N,N′‐methylenebisacrylamide, a facilitating of Na+ transport at extreme temperatures is realized. Besides, flexible flame retardance ceramic SiO2 nanofibers greatly enhance high‐temperature safety. The ultrathin functional AlF3 layer generated by binder‐free magnetron sputtering suppresses the dendrites, eliminating the interfacial issues between the electrolyte and anode, which is proved by 5500 h of ultrasteady plating/stripping. Superior ionic conductivity of 0.153 mS cm−1 at −30 °C implies fast Na+ transport, which is further evidenced by molecular dynamics simulations. Rate performance at 0.05–10 C from −30 to 130 °C further demonstrates the excellent electrochemical performance of the electrolyte. This work provides encouraging guidance for high‐safety SSEs with rapid Na+ conduction for SIBs operating at extra‐wide temperatures. [ABSTRACT FROM AUTHOR]

In advancing battery technologies, primary attention is paid to developing and optimizing low-cost electrode materials capable of fast reversible ion insertion and extraction with good cycling ability. Sodium-ion batteries stand out due to their inexpensive price and comparable operating principle to lithium-ion batteries. To achieve this target, various graphene-based nanocomposites fabricate strategies have been proposed to help realize the nanostructured electrode for high electrochemical performance sodium-ion batteries. In this review, the graphene-based nanocomposites were introduced according to the following main categories: graphene surface modification and doping, three-dimensional structured graphene, graphene coated on the surface of active materials, and the intercalation layer stacked graphene. Through one or more of the above strategies, graphene is compounded with active substances to prepare the nanocomposite electrode, which is applied as the anode or cathode to sodium-ion batteries. The recent research progress of graphene-based nanocomposites for SIBs is also summarized in this study based on the above categories, especially for nanocomposite fabricate methods, the structural characteristics of electrodes as well as the influence of graphene on the performance of the SIBs. In addition, the relevant mechanism is also within the scope of this discussion, such as synergistic effect of graphene with active substances, the insertion/deintercalation process of sodium ions in different kinds of nanocomposites, and electrochemical reaction mechanism in the energy storage. At the end of this study, a series of strategies are summarized to address the challenges of graphene-based nanocomposites and several critical research prospects of SIBs that provide insights for future investigations. [ABSTRACT FROM AUTHOR]

Na 0.23 TiO 2 particles coated on a nitrogen-doped carbon sphere (NTO@NCS) were synthesized using dihydroxybenzene and hexamethylenetetramine as carbon and nitrogen sources, respectively. In the NTO@NCS-R sample, Na 0.23 TiO 2 particles uniformly cover the surface of electrically conductive NCS by forming the Ti-O-C bonds between Na 0 · 23 TiO 2 and NCS. The feature is favorable to provide the NTO electrode the structural robustness and sodium ion diffusion during cycling. The NTO@NCS-R electrode exhibits an outstanding discharge capacity of 193.1 mAh g−1 at 0.1 A g−1 after 300 cycles in the voltage range of 0.01–2.5 V, compared to bare Na 0 · 23 TiO 2 , NTO@NCS-C, and NTO@NCS-H. In addition, NTO@NCS-R exhibits a discharge capacity of 114.4 mAh g−1 at 1.0 A g−1 at 2000th cycle and 58.7 mAh g−1 at 2.0 A g−1 at 8000th cycle, respectively, proving fast sodium ion diffusion and excellent cycle stability during long-term cycles. [Display omitted] • Nitrogen-doped carbon (NCS) was introduced into Na 0·23 TiO 2 composites for the first time. • Na 0 · 23 TiO 2 particles are uniformly distributed on NCS with Ti-O-C bonds. • NTO@NCS-R demonstrates remarkable electrochemical performance during cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mo 4/3 B 2 T x -MoS 2 @C were prepared and delivered superior sodium storage performance. • Mo 4/3 B 2 T x induced 3D hydrangea structure and built-in electric field at interface. • Copious sulfur vacancies offered additional active sites for ion storage. • Weakened Na-S bonds optimized the recombination energies of Mo-S bond. • Fast diffusion channel and rapid conversion reaction kinetic favored Na storage. Molybdenum sulfide (MoS 2) with large layer distance and high theoretical capacity has been identified as one of the most promising anodes for sodium ion batteries, but the poor intrinsic conductivity and severe structural agglomeration restricted its diffusion kinetic and specific capacity. In this work, the synergistic effect of heterogeneous interface and Na 2 S adsorption/conversion active sites was employed to construct Mo 4/3 B 2 T x -MoS 2 @C composites using a self-assembly and calcination strategy. Theoretical calculation and experimental results demonstrated that the charge transfer and interface between Mo 4/3 B 2 T x and MoS 2 along with the 3D hydrangea-like structure improved the intrinsic conductivity and provided fast ion diffusion channels, boosting the electrochemical kinetics; while the favorable adsorption of Na 2 S and weakened Na-S bond at Mo 4/3 B 2 T x -Mo interface optimized the recombination energies of Mo-S bond, accelerating the ion diffusion and enhancing the electrochemical reversibility. In addition, the copious sulfur vacancies provided additional active sites for ion storage, ameliorating the electrochemical capacity. As expected, the novel Mo 4/3 B 2 T x -MoS 2 @C electrode delivered a satisfactory rate capacity (340.6 mAh g−1 at 1 A g−1) and durable cyclic performance (267.2 mAh g−1 after 600 cycles at 2 A g−1). When paring with Na 3 V 2 (PO 4) 3 , the Mo 4/3 B 2 T x -MoS 2 @C||Na 3 V 2 (PO 4) 3 full cell exhibited high energy densities of 234.0 and 131.7 Wh kg−1 at 215.7 W kg−1 and 4.4 kW kg−1, respectively. The proposed synergistic strategy of heterogeneous interface and Na 2 S adsorption/conversion active sites provided a new guidance for the rational design of transitional metal sulfide anodes for sodium ion batteries. [ABSTRACT FROM AUTHOR]

Carbon spheres are appealing anode materials for advanced sodium ions batteries. However, several major hurdles to address are the stress-accumulation associated with the drastic volume change, the sluggish sodium ions diffusion kinetics, and poor electrochemically active sites inside. Herein, the von Mises stress distribution uncovers the critical role of the radial channel on the strain relaxation behavior based on the finite element method. Based on the finite element simulation, the radial porous hollow carbon spheres are proposed and synthesized by a universal strategy with a hard-template approach and dynamic graphitization. RPHCSs dominate opened micro-mesoporous features through the shell. With fast sodium ion diffusivity kinetics and much more accessible electrochemical active sites in shell, RPHCSs electrodes deliver a high specific capacity of 103.0 mAh g−1 even at 4000 mA g−1 with a high capacity contribution ratio > 0.1 V (81.1 %), suggesting its great superiority in the application of high-rate sodium ions storage. Such architecture provides a promising structural platform for the fabrication of high-performance carbon spheres material for other electrochemical energy storage systems. [Display omitted] • Radial channel in a hollow carbon sphere can effectively regulate and release the strain induced from sodiation. • Radial pores in resin-derived hollow carbon spheres can be engineered by nickel ions etching strategy. • Radial porous hollow carbon spheres show great outstanding superiority in high-rate and high-safe sodium ions batteries. [ABSTRACT FROM AUTHOR]

Sodium super‐ionic conductor (NASICON)‐structured phosphates are emerging as rising stars as cathodes for sodium‐ion batteries. However, they usually suffer from a relatively low capacity due to the limited activated redox couples and low intrinsic electronic conductivity. Herein, a reduced graphene oxide supported NASICON Na3Cr0.5V1.5(PO4)3 cathode (VC/C‐G) is designed, which displays ultrafast (up to 50 C) and ultrastable (1 000 cycles at 20 C) Na+ storage properties. The VC/C‐G can reach a high energy density of ≈470 W h kg−1 at 0.2 C with a specific capacity of 176 mAh g−1 (equivalent to the theoretical value); this corresponds to a three‐electron transfer reaction based on fully activated V5+/V4+, V4+/V3+, V3+/V2+ couples. In situ X‐ray diffraction (XRD) results disclose a combination of solid‐solution reaction and biphasic reaction mechanisms upon cycling. Density functional theory calculations reveal a narrow forbidden‐band gap of 1.41 eV and a low Na+ diffusion energy barrier of 0.194 eV. Furthermore, VC/C‐G shows excellent fast‐charging performance by only taking ≈11 min to reach 80% state of charge. The work provides a widely applicable strategy for realizing multi‐electron cathode design for high‐performance SIBs. [ABSTRACT FROM AUTHOR]

To get a robust architecture for rapid and permanent ion insertion/extraction, various frameworks are constructed, attempting to enhance the high‐rate lifespan. However, uncontrollable structural evolution always results in the structural failure derived from the continuous increasing inner strain during the cycling. Herein, inspired by the nest structure, a stable framework with wave‐like surface morphology and cross‐linked inner configuration is fabricated, which possesses fast ion migration channel and stable structure. Most importantly, the concept of synchronous self‐evolution confinement is proposed for high‐capacity conversion‐type anode materials, which can control the aggregated inner strain and alleviate the inescapable electrode pulverization, thus ensuring the electrode stability and boosting the structure integrity during the repeated cycling. When serving as an anode for sodium ion batteries, the initial nest‐like (SnFe)S2 heterogeneous mildly evolves into a stable architecture with exceptional performance, expressing a prominent rate property (389.4 mA h g−1 at 30 A g−1) and stable durability (627.41 mA h g−1 at 10 A g−1 for 800 cycles). Significantly, this route of strain engineering sheds significant light on solving large volume‐expansion‐type materials for high reversible capacity, especially in the exploration of electrochemical energy storages. [ABSTRACT FROM AUTHOR]

Due to its properties (stable, affordable and non‐toxic), titanium dioxide (TiO2) has a promising future as electrode material for sodium‐ion batteries (SIBs). Its Na+ insertion/deinsertion mechanism, on the other hand, results in poor electronic conductivity and sluggish ionic diffusivity, leading to rapid capacity fading. Herein, a molten salt method is employed to creat abundant carbon pores framework, being capable of supporting plentiful ultra‐fine TiO2 adhering (U‐TiO2/C). With this unique porous structure of lots of exposed active sites, the U‐TiO2/C composite provides a faster ions transport and volume expansion buffer zone during cycling. As anode for SIBs, the U‐TiO2/C manifests splendid electrochemical performance. Specifically, the U‐TiO2/C electrode delivers a high capacity of 202.7 mAh g−1 after 100 cycles at 0.1 A g−1 and 91.4 mAh g−1 at 1.0 A g−1 after 160 cycles. Even with the increased current density to 10.0 A g−1, the U‐TiO2/C electrode still performs a high capacity of 69.5 mAh g−1 after 2500 cycles. Detailed kinetic analysis has been investigated to quantificationally demonstrate that the surface pseudocapacitive storage behavior plays a dominant role in the enhanced sodium storage. [ABSTRACT FROM AUTHOR]

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Sodium‐ion batteries (SIBs) are considered a promising candidate in green energy storage due to their considerable abundance. The low mass loading (less than 2.0 mg cm−2) of SIBs‐based cathodes cannot meet the energy density on the practical device level, which is mainly restricted by sluggish Na+ transport. To the end, a facile and compatible strategy was demonstrated by utilizing hyaluronic acid (HA) binder to achieve fast ion transport and targeted energy density for Na3V2(PO4)3 (NVP) cathodes. As a novel functional aqueous binder, HA allowed cathodic materials to organize the unique conductive network. The network‐like electrode structure could buffer volume changes during sodiation/desodiation process and provide bi‐continuous charge transport channels for both Na+ and electrons at the interface. HA promoted the formation of the stable solid permeable interface films, protecting the electrochemical stability of the cathode and ensuring its good cycle performance. These functions of HA binder enabled that NVP delivered a reversible discharge capacity of 107.3 mAh g−1 at 0.5 C (1 C=117 mA g−1), which showed no sacrifice of electrochemical performances with mass loading increasing from 1.1 to 4.4 mg cm−2. Even at a high rate of 20 C, NVP‐HA (loading 4.0 mg cm−2) could reserve a good capacity of 76.8 mAh g−1 with the retention of 99.3 % after 2000 cycles. This study provides a novel strategy to achieve high energy density for SIBs in large‐scale energy storage. [ABSTRACT FROM AUTHOR]

The electrode materials with long cycle life are important for the large-scale application of sodium ion batteries. In this work, P2-type Na0.71Co0.96-xTixO2 (x = 0, 0.057, 0.073, 0.09) were synthesized by molten-salt method. The Ti doping content could influence the crystallographic unit cell volume, particle size, oxygen vacancies, and surface charge density of those samples. When x = 0.073, the P2-type Na0.71Co0.96-xTixO2 (x = 0.073) exhibits superior reversible capacity and rate performance due to the appropriate synergistic effect. In particular, the initial discharge capacity of NCTO-0.073 is about 118.5 mAh g−1 at 100 mA g−1. Even the current density gets to 1000 mA g−1, the initial discharge capacity remains 71.7 mAh g−1 after 1000 cycling with the capacity retention of 67.90%. The electrochemical kinetics analysis further prove that the P2-type Na0.71Co0.96-xTixO2 (x = 0.073) owns outstanding electrical conductivity and fast sodium ion diffusion behavior to promote the electrochemical reaction during the charging/discharging. These results will contribute to the industrialized application of stable high-performance cathodes for sodium ion batteries. [ABSTRACT FROM AUTHOR]

The sodium dual ion battery (Na‐DIB) technology is proposed as highly promising alternative over lithium‐ion batteries for the stationary electrochemical energy‐storage devices. However, the sluggish reaction kinetics of anode materials seriously impedes their practical implementation. Herein, a Na‐DIB based on TiSe2‐graphite is reported. The high diffusion coefficient of Na‐ions (3.21×10−11–1.20×10−9 cm2 s−1) and the very low Na‐ion diffusion barrier (0.50 eV) lead to very fast electrode kinetics, alike in conventional surface capacitive storage systems. In‐situ investigations reveal that the fast Na‐ion diffusion involves four insertion stage compositions. A prototype cell shows a reversible capacity of 81.8 mAh g−1 at current density of 100 mA g−1, excellent stability with 83.52 % capacity retention over 200 cycles and excellent rate performance, suggesting its potential for next‐generation large scale high‐performance stationary energy storage systems. [ABSTRACT FROM AUTHOR]

In this study, the sodium ion adsorption, as a desalination process of saline water, on polyacrylic acid grafted on graphene oxide (PAA-g-GO) was investigated. According to the results of GPC and FTIR analyses, it was confirmed that the synthesized adsorbent has a very effective function for Na+ adsorption. The remarkable finding about the synthesized adsorbent was that in all the tested pH range (8–10) and sodium ion concentrations (0.1–1 M), the measured adsorption capacities were reported to be more than 1750 mg/g. However, it is interesting that the maximum adsorption capacity was obtained a significant amount of 7462.31 mg/g at pH =10. According to the adsorption kinetics analysis results, the equilibrium time was obtained about 90 min. Also, by examining the effect of pH on the amount of sodium ion adsorption, it was found that it increased by increasing pH value. Adsorption data were also modeled with the Redlich-Peterson isotherm with R2 greater than 0.99 for all range of examined pHs. By examining the effect of adsorbent dosage on Na+ adsorption, it was found that the effect of the adsorbent dosage was very high at low initial concentrations (0.1 to 0.2 M), but this effect decreased by increasing the dosage. [Display omitted] • Poly acrylic acid was successfully grafted on graphene oxide (PAA-g-GO) as a new sodium ion adsorbent. • PAA-g-GO demonstrated exceptional sodium adsorption capacity, reaching 7462.31 mg/g at pH 10 and 1 M initial concentration. • The adsorbent exhibited a relatively short equilibrium time, indicating fast sodium ion adsorption. [ABSTRACT FROM AUTHOR]

We carried out first-principles calculations on titanium-doped O3-type NaNi 0.25 Fe 0.25 Mn 0.5 O 2 oxide material for titanium substitution at 0.02, 0.04, 0.06, 0.08, and 0.1. The results obtained show that materials doped with titanium have higher structural stability than undoped material. Also after doping, the conductivity of the materials increases greatly but Na(Ni 0.25 Fe 0.25 Mn 0.5) 0.98 Ti 0.02 O 2 is slightly more conductive (ΔEg = 0.017 eV). Na(Ni 0.25 Fe 0.25 Mn 0.5) 1-x Ti x O 2 (NNFM-Ti x) (x = 0.02, 0.04, 0.06, 0.08, and 0.1) indicates a larger sodium layer, which allows easy migration of sodium ions during charge/discharge processes than NNFM. Sodium ions diffuse faster in NNFM-Ti 0.06 and NNFM-Ti 0.08 compared to other doped-NNFMs. In addition, the Pugh index value of NNFM (1.8222) is lower than that of NNFM-Ti 0.02 , NNFM-Ti 0.04 , NNFM-Ti 0.06 , NNFM-Ti 0.08, and NNFM-Ti 0.1 (2.1376), demonstrating enhancement of elastic ductility after doping. Titanium-doped materials exhibited improved stability under temperature effects between −20 and 60 °C, which represent the operating temperature range of sodium-ion batteries, although this effect did not vary much with the doping rate. The improved thermodynamic stability indicates that the doped materials can better resist degradation, have high efficiency, and a long cycle life. These Na(Ni 0.25 Fe 0.25 Mn 0.5) 1-x Ti x O 2 materials, particularly those with the titanium rate at 0.06 and 0.08 are therefore powerful materials for the accomplishment of efficient sodium-ion batteries cathodes. [Display omitted] • Ti-doped materials have higher structural stability than the undoped one. • Na + can diffuse rapidly in NNFM-Ti 0.06 and NNFM-Ti 0.08 compared to others. • NNFM-Ti 0.02 is slightly more conductive than the other Ti-doped materials. [ABSTRACT FROM AUTHOR]

• In-situ grafting method is developed to tun the defects of coal-derived hard carbon. • Coal-derived hard carbon with low defects exhibits obviously improved initial Coulombic efficiency (ICE). • High capacity, outstanding rate performance and excellent capacity retention are demonstrated for coal-derived hard carbon anode. • The "adsorption-intercalation/filling" sodium ion storage mechanism in hard carbon is also confirmed. Sodium-ion batteries is not essential but also potential to support energy storage system due to the low cost. It's worth noting that low price and high carbon production helps coal extraordinary promise as hard carbon precursor. However, low initial coulombic efficiency (ICE) and practical Na+ storage specific capacity barrier their application owing to lots of defects. Herein, a grafting method is proposed to decrease defects, introducing glucose with simple one step carbonization process. Utilizing the reaction between glucose and coal reduces the defects, which generates a high ICE with less irreversible sodium ion consumption. Meanwhile the expanded carbon layer spaces enable the fast sodium ions transfer, leading to an optimized sodium storage performance. The grafted glucose obviously decreases the defects during the carbonization process and contributes extra sodium storage capacity. The optimal CG0.1 exhibits higher reversible capacity of 293 mAh∙g−1 and ICE of 84 % than pristine coal pyrolytic carbon (250 mAh∙g−1 and 79 %). Besides, it also delivers outstanding capacity retention with 95.3 % and 95.8 % after 1000 cycles at 0.3 A∙g−1 (240 mAh∙g−1) and at 1 A∙g−1 (207 mAh∙g−1). [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) Si-based sodium ion microbatteries (SIMBs) are one of the most promising micro/nano power sources to meet the urgent demands of the micro/nano electromechanical system (M/NEMS) and the tiny smart semiconductor devices. Herein, the Sb electrode is firmly anchored on the 3D hierarchical Si/graphene supporting structure and embraces enhanced electrochemical performance when employed as anode for Si-based SIMBs. Both the enlarged surface area and the reduced electrons&ions transporting distance are beneficial to promote more Na ions reversibly and fast stored in the Sb active material. Moreover, the volume expansion of the Sb electrode during cycling can be well alleviated due to the enough space existed in the 3D micro/nanostructures, thus bring improved cycle life, which are verified from the post morphology characterizations. Systematical Na ion storage behaviors of the 3D Si/graphene/Sb (3D Si/Gr/Sb) microrod (MR) arrays electrode are investigated from the different scan rates of cyclic voltammetry (CV) results, ex-situ XRD/Raman tests, and first-principles theoretical calculations, which prove that the favorable kinetics in the 3D multilayer electrode configurations. Superb cycle stability of the as-constructed full battery of 3D Si/Gr/Sb||NaNiFeMnO 2 implies that the potential application of the 3D hierarchical electrode. Illustration of the promoted kinetics of the unique 3D Si/Graphene/Sb electrode. [Display omitted] • Attractive 3D Si/Gr/Sb anode for Na ion microbattery. • 3D graphene interlayer positively promotes the kinetics. • Improvement in hierarchical 3D Si/Gr/Sb electrode. • Systematic investigation on Na ion storage mechanism. [ABSTRACT FROM AUTHOR]

• FeSe 2 /C composites were prepared by an in-situ transformation process. • FeSe 2 /C showed enhanced reaction kinetic and fast ion diffusion. • FeSe 2 /C delivered superior rate performance and cycling stability in SIBs. Transition metal selenides are considered as potential anode materials for sodium-ion batteries (SIBs) due to their high theoretical capacity. However, the slow kinetic reaction, poor conductivity and severe volume change during sodium ion intercalation/deintercalation process limit its large-scale application. In this study, FeSe 2 /C was prepared through hydrothermal and subsequent annealing process. The conductive carbon layer of FeSe 2 /C can not only promote sodium ion diffusion and electron transfer but also improve the conductivity and release structure damage. As a result, when used as an anode in SIBs, the obtained FeSe 2 /C exhibits an excellent rate capability of 420 mAh g−1 at 20 A g−1 and high cycle stability of 412 mAh g−1 at 10 A g−1 after 1000 cycles. The excellent electrochemical properties suggest that FeSe 2 /C is a promising anode material for SIBs. [ABSTRACT FROM AUTHOR]

Solid ionic conductors are one key component of all-solid-state batteries, and recent studies with lithium, sodium and potassium phosphidosilicates revealed remarkable ion conduction capabilities in these compounds. We report the synthesis and crystal structures of two quaternary phosphidosilicates with sodium and barium, which crystallize in new structure types. Na1.25Ba0.875Si3P5 contains layers of T3 supertetrahedra, while Na31Ba5Si52P83 forms defect T5 entities and contains Si–Si bonds and P3 trimers. Though T1-relaxometry data indicate a relatively low activation energy for Na+ migration of 0.16 eV, the crystal structures lack sufficient three-dimensional migration paths necessary for fast sodium ion conductvity. [ABSTRACT FROM AUTHOR]

Solid ionic conductors are one key component of all-solid-state batteries, and recent studies with lithium, sodium and potassium phosphidosilicates revealed remarkable ion conduction capabilities in these compounds. We report the synthesis and crystal structures of two quaternary phosphidosilicates with sodium and barium, which crystallize in new structure types. Na1.25Ba0.875Si3P5 contains layers of T3 supertetrahedra, while Na31Ba5Si52P83 forms defect T5 entities and contains Si–Si bonds and P3 trimers. Though T1-relaxometry data indicate a relatively low activation energy for Na+ migration of 0.16 eV, the crystal structures lack sufficient three-dimensional migration paths necessary for fast sodium ion conductvity. [ABSTRACT FROM AUTHOR]

Although some strategies have been triggered to address the intrinsic drawbacks of zinc (Zn) anodes in aqueous Zn‐ion batteries (ZIBs), the larger issue of Zn anodes unable to cycle at a high current density with large areal capacity is neglected. Herein, the zinc phosphorus solid solution alloy (ZnP) coated on Zn foil (Zn@ZnP) prepared via a high‐efficiency electrodeposition method as a novel strategy is proposed. The phosphorus (P) atoms in the coating layer are beneficial to fast ion transfer and reducing the electrochemical activation energy during Zn stripping/plating processes. Besides, a lower energy barrier of Zn2+ transferring into the coating can be attained due to the additional P. The results show that the as‐prepared Zn@ZnP anode in the symmetric cell can be cycled at a current density of 15 mA cm−2 with an areal capacity of 48 mAh cm−2 (depth of discharge, DOD ≈ 82%) and even at an ultrahigh current density of 20 mA cm−2 and DOD ≈ 51%. Importantly, a discharge capacity of 154.4 mAh g−1 in the Zn/MnO2 full cell can be attained after 1000 cycles at 1 A g−1. The remarkable effect achieved by the developed strategy confirms its prospect in the large‐scale application of ZIBs for high‐power devices. [ABSTRACT FROM AUTHOR]

• The modified electrospun fibers with semi-ionic C F bond was prepared by CF 4 plasma. • The semi-ionic C F bond benefit to the fast ion and electron transfer for electrode. • Rate performance and long cycles of anode depend on the content of semi-ionic C F bond. • F doped N -enriched fibers deliver long term capacity with 150 mA h g−1 over 2000 cycles. The quest for getting more efficient carbonous anodes for sodium ion batteries (NIBs) prepared by simple and economical methods continues to be an important endeavor. Herein, a plasma-controlled method is developed for preparing semi-ionic C F bonds decorating nitrogen-enriched electrospinning carbon nanofibers (NCNFs) as a free-standing anode for NIBs. The semi-ionic C F bonds are beneficial to the fast ion and electron transfer for a free-standing electrode, which remarkably improves the rate performances of NCNFs as the NIBs anodes. The optimized sample delivers a reversible capacity of 199 mA h g−1 at 0.1 A g−1 and displays excellent long-term stability with reversible specific capacity around 150 mA h g−1 over 2000 cycles at 500 mA g−1 after the rate capability test. Moreover, the presence of semi-ionic C F bonds on plasma nitrogen-enriched electrospinning carbon nanofibers surfaces can reduce the resistance of the anode, thereby showing a more stable solid electrolyte interphase SEI) after electrochemical cycles. [ABSTRACT FROM AUTHOR]

Summary: A valid 3D sandwich‐like architecture of highly conductive Ti3C2Tx nanosheets with efficient 2D polar adsorption surfaces was evenly intercalated into graphene oxide (GO) skeletons with strong bridging via modified liquid phase impregnation, followed by a novel photo‐synthetic nitrogen doping process (N‐RGO/Ti3C2Tx). This novel photo‐synthetic nitrogen doping method not only reduced the GO in a short time but also induced nitrogen doping into the composite easily. Within the rationally designed sandwich‐like architecture, Ti3C2Tx interacted with reduced GO to construct a 3D conductive layer structure while inhibiting mutual stacking, thereby facilitating fast ion/electron transport and strong chemisorption for polysulfides, and also effectively buffering the volume expansion of electrodes during the discharge. In addition, the moderate chemical modulation induced by nitrogen doping achieved abundant defects and active sites, thereby improving the chemical immobilization for polysulfides. As sulfur host, the N‐RGO/Ti3C2Tx sandwich‐like architecture with 76.4 wt% sulfur could deliver excellent electrochemical performance due to the synergy of the above‐mentioned merits. A superior reversible capacity of approximately 1180 mAh g−1 could be achieved over 200 cycles at 0.1 C. Even after cycling 200 times at 0.5 C, a high capacity of 850 mAh g−1 could still be obtained with a capacity retention of 82.5%. We rationally designed a novel structure and then used a facile photo‐synthetic nitrogen doping strategy for surface modification, thus offering a new idea for designing multifunctional sulfur host for high‐performance lithium‐sulfur batteries. [ABSTRACT FROM AUTHOR]

High‐efficiency energy storage technologies and devices have gained numerous attention because of their ever‐increasing requirement. Sodium‐ion capacitors (SICs), as a burgeoning electrochemical energy storage device, combine virtues of rechargeable batteries and electrochemical double layer supercapacitors, delivering both high energy–power density and long cycling life. In the past decades, great efforts have been made to find suitable anode material to conquer the kinetic imbalance between the battery‐type anode with sluggish bulk redox reaction and the capacitor‐type cathode with fast ion absorption/desorption process. By exploring high‐rate performance anode materials, the great reaction kinetic gap between cathodes and anodes can be narrowed down, which directly affects the energy–power densities of SICs. In this article, an overview of advanced battery‐type anode materials is offered for high‐performance SICs with an emphasis on anode structural design and improved energy–power density, including carbonaceous materials, metallic compounds, MXene, organic polymers, and so on. Furthermore, the implementation of presodiation for the sake of optimizing the SICs is also illustrated. Finally, the challenges faced and the perspectives for future developing trends of SICs are discussed. [ABSTRACT FROM AUTHOR]

It is highly attractive for constructing CoS x -based electrode architectures in sodium ion batteries (SIBs). Herein, a three-dimensional flower-shaped CoS 1.097 nanoflakes grown on carbon cloth is developed and examined as flexible anode configuration for SIBs, showing a large discharge capacity of 835.7 mAh g−1 at 0.1 A g−1 and ultrastable lifetime of 1000 cycles at 5 A g−1. The superior sodium storage capability can be attributed to the unique flexible electrode with connected three-dimensional hierarchical porous structure, which makes for ensuring good electrical connection, sustaining the structural integrity of electrode and facilitating fast ion diffusion kinetics upon cycling. Image, graphical abstract [ABSTRACT FROM AUTHOR]

New sodium vanadium(III) hydrogenphosphate hydrate NaV(HPO4)2(H2O)0.5 and sodium vanadium(III) hydrogenphosphate β‐NaV(HPO4)2 were prepared in mild hydrothermal conditions. The crystal structures of NaV(HPO4)2(H2O)0.5 [space group Cc, Z = 4, a = 8.46174(19) Å, b = 9.52583(19) Å, c = 8.69376(15) Å, β = 110.9553(11) °, V = 654.41(2) Å3] and β‐NaV(HPO4)2 [space group C2/c, Z = 4, a = 7.8681(3) Å, b = 9.8451(3) Å, c = 8.5180(2) Å, β = 107.626(2) °, V = 628.85(3) Å3] were solved and refined from X‐ray powder diffraction data. Both compounds were used as precursors in a new route for the preparation of attractive cathode material β‐NaVP2O7. The formation of the structure motive providing fast sodium ion diffusion at the first synthesis stage and its further conservation upon stepwise dehydration was revealed. The oversized Na+‐embedding channels are stabilized by site‐coordinated water in NaV(HPO4)2(H2O)0.5 structure. The topology resemblance and difference in known sodium vanadium(III) complex phosphates are discussed. [ABSTRACT FROM AUTHOR]