Potential Anode For Sodium-ion Batteries Research Articles

Synergistic effect of in-situ carbon-coated mixed phase iron oxides and 3d electrode architectures as anodes for high-performance sodium-ion batteries

Due to the high theoretical capacity, iron-oxide-based Fe2O3 (1007 mAh g−1) and Fe3O4 (926 mAh g−1) materials can be a promising conversion-type anode material for Sodium-ion batteries (SIBs). However, the low electronic conductivity (10−14 S cm−1) and 200% volume expansion of iron oxide lead to poor cycle life and capacity retention, limiting its commercial application. In this work, carbon-coated mixed-phase iron oxide C-Fe2O3-Fe3O4 (C-IO) was synthesized by pyrolysis using ferrocene precursor. Subsequently, a 3D carbon fiber (CF) network was introduced to improve the electrochemical performance of the material by resolving the volume expansion and pulverization issues. Both the CF network and Fe3O4 provide an electron transport pathway. The conventional Cu-C-IO electrodes deliver a 2nd cycle capacity of 335 mAh g−1 at 250 mA g−1 and exhibit 61.5% capacity retention after 500 cycles. In contrast, the 3D-CF-based IO electrodes show 2nd cycle capacity of 607 mAh g−1 at 50 mA g−1 with 96.4% capacity retention after 35 cycles and 420 mAh g−1 with ∼85.4% capacity retention after 500 cycles at 250 mA g−1 (w.r.t. CF and C-IO active mass, CF contribute ∼ 27% and C-IO ∼ 73% capacity), making it a potential anode for SIBs.

Vacancies-Induced Delocalized States Cobalt Phosphide for Binder-Free Anode Toward Stable and High-Rate Sodium-Ion Batteries.

Metal phosphides with easy synthesis, controllable morphology, and high capacity are considered as potential anodes for sodium-ion batteries (SIBs). However, the inherent shortcomings of metal phosphating materials, such as conductivity, kinetics, volume strain, etc are not satisfactory, which hinders their large-scale application. Here, a CoP@carbon nanofibers-composite containing rich Co─N─C heterointerface and phosphorus vacancies grown on carbon cloth (CoP1-x@MEC) is synthesized as SIB anode to accomplish extraordinary capacity and ultra-long cycle life. The hybrid composite nanoreactor effectively impregnates defective CoP as active reaction center while offering Co─N─C layer to buffer the volume expansion during charge-discharge process. These vast active interfaces, favored electrolyte infiltration, and a well-structured ion-electron transport network synergistically improve Na+ storage and electrode kinetics. By virtue of these superiorities, CoP1-x@MEC binder-free anode delivers superb SIBs performance including a high areal capacity (2.47 mAh cm-2@0.2mA cm-2), high rate capability (0.443 mAh cm-2@6mA cm-2), and long cycling stability (300 cycles without decay), thus holding great promise for inexpensive binder-free anode-based SIBs for practical applications.

Binderless Electrodeposited NiCo2S4-MWCNT as a Potential Anode Material for Sodium-Ion Batteries

Conversion type ternary NiCo2S4, exhibiting high electrical conductivity (∼1.25 × 106 S m−1) and high theoretical capacity (703 mAh g−1), has gained interest as an anode material for sodium-ion batteries (SIBs). Despite its potential, NiCo2S4 (NCS) has extensive volume expansion during cycling. This study introduces the NCS-multi-walled carbon nanotube (MWCNT) onto a carbon fiber (CF) electrode (NCS and NCS-MWCNT@CF), developed through electrodeposition, which addresses these limitations. The unique sheet-like morphology of NCS, featuring abundant pores, ensures good access to the electrolyte. Incorporating a three-dimensional conductive CF framework that acts as a free-standing current collector helps prevent the agglomeration of NCS particles and mitigates volume expansion by providing enough buffer space in the layers of the CF matrix. Our findings reveal that NCS on CF electrodes deliver a second cycle capacity of 620 mA g−1 at 30 mA g−1 and retain 72% capacity after 200 cycles. At 200 mA g−1, the NCS@CF electrodes deliver 378 mAh g−1 in the second cycle with 68% capacity retention in the 200th cycle, whereas NCS-MWCNT@CF delivers 538 mAh g−1 at 200 mA g−1, maintaining 86 % capacity after 100 cycles, making it a potential anode for SIBs.

Synergistic Effect of 3D Electrode Architecture and In Situ Carbon Coating on the Electrochemical Performance of SnO2 Anodes for Sodium-Ion Batteries

SnO2, owing to its high theoretical capacity of 1378 mAh g−1 and low sodium insertion potential, is one of the attractive anode materials for Sodium-ion batteries (SIBs). However, extensive volume expansion (∼300 %), significant capacity loss, particle agglomeration, and low conductivity (1.82 × 10−8 S cm−1) of SnO2 limit its commercial applications. In this work, SnO2 nano-particles have been synthesized via a one-step hydrothermal method. Subsequently, 3D electrode architecture is developed using pitch-coated SnO2 nanomaterial onto carbon fiber (CF) current collector to mitigate the inherent challenges of SnO2 anode. Compared to the conventional SnO2 electrode, the optimized CF-SnO2- carbon composite electrodes show an excellent second-cycle stable capacity of 843 mAh g−1 at 30 mA g−1 with 95 % capacity retention after 100 cycles. This CF-SnO2-carbon composite electrode further delivers a stable capacity of 419 mAh g−1 at 300 mA g−1, having 80 % capacity retention after 200 cycles, and shows excellent C-rate performance. Conductive CF backbone and carbon coating accommodate the volume expansion of the active material, acting as a buffer matrix and reducing the electrode pulverization. This work entails a carbon fiber-based electrode engineering approach to fabricate a binder-less metal current collector-free freestanding electrode as a potential anode for SIBs.

Achieving high-rate capacity FeSe2@N-Doped carbon decorated with Ti3C2Tx MXenes for sodium ion batteries

Transition metal selenides have been studied as potential anodes for sodium-ion batteries (SIBs) due to their high theoretical capacity and electric conductivity. However, the serious volume expansion, particle aggregation and the dissolution of polyselenium can lead to inferior cycle performance. Herein, the ingeniously designed FeSe2 hollow spheres with the nitrogen-doped carbon shells and Ti3C2Tx MXene materials have been synthesized and exhibited the excellent rate and cycle performance for SIBs, achieving the specific capacity of 344 mAh g−1 with the charging process of ∼26.4 s at 50 A g−1 and the reversible capacity of 287 mAh g−1 after 1200 cycles. The synergy effect of nitrogen-doped carbon shells and MXene layers with the inner void can facilitate mass transport/electron transfer, alleviate the volume expansion of FeSe2, and reduce the direct contact of FeSe2 with the electrolyte, satisfying the sodium storage performance and ultrahigh stability. Moreover, the full cells assembled with pre-sodiated FeSe2@NC@MXene as anode and Na3V2(PO4)3@C as cathode deliver a reversible capacity of 466 mAh g−1 after 600 cycles at 1 A g−1, with a capacity retention rate of 90.3 %. This work may present a promising way for the high-rate capacity materials for the applications as sodium-ion battery anode.

Construction of FeSe2 nanoparticles encapsulated in TiN/N-doped carbon nanofibers intertwined with in-situ grown CNTs for pseudocapacitive Na+ storage

Metal selenides are recognized as potential anodes for sodium-ion batteries because of their high theoretical capacity. However, they face the hurdles of low electronic conductivity and significant volume change. In this study, a composite material consisting of FeSe2 nanoparticles enclosed within TiN/N-doped carbon nanofibers intertwined with in-situ grown carbon nanotubes (FeSe2@TNCF/CNTs) is successfully prepared by electrospinning, carbonization, and selenization approach. The TiN/N-doped carbon nanofibers enhance electronic conductivity, active sites for sodium-ion storage, and structural stability. Moreover, carbon nanotubes (CNTs) that in-situ grown on the carbon nanofibers not only enhance conductivity but also facilitate electrolyte penetration and buffer volume expansion. Benefiting from the synergistic effects of FeSe2, TiN, N-doped carbon nanofibers and CNTs, the hybrid FeSe2@TNCF/CNTs anode demonstrates long-term cycling stability and ultrafast pseudocapacitive sodium storage capability, with a specific capacity of 388.5 mAh/g delivered at 0.2 A/g after 1000 cycles. This work could provide inspiration for further research into the design and manufacture of high-performance materials for use in energy storage systems.

Metal doping and vacancy synergistic induced electron/ion engineering to optimize the redox kinetics of sodium storage: A case study Mo1-xWxSe2

Transition metal dichalcogenides have emerged as potential anodes for sodium-ion batteries (SIBs) and dual-ion batteries (DIBs), but their sodium storage properties require further improvement due to their ubiquitous shortcomings including inherently poor electronic conductivity, considerable volume variations and severe structural collapse of electrodes during electrochemical reactions. Here, we report a Se vacancy-tunable Mo1-xWxSe2 embedded N-doped porous carbon superstructure (Mo1-xWxSe2/N-PC, x = 0–1) via a controllable self-assembly approach and subsequent selenization process. Varying the relative metal cation doping concentration can in situ adjust the anion Se vacancy concentration without requiring additional post-treatments. As a result, the most optimized Mo0.5W0.5Se2/N-PC for SIBs presents high capacities of 688 mAh g−1 at 0.1 A g−1 after 300 cycles. Electrochemical kinetic analysis and density functional theory calculations verify that abundant Se vacancies and metallic W doping have significant effects on improving ionic and electron diffusion kinetics. Furthermore, the DIB full cell assembled using Mo0.5W0.5Se2/N-PC anode combined with the expanded graphite cathode exhibit durable cycling stability (104 mAh g−1 at 1.0 A g−1 over 700 cycles) and outstanding rate performance (142 mAh g−1 at 4.0 A g−1). The proposed approach for fabricating tunable vacancy-modulated TMD superstructures provides an effective method for constructing advanced electrode materials for energy storage systems.

Stabilize Sodium Metal Anode by Integrated Patterning of Laser-Induced Graphene with Regulated Na Deposition Behavior.

Metallic sodium is regarded as the most potential anode for sodium-ion batteries due to its high capacity and earth-abundancy. Nevertheless, uncontrolled Na dendrite growth and infinite volume change remain great challenges for developing high-performance sodium metal batteries. This work provides a simple and general approach to stabilize sodium metal anode (SMA) by constructing Sn nanoparticles-anchored laser-induced graphene on copper foil (Sn@LIG@Cu) consisting of Sn@LIG composite, polyimide (PI) columns, and Cu current collector. The Sn-based sodiophilic species effectively reduce the Na nucleation overpotential and regulate the dendrite Na-free deposition. While the flexible PI columns act as binder and buffer the volume variation of Na during cycling. Besides, the unique patterned structure provides continuous and rapid channels for ion transportation, promoting the Na+ transport kinetics. Therefore, the as-fabricated Sn@LIG@Cu electrode exhibits outstanding rate performance to 40mA cm-2 and excellent cycling stability without dendrite growth, which is confirmed by in-situ optical microscopy observation. Moreover, the practical full cell based on such an anode displays a favorable rate capability of up to 10 C and cycling performance at 5 C for 600 cycles. This work thus demonstrates a facile, highly-efficient, and scalable approach to stabilize SMAs and can be extended to other battery systems.

Ion-Exchange Route Induced Heterostructured CoS2/FeS Nanoparticles Confined in Hollow N-Doped Carbon Frameworks for Enhanced Sodium Storage Performance

As a result of the high theoretical capacities, transition metal sulfides have attracted increasing attention as potential anodes for sodium-ion batteries (SIBs), but severely suffer from large volumetric variations, sluggish kinetics, and polysulfide shuttling. Herein, utilizing metal–organic frameworks (MOFs) as functional templates, heterostructured CoS2/FeS nanoparticles confined in a hollow N-doped carbon framework are successfully fabricated via a controlled ion-exchange reaction combined with subsequent carbonization and sulfurization processes. The construction of CoS2/FeS heterointerfaces promotes electron transfer and provides more active sites, while the derived N-doped carbon framework with a unique hollow interior effectively improves the electrical conductivity, alleviates the volumetric variations, and facilitates the sodium storage process with shortened Na+ diffusion paths. As anodes for SIBs, the optimal CoS2/FeS hybrid composite exhibits a high initial Coulombic efficiency (ICE) of 89.3%, a prolonged cycle life with a capacity of 494 mAh g–1 over 500 cycles under a current density of 1.0 A g–1, and an excellent rate capability of 428 mAh g–1 at 5.0 A g–1, showing the great promise for SIBs. This research offers an efficient and feasible approach for exploring and fabricating bimetallic sulfide heterostructures with a unique hollow structure for high-performance metal-ion batteries.

CoSe2 nanodots embedded in N-doped dual-carbon nanospheres for boosting sodium-ion storage

Cobalt diselenide (CoSe2) is regarded as a rising star as anode materials for sodium-ion batteries (SIBs) due to fast sodium diffusion kinetics, and high theoretic capacity. Nonetheless, the intrinsic conversion reaction mechanism inevitably causes large volume variation accompanying the insertion of sodium ion, resulting in poor cycling stability. Furthermore, its low electronic conductivity always raises unsatisfactory rate capability. In this work, we design CoSe2 nanodots embedded in N-doped dual-carbon nanospheres (CoSe2/NC@NCSs) via a hard template assisted one-step selenization strategy as potential anode for SIBs. The unique hollow dual-carbon spheres as conductive matrix can provide fast electron transfer path for CoSe2 nanodots. Meanwhile, dual-carbon spheres with inner void acts as protective barrier for confining CoSe2 nanodots during sodiation/desodiation. Benefit from the synergetic merits of hollow dual-carbon spheres and CoSe2 nanodots, our CoSe2/NC@NCSs electrode exhibits competitive electrochemical performance with a reversible capacity of 386 mAh g−1 (0.2 A g−1), and an inspiring cyclability (148 mAh g−1 at 2 A g−1) over 800 cycles. A CoSe2/NC@NCSs//AC device was fabricated and exhibits stable cyclability at 1 A g−1 over 450 cycles, manifesting the great potential for sodium-ion hybrid capacitors. Our work paves a new route for the electrode design strategy for SIBs.

Hollow sphere of heterojunction (NiCu)S/NC as advanced anode for sodium-ion battery

Metal sulfide is considered as a potential anode for sodium-ion batteries (SIBs), due to the high theoretical capacity, strong thermodynamic stability and low-cost. However, their cycle capacity and rate performance are limited by the excessive expansion rate and low intrinsic conductivity. Herein, heterogeneous hollow sphere NiS-Cu9S5/NC (labeled as (NiCu)S/NC) based on Oswald ripening mechanism was prepared through a simple and feasible methodology. From a structural perspective, the hollow structure provides an expansion buffer and raises the electrochemical active area. In terms of electron/ion during the cycles, Na+ storage mechanism is optimized by NiS/Cu9S5 heterogeneous interface, which increases the storage sites and shortens the migration path of Na+. The formation of built-in electric field strengthens the electron/ion mobility. Based on the first principle calculations, it is further proved the formation of heterogeneous interfaces and the direction of electron flow. As the anode for SIBs, the synthesized (NiCu)S/NC delivers high reverse capacity (559.2 mA h g−1 at 0.5 A g−1), outstanding rate performance (185.3 mA h g−1 at 15 A g−1), long-durable stability (342.6 mA h g−1 at 4 A g−1 after 1500 cycles, 150.0 mA h g−1 at 10 A g−1 after 20,000 cycles with 0.0025% average attenuation rate). The matching cathode electrode Na3V2(PO4)3/C is assembled with (NiCu)S/NC for the full-battery that achieves high energy density (253.7 W h kg−1) and reverse capacity (288.7 mA h g−1). The present work provides a distinctive strategy for constructing electrodes with excellent capacity and stability for SIBs.

Controllable fabrication of vanadium selenium nanosheets for a high-performance Na-ion battery anode.

Vanadium selenium has gained attention as a potential anode for sodium-ion batteries (SIBs) due to the tunable crystal structure, effective channels for Na+ diffusion, and high theoretical specific capacity. However, the pursuit of vanadium selenium remains an enormous challenge. Herein, we demonstrated that V2Se9 nanosheets could be fabricated facilely and efficiently via a one-pot synthesis method with the careful selection of the solvent/surfactant. The V2Se9 anode have demonstrated excellent electrochemical performance for SIBs. An intercalation and conversion mechanism of Na-storage in V2Se9 were clarified by ex situ X-ray diffraction. This work develops an effective strategy to fabricate transition metal chalcogenides for high-performance sodium storage.

Effect of fluoro and hydroxy analogies of diglyme on sodium-ion storage in graphite: a computational study.

Diglyme co-intercalation with sodium ion (Na+) into graphite can enable the use of graphite as a potential anode for sodium-ion batteries (NIBs). However, the presence of diglyme molecules in Na+ intercalated graphite limits Na+ storage capacity and increases volume changes. In this work, the effect of functionalising diglyme molecules with fluoro and hydroxy groups on Na+ storage properties in graphite were computationally studied. It was found that the functionalisation can significantly alter the binding between sodium and the solvent ligand as well as between the sodium-solvent complex and the graphite. The hydroxy-functionalised diglyme exhibits the strongest binding to the graphite of the other functionalised diglyme compounds considered. The calculations also reveal that the graphene layer affects the electron distribution on the diglyme molecule and Na, so the diglyme complexed Na binds more strongly to the graphene layer than the Na alone. We also propose a mechanism for the early stages of the intercalation mechanism that involves a reorientation of the sodium-diglyme complex and suggest how the solvent can be designed to optimise the co-intercalation process.

Pomegranate-inspired porous SnSe/ZnSe@C anode: A stress-buffer nanostructure for fast and ultrastable sodium-ion storage

Tin selenide (SnSe) is considered as a potential anode for sodium-ion batteries (SIBs) owing to its high theoretical specific capacity. Unfortunately, it suffers from drastic volume expansion/contraction during sodium ions insertion/extraction, resulting in poor cycling stability. Herein, a pomegranate-inspired porous carbon shell wrapped heterogeneous SnSe/ZnSe composite (SnSe/ZnSe@C) is exquisitely designed and fabricated through electrostatic spraying followed by high-temperature selenization. The polyacrylonitrile-derived carbon shell acts as an adhesive to link the porous cubic SnSe/ZnSe and form highly interconnected microcircuits to improve the electron/ion transfer efficiency and inhibit the bulk volume change of internal metallic selenide nanoparticles and polyselenides dissolution during repeated cycling. Moreover, the abundant heterostructure interface of SnSe/ZnSe further significantly accelerates the electrons/ions transport. As a result, the as-prepared SnSe/ZnSe@C electrode exhibits a high specific capacity (508.3 mAh g−1 at 0.05 A g−1), excellent rate performance (177.8 mAh g−1 at 10.0 A g−1), and remarkable cycling stability (195.9 mAh g−1 after 10,000 cycles at 5.0 A g−1). Furthermore, in-situ X-ray diffraction (XRD)/Raman, ex-situ transmission electron microscopy, and kinetic analysis clearly reveal a four-step electrochemical reaction process and battery-capacitor dual-mode sodium storage mechanism. This work provides a new perspective for developing commercial SIBs anode materials with high capacity and long lifespan.

Fluorine-Doped Hard Carbon as the Advanced Performance Anode Material of Sodium-Ion Batteries

F-doping hard carbon (F–HC) was synthesized through a mild fluorination at temperature at relative low temperature as the potential anode for sodium-ion batteries (SIBs). The F-doping treatment to HC expands interlayer distance and creates some defects in the graphitic framework, which has the ability to improve Na+ storage capability through the intercalation and pore-filling process a simultaneously. In addition, the electrically conductive semi-ionic C–F bond in F–HC that can be adjusted by the fluorination temperature facilitates electron transport throughout the electrode. Therefore, F–HC exhibits higher specific capability and better cycling stability than pristine HC. Particularly, F–HC fluorinated at 100 °C (F–HC100) delivers the reversible capability of 343 mAh/g at 50 mAh/g, with the Coulombic efficiency of 78.13%, and the capacity retention remains as 95.81% after 100 cycles. Moreover, the specific capacity of F–HC100 returns to 340 mAh/g after the rate capability test demonstrates its stability even at high current density. The enhanced specific capacity of F–HC, especially at low-voltage region, has the great potential as the anode of SIBs with high energy density.

Metal-organic framework derived cobalt phosphide nanoparticles encapsulated within hierarchical hollow carbon superstructure for stable sodium storage

Metal-organic framework (MOF) derivatives with controllable morphology, porosity, and high specific area are considered as potential anodes for sodium-ion batteries (SIBs). However, the poor conductivity and sluggish diffusion kinetics of Na+ of MOF-derived materials result in rapid capacity decline and inferior rate capability. Herein, a hierarchical hollow superstructure composed of CoP nanoparticles anchored on the N-doped carbon polyhedral frameworks with the epitaxial growth of carbon nanotubes (CoP@N-HP/CT), is prepared by MOF coating, and subsequent carbonization − oxidation − phosphorization strategy. Owing to the elaborate hierarchical hollow superstructure, the CoP@N-HP/CT composites achieve long cycling stability (over 2500 cycles), and good rate capability as SIBs anodes. The remarkable electrochemical performance of the CoP@N-HP/CT hybrids is attributed to their high capacitive contribution and fast sodium ion diffusion rate. Furthermore, the sodium storage behaviors of the CoP@N-HP/CT are revealed by ex-situ X-ray photoelectron spectroscopy and transmission electron microscope techniques. Thus, the well-designed hierarchical hollow CoP@N-HP/CT superstructure gives an insight into the superior anodes for sodium storage.

Pseudocapacitive sodium storage of Fe1−xS@N-doped carbon for low-temperature operation

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.

Ultrafast flame growth of carbon nanotubes for high-rate sodium storage

Sodium-ion batteries (SIBs) are one of the most promising alternatives to lithium-ion batteries as large-scale energy storage systems (ESSs), owing to the natural abundance and low cost of sodium. Because of its capability to accommodate large-sized Na+, amorphous carbon stands out as potential anode for SIBs among the reported carbonaceous materials. However, the practical application of amorphous carbon is still limited by the poor cycling stability and unsatisfactory rate capability. Herein, we report a binder-free SIB anode by directly growing carbon nanotubes on nickel foam (CNTs-NF) via a simple and fast flame approach. Owing to highly disordered turbostratic structures and presence of abundant defects, the CNTs-NF anode delivers excellent electrochemical performance. Electrochemical impedance spectroscopy and cyclic voltammetry demonstrate low charge transfer impedance and surface-induced capacitive behavior, which favor fast transport/diffusion of electrons/ions. Particularly, such anode exhibits a high reversible capacity of 258 mA h g−1 at 0.1 A g−1 with an initial Coulombic efficiency of as high as 82.2% and superior rate capability of 95 mA h g−1 at an ultrahigh current density of 20 A g−1. The high-rate CNTs-NF anode holds great potential in application for large-scale ESSs.

Electrochemical Performance of Hard Carbon Anode in Moderately Concentrated Electrolytes

Hard carbon (HC), probably the most potential anode for sodium-ion batteries, currently encounters three major obstacles, which are low first-cycle coulombic efficiency, unsatisfactory charge–discharge kinetics, and insufficient cyclic stability. Our developed electrolyte can effectively improve these properties. The concept of using moderately concentrated electrolyte is proposed to deal with the limitations of high cost, low conductivity, and poor viscosity (or wettability) of superconcentrated electrolytes. The crucial roles of ethylene carbonate in the moderately concentrated electrolyte are explored in this study. With the formation of well-balanced robust inorganic–organic solid–electrolyte interphase, the first-cycle as well as steady-state coulombic efficiency of the HC electrode significantly improved to 85% and >99.9%, respectively. This electrolyte significantly improved the charge−discharge capacities at high current rates. Furthermore, after 500 sodiation−desodiation cycles, 95% of the initial capacity can be maintained. The proposed electrolyte design strategies are expected to be applicable to other battery electrodes to boost their energy-storage performance.

Graphitic carbon foams as anodes for sodium-ion batteries in glyme-based electrolytes

The electrochemical performance as potential anodes for sodium-ion batteries of boron-doped and non-doped graphitic carbon foams is investigated by galvanostic cycling versus Na/Na+ at different electrical current densities, in glyme-based electrolytes which are known to allow the intercalation of the Na+ ions into graphite. The influence of materials composition and graphitic degree on battery parameters is firstly determined and further discussed by analyzing the mechanism of the electrochemical storage of Na+ ions into these materials which was found to occur through different combinations of pseudocapacitive intercalation and diffusion-controlled intercalation processes. In summary, the results of this study have demonstrated that graphitic carbon foams match a very acceptable capacity with excellent cycle stability as well as performance at high electrical current densities (up to ∼ 90 mAh g−1 after 300 cycles at 1.9 A g−1 with coulombic efficiency ∼ 100%) which make them suitable for sodium-ion battery applications. Overall, the increase of the interlayer spacing between the graphene layers and the presence of boron promote the pseudocapacitive intercalation which is responsible for the remarkable rate performance of these materials, whereas the improvement of diffusion-controlled intercalation capacity is mainly related to larger boron content.