Anode Material For Sodium-ion Batteries Research Articles

Multiple heteroatom-doped cobalt sulfoselenide@C yolk-shell microsphere as excellent anode materials for sodium-ion batteries and their conversion reaction mechanism with sodium ions

To address the sluggish reaction kinetics commonly associated with the transition metal chalcogenide anodes in their interaction with alkali metal ions, introducing heterostructures into these materials is proposed as a novel approach. Herein, we introduce a fabrication method for yolk-shell structured microsphere comprising heteroatom-doped cobalt sulfoselenide nanocrystals using a recycled solution. The prepared material demonstrates a composition of sulfur-doped cobalt selenide, forming hetero-anion metal compounds. A detailed study of the reaction mechanism in cobalt sulfoselenide reveals the formation of Na2S/Na2Se heterointerfaces during the conversion reaction, which facilitate a rapid diffusion of Na-ions. Furthermore, heteroatom doping in the cobalt sulfoselenide nanocrystals, induced by cobalt recycling process, leads to the lattice expansion, further enhancing the Na-ion diffusion kinetics. Additionally, through an infiltration of pitch solution and a simple heat-treatment, pitch-derived carbon is coated on the cobalt sulfoselenide nanocrystals. This carbon layer can effectively accommodate the volumetric stress during repeated cycling, enhancing the stability. Consequently, carbon-coated heteroatom-doped cobalt sulfoselenide yolk-shell microsphere anode exhibits stable cycling stability (560 mA h g−1 for 100 cycles at 0.2 A g−1) as well as great rate capability (140 mA h g−1 at 15 A g−1) for sodium-ion batteries (SIBs).

O-Targeted Carbon Hybrid Orbital Conversion to Produce sp2-Rich Closed Pores for Sodium-Storage Hard Carbon.

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 347.3mAhg-1 at 20mAg-1 with the ICE of 90.5%, and a capacity of 110.4mAhg-1 at 5.0Ag-1 after 10000 cycles.

Understanding the Sodium Storage Behavior of Closed Pores/Carbonyl Groups in Hard Carbon.

Hard carbon (HC) is a promising anode material for sodium-ion batteries. However, the intrinsic relationship between the closed pores/surface groups and sodium storage performance has been unclear, leading to difficulties in targeted regulation. In this study, renewable tannin extracts were used as raw materials to prepare HC anodes with abundant tunable closed pores and carbonyl groups through a pyrolytic modulation strategy. Combining ex situ characterizations reveals that closed pores and carbonyl groups are regulated by the pyrolytic process. Further, it is demonstrated that the plateau region is mainly contributed by the closed pores; highly stable fluorine-rich solid electrolyte interphase compositions are produced through carbonyl-induced interfacial catalysis. The optimized HC anode displays good cycling stability, exhibiting a high reversible capacity (360.96 mAh g-1) at 30 mA g-1 and capacity retention of up to 94% after 500 cycles at 1 A g-1. Moreover, the full battery assembled with Na3V2(PO4)3/C demonstrates a stable cycling performance. These findings provide a fresh knowledge of the structural design of high-performance HC anode materials and the mechanism of sodium storage in HC.

Design and Synthesis of Sb-doped CuS@C Hollow Nanocubes as Efficient Anode Materials for Sodium-Ion Battery.

CuShave received widespread attention for application as anode materials in sodium-ion batteries due to their potent capabilities and eco-friendly properties. However, it is a challenge to achieve a high rate capability and long cycle stability owing to the heterogeneous transfer of sodium ions during charge-discharge, the interior poor electron conductivity and repeated volumetric expansion of copper sulfide. In this study, Sb-doped CuS hollow nanocubes coated with carbon shells (Sb-CuS@C) was designed and constructed as anode nanomaterials in sodium ion batteries. Thanks to the intrinsic good electron conductivity and chemical stability of carbon shells, Sb-CuS@C possesses a higher overall electron transfer as anode material, avoids agglomeration and structural destruction during the cycling. As a result, the synthesized Sb-CuS@C achieved an excellent reversible capacity of 595 mA h g-1 after 100 cycles at 0.5 A g-1 and a good rate capability of 340 mA h g-1 at a higher 10 A g-1. DFT calculations clarify that the uniformly doped Sb would act as active sodiophilic nucleation sites to help adsorbing Na+ during discharging and leading uniform sodium deposition. This work provides a new insight into the structural and componential modification for common transition-metal sulfides towards application as anode materials in SIB.

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

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

Iron-cobalt phosphide/nitrogen-doped carbon composite derived from prussian blue analogues as anode materials for sodium-ion batteries

Transition metal phosphides (TMPs) are recognized as attractive substitutes for lithium/sodium storage owing to their notable capacity and outstanding safety features. However, they face significant challenges in applications, particularly poor cycling stability and rapid capacity decay. In this study, we report a simple strategy utilizing dopamine-coated Prussian blue analogues as precursors to prepare bimetallic iron‑cobalt phosphide/nitrogen-doped carbon (Fe1-xCoxP/NC) composite materials via a one-step carbothermal phosphorization process. Benefiting from their nanostructured advantages and electronic interactions between Fe and Co sites, Fe0.17Co0.83P/NC, prepared by adjusting and optimizing the ion ratio, exhibits excellent rate capability and cycling performance as an anode material for sodium-ion batteries. It achieves a high specific capacity of 505.6 mAh g−1 at 0.5 A g−1. Even after 1000 cycles at a high current of 1 A g−1, the reversible specific capacity remains at 413.6 mAh g−1. Ex-situ XRD studies confirm that Fe0.17Co0.83P/NC stores Na+ via a conversion mechanism, where the crystalline CoP phase transforms into Na3P phase during the discharging process.

Hybrid of sub-1 nm single-dispersed polyoxometalate and reduced graphene oxide as advanced anodes for durable sodium-ion batteries

Polyoxometalates (POMs) are widely thought as promising choices for sodium-ion batteries (SIBs) because of their refined molecular structures and excellent reversible multielectron charge-discharge behaviors. Nevertheless, the POMs anion clusters could dissolve in the electrolyte when attacked by solvent molecules, thus reducing active sites and affecting the actual performance of these POMs-based electrodes. Herein, we report the development of a new type of electrode system that produces single-dispersed POMs molecular cluster/polydopamine/reduced graphene oxide composites ({PMo12}/PDA@rGO) through a self-assembly method. PDA acts as the role of “killing two birds with one stone”. It not only works as the linker to promote the formation of stable and uniform monodisperse {PMo12} clusters on the rGO surface, but also prevents the POMs from desorbing and dissolving upon deep cycling test. As a consequence, when used as the anode material for SIBs, the obtained {PMo12}/PDA@rGO exhibits an admirable long-term cycling performance, for instance, it holds a high Na-storage capacity of 277.5 mAh g−1 with an average Coulomb efficiency up to 99.89 % over 2000 cycles at 1 A g−1. This work offers versatile possibilities for designing POMs-based composites and provides new insight into developing single dispersed POMs for advanced SIBs.

Revealing the potential of a C6BN/black phosphorene nanocomposite as an anode material for sodium-ion batteries by atomistic simulation: DFT and AIMD

Black phosphorus (BP) has recently been regarded as a promising anode for sodium-ion batteries (SIBs) owing to its high storage capacity, rapid Na mobility in its lamellar structure, and low redox potential. However, its poor cyclability due to structural instability hampers its further implementation in SIBs. Here, we propose to design a novel two-dimensional nanocomposite by vertically stacking a C6BN sheet on a black phosphorene layer (C6BN/Black-Pn). Atomistic simulations by the van der Waals corrected density functional theory method were conducted to assess the suitability of the designed C6BN/Black-Pn model as a potential anode in SIBs. Benefiting from C6BN's electronic and chemical features, Black-Pn's band gap in C6BN/Black-Pn is diminished to 0.14 eV, which disappears and indicates metallic character upon sodiation. Additionally, the optimized Na adsorption energy within the nanocomposite is decreased to −2.06 eV, compared to −1.76 eV in pure Black-Pn and −0.98 eV in C6BN, with a modest diffusion barrier of 0.23 eV. A maximal theoretical capacity of 568.77 mAh/g and a low potential of 0.48 V are predicted for the nanocomposite. The above evaluation of C6BN/Black-Pn electrode for SIBs may provide better insights into adopting a physical approach to address BP electrochemical failures for advanced energy storage.

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

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

Ab Initio Prediction of Two-Dimensional GeSiBi2 Monolayer as Potential Anode Materials for Sodium-Ion Batteries.

The conceptualization and deployment of electrode materials for rechargeable sodium-ion batteries are key concerns for next-generation energy storage systems. In this contribution, the configuration stability of single-layer GeSiBi2 is systematically discussed based on first-principles calculations, and its potential as an anode material is further investigated. It is demonstrated that the phonon spectrum confirms the dynamic stability and the adsorption energy identifies a strong interaction between Na atoms and the substrate material. The electronic bands indicative of inherent metallicity contribute to the enhancement of electronic conductivity after Na adsorption. The multilayer adsorption of Na provides a theoretical capacity of 361.7 mAh/g, which is comparable to that of other representative two-dimensional anode materials. Moreover, the low diffusion barriers of 0.19 and 0.15 eV further guarantee the fast diffusion kinetics. These contributions signal that GeSiBi2 can be a compatible candidate for sodium-ion batteries anodes.

Novel nitrogen-doped carbon-coated SnSe2 based on a post-synthetically modified MOF as a high-performance anode material for LIBs and SIBs.

SnSe2 with high theoretical capacity has been identified as an emerging anode candidate for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). However, the rate performance and cycling performance of this material in practical applications are still limited by unavoidable volume expansion and low conductivity. In this work, we designed and synthesized nitrogen-doped carbon-coated SnSe2/C-N composites using 2-aminoterephthalic acid (C8H7NO4) as a nitrogen-containing compound for modification by hydrothermal and vacuum calcination methods to achieve efficient utilization of active sites and optimization of the electronic structure. The carbon skeleton inherited from the Sn-MOF precursor can effectively improve the electronic conduction properties of SnSe2. N-doping in the Sn-MOF can increase the positive and negative electrostatic potential energy regions on the molecular surface to further improve the electrical conductivity, and effectively reduce the binding energy with Li+/Na+ which was determined by Density Functional Theory (DFT) methods. In addition, the N-doped carbon skeleton also introduces a larger space for Li+/Na+ intercalation and enhances the mechanical properties. In particular, the post-synthetically modified MOF-derived SnSe2/C-N materials exhibit excellent cyclability, with a reversible capacity of 695 mA h g-1 for LIBs and 259 mA h g-1 for SIBs after 100 cycles at 100 mA g-1.

Azatriangulenetrione as the Anode Material for Sodium-Ion Batteries: Reversible Redox Chemistry Mediated by Lone Pair Electrons.

Redox-active organic molecules have potential as electrode materials, but their cycling stability is often limited by the irreversible formation of σ-bonds from the radical intermediates. Herein, we present an effective approach to achieve high reversibility by using lone pair electrons to mediate intramolecular radical-radical coupling. Azatriangulenetrione (1) was examined as the anode in sodium-ion batteries, which displayed a reversible four-step, one-electron redox chemistry. In situ electron spin resonance, ex situ Fourier transform infrared/X-ray photoelectron spectroscopy, and density functional theory calculation revealed that the unstable radical anions can couple with each other through the lone pair electrons of the central nitrogen atom, leading to stabilized radical species. Furthermore, scan-rate-dependent cyclic voltammetry measurements and galvanostatic intermittent titration techniques demonstrated that the redox reaction kinetics for radical formation were much faster than the radical paring process. This study offers deep insights into the design of highly reversible organic electrodes.

Heterogeneous carbon coated resin-based hard carbon anode material for high-performance sodium ion batteries

Resin-based hard carbons are promising anode materials for sodium ion batteries (SIBs) due to their high storage capacity and purity. However, the low initial coulombic efficiency (ICE) still hinders their practical application. Crosslinking and high-temperature pyrolysis strategies have been demonstrated to improve ICE effectively, but the complex process and high energy consumption hinder their industrialization. This paper proposes a facile synthesis of resin-based hard carbon with a soft carbon coating strategy to improve ICE. By carbonizing commercial phenolic resin at 1150℃, hard carbon with a reversible capacity of 291.6 mAh g−1 and 82.6 % ICE was obtained. After asphalt-based soft carbon coating, the optimized sample (CHC-1150) with a heterogeneous carbon coating layer of about 8.5 nm displays a high reversible capacity and ICE of 309.8 mAh g−1 and 88.2 %. Moreover, when combined with NaFe1/3Ni1/3Mn1/3O2 cathode, the assembled 18650 cylindrical-type batteries deliver a high ICE of 84.3 %, excellent low-temperature capability and cycling stability. Additionally, the disassembly results after cycling indicate that the soft carbon layer can inhibit the decomposition of electrolytes and avoid sodium plating. These encouraging results suggest that heterogeneous carbon coating should be a promising strategy to promote the electrochemical performance of resin-based hard carbon anode materials for SIBs.

Sustainable conversion of vine shoots and pig manure into high-performance anode materials for sodium-ion batteries

Sodium-ion batteries (SIBs) are considered promising candidates for future grid energy storage, with hard carbons emerging as key commercial anode materials. This study presents a novel approach to synthesize N-doped hard carbons via co-hydrothermal treatment of vine shoots and pig manure and subsequent thermal annealing of the resulting hydrochar. This method enhances the development of micro- and ultra-microporosity in the synthesized hard carbons, with nitrogen, and to a lesser extent phosphorus and sulfur, introduced as doping elements. Furthermore, the incorporation of hydrochloric acid during the hydrothermal step promotes biomass hydrolysis, leading to increased mesoporosity and the formation of microsphere clusters. In the realm of electrochemical performance, an investigation into various ester- and ether-based electrolytes has revealed NaPF6 in diglyme as the best formulation, thanks to its thinner and more stable solid electrolyte interface (SEI). Using this electrolyte, the best-performing electrode showed an initial Coulombic efficiency (ICE) of 73 %, with reversible capacities of 239, 180, 86, and 57 mAh g−1 at 0.1, 1, 5, and 10 A g−1, respectively. In addition, the electrode exhibited a remarkable capacity retention of 88 % after 250 cycles as well as a compatible behavior when paired with a NVPF-based cathode.

Recent advances in alloying anode materials for sodium-ion batteries: material design and prospects

Recent advances in alloying anode materials for sodium-ion batteries: material design and prospects

Unlocking the potential of a chemically modified blue phosphorene as anode materials for high-performance sodium-ion batteries

Blue phosphorene (Blu-Pn) has recently been identified as a new two-dimensional (2D) form of black phosphorus via the epitaxial growth method and has shown the ability to host a substantial amount of Na while serving as an anode in sodium-ion batteries (NIBs). However, its structural instability is an issue that hinders its further exploitability in NIBs. In this paper, we propose to chemically modify the Blu-Pn network by substituting six phosphorus atoms with a carbon source in the form of a C6 ring, constructing a new and robust CP2 nanosheet. Based on the state-of-the-art non-local van der Waals corrected density functional theory and ab initio molecular dynamic (AIMD) simulations, we systematically explore the feasibility of the designed CP2 as a potential anode material for NIBs. Adding a C6 ring in the Blu-Pn lattice reduces its energy gap from 2 eV to 1.3 eV, which disappears after Na adsorption, indicating a conductive character. Attributed to the synergistic effect, the adsorption energy of Na on CP2 nanosheet (−2.22 eV) is greatly decreased in comparison to the pristine carbon source (e.g., graphene with −0.78 eV) and pristine Blu-Pn (−1.85 eV). The Na diffusivity on CP2 at 300 K is predicted to be 4.90 × 10−11 m2/s by AIMD. The specific capacity is up to 604.1 mAh/g, which exceeds that of the commercialized graphite anode (372 mA h/g). Ultimately, the designed electrode provides a small open circuit potential of 0.66 V that falls within a desirable voltage range. This work paves the way for exploring Blu-Pn 2D anode materials for NIBs technology and provides valuable insights into surface chemical modification towards the long-term stability of Blu-Pn.

Fabrication of a Stable and Highly Effective Anode Material for Li-Ion/Na-Ion Batteries Utilizing ZIF-12.

Transition metal selenides (TMSs) are receiving considerable interest as improved anode materials for sodium-ion batteries (SIBs) and lithium-ion batteries (LIBs) due to their considerable theoretical capacity and excellent redox reversibility. Herein, ZIF-12 (zeolitic imidazolate framework) structure is used for the synthesis of Cu2Se/Co3Se4@NPC anode material by pyrolysis of ZIF-12/Se mixture. When Cu2Se/Co3Se4@NPC composite is utilized as an anode electrode material in LIB and SIB half cells, the material demonstrates excellent electrochemical performance and remarkable cycle stability with retaining high capacities. In LIB and SIB half cells, the Cu2Se/Co3Se4@NPC anode material shows the ultralong lifespan at 2000 mAg-1, retaining a capacity of 543 mAhg-1 after 750 cycles, and retaining a capacity of 251 mAhg-1 after 200 cycles at 100 mAg-1, respectively. The porous structure of the Cu2Se/Co3Se4@NPC anode material can not only effectively tolerate the volume expansion of the electrode during discharging and charging, but also facilitate the penetration of electrolyte and efficiently prevents the clustering of active particles. In situ X-ray difraction (XRD) analysis results reveal the high potential of Cu2Se/Co3Se4@NPC composite in building efficient LIBs and SIBs due to reversible conversion reactions of Cu2Se/Co3Se4@NPC for lithium-ion and sodium-ion storage.

Insight into the configuration of hard-soft carbon composites for high performance sodium-ion batteries

Hard carbon materials are considered suitable anode materials for sodium-ion batteries due to their abundant defect sites and large interlayer distance, which are respectively beneficial to the adsorption/desorption and insertion/extraction behaviors of Na+ during the electrochemical process. However, the poor electrical conductivity resulting from the intrinsic short-range ordered structure in the carbon skeleton and limited active sites significantly hinders their electrochemical performance. Herein, hard and soft carbon composites with various configurations are developed using a layer-by-layer coating method with SiO2 nanospheres as templates. These composites, including the hard carbon coated soft carbon composite structure (SC@HC), soft carbon coated hard carbon composite structure (HC@SC), and uniformly mixed soft and hard carbon composites (HSC), are prepared through confined-carbonization under the outermost SiO2 layer. The resulting hollow nanospheres possess ultra-small diameters (approximately 50 nm), ultra-thin wall thicknesses (5-6 nm), and different hard/soft carbon layer arrangements. Evaluation of sodium storage properties showed that the combination of soft and hard carbon outperformed pure soft or hard carbon, with HC@SC configuration offering materials with larger interlayer spacing, higher defect concentration, and a more complete conductive network. This enhances sodium storage capacity (293 mAh g-1@1 A g-1) and rate performance (242 mAh g-1@5 A g-1). The findings of this study present a novel approach to designing soft and hard carbon composites for high-performance sodium-ion batteries.

In Situ Lattice-Resolution Revelation of the Origins of Unexplored Anisotropic Sodiation Kinetics and Phase Transition in the Niobium Sulfide Anode.

Layered transition metal dichalcogenides (TMDs) have exhibited huge potential as anode materials for sodium-ion batteries. Most of them usually store sodium via an intercalation-conversion mechanism, but niobium sulfide (NbS2) may be an exception. Herein, through in situ transmission electron microscopy, we carefully investigated the insertion behaviors of Na ions in NbS2 and directly visualized anisotropic sodiation kinetics. Lattice-resolution imaging coupled with density functional theory calculations reveals the preferential diffusion of Na ions within layers of NbS2, accompanied by observable interlayer lattice expansion. Impressively, the Na-inserted layers can still withstand in situ mechanical testing. Further in situ observation vertical to the a/b plane of NbS2 tracked the illusive conversion reaction, which could result from interlayer gliding or wrinkling associated with stress accumulation. In situ electron diffraction measurements ruled out the possibility of such a conversion mechanism and identified a phase transition from pristine 3R-NbS2 to 2H-NaNbS2. Therefore, the NbS2 anode stores Na ions via only the intercalation mechanism, which conceptually differs from the well-known intercalation-conversion mechanism of typical TMDs. These findings not only decipher the whole sodiation process of the NbS2 anode but also provide valuable reference for unraveling the precise sodium storage mechanism in other TMDs.

In Situ Lattice-Resolution Revelation of the Origins of Unexplored Anisotropic Sodiation Kinetics and Phase Transition in the Niobium Sulfide Anode.

Layered transition metal dichalcogenides (TMDs) have exhibited huge potential as anode materials for sodium-ion batteries. Most of them usually store sodium via an intercalation-conversion mechanism, but niobium sulfide (NbS2) may be an exception. Herein, through in situ transmission electron microscopy, we carefully investigated the insertion behaviors of Na ions in NbS2 and directly visualized anisotropic sodiation kinetics. Lattice-resolution imaging coupled with density functional theory calculations reveals the preferential diffusion of Na ions within layers of NbS2, accompanied by observable interlayer lattice expansion. Impressively, the Na-inserted layers can still withstand in situ mechanical testing. Further in situ observation vertical to the a/b plane of NbS2 tracked the illusive conversion reaction, which could result from interlayer gliding or wrinkling associated with stress accumulation. In situ electron diffraction measurements ruled out the possibility of such a conversion mechanism and identified a phase transition from pristine 3R-NbS2 to 2H-NaNbS2. Therefore, the NbS2 anode stores Na ions via only the intercalation mechanism, which conceptually differs from the well-known intercalation-conversion mechanism of typical TMDs. These findings not only decipher the whole sodiation process of the NbS2 anode but also provide valuable reference for unraveling the precise sodium storage mechanism in other TMDs.