Anode For Sodium-ion Batteries Research Articles

Study on Tin-Cobalt Bimetallic Phosphide Nanoparticles as a Negative Electrode of Sodium-Ion Batteries.

Tin phosphide (Sn4P3) holds great promise because sodium-ion batteries use this material as an anode with impressive theoretical capacity. In this paper, it is reported that Co-doped Sn4P3 is embedded into carbon-based materials and SnCoP/C with a porous skeleton is prepared. As a result, SnCoP/C-2, as the material utilized in sodium-ion battery anodes, exhibits reversible capacities at 415.6, 345.9, and 315.6 mAh g-1 at current intensities of 0.5, 1.0, and 2.0 A g-1, respectively. The electrochemical reversibility, cycle stability, and rate performance of SnCoP/C samples are obviously better than those of Sn4P3/C. Cobalt in SnCoP/C stabilizes the conductive matrix of tin phosphide and promotes the diffusion kinetics of sodium. These results show that, with an appropriate amount of cobalt doping, highly dispersed nanoparticles can be formed in the tin phosphide matrix, which can significantly enhance the cycle stability of tin-based electrode materials.

Constructing hierarchical MoS2/WS2 heterostructures in dual carbon layer for enhanced sodium ions batteries performance

The escalating global demand for clean energy has spurred substantial interest in sodium-ion batteries (SIBs) as a promising solution for large-scale energy storage systems. However, the insufficient reaction kinetics and considerable volume changes inherent to anode materials present significant hurdles to enhancing the electrochemical performance of SIBs. In this study, hierarchical MoS2/WS2 heterostructures were constructed into dual carbon layers (HC@MoS2/WS2@NC) and assessed their suitability as anodes for SIBs. The internal hard carbon core (HC) and outer nitrogen-doped carbon shell (NC) effectively anchor MoS2/WS2, thereby significantly improving its structural stability. Moreover, the conductive carbon components expedite electron transport during charge–discharge processes. Critically, the intelligently engineered interface between MoS2 and WS2 modulates the interfacial energy barrier and electric field distribution, promoting faster ion transport rates. Capitalizing on these advantageous features, the HC@MoS2/WS2@NC nanocomposite exhibits outstanding electrochemical performance when utilized as an anode in SIBs. Specifically, it delivers a high capacity of 415 mAh/g at a current density of 0.2 A/g after 100 cycles. At a larger current density of 2 A/g, it maintains a commendable capacity of 333 mAh/g even after 1000 cycles. Additionally, when integrated into a full battery configuration with a Na3V2(PO4)3 cathode, the Na3V2(PO4)3//HC@MoS2/WS2@NC full cell delivers a high capacity of 120 mAh/g after 300 cycles at 1 A/g. This work emphasizes the substantial improvement in battery performance that can be attained through the implementation of dual carbon confinement, offering a constructive approach to guide the design and development of next-generation anode materials for SIBs.

Mechanical Activation of Graphite for Na-Ion Battery Anodes: Unexpected Reversible Reaction on Solid Electrolyte Interphase via X-Ray Analysis.

Although sodium-ion batteries (SIBs) offer promising low-cost alternatives to lithium-ion batteries (LIBs), several challenges need to be overcome for their widespread adoption. A primary concern is the optimization of carbon anodes. Graphite, vital to the commercial viability of LIBs, has a limited capacity for sodium ions. Numerous alternatives to graphite are explored, particularly focusing on disordered carbons, including hard carbon. However, compared with graphite, most of these materials underperform in LIBs. Furthermore, the reaction mechanism between carbon and sodium ions remains ambiguous owing to the structural diversity of disordered carbon. A straightforward mechanical approach is introduced to enhance the sodium ion storage capacity of graphite, supported by comprehensive analytical techniques. Mechanically activated graphite delivers a notable reversible capacity of 290.5 mAh·g-1 at a current density of 10 mA·g-1. Moreover, it maintains a capacity of 157.7 mAh·g-1 even at a current density of 1 A·g-1, benefiting from the defect-rich structure achieved by mechanical activation. Soft X-ray analysis revealed that this defect-rich carbon employs a sodium-ion storage mechanism distinct from that of hard carbon. This leads to an unexpected reversible reaction on the solid electrolyte surface. These insights pave the way for innovative design approaches for carbon electrodes in SIB anodes.

Revealing Na+‐coordination Induced Failure Mechanism of Metal Sulfide Anode for Sodium Ion Batteries

Metal sulfide (MS) is regarded as a promising candidate of the anode materials for sodium‐ion battery (SIB) with ideal capacity and low cost, yet still suffers from the inferior cycling stability and voltage degradation. Herein, the coordination relationship between the discharge product Na2S with the Na+ (NaPF6) in the electrolyte, is revealed as the root cause for the cycling failure of MS. Na+‐coordination effect assistants the dissolution of Na2S, further delocalizing Na2S from the reaction interface under the function of electric field, which leads to the solo oxidation of the discharge product element metal without the participation of Na2S. Besides, the higher highest occupied molecular orbital of Na2S suggest the facilitated Na2S solo oxidation to produce sodium polysulfides (NaPSs). Based on these, lowering the Na+ concentration of the electrolyte is proposed as a potential improvement strategy to change the coordination environment of Na2S, suppressing the side reactions of the solo‐oxidation of element metal and Na2S. Consequently, the enhanced conversion reaction reversibility and prolonged cycle life are achieved. This work renders in‐depth perception of failure mechanism and inspiration for realizing advanced conversion‐type anode.

Revealing Na+-coordination Induced Failure Mechanism of Metal Sulfide Anode for Sodium Ion Batteries.

Metal sulfide (MS) is regarded as a promising candidate of the anode materials for sodium-ion battery (SIB) with ideal capacity and low cost, yet still suffers from the inferior cycling stability and voltage degradation. Herein, the coordination relationship between the discharge product Na2S with the Na+ (NaPF6) in the electrolyte, is revealed as the root cause for the cycling failure of MS. Na+-coordination effect assistants the dissolution of Na2S, further delocalizing Na2S from the reaction interface under the function of electric field, which leads to the solo oxidation of the discharge product element metal without the participation of Na2S. Besides, the higher highest occupied molecular orbital of Na2S suggest the facilitated Na2S solo oxidation to produce sodium polysulfides (NaPSs). Based on these, lowering the Na+ concentration of the electrolyte is proposed as a potential improvement strategy to change the coordination environment of Na2S, suppressing the side reactions of the solo-oxidation of element metal and Na2S. Consequently, the enhanced conversion reaction reversibility and prolonged cycle life are achieved. This work renders in-depth perception of failure mechanism and inspiration for realizing advanced conversion-type anode.

Coal-based hard carbon anode for high-performance sodium ion batteries via coal-based graphene oxide as a multi-functional binder

Coal-based hard carbon for sodium ion batteries (SIBs) was successfully prepared using Shenfu bituminous coal (SFC) by one-step pyrolysis method. In the present work, we reported a novel method to fabricate carbon electrodes for SIBs from coal-based hard carbon with coal-based graphene oxide (CGO) as a multi-functional conductive binder to realize dual functional utilization of coal. As compared to traditional binder (CMC), electrodes with the CGO binder exhibits significantly increased reversible capacity and rate capability. This work provides a facile method for coal-based carbon materials used in SIBs.

One-Step Construction of Closed Pores Enabling High Plateau Capacity Hard Carbon Anodes for Sodium-Ion Batteries: Closed-Pore Formation and Energy Storage Mechanisms.

Closed pores play a crucial role in improving the low-voltage (<0.1 V) plateau capacity of hard carbon anodes for sodium-ion batteries (SIBs). However, the lack of simple and effective closed-pore construction strategies, as well as the unclear closed-pore formation mechanism, has severely hindered the development of high plateau capacity hard carbon anodes. Herein, we present an effective closed-pore construction strategy by one-step pyrolysis of zinc gluconate (ZG) and elucidate the corresponding mechanism of closed-pore formation. The closed-pore formation mechanism during the pyrolysis of ZG mainly involves (i) the precipitation of ZnO nanoparticles and the ZnO etching on carbon under 1100 °C to generate open pores of 0.45-4 nm and (ii) the development of graphitic domains and the shrinkage of the partial open pores at 1100-1500 °C to convert the open pores to closed pores. Benefiting from the considerable closed-pore content and suitable microstructure, the optimized hard carbon achieves an ultrahigh reversible specific capacity of 481.5 mA h g-1 and an extraordinary plateau capacity of 389 mA h g-1 for use as the anode of SIBs. Additionally, some in situ and ex situ characterizations demonstrate that the high-voltage slope capacity and the low-voltage plateau capacity stem from the adsorption of Na+ at the defect sites and Na-cluster formation in closed pores, respectively.

Synergistic Effects of Confinement Structure and Local‐Expanded Interlayer Spacing in Fe2Mo3O8@C@MoS2 Toward High‐Efficient Sodium Ion Storage

AbstractDeveloping multicomponent composite materials with delicate morphology and tailored structure is of vital importance for designing advanced sodium‐ion batteries (SIBs). Herein, a confinement‐structured Fe2Mo3O8@C@MoS2 with local‐expanded interlayer spacing is designed via high‐temperature phase transition from FeMoO4 to Fe2Mo3O8 and the tactically introducing dopamine molecules into the interlayer of MoS2 nanosheets. By analysis of the in situ generated solid electrolyte interphase film in different electrolytes, the favorable compatibility of Fe2Mo3O8@C@MoS2 in ether‐based electrolytes is well illustrated. Importantly, the sodium storage mechanism and detailed structural evolution of Fe2Mo3O8 are established for the first time by in situ X‐ray diffraction. Furthermore, theoretical calculations indicate the unique structure facilitates internal charge transfer and enhances Na+ adsorption ability. Thanks to the unique confinement structure, local‐expanded interlayers and robust framework, the Fe2Mo3O8@C@MoS2 composite achieves a high reversible specific capacity of 636 mAh g‒1 at 0.1 A g‒1, excellent rate capability (301 mAh g‒1 at 5.0 A g‒1) and ultralong cycling stability (365 mAh g–1 after 6000 cycles at 2.0 A g–1). The study provides an essential understanding of the Na storage mechanism of Fe2Mo3O8 and a promising strategy for constructing high‐performance anodes for SIBs.

Modulating the graphitic domains of hard carbons via tuning resin crosslinking degree to achieve high rate and stable sodium storage

Sodium-ion batteries (SIBs) are regarded as an outstanding alternative to lithium-ion batteries (LIBs) due to abundant sodium sources and their similar chemistry. As a most promising anode of SIBs, hard carbons (HCs) receive extensive attention because of their low potential and low cost, but their rational design for commercial SIBs is restricted by their variable and complicated microstructure, which is analogous to that of graphite in LIBs. Herein, a series of controllable HC materials derived from 3-aminophenol formaldehyde resin (AFR) were designed and fabricated. We discover that the optimized HC features expanded graphite regions, highly developed nanopores, and reduced defect content, contributing to the enhanced Na+ storage. This optimization is achieved by adjusting the resin crosslinking degree of the precursor. Specifically, a resin precursor with a higher crosslinking degree can produce HC with a larger interlayer distance, relatively higher crystallinity, and a lower specific surface area. Encouragingly, the as-optimized AFR-HC electrode manifests superior electrochemical performance in the aspect of high capacity (383 mAh·g-1 at 0.05 A·g-1), better rate capability (140 mAh·g-1 at 20 A·g-1), and high initial coulombic efficiency (82%) than other contrast samples. Moreover, the as-constructed full cell coupled with a Na3V2(PO4)3 cathode shows an energy density of 250 Wh·kg-1. Together with the simple synthesis, cost-efficiency of the precursors and superior electrochemical performance, AFR-HCs are promising for the commercial application.

Quasi-diffusion controlled high rate sodium-ion storage performance of flame pyrolysis derived spherical hard carbon

Hard carbon (HC) is identified as a potential anode for sodium ion batteries (SIBs) due to its outstanding electrochemical performance. However, selection of synthesis routes and its precursors remain crucial to develop the HC of desired microstructures for enhanced sodium-ion storage. Herein, we employed novel flame pyrolysis route to prepare spherical HC nanoparticles (<100 nm) from a liquid precursor derived from a low-cost bio-source. The as prepared carbon has been subjected to different calcination temperatures to optimize the porosity and surface area in order to achieve maximum sodium ion storage. The HC calcined at 1200 °C has shown the optimum electrochemical performance with a high reversible capacity of ∼287 mAh/g at 0.1C (1C = 300 mA/g). It shows 72 % of capacity retention after 490 cycles when cycled at 1C, with initial reversible specific capacity of ∼235 mAh/g. Excellent rate performance has been seen even at 20 C (6 A/g) with high specific capacity of 118 mAh/g at 70 % capacity retention after 2000 cycles, which is one of the highest values reported so far. Structural and morphological characterization of HC prepared at different temperatures are carried out using X-ray powder diffraction (XRD), small angle X-ray scattering (SAXS), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. Particle size and morphology altogether have played significant role in achieving high specific capacity and C-rate performance by providing shorter diffusion path and larger sodium ion storage sites.

Pure and (Sn or Mg) Doped GeFe2O4 as Anodes for Sodium-Ion Batteries

Pure and (Sn or Mg) Doped GeFe2O4 as Anodes for Sodium-Ion Batteries

Investigation of hexagonal boron nitride monolayer with pores as an anode material for sodium-ion batteries

The hexagonal boron nitride monolayer (h-BNML) used as an anode material for metal-ion batteries was assumed pristine form. However, inspired by the imperfections in natural materials, this study investigates the effect of defects on the electrochemical properties of h-BNML. Within the current piece of research, h-BNML with pores is introduced to develop an anode material for sodium ion battery (SIBs) by undertaking density-functional theory (DFT) computations. During the diffusion and storage process of Na ions, the pores effect was thoroughly investigated. The boron atoms were removed from the structure of the pure h-BNML in order to form the h-BNML with pores, which mimicked the pore formation. Based on the DFT results, after the pore formation, the h-BNML retained its planarity. Following the introduction of vacancies, significant alterations occurred in the electronic structure characteristics of h-BNML within the pores, facilitating the effective adsorption of Na ions within the pore. The results of quantum theory of atoms in molecules indicated that there were interactions between the pores and Na ions through an electrostatic-type attraction. The h-BNML with pores was capable of retaining a large number of Na ions at its surface without any change in its planar structure. This led to an increase in its theoretical specific capacity, which increased with porosity. Hence, unlike the pure h-BNML, the pore formation improved the diffusion of Na ions. This can be promising to designing highly efficient anodes for SIBs. The methodological approach in this study can be used for tailoring porous BN materials for SIBs.

Preparation of nanodiamonds modified hard carbon with uniform spherical feature for improving sodium-ion storage performances

Sodium-ion batteries (SIBs) have received remarkable attention due to their abundant sodium (Na) content and low resources cost. However, the absence of high-performance anode materials make carbon-based SIBs still a challenge. Herein, nano-diamonds (NDs) modified gleditsia japonica shell carbon to form a uniform carbon microsphere, which improves the graphitization degree and Na ion adsorption, NDs also act as a strong scaffold to maintain its stability. This spherical carbon-based material exhibits superior performances including the enhanced capacity (270 mA h g−1 at 0.2C after 100 cycles) and long-cycle stability (155 mA h g−1 at 2C after 1000 cycles) when incorporated into SIBs. This work provides a green and simple synthesis strategy for fabricating high performance porous spherical carbon used for SIBs anode.

TD-graphene: Theoretical prediction of a high-performance anode material for sodium-ion batteries with intrinsic metallicity, high capacity, and fast ion mobility

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.

Exploring Carbonization Temperature to Create Closed Pores for Hard Carbon as High-Performance Sodium-Ion Battery Anodes.

Biomass-derived porous carbon materials are meaningful to employ as a hard carbon precursor for anode materials of sodium-ion batteries (SIBs) from a sustainability perspective. Here, a straightforward approach is proposed to develop rich closed pores in pinenut-derived carbon, with the aim of improving Na+ plateau storage by adjusting the pyrolysis temperature. The optimized sample, namely the pinenut-derived carbon at 1300 °C, demonstrates remarkable reversible specific capacity of 278 mAh g-1, along with a high initial Coulomb efficiency of 85% and robust cycling stability (with a capacity retention of 89% after 800 cycles at 0.2 A g-1). In situ and ex situ analyses unveil that the developed closed pores play a significant role in enhancing the plateau capacity, providing compelling evidence for the "adsorption-filling" mechanism. Moreover, the corresponding full-cell achieves a high energy density of 245.7Wh kg-1 (based on the total weight of both electrode active materials) and exhibits outstanding rate capability (191.4 mAh g-1 at 3 A g-1).

Robust pseudocapacitive Na+ intercalation induced by MoS2 on active Mo2C current collector interface for high areal capacity sodium-ion batteries

Sodium-ion batteries (SIBs) have emerged as compelling alternatives in the realm of electrochemical energy devices, poised to substitute lithium-ion batteries (LIBs). The primary challenge encompasses not only the scarcity of anode materials exhibiting exceptional Na+ storage capacity but also the endeavor to achieve high areal capacity. To address this challenge, a comprehensive strategy is proposed that entails utilizing a highly conductive molybdenum dicarbide (Mo2C) current collector (denoted as CCM) as a supporting scaffold for the bottom-up growth of molybdenum disulfide nanosheets (MoS2, serving as the main active component) (denoted as CCM@MoS2). The CCM improves interfacial bonding with MoS2 nanosheets and offers additional capacity to accommodate the increased Na+ insertion activity. Both theoretical and kinetic analyses reveal that the enhanced Na+ storage properties primarily stem from favorable adsorption energy, reduced diffusion barrier, and intercalation pseudocapacitance due to the strong electronic interfacial interaction between active CCM and MoS2. Hence, the as-prepared optimized CCM@MoS2 electrode exhibits a superior areal capacity of 6.36 mAh cm−2 at 0.4 mA cm−2, excellent rate capability of 1.02 mAh cm−2 at 24 mA cm−2 and long cycle life up to 500 cycles at 4 mA cm−2. Interesting, our as-prepared CCM@MoS2 electrode shows better performance for Na+ storage than Li+ storage at higher current density, affirming the enhanced kinetics in our architecture. This work proposes a rational strategy to enhance the areal capacity and stability of MoS2-based anode for SIBs and beyond.

Hybrid-Mechanism Synergistic Flexible Nb2O5@WS2@C Carbon Nanofiber Anode for Superior Sodium Storage.

Sodium-ion batteries (SIBs) have demonstrated remarkable development potential and commercial prospects. However, in the current state of research, the development of high-energy-density, long-cycle-life, high-rate-performance anode materials for SIBs remains a huge challenge. Free-standing flexible electrodes, owing to their ability to achieve higher energy density without the need for current collectors, binders, and conductive additives, have garnered significant attention across various fields. In this work, we designed and fabricated a free-standing three-dimensional flexible Nb2O5@WS2@C carbon nanofiber (CNF) anode based on a hybrid adsorption-intercalation-conversion mechanism of sodium storage, using electrospinning and hydrothermal synthesis processes. The hybrid structure, aided by synergistic effects, releases the advantages of all materials, demonstrating a superior rate performance (288, 248, 211, 158, 90, and 48 mA h g-1 at the current density of 0.2, 0.5, 1, 2, 5, and 10 A g-1, respectively) and good cycling stability (160 mA h g-1 after 200 cycles at 1 A g-1). This work provides certain guiding significance for future research on hybrid and flexible anodes of SIBs.

One-step Solid-State Synthesis of V1.13Se2/V2O3 Heterostructure as a High Pseudocapacitance Anode for Fast-Charging Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) offer several benefits, including cost-efficiency and fast-charging characteristics, positioning them as attractive substitutes for lithium-ion batteries in energy storage applications. However, the inferior capacity and cycling stability of electrodes in SIBs necessitate further enhancement due to sluggish reaction kinetics. In this respect, the utilization of heterostructures, which can provide an inherent electric field and abundant active sites on the surface, has emerged as a promising strategy for augmenting the cycling stability and rate features of the electrodes. This work delves into the utilization of V1.13Se2/V2O3 heterostructure materials as anodes, initially fabricated via a simplified one-step solid-state sintering technique. The high pseudocapacitance and low characteristic relaxation time constant give the V1.13Se2/V2O3 heterostructure impressive properties, such as a high capacity of 328.5 mAh g-1 even after 1500 cycles at a high current density of 2 A g-1 and rate capability of 278.9 mAh g-1 at 5 A g-1. Moreover, the assembled sodium-ion full battery delivers a capacity of 118.5 mAh g-1 after 1000 cycles at 1 A g-1. These findings provide novel insight and guidance for the rapid synthesis of heterojunction materials and the advancement of SIBs.

Electrochemical Behavior of the Biomass Hard Carbon Derived from Waste Corncob as a Sodium-Ion Battery Anode

Electrochemical Behavior of the Biomass Hard Carbon Derived from Waste Corncob as a Sodium-Ion Battery Anode

Deciphering multistep transformation mechanism of cobalt-vanadium bimetallic sulfides anode in sodium storage

Transition metal sulfides as a high specific capacity sodium-ion batteries (SIBs) anode which have been suffering from successive phase transitions bringing about stress changes, poor electronic conductivity and ineffective ion transport kinetics. Combining self-sacrificial templates and ion-exchange transition reaction mechanisms, herein, cobalt, vanadium bimetallic sulfides hollow nano-cubic boxes with nitrogen-doped nanocarbon coating layer (CoV2S4@NC) are designed to solve these symbiosis problems. With a combination of in-situ Raman, ex-situ XPS/TEM, and density-functional theory calculations, the synergistically coordination mechanism between cobalt and vanadium binary metal during multi-step conversion processes is responsible for the faster charge transfer kinetics and boosted Na+ pseudocapacitance storage capability. Furthermore, the hollow cubic structure combined with the carbon shell layer can release the internal stress during phase transitions and avoid the recurrent growth of SEI film by volume change during the electrochemical process, thus realizing a superior electrode/electrolyte interface. Thus, when used as anode materials for SIBs, the prepared anode materials display excellent electrochemical performance, delivering capacity of 492 mA h g−1 at a current density of 10 A g−1 and high capacity stability with 484 mAh g−1 after 1000 cycles at 5 A g−1. More importantly, the assembled full cell (Na3V2(PO4)3//CoV2S4@NC) also shows high capacity of 574 mAh g−1 with 94.7% capacity retention after 85 cycles, suggesting the potential application of bimetallic sulfides in SIBs.