Sodium Storage Capacity Research Articles

Enabling Full Conversion Reaction with High Reversibility to Approach Theoretical Capacity for Sodium Storage

AbstractConversion‐type electrode materials are emerging as promising candidates for high‐energy rechargeable batteries, owing to their substantially higher theoretical capacity relative to intercalation‐based materials. Nevertheless, the full benefit from conversion‐type electrode materials remains out of reach in sodium‐ion batteries, due to the inadequate conversion reaction toward sodium and the poor reversibility during desodiation. Here, a full conversion reaction with high reversibility is demonstrated through promoting the initial sodium intercalation and subsequent reconversion kinetics by transition metal doping. The doping‐induced lowering of the sodium intercalation energy in thermodynamics effectively drives the full conversion reaction, while the metal transition of the doped element enhances reconversion kinetics in achieving high reversibility. The obtained results open a new avenue for the development of high‐performance conversion‐type electrodes and provide a novel understanding of the conversion reaction mechanism.

Pulsed Laser Deposited Nanoporous Carbon As a Lithium Ion Battery Anode

Lithium-ion batteries (LIBs) find applications ranging from portable electronics to electric vehicles, due to their higher energy densities (~ 250 Wh.hr kg-1) than other rechargeable batteries. Since the invention of LIBs, commercialized anodes have mostly consisted of carbon-based materials such as natural graphite, mesophase carbon microbeads (MCMB) massive artificial graphite (MAG), and hard carbons. However, the employment of LIBs in electric vehicles is increasing demand for higher energy density LIBs. Graphite-based anodes are limited to a charge storage capacity of 372 mAh g-1 due to the tight interplanar spacing (3.35 Å) between the graphene sheets. Several alternative anode materials have been proposed to replace graphite. In particular, Si and Sn alloys are extensively studied, but enormous volume change while cycling is hindering their commercialization. Lithium titianate (Li4Ti5O12) anodes are successfully commercialized, but low lithium storage capacity (175 mAh g-1) and high voltage (~1.5 V) prevents their use for high energy density applications. Carbon allotropes with modified structures and crystallinity can achieve higher capacity relative to graphite, so they are potential candidates to enable higher energy density LIBs. Carbon materials vary drastically in terms of interplanar spacing, termination groups on the edges of graphite/graphene fragments, defects, and porosity within the carbon structures. These variations significantly affect the Coulombic efficiency, lithium storage capacity, irreversible capacity loss during the first cycle, and the voltage range for lithiation. We will present an investigation of nanoporous carbon (NPC) prepared via pulsed laser deposition as a model system to understand lithiation mechanisms in carbon anodes. NPC is grown directly on stainless steel current collectors at room temperature, resulting in randomly-oriented stacks consisting of a few layers of aligned nm-sized graphene sheets. NPC mass density can be controlled from 2.0 g/cm3 to below 0.1 g/cm3 by varying the carbon deposition energetics, enabling the tuning of interplanar spacing and porosity within NPC. Low-density NPC exhibits as much as a 55% larger interplanar spacing compared to graphite-like high-density NPC and larger open pore spaces between stacks of sheets. The ability to control interplanar spacings and porosity in otherwise identical carbon samples allows for a systematic study to understand how these characteristics affect lithiation and de-lithiation processes in graphene-like carbon materials. We will discuss how the mass density of this 3D graphene-like NPC nanomaterial affects lithiation mechanisms and will demonstrate that NPC anode storage capacity systematically increases with decreasing mass density. High capacity is enabled by a plethora of grain boundaries, large and controlled interplanar spacings between graphene sheets, and nanopores between the randomly-aligned sheet fragments, all potentially contributing to extra lithium storage sites. The primary mechanisms for lithium storage in nanoporous carbon varies with mass density. For example, the capacity increases with cycling for the lowest mass density materials, potentially indicating that lithium plates within the nanopores as electrolyte penetrates deeper into the structure with each cycle. NPC mass density also correlates with Coulombic efficiency, such that lower density NPC demonstrates lower coulombic efficiency. This may be related to solid electrolyte interphase formation in the lower mass density samples since the electrolyte is more likely to penetrate into the structure and enable higher carbon-electrolyte interface surface areas. However, initial data suggests that lower Coulombic efficiency with lower mass density is likely related to the trapping of lithium ions at termination groups on the edges of graphene sheets. This trapping of lithium can be reversed by increasing the voltage during delithiation. Finally, we will also present data showing that NPC can be sodiated. Sodiation processes mimic those of lithiation, with sodium storage capacity increasing with decreasing NPC mass-density. We thank Lyle Brunke for assistance growing NPC films and Carlos Gutierrez for programmatic guidance. This work was supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA-0003525. SAND2019-4730 A

N/S-Co-Doped Porous Carbon Sheets Derived from Bagasse as High-Performance Anode Materials for Sodium-Ion Batteries.

Heteroatom doping is considered to be an efficient strategy to improve the electrochemical performance of carbon-based anode materials for Na-ion batteries (SIBs), due to the introduction of an unbalanced electron atmosphere and increased electrochemical reactive sites of carbon. However, developing green and low-cost approaches to synthesize heteroatom dual-doped carbon with an appropriate porous structure, is still challenging. Here, N/S-co-doped porous carbon sheets, with a main pore size, in the range 1.8–10 nm, has been fabricated through a simple thermal treatment method, using KOH-treated waste bagasse, as a carbon source, and thiourea, as the N and S precursor. The N/S-co-doped carbon sheet electrodes possess significant defects, high specific surface area, enhanced electronic conductivity, improved sodium storage capacity, and long-term cyclability, thereby delivering a high capacity of 223 mA h g−1 at 0.2 A g−1 after 500 cycles and retaining 155 mA h g−1 at 1 A g−1 for 2000 cycles. This work provides a low-cost route to fabricate high-performance dual-doped porous carbonaceous anode materials for SIBs.

Mesoporous MnO2 based composite electrode for efficient alkali-metal-ion storage

The mesoporous δ-MnO2-based nanostructure is elaborately designed for overcoming the main bottleneck problems for lithium and sodium storage. Based on density functional theory, MnO2 composite possesses high binder energy and low migration barrier for energy storage, which are beneficial for improving sluggish electrochemical kinetics. Additionally, dendritic metal growth is inhibited via electrostatic force. All these merits ensure the exceptional rate and cycle performance during cycling process. Coupling MnO2 with Ni-Co-Oxide promotes homogeneous nucleation sites, guiding Li/Na metal deposition/exfoliation and suppressing dendritic lithium/sodium growth. Simultaneously, abundant grain boundaries between MnO2-C and Ni-Co-Oxide bring more enriched sites for fast ion diffusion and pseudo-capacitive storage processes. The enriched surface defects lower the impedance to achieve fast transport kinetics. Making full use of the structure, component and composition, such MnO2 based electrodes exhibit superior cycle ability and high capacity for both lithium and sodium storage. This work supplies the robust SEI design protocol and sheds new light on developing stable lithium and sodium ion batteries.

Zinc Ferrite Nanorod‐Assembled Mesoporous Microspheres as Advanced Anode Materials for Sodium‐Ion Batteries

Mesoporous zinc ferrite (ZnFe2O4) microspheres assembled by nanorods are fabricated through a facile hydrothermal approach, followed by a calcination strategy. The fabricated mesoporous ZnFe2O4 has a diameter of approximately 500–800 nm with a high surface area of 91.6 m2 g−1. The utilization of the microspheres that serve as anode materials for sodium‐ion batteries is studied for the first time. The electrochemical results demonstrate that the ZnFe2O4 anode experiences a series of conversion and alloying reactions for reversible sodium storage and exhibits high sodium storage capacity and excellent stability. It exhibits a reversible capacity as high as 350 mAh g−1 after 300 cycles at 100 mA g−1, which is superior to other reported ZnO and ZnMxOy (M = Co, Sn, Ge) electrodes. The existence of the mesoporous structure is responsible for the excellent electrochemical properties of the microspheres, which not only enhances the electrochemical kinetics but also offers additional space to alleviate the strain associated with sodiation/desodiation.

Manganese nitride stabilized on reduced graphene oxide substrate for high performance sodium ion batteries, super-capacitors and EMI shielding

Though the utility of manganese compounds such as oxides, sulphides has been well researched in energy storage applications such as super-capacitors and lithium-ion batteries, the utility of manganese nitrides hasn't been reported yet, especially as anode in sodium-ion batteries. In this manuscript we report synthesis of manganese nitride decorated reduced graphene oxide (MnN@rGO) prepared by simple microwave nitridation technique and its utility as anode material in sodium-ion batteries, electrodes in super-capacitors and in EMI shielding applications. In energy storage applications such as sodium ion batteries, MnN@rGO electrodes exhibited sodium storage capacity of 716 mAhg−1 whereas when used as electrodes in super-capacitors, a high capacitance value of 639.2 Fg-1 at scan rates of 10 mVs−1 in 1 M Na2SO4 aqueous electrolyte was achieved. The EMI shielding effectiveness measured in the X-band region of 2–18 GHz was about 30–32 dB which is 300% more than reduced graphene oxide.

Three-dimensional porous carbon doped with N, O and P heteroatoms as high-performance anode materials for sodium ion batteries

Porous carbon (PC) materials are the excellent alternative to anodes of high performance sodium ion batteries (SIBs). However, most PC materials are prepared with complicated and multi-step template method, which limits the mass production. Herein, we present a simple and repeatable calcination approach to synthesize three-dimensional porous carbon (3D-PC) materials using poly(p-phenylenediamine) hydrogel as precursor. N, O and P heteroatoms are successfully introduced into 3D-PC to provide more sodium storage sites. The obtained 3D-PC delivers high sodium storage capacity of 332 mAh g−1 at 50 mA g−1 and the reversible capacity still retains 139 mAh g−1 at 10 A g−1. Moreover, 3D-PC also shows ultralong cycling life, the stable capacities of 212 mAh g−1 and 120 mAh g−1 after 1000 cycles even at the high current density of 0.5 A g−1 and 5 A g−1, respectively. These results illustrate that 3D-PC electrode displays great rate capability and excellent cycling stability, which would be ascribed to surface-dominated sodium storage mechanism according to quantitative analysis. This method is low cost and effective for preparing high-performance porous carbon anodes for SIBs.

Abnormal sodium and water homeostasis in mice with defective heparan sulfate polymerization.

Glycosaminoglycans in the skin interstitium and endothelial surface layer have been shown to be involved in local sodium accumulation without commensurate water retention. Dysfunction of heparan sulfate glycosaminoglycans may therefore disrupt sodium and water homeostasis. In this study, we investigated the effects of combined heterozygous loss of heparan sulfate polymerization genes (exostosin glycosyltransferase 1 and 2; Ext1+/-Ext2+/-) on sodium and water homeostasis. Sodium storage capacity was decreased in Ext1+/-Ext2+/- mice as reflected by a 77% reduction in endothelial surface layer thickness and a lower skin sodium-to-glycosaminoglycan ratio. Also, these mice were characterized by a higher heart rate, increased fluid intake, increased plasma osmolality and a decreased skin water and sodium content, suggesting volume depletion. Upon chronic high sodium intake, the initial volume depletion was restored but no blood pressure increase was observed. Acute hypertonic saline infusion resulted in a distinct blood pressure response: we observed a significant 15% decrease in control mice whereas blood pressure did not change in Ext1+/-Ext2+/- mice. This differential blood pressure response may be explained by the reduced capacity for sodium storage and/or the impaired vasodilation response, as measured by wire myography, which was observed in Ext1+/-Ext2+/- mice. Together, these data demonstrate that defective heparan sulfate glycosaminoglycan synthesis leads to abnormal sodium and water homeostasis and an abnormal response to sodium loading, most likely caused by inadequate capacity for local sodium storage.

Synthesis of CoSe2 nanoparticles embedded in N-doped carbon with conformal TiO2 shell for sodium-ion batteries

CoSe2 is a potential anode material for sodium-ion batteries in terms of their high sodium storage capacity and tunable properties. However, structural degradation and unstable interphase during the reversible sodiation and de-sodiation lead to fast capacity decay. In this work, we develop a nanocomposite architecture based on CoSe2 nanoparticles embedded in N-doped carbon matrix with conformal TiO2 coating (CoSe2@NC@TiO2) by using a metal-organic framework-assisted strategy. The small CoSe2 nanoparticles and N-doped carbon matrix facilitate charge transport and suppress the structural degradation, while the redox-active TiO2 shell further strengthens the structural and interfacial stability without decreasing the capacity. The as-prepared CoSe2@NC@TiO2 nanocomposite particles deliver a reversible sodium storage capacity of 520 mAh g−1 at 0.1 A g−1 with a capacity retention of 78% after 200 cycles, in contrast to the rapid capacity fading after 50 cycles of the pristine CoSe2@NC particles without TiO2 shell.

Preparation and sodium storage performance of V2O5·nH2O/graphene composites

V2O5·nH2O/graphene composites have been fabricated via a facile sol–gel method followed with an annealing treatment in air. The influence of incorporation of graphene on the microstructure and sodium storage performance of V2O5·nH2O were investigated. XRD, Raman, and TGA analyses validated that graphene was successfully incorporated in V2O5·nH2O particles; XPS tests revealed that the incorporation of graphene induced more V4+ in the V2O5·nH2O. When evaluated as cathode materials for sodium-ion batteries (SIBs), the V2O5·nH2O/graphene composites exhibited higher sodium storage capacity, better rate capability, enhanced Na+ diffusivity, and lower electrochemical reaction resistance as compared to the pure V2O5·nH2O. However, the incorporation of graphene had no improvement of the cycling stability of V2O5·nH2O. Ex situ XRD demonstrated that the layered structure of V2O5·nH2O collapsed upon cycling, which accounts for the capacity decay of the samples.

Nano Hard Carbon Anodes for Sodium-Ion Batteries.

A hindrance to the practical use of sodium-ion batteries is the lack of adequate anode materials. By utilizing the co-intercalation reaction, graphite, which is the most common anode material of lithium-ion batteries, was used for storing sodium ion. However, its performance, such as reversible capacity and coulombic efficiency, remains unsatisfactory for practical needs. Therefore, to overcome these drawbacks, a new carbon material was synthesized so that co-intercalation could occur efficiently. This carbon material has the same morphology as carbon black; that is, it has a wide pathway due to a turbostratic structure, and a short pathway due to small primary particles that allows the co-intercalation reaction to occur efficiently. Additionally, due to the numerous voids present in the inner amorphous structure, the sodium storage capacity was greatly increased. Furthermore, owing to the coarse co-intercalation reaction due to the surface pore structure, the formation of solid-electrolyte interphase was greatly suppressed and the first cycle coulombic efficiency reached 80%. This study shows that the carbon material alone can be used to design good electrode materials for sodium-ion batteries without the use of next-generation materials.

Electrochemically Induced Amorphization and Unique Lithium and Sodium Storage Pathways in FeSbO4 Nanocrystals.

The increasing energy demands have prompted research on conversion and alloying materials, offering high lithium and sodium storage capacities. However, most of these materials suffer from huge volume expansion and degradation over the thousands of charging and discharging cycles required for commercial applications. In this study, we demonstrate a facile route to synthesize FeSbO4 nanocrystals that possess theoretical lithium and sodium storage capacity of 1220 mAh g-1. Operando X-ray diffraction studies reveal the electrochemically induced amorphization of the nanocrystals upon alkali-ion storage. We achieved specific storage capacities of ∼600 mAh g-1 for lithium and ∼300 mAh g-1 for sodium, respectively. The disparity in the lithium and sodium electrochemistry arises from the unique lithiation/sodiation pathways adopted by the nanocrystals. This study offers new insights into the chemistry and mechanism of conversion- and alloying-based energy storage materials that would greatly assist the development of next-generation active materials for energy storage.

Rod-like NaV3O8 as cathode materials with high capacity and stability for sodium storage

In this study, NaV3O8 nanorods are successfully prepared using nonionic surface-active agents Pluronic-F127 as structure-directing agent. The as-prepared NaV3O8 nanorods calcinated at different temperatures are characterized by various techniques, including X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy. The NaV3O8 calcinated at 400 °C for 20 h shows appropriate sizes and uniform morphologies of the nanorods, 4–7 μm in length and 0.2–0.5 μm in diameter. The NaV3O8 nanorods as cathode materials for Na-ion batteries deliver high discharge capacity reaching up 110.4 mAh g−1 at current density of 120 mA g−1, as well as long lifespan by maintaining capacity of 162.1 mAh g−1 after 500 charge-discharge cycles. Also, a high reversible capacity of 83.9 mAh g−1 can be retained after 500 cycles at high rate of 2 A g−1. The obtained outstanding electrochemical performances are associated with the unique micro-nano structures, which does not only facilitate transport of Na+ ion, but also resist erosion from electrolytes. Overall, the results suggest the promise of NaV3O8 nanorods as cathode materials for high capacity, high power and long lifespan Na-ion batteries. This work may open an innovative route to discover diverse electrode materials with nanostructure for energy storage system.

Ni2P Nanosheets on Carbon Cloth: An Efficient Flexible Electrode for Sodium-Ion Batteries.

Transition-metal phosphides have been increasingly investigated because of their high theoretical specific capacity and low potential for sodium storage. Herein, we describe the development of Ni2P nanosheets on carbon cloth (Ni2P Ns/CC), which behaves as a flexible 3D anode for sodium-ion batteries. Such a Ni2P Ns/CC delivers a high capacity of 399 mA h g-1 at 0.2 A g-1. At 2 A g-1, it still delivers 72 mA h g-1 even after 1000 cycles. The impressive performance is attributed to such a self-supported structure. Moreover, a possible conversion reaction mechanism is also carefully revealed.

Hierarchical MoS2 Hollow Architectures with Abundant Mo Vacancies for Efficient Sodium Storage.

Achieving a molecular level understanding of surface performance of nanomaterials by modulating the electronic structure is important but challenging. Here, we have developed a hollow microcube framework constructed by Mo-defect-rich ultrathin MoS2 nanosheets (HMF-MoS2) through a zeolite-like-framework-engaged strategy. The hollow structured HMF-MoS2 delivers an impressive specific capacity (384.3 mA h g-1 after 100 cycles at 100 mA g-1) and cycle stability (267 mA h g-1 after 125 cycles at 1 A g-1) for sodium storage. As evidenced by experiments and density functional theory calculations, abundant Mo vacancies in MoS2 can greatly accelerate the charge transfer and enhance the interaction between MoS2 and sodium, resulting in the promotion of sodium storage. Kinetic analysis result reveals that the ultrafast sodium ion storage of HMF-MoS2 could be associated with the significant contribution of capacitive energy storage. This work highlights the detailed molecular level understanding of chemical reaction on MoS2 surface by defect and morphology engineering, which can be applied to other metal sulfides for energy storage devices.

Hierarchical Metal Sulfide/Carbon Spheres: A Generalized Synthesis and High Sodium-Storage Performance.

The development of suitable anode materials is far from satisfactory and is a major scientific challenge for a competitive sodium-ion battery technology. Metal sulfides have demonstrated encouraging results, but still suffer from sluggish kinetics and severe capacity decay associated with the phase change. Herein we show that rational electrode design, that is, building efficient electron/ion mixed-conducting networks, can overcome the problems resulting from conversion reactions. A general strategy for the preparation of hierarchical carbon-coated metal sulfide (MS⊂C) spheres through thermal sulfurization of metal glycerate has been developed. We demonstrate the concept by synthesizing highly uniform hierarchical carbon coated vanadium sulfide (V2 S3 ⊂C) spheres, which exhibit a highly reversibly sodium storage capacity of 777 mAh g-1 at 100 mA g-1 , excellent rate capability (410 mAh g-1 at 4000 mA g-1 ), and impressive cycling ability.

Hierarchical Metal Sulfide/Carbon Spheres: A Generalized Synthesis and High Sodium‐Storage Performance

AbstractThe development of suitable anode materials is far from satisfactory and is a major scientific challenge for a competitive sodium‐ion battery technology. Metal sulfides have demonstrated encouraging results, but still suffer from sluggish kinetics and severe capacity decay associated with the phase change. Herein we show that rational electrode design, that is, building efficient electron/ion mixed‐conducting networks, can overcome the problems resulting from conversion reactions. A general strategy for the preparation of hierarchical carbon‐coated metal sulfide (MS⊂C) spheres through thermal sulfurization of metal glycerate has been developed. We demonstrate the concept by synthesizing highly uniform hierarchical carbon coated vanadium sulfide (V2S3⊂C) spheres, which exhibit a highly reversibly sodium storage capacity of 777 mAh g−1 at 100 mA g−1, excellent rate capability (410 mAh g−1 at 4000 mA g−1), and impressive cycling ability.

Hard–Soft Carbon Composite Anodes with Synergistic Sodium Storage Performance

AbstractA series of hard–soft carbon composite materials is produced from biomass and oil waste and applied as low‐cost anodes for sodium‐ion batteries to study the fundamentals behind the dependence of Na storage on their structural features. A good reversible capacity of 282 mAh g−1 is obtained at a current density of 30 mA g−1 with a high initial Coulombic efficiency of 80% at a carbonization temperature of only 1000 °C by adjusting the ratio of hard to soft carbon. The performance is superior to the pure hard or soft carbon anodes produced at the same temperatures. This synergy between hard and soft carbon resulting in an excellent performance is due to the blockage of some open pores in hard carbon by the soft carbon, which suppresses the solid electrolyte interface formation and increases the reversible sodium storage capacity.

Apricot shell derived hard carbons and their tin oxide composites as anode materials for sodium-ion batteries

To be used in sodium ion batteries, preparation of the hard carbon anode materials from the bio waste source of apricot shell (AS) via hydrothermal carbonization (HTC) is introduced. Further pyrolysis at different temperature conditions are applied in order to attain sufficient conductivity and higher surface area that are essential for battery applications. With the purpose of increasing the sodium storage capacity values, SnO2 nanoparticles under HTC conditions are also incorporated into the AS derived carbons. The superior capacity values are obtained with 1000 °C temperature treated hard carbon anode materials with 184 mAh/g of capacity over 250 cycles. In-situ preparation method for the SnO2 hard carbon anode results much improved electrochemical properties. In contrast, mechanically mixing of SnO2 with hard carbon results fast capacity fading since SnO2 particles are not coated with AS derived carbon which functions as volume expansion suppressor of the nanoparticles.

Sb–Si Alloys and Multilayers for Sodium-Ion Battery Anodes

Silicon has a theoretical sodium-storage capacity of 954 mAh/g, which even exceeds that of tin (847 mAh/g). However, this capacity has never been reached in practice. Antimony is one of the best-pe...