Sodium-ion Storage Devices Research Articles

Defect-induced electron rich nanodomains in CoSe0.5S1.5/GA realize fast ion migration kinetics as sodium-ion capacitor anode

Optimizing charge migration and alleviating volume expansion in anode materials are the key to improve the electrochemical performance for sodium-ion storage devices. Herein, a hierarchical porous conducting matrix confining defect-rich selenium doped cobalt dichalcogenide (CoSe0.5S1.5/GA) is constructed as a promising SICs anode based on the guidance of theoretical calculation analysis. The increased defect concentration significantly enhanced the disorder degree of the compound and presented electron aggregation around the S atoms, which effectively modulated the electronic structure, further enabling high rate and ultra-capacity sodium storage. Moreover, strong interfacial coupling could construct spatial constraint to alleviate volume expansion as well as maintain electrode integrity and stability. The CoSe0.5S1.5/GA electrode can deliver a high capacity of 310.1 mA h g−1 after 2000 cycles at 1 A g−1, and the CoSe0.5S1.5/GA//AC sodium ion capacitor can exhibit an outstanding energy density of 237.5 W h kg−1. A series of characterization and theoretical calculation convincingly reveal that the defect moieties can regulate the Na+ storage and diffusion kinetics, which prove that our defect manufacture coupling with space-confined strategy can provide deep insights into the development of high-performance Na+ storage devices.

Mechanism of interfacial effects in sodium-ion storage devices

Mechanism of interfacial effects in sodium-ion storage devices

Bundled carbon nanofiber arrays grown on Cu-Ni tube textile boosting superior sodium-ion storage kinetics

Achieving high energy and power density in micro sodium-ion storage device is imperative and challenging due to the large radius of sodium ions and induced sluggish sodiation kinetics. Herein, we develop a vertically aligned carbon nanofiber arrays with a graphite dome (G-CNFAs/Textile) using the unique Cu-Ni solid solution textile as catalyst and thin substrate. As a flexible electrode with a maximum thickness of 4.0 µm, the G-CNFAs/Textile combines the merits of the thinner intertwined/ interconnected carbon nanofiber bundles, high porosity and abundant defects, thereby deriving enhanced sodium-ion storage kinetics. As a result, the flexible micrometer-scale G-CNFAs/Textile not only delivers an impressive gravimetric performance of 332.6 mA h g−1 at 1000 mA g−1 after 500 cycle numbers, but also exhibits outstanding volumetric capacity of ca. 1387.6 mA h cm−3 in half-type SIBs. Meanwhile, as the submicron-scale self-supporting symmetric electrode of SICs, the G-CNFAs//G-CNFAs capacitor also presents an impressive gravimetric capacitance of 66.5 F g−1 at 0.1 A g−1, superior energy-power density (80.9 W h kg−1 and 7771.8 W kg−1), as well as outstanding cyclic stability. Thus, we hope that this flexible micro-submicron-scale electrode structures could provide inspirations for thin, light-weight and miniaturized sodium-ion storage devices.

Surface-controlled sodium-ion storage mechanism of Li4Ti5O12 anode

Sodium-ion batteries (SIBs) are the promising candidate in grid systems owing to the wide distribution and abundance of sodium resources. However, the charge storage mechanism and size-effect of the active materials for SIBs remain largely unexplored. Herein, we synchronously investigate the electrochemical properties and structural evolutions of Li4Ti5O12 (LTO) anode for Li+ and Na+ storage, along with the nano-size effect on their charge storage behaviors. Through detailed kinetic analysis, it is found the Li+ storage in LTO is diffusion-controlled in bulk and shows increased surface-controlled contributions when the size is reduced to 18 nm. In comparison, for the Na+ storage, the domination step is surface-controlled in all the sizes of LTO from 260 to 18 nm, with over 55% contribution even at the low sweep rate of 0.1 mV s−1. The limited near-surface reaction region and low diffusion kinetics determine the surface-controlled Na+ storage behaviors and the specific capacities. The suitable size of LTO-18 nm anode displays a high capacity of ∼140 mAh g−1 (at 0.05 A g−1, ∼0.29C), high-rate capability (42 mAh g−1 at ∼57C), and long-term cycling stability (over 1200 cycles). Our finding provides insights into a precise design of nanomaterials for high-power sodium-ion storage devices.

Graphene wrapped TiO2@MoSe2 nano-microspheres with sandwich structure for high-performance sodium-ion hybrid capacitor

Sodium-ion hybrid capacitors (SIHCs) have received extensive attention and research due to their combined advantages of high power performance and high energy density. However, the lack of high-performance anode materials has been a challenge for sodium storage devices. Herein, a heteroatom co-doped hollow spherical TiO2@MoSe2/reduced graphene oxide (RGO) with pea pods structure is designed and synthesized. This unique composite is made of TiO2 as the stable framework, MoSe2 sheet as the main active materials, and RGO conductive network as the protective cover. The sandwich structure provides stable and ordered transport channels for electrons and Na+, and greatly increases the number of active sites. As a result, TiO2@MoSe2/RGO exhibits satisfactory electrochemical performance. At a high current density of 2 A g-1, TiO2@MoSe2/RGO still maintains a capacity of 106 mAh g-1 after 1000 cycles. The hybrid device possesses an energy density of 135 Wh kg−1 at power density of 1667 W kg−1, demonstrating the design concept of heterogeneous composite provides a new route for the development of electrode materials in sodium-ion storage devices.

A modified reduced graphite oxide anode for sodium ion storage in ether‐based electrolyte

In this work, reduced graphite oxide (rGO) with a long-range-ordered layered structure and an expanded interlayer spacing is synthesized and utilized as an anode for sodium ion storage. Unlike Na+-solvent co-intercalation in flake graphite, the interaction between Na-ions and graphene layers of the rGO shows a capacitive behavior. All the surface defects, pores, and functional groups generated on the surface of rGO can contribute to additional capacity of sodium storage. Thereby, a reversible capacity of 145.7 mAh g−1 at 1 A g−1 and a rate performance of 131.7 mAh g−1 at 1.8 A g−1 could be obtained. Capacity retention of 87.7 % after 900 cycles at 400 mA g−1 was also achieved. Further enhancement in cycling stability, with little capacity decay after 1500 cycles, was obtained after incorporating Ag onto the surface of the rGO. The rGO-Ag anode delivered higher energy density and power density as compared to rGO at the same current density. Even at a power density of 5493 W kg−1 (3A g−1, 24 C), the energy density was as high as 236.2 Wh kg−1. These results contribute to the development of a low-cost, high-performance sodium ion storage devices.

Boosting Capacitive Sodium-Ion Storage in Electrochemically Exfoliated Graphite for Sodium-Ion Capacitors.

Sodium (Na)-ion capacitors possess higher energy density than supercapacitors and higher power density than Na-ion batteries. However, kinetic mismatches between fast capacitive charge storage on the cathode and sluggish battery-type reactions on the anode lead to a poor charge/discharge rate capability and insufficient power output of Na-ion capacitors. Thus, developing suitable anode materials for Na-ion capacitors is urgently desirable. This work demonstrates an electrochemically exfoliated graphite (EEG) anode with enhanced capacitive charge storage, greatly boosting the Na-ion reaction kinetics of co-intercalation. The EEG anode shows a high reversible capacity of 109 mAh g-1 and maintains a good capacity retention of 90% after 1000 cycles. The assembled Na-ion capacitor using the EEG anode can finish the charge/discharge process in less than 10 s, which achieves an ultrahigh power density of 17,500 W kg-1 with an energy density of 17 Wh kg-1. The high capacitive contributions at both the anode and cathode contribute to the fast rate capability and high power output of the fabricated Na-ion capacitors. This work will promote the development of ultrafast charging sodium-ion storage devices.

Surface pseudocapacitance of mesoporous Mo3N2 nanowire anode toward reversible high-rate sodium-ion storage

The mesoporous Mo 3 N 2 nanowires exhibit a capacitance-dominated sodium-ion storage process, which enables the high-rate capabilities. Besides, the sodium-ion storage mechanism of mesoporous Mo 3 N 2 nanowires is surface redox reaction. Sodium-ion storage devices are highly desirable for large-scale energy storage applications owing to the wide availability of sodium resources and low cost. Transition metal nitrides (TMNs) are promising anode materials for sodium-ion storage, while their detailed reaction mechanism remains unexplored. Herein, we synthesize the mesoporous Mo 3 N 2 nanowires (Meso-Mo 3 N 2 -NWs). The sodium-ion storage mechanism of Mo 3 N 2 is systematically investigated through in-situ XRD, ex-situ experimental characterizations and detailed kinetics analysis. Briefly, the Mo 3 N 2 undergoes a surface pseudocapacitive redox charge storage process. Benefiting from the rapid surface redox reaction, the Meso-Mo 3 N 2 -NWs anode delivers high specific capacity (282 mAh g −1 at 0.1 A g −1 ), excellent rate capability (87 mAh g −1 at 16 A g −1 ) and long cycling stability (a capacity retention of 78.6% after 800 cycles at 1 A g −1 ). The present work highlights that the surface pseudocapacitive sodium-ion storage mechanism enables to overcome the sluggish sodium-ion diffusion process, which opens a new direction to design and synthesize high-rate sodium-ion storage materials.

Ferroconcrete-inspired design of a nonwoven graphene fiber fabric reinforced electrode for flexible fast-charging sodium ion storage devices

Ferroconcrete-inspired graphene fiber nonwoven fabrics integrated with multi-functionalities for use as free-standing anodes/cathodes give superior performances as flexible sodium ion capacitors.

Flexible and additive-free organic electrodes for aqueous sodium ion batteries

Organic materials with redox activities are promising candidates for aqueous flexible sodium ion storage devices (AFSISDs) due to their mechanical flexibility and low dissolution in aqueous electrolytes.

N-Doped Modified Graphene/Fe2O3 Nanocomposites as High-Performance Anode Material for Sodium Ion Storage.

Sodium-ion storage devices have received widespread attention because of their abundant sodium resources, low cost and high energy density, which verges on lithium-ion storage devices. Electrochemical redox reactions of metal oxides offer a new approach to construct high-capacity anodes for sodium-ion storage devices. However, the poor rate performance, low Coulombic efficiency, and undesirable cycle stability of the redox conversion anodes remain a huge challenge for the practical application of sodium ion energy storage devices due to sluggish kinetics and irreversible structural change of most conversion anodes during cycling. Herein, a nitrogen-doping graphene/Fe2O3 (N-GF-300) composite material was successfully prepared as a sodium-ion storage anode for sodium ion batteries and sodium ion supercapacitors through a water bath and an annealing process, where Fe2O3 nanoparticles with a homogenous size of about 30 nm were uniformly anchored on the graphene nanosheets. The nitrogen-doping graphene structure enhanced the connection between Fe2O3 nanoparticles with graphene nanosheets to improve electrical conductivity and buffer the volume change of the material for high capacity and stable cycle performance. The N-GF-300 anode material delivered a high reversible discharge capacity of 638 mAh g−1 at a current density of 0.1 A g−1 and retained 428.3 mAh g−1 at 0.5 A g−1 after 100 cycles, indicating a strong cyclability of the SIBs. The asymmetrical N-GF-300//graphene SIC exhibited a high energy density and power density with 58 Wh kg−1 at 1365 W kg−1 in organic solution. The experimental results from this work clearly illustrate that the nitrogen-doping graphene/Fe2O3 composite material N-GF-300 is a potential feasibility for sodium-ion storage devices, which further reveals that the nitrogen doping approach is an effective technique for modifying carbon matrix composites for high reaction kinetics during cycles in sodium-ion storage devices and even other electrochemical storage devices.

RGO-modified CoWO4 nanoparticles as new high-performance electrode materials for sodium-ion storage

In this work, the RGO-modified CoWO4 nanoparticles are synthesized by a feasible hydrothermal approach and studied as the high-performance sodium-ion storage materials. RGO can effectively improve overall electrical conductivity and maintain the stability of the composite structure. The composites exhibit a stabilized reversible capacity of 160 mAh g−1 at the current density of 100 mA g−1 after 100 cycles when tested as the anode materials of sodium-ion batteries (SIBs). The sodium-ion capacitors (SICs) were assembled using CoWO4/RGO nanocomposites as the negative electrode materials and the active carbon (AC) as the positive electrode materials. It could deliver a capacitance about 31 F g−1 at the current density of 100 mA g−1 and display a specific energy of 87.2 Wh kg−1 at the power density of 224.6 W kg−1. The outstanding electrochemical properties and high energy density of CoWO4/RGO anode materials indicate the huge potential for its application to sodium-ion storage devices.

Three-dimensional carbon framework as a promising anode material for high performance sodium ion storage devices

This paper presents a way to prepare three-dimensional carbon framework (3DCF) anode material for sodium ion batteries (SIBs) and hybrid capacitors (SIHCs). Based on ethanol/sodium hydroxide electrolyte, 3DCFs are synthesized by electrolysis combined with subsequent calcination process. The obtained 3DCFs have the unique structure with interconnected, porous structure and defective features, which facilitates the sodium ion storage. When used as anode material for SIBs, 3DCFs display high specific capacity and rate capability, and excellent long-term cyclability. We have also assembled the SIHC devices by employing the 3DCFs as anode and sodium alginate derived activated carbon (SDAC) as cathode, the optimal 3DCFs//SDAC devices display high energy density of 133.2 Wh kg−1 and high power output of 20.0 kW kg−1 within the voltage window of 0–4.0 V, as well as long-term cycling life for 4000 cycles. This work provides opens up opportunities for fabricating novel nano-structured electrode material and constructing high performance sodium ion storage devices.

Superelastic 3D few-layer MoS2/carbon framework heterogeneous electrodes for highly reversible sodium-ion batteries

Rational design of electrode materials for sodium-ion batteries with high flexibility is still challenging. Here, superelastic 3D few-layer MoS2/carbon framework heterogeneous electrodes (abbreviated as, MoS2@CF) are fabricated by a simple vacuum infiltration and heating process. The interconnected ultrathin MoS2 network filled with carbon framework forms a 3D heterogeneous network with hierarchical pore structure. The unique structure of the electrodes results in excellent mechanical and electrochemical performances. The MoS2@CF electrodes exhibit superior elasticity and recoverability. After 180° bending repeatedly, the electrodes still can recover their initial sizes. Moreover, the electrodes show outstanding cycling stabilities with high reversible capacities reaching up 240 mA h g−1 after 500 cycles at 1 A g−1 (capacity retention of ~ 99%). Full-cells assembled with MoS2@CF anodes and Na3V2(PO4)3 cathodes show high reversible capacity (~ 252 mA h g−1 at 0.5 A g−1). Overall, the superior mechanical properties and high electrochemical performances indicate the promising potential of MoS2@CF electrodes in large-scale flexible sodium-ion storage devices.

Enhanced sodium storage capability enabled by super wide-interlayer-spacing MoS2 integrated on carbon fibers

Developing advanced electrode materials for effective pseudocapacitive charge storage is one of effective strategies to enhance the rate capability and cycling stability of sodium ion storage devices. Herein, we fabricate MoS2 nanoflowers with super wide interlayer spacing (nearly twice as large as that of the original MoS2) supported on carbon fibers (named as E-MoS2/carbon fibers) and demonstrate its superior electrochemical performances as flexible and binder-free anodes for sodium-ion batteries (SIBs) and sodium-ion hybrid capacitors (SIHCs). Grafting MoS2 nanoflowers onto the carbon fiber networks not only ensures the fast electron transfer, but also endows it with flexible feature. The super wide interlayer spacing of MoS2 nanoflowers can not only decrease the ion diffusion pathways and resistance, but also increase their available and accessible active surface area, thus guaranteeing the rapid mass transport. Also, it can accommodate the large internal strain during discharge/charge processes. Benefiting from these combined structure merits, the E-MoS2/carbon fibers electrodes deliver an ultralong cycling stability up to 3000 cycles and the superior rate capacity of 104mAhg−1 at 20Ag−1, which just takes ca. 18.7s to fully charge/discharge. When further employed as the anode for SIHCs, it delivers high energy and power densities due to the high pseudocapacitive charge storage of the super wide interlayer spacing E-MoS2/carbon fibers.