Anodes For Sodium Storage Research Articles

Three-Dimensional (3D) Ordered Macroporous Bimetallic (Mn,Fe) Selenide/Carbon Composite with Heterojunction Interface for High-Performance Sodium Ion Batteries.

Transition-metal selenides have captured significant research attention as anode materials for sodium ion batteries (SIBs) due to their high theoretical specific capacities and excellent electronic conductivity. However, volumetric expansion and inferior cycle life still hinder their practical application. Herein, a three-dimensional (3D) ordered macroporous bimetallic (Mn,Fe) selenide modified by a carbon layer (denoted as 3DOM-MnFeSex@C) composite containing a heterojunction interface is fabricated through selenizing a 3D ordered macroporous Mn-based Prussian Blue analogue single crystal. The 3DOM-MnFeSex@C exhibits hierarchically porous architecture with enhanced mass-transfer efficiency; MnSe and FeSe2 particles are encapsulated into macroporous carbon framework, which can significantly promote the electronic conductivity and maintain the structural integrity. The density functional theory calculation indicates that the heterojunction interface between MnSe and FeSe2 has been successfully engineered so that Na+ can be readily adsorbed and rapidly converted, thus promoting the reaction kinetics and extending the cyclic life. As expected, the 3DOM-MnFeSex@C composite delivers excellent rate performance (277.6 mA h g-1 at 10 A g-1), and prolonged cycling life (191.6 mA h g-1 even after 1000 cycles at 2 A g-1) as a sodium storage anode. The sodium storage mechanism of the composite was further investigated by in situ X-ray diffraction and ex situ high-resolution transmission electron microscopy characterization techniques.

Epitaxial growth of Cu2-xSe on Cu (220) crystal plane as high property anode for sodium storage

Three-dimentional (3D) transition metal selenides with sufficient channels could produce significant superiority on enhancing reaction kinetics for sodium-ion batteries. However, the thorough exploration of 3D architecture with a facile strategy is still challenging. Here we report that a polycrystalline Cu2-xSe film was epitaxial grown on (220) facets-exposed Cu by direct selenization of a nanoporous Cu skeleton, which is obtained by dealloying rolled CuMn@Cu alloy foil. Density functional theory calculation result shows strong adsorption energy for Se atoms on Cu (220) planes during selenization reaction, rendering a low energy consumption. By virtue of this core-shell 3D nanoporous architecture to offer abundant active sites and endow fast electron/ion transportation, the nanoporous Cu2-xSe@Cu-0.15 composite electrode exhibits remarkable sodium-ion storage properties with high reversible capacity of 950.6 µAh/cm2 at 50 µA/cm2, suprior rate capability of 457.6 µAh/cm2 at 500 µA/cm2, as well as an ultra-long stability at a high current density. Mechanism investigation reveals that the electrochemical reaction is a typical conversion-type reaction with different intermediates. This novel electrode synthetic strategy provides useful instructions to design the high-performance anode material for sodium-ion batteries.

Facile synthesis of a novel P-doped carbon coated nickel phosphides nanorods as sodium storage anode materials

Nickel-based phosphides as anode materials of sodium ion batteries have high capacity, but poor cycle stability and low electrical conductivity. Rational structural design for nickel-based phosphides with carbon provides a new way to address the above shortcomings. This paper presents a simple method to synthesize a novel carbon coated NixP (x = 2.4–3.0, denoted as NixP@PC) nanorods using phosphoric acid resin as phosphorus and carbon sources. The NixP nanocrystals are in-situ generated in the P-doped carbon without further phosphatization. The carbon layer can confine the volume changes during charging/discharging process. Additionally, the enriched P doping in the carbon layer greatly increases the electrical conductivity of the NixP-based composite and provides more active sites for sodium storage. The as-obtained NixP@PC nanorods reveal excellent reversible sodium storage performance (271.6 mA·h/g based on the mass of NixP@PC at 0.1 A/g after 300 cycles) and outstanding cycling stability (0.005% capacity decay per cycle after 5 000 cycles at 2 A/g). Meanwhile, the formation mechanism of NixP@PC is evidenced by monitoring the evolution of morphology and structure during the preparing process. This paper may provide a feasible way for constructing high-performance transitional metal compounds for sodium-ion batteries.

Concentrated Laminate Structure in Dense MXene Monoliths Promises High‐Capacity Sodium Storage

MXenes have great potential as fast‐charging anodes for sodium storage due to their excellent electrical conductivity, high pseudocapacitive charge storage, and large interlayer distance. The intercalation pseudocapacitance provided by the active sites within the laminate MXene nanosheets is generally the major contributor to their sodium‐storage capacity. Thus, it is highly preferred to construct porous materials with abundant laminate structures to overcome the ion‐diffusion limitation in MXene multilayer films and increase the accessible interlayer sites. Herein, the enhancement of laminate structures in a pre‐assembled Ti3C2Tx network is achieved, under the effects of interlayer slipping of MXene nanosheets during capillary densification, and finally obtained a dense monolith with both high density (2.37 g cm−3) and high porosity (87.3 m2 g−1). This MXene anode material delivers a high capacity of 185 mAh g−1 and a superior rate performance of 55 mAh g−1 (5 A g−1). With improvement of both density and gravimetric capacity, this monolith has a high volumetric capacity of up to 200 mAh cm−3 at 1 A g−1 even after 2000 cycles. Herein, new insights are provided into the design of high‐capacity MXene anodes for sodium‐ion batteries and control of different 2D materials in compact structures.

Constructing bimetallic heterostructure as anodes for sodium storage with superior stability and high capacity

Heterostructure materials hold promise as future-generation anodes for sodium-based energy storage. However, the complexity and time-intensity of heterojunction fabrication processes limit their large-scale application. This study utilizes an ultrafast, one-step microwave process to successfully design and fabricate bimetallic selenides heterojunction nanoparticles, anchored on a three-dimensional porous carbon substrate (NiSe2–SnSe2/C). The in-situ formation of NiSe2–SnSe2 heterostructure optimizes sodium ion adsorption and transfer, which facilitates reaction kinetics and subsequently improves both the rate capability and cycle life. The NiSe2–SnSe2/C electrodes demonstrate a high-rate capability (719.8 mAh g−1 at 0.1 A g−1, and 667.9 mAh g−1 after a 50-fold increase in current density to 5 A g−1), maintaining high stability even after 10,000 cycles at 5 A g−1. The impact of the NiSe2–SnSe2 heterostructure on reaction kinetics was examined using density functional theory. The NiSe2–SnSe2/C anode, when coupled with the Na3V2(PO4)3 cathode in a full battery, demonstrated an impressive energy density of 155 Wh kg−1. This work exemplifies an ultrafast synthetic method for constructing heterostructure materials having great rate, high capacity and strong stability for sodium storage, making them promising candidates for large-scale energy storage applications.

Constructing atomically dispersed Snδ+ sites in porous carbon nanosheets to boost lithium-/sodium-storage capability

Nanoscale carbon-supported single atomic metal active centers (Mδ+) have recently caught much attention as a high-efficient catalyst in energy-conversion/-storage fields. Further works extended to employ these materials as the lithium-/sodium-storage anode. Inspired by the progresses, porous carbon nanosheets with abundant Snδ+ sites (Sn-PCNS) are prepared by easy-controllable template-directed method and post carbonization process in this work. Here, atomically dispersed Snδ+ is stabilized mainly by O/N moieties in carbon framework, which can enhance the electron transfer and Li+-/Na+-diffusion kinetics, thus benefiting the Li+-/Na+-storage capabilities. As a result, the Sn-PCNS electrode can deliver a high lithium-storage capacity of 428 mA h g−1 at 10 A g−1 and show a long-term cycling performance for sodium storage at high rate (∼ 120 mA h g−1 at 5 A g−1 after 1000 cycles). This work not only provides a strategy for the preparation of new sheet-like carbon-based nanomaterials, but also offer an opportunity to promote the application of carbon-supported single atomic metal active centers in energy conversion and storage.

Interfacial-Catalysis-Enabled Layered and Inorganic-Rich SEI on Hard Carbon Anodes in Ester Electrolytes for Sodium-Ion Batteries.

Constructing a homogenous and inorganic-rich solid electrolyte interface (SEI) can efficiently improve the overall sodium-storage performance of hard carbon (HC) anodes. However, the thick and heterogenous SEI derived from conventional ester electrolytes fails to meet the above requirements. Herein, an innovative interfacial catalysis mechanism is proposed to design a favorable SEI in ester electrolytes by reconstructing the surface functionality of HC, of which abundant CO (carbonyl) bonds are accurately and homogenously implanted. The CO (carbonyl) bonds act as active centers that controllably catalyze the preferential reduction of salts and directionally guide SEI growth to form a homogenous, layered, and inorganic-rich SEI. Therefore, excessive solvent decomposition is suppressed, and the interfacial Na+ transfer and structural stability of SEI on HC anodes are greatly promoted, contributing to a comprehensive enhancement in sodium-storage performance. The optimal anodes exhibit an outstanding reversible capacity (379.6 mAh g-1 ), an ultrahigh initial Coulombic efficiency (93.2%), a largely improved rate capability, and an extremely stable cycling performance with a capacity decay rate of 0.0018% for 10 000 cycles at 5 A g-1 . This work provides novel insights into smart regulation of interface chemistry to realize high-performance HC anodes for sodium storage.

Polyimide-engineered sodium titanate anode for sodium storage with improved structure and interface stability

Na2Ti3O7 (NTO) anode has been long-term plagued by the rapid capacity decay due to the irreversible structural evolution and interfacial side reaction at low sodium insertion potential. Most reported investigations about NTO anode mainly focus on designing nanostructure to shorten ion diffusion and increase the electrochemical activity. However, few attentions have been paid to promote the cycle stability of bulk NTO. Surface/interface engineering through the incorporation of well-designed coating layer has been verified an effective strategy to stabilize the structure and interface of the electrodes. Herein, a polyimide-engineered bulk Na2Ti3O7 (NTO@PI) is proposed to promote its structure and interface stability upon cycles. The continuous PI layer with intrinsic flexibility as a protection skin can suppress the self-relaxation of discharged product and promote the structural stability during cycles. Meanwhile, PI protective layer with superior chemical stability not only hinders the side reaction occurred at NTO/electrolyte interface, but also serves as a barrier layer to preclude the erosion of H2O when exposed to air. Moreover, the PI layer with intrinsic ionic conductivity is capable of boosting Na-ion transportation from electrolyte into the NTO lattice as well. This work stresses a rational strategy for the surface/interface regulation of long-lasting and practical Ti-based anodes.

Engineering CSFe Bond Confinement Effect to Stabilize Metallic-Phase Sulfide for High Power Density Sodium-Ion Batteries.

Metallic-phase iron sulfide (e.g., Fe7 S8 ) is a promising candidate for high power density sodium storage anode due to the inherent metal electronic conductivity and unhindered sodium-ion diffusion kinetics. Nevertheless, long-cycle stability can not be achieved simultaneously while designing a fast-charging Fe7 S8 -based anode. Herein, Fe7 S8 encapsulated in carbon-sulfur bonds doped hollow carbon fibers (NHCFs-S-Fe7 S8 ) is designed and synthesized for sodium-ion storage. The NHCFs-S-Fe7 S8 including metallic-phase Fe7 S8 embrace higher electron specific conductivity, electrochemical reversibility, and fast sodium-ion diffusion. Moreover, the carbonaceous fibers with polar CSFe bonds of NHCFs-S-Fe7 S8 exhibit a fixed confinement effect for electrochemical conversion intermediates contributing to long cycle life. In conclusion, combined with theoretical study and experimental analysis, the multinomial optimized NHCFs-S-Fe7 S8 is demonstrated to integrate a suitable structure for higher capacity, fast charging, and longer cycle life. The full cell shows a power density of 1639.6Wkg-1 and an energy density of 204.5Whkg-1 , respectively, over 120 long cycles of stability at 1.1Ag-1 . The underlying mechanism of metal sulfide structure engineering is revealed by in-depth analysis, which provides constructive guidance for designing the next generation of durable high-power density sodium storage anodes.

CuFeSe2/Cu2Se@C heterostructures as high-rate ultra-stable anodes for sodium ion half/full batteries

Transition metal selenides can be potentially implemented as a new generation of sodium storage anode owing to their abundance and high theoretical specific capacity. However, their practical applications are limited by large volume changes and slow kinetics. Therefore, the construction of transition metal selenide heterojunctions with long cycle stability and high capacity as anodes in sodium ion batteries remains challenging. In this study, carbon coated CuFeSe2/Cu2Se heterojunctions (CFS/CS@C) were successfully prepared via a simple aging and annealing strategy. The abundant heterojunction interfaces and carbon layers accelerated charge transfer, promoted the reaction kinetics, enhanced the electrical conductivity, and extended the cycle life. Consequently, the target material yielded ultra-long cycle stability (301.2 mAh/g at 10.0 A/g after 3000 cycles) and excellent rate performance (330.96 mAh/g at 20 A/g). The directly constructed full cell also exhibited remarkable cycling stability (138.6 mAh/g after 200 cycles at 0.5 A/g). Accordingly, this work demonstrated the construction of transition metal selenide composites as high-performance electrochemical energy storage electrodes.

Carbon coated Co(PO3)2/CoSe2 heterostructure as high performance sodium storage anode

Heterostructure fabrication is believed to acquire promoted charge transfer and improved surface storage contribution, thus obtaining high-performance anodes for sodium-ion batteries. Herein, the simultaneous phosphatization and selenization of polydopamine functionalized ZIF-67 is adopted to engineer N-doped carbon coated Co(PO3)2/CoSe2 heterostructure. The hetero-interface with plenty of surface sites is activated with large surface reaction and fast sodium ion transport dynamics. The multiphase synergism and carbon coating layer assure high conductivity and structural stability. The designed sample delivers impressive anode performance, exhibiting a high sodium storage capacity of 333.4 mAh g−1 at 0.1 A g−1 and 192.7 mAh g−1 after 1000 cycles at 2 A g−1. This simple and reasonable method can be utilized to construct other transition metal based heterostructures with multiphase synergism for the application of advanced anodes.

Embedding antimony nanoparticles into metal–organic framework derived TiO2@carbon nanotablets for high-performance sodium storage

Titanium dioxide (TiO2) has been widely investigated as a candidate for anode materials of sodium-ion batteries (SIBs) due to its low cost and high abundance. However, the intrinsic sluggish ion/electron transfer rate hinders its practical applications for high energy density storage devices. In contrast, antimony (Sb) shows high specific theoretical capacity (660 mAh/g) as well as excellent electron conductivity, but the large volume variation upon cycling usually leads to severe capacity fading. Herein, with the objective of achieving high-performance sodium storage anode materials, TiO2@C-Sb nanotablets with a small amount of Sb content (6.4 wt%) are developed through calcination Ti-metal–organic framework (MIL-125) derived TiO2@C/SbCl3 mixture under reductive atmosphere. Benefitting from the synergetic effect of well-dispersed Sb nanoparticles as well as robust porous TiO2@C substrate, the TiO2@C-Sb shows enhanced electron/ion transfer rate and predominantly pseudocapacitive sodium storage behavior, delivering a reversible capacity of 219 mAh/g at 0.5 A/g even after 1000 cycles. More significantly, this method may be commonly used to incorporate other alloy-based high-theoretical materials into MIL-125-derived TiO2@C, which is promising for developing high-energy-density TiO2-based energy storage devices.

InSitu Growth of Iron Sulfide on Fast Charge Transfer V2 C-MXene for Superior Sodium Storage Anodes.

Due to the upstream pressure of lithium resources, low-cost sodium-ion batteries (SIBs) have become the most potential candidates for energy storage systems in the new era. However, anode materials of SIBs have always been a major problem in their development. To address this, V2 C/Fe7 S8 @C composites with hierarchical structures prepared via an insitu synthesis method are proposed here. The 2D V2 C-MXene as the growth substrate for Fe7 S8 greatly improves the rate capability of SIBs, and the carbon layer on the surface provides a guarantee for charge-discharge stability. Unexpectedly, the V2 C/Fe7 S8 @C anode achieves satisfactory sodium storage capacity and exceptional rate performance (389.7mAhg-1 at 5Ag-1 ). The sodium storage mechanism and origin of composites are thoroughly studied via exsitu characterization techniques and first-principles calculations. Furthermore, the constructed sodium-ion capacitor assembled with N-doped porous carbon delivers excellent energy density (135Whkg-1 ) and power density (11kWkg-1 ), showing certain practical value. This work provides an advanced system of sodium storage anode materials and broadens the possibility of MXene-based materials in the energy storage.

Wafer-biscuits-like few-graphene-layers carbon with N, P, S triple-doping for efficient and stable sodium-ion storage

Carbon-based materials are one of the most attractive anodes for sodium-ion batteries because of their wide availability, facile synthesis, and low cost. However, rational designing carbon-based architecture towards upgrading the electrochemical performance of anodes for sodium storage has been a great challenge. Herein, we prepared N, P, S triple-doped few-graphene-layers carbon with expanded interlayer spacing via a scalable template approach. The few-graphene-layers carbon negatively replicates the structure of the layered template to generate a wafer-biscuit-like architecture, which prevents the restack of carbon nanosheets. The interlayer spacing and heteroatom contents of wafer-biscuit-like carbon architecture can be modulated by varying carbonization temperatures. Consequently, the optimum carbon anode delivers a high reversible capacity of 329 mAh g−1, good rate capability, and long-term stability of 300 cycles at 1 A g−1. Furthermore, the sodium storage mechanism of wafer-biscuit-like carbon anodes has been systematically explored.

PPy-derived carbon nanoparticles anchored on TiO2/C nanofibers as sodium-ion battery anodes with ultra-long cycle stability

• PPy was used as a N-doping carbon source to modify TiO 2 /C nanofibers. • More OVs were introduced in TiO 2 due to the PPy-derived carbon (PC). • The PC nanoparticles improved the cyclic stability of TiO 2 /C nanofibres. As the anode material of sodium-ion batteries (SIBs), TiO 2 exhibits low sodium storage potential and small structural changes in the sodium storage process. To improve the pseudocapacitive behavior of TiO 2 , PPy was used as an N-containing carbon source to modify TiO 2 /C (TC) porous nanofibers. PPy-derived carbon (PC) nanoparticles anchored on TC nanofibers (PCTC) by a simple chemical oxidation method. The PC nanoparticles significantly improved the electrical conductivity of PCTC nanofibers with oxygen vacancies (OVs), while substantially improving the structural stability. As a result, PCTC exhibits a high reversible specific capacity (179.8 mAh g -1 at 1.0 A g -1 ) and a very long cycle life (206.4 mAh g -1 after 1000 cycles at 1.0 A g -1 ) when used as anodes of SIBs. The superior sodium storage performance of PCTC nanofibres is attributed to the special structure with N-doping and OVs, resulting in high pseudo-capacitance contribution (95%, 2.0 mV s -1 ). This OVs-creating approach can improve the pseudocapacitance of oxide anodes for sodium storage.

Superimposed effect of hollow carbon polyhedron and interconnected graphene network to achieve CoTe2 anode for fast and ultralong sodium storage

Owing to the high trap density, large ionic radius, and unique crystal structure, CoTe2 shows great potential as anodes for sodium storage. However, the intrinsic poor electronic conductivity and large volume variation of CoTe2 during the charge-discharge process result in inferior electrochemical performance. Herein, three-dimensional hollow porous carbon dodecahedron composed of CoTe2 microparticles on reduced graphene oxide (rGO) nanosheets (denoted as CoTe2@3DG) is prepared by coordination regulation between rGO and Co-MOF (ZIF-67) and subsequent tellurization reaction. The CoTe2@3DG hybrids combine the synergistic advantages of the double-carbon skeleton and provide efficient volume expansion space of CoTe2 nanoparticles throughout cycling to realize excellent electrochemical capability. The electrochemical analysis and in-situ X-ray diffraction measurement reveal the fast electrons/sodium-ions transfer kinetics and phase evolution mechanism for sodium storage. Thus, the CoTe2@3DG hybrids display an excellent cycling stability (∼103 mAh g−1 is maintained after 4500 cycles at 1.0 A g−1) as well as excellent rate capability (135 mAh g−1 at 5.0 A g−1). This work proposes a simple and facile double-carbon-encapsulation technique for improving sodium storage performance in anode materials with conversion mechanisms.

NiSe2 Nanoparticles Decorated on Carbon Nanosheet Arrays as Anodes for Sodium Storage

NiSe₂ Nanoparticles Decorated on Carbon Nanosheet Arrays as Anodes for Sodium Storage

From micro to macro: Freestanding electrode based on low crystalline Cu2−xSe for sodium storage

The development of electrode materials is a crucial parameter in improving sodium storage’s electrochemical performance. In this study, Cu2−xSe obtained from Cu-based metal–organic frameworks embedded in nanofibers (Cu2−xSe@C@NCNFs) shows excellent electrochemical performance as a freestanding anode for sodium storage. The “macro” aspects of 1D nanofibers as the skeleton not only inhibit Cu2−xSe agglomeration and structural collapse during the charge–discharge process, but also enhance the electrical conductivity. In this “from micro to macro” unique structure, on the “micro” aspect, Cu2−xSe nanoparticles with low crystallinity enhance the specific capacity and electrochemical reaction kinetics further. Moreover, the initial Coulombic efficiency can be as high as 66.3%. Furthermore, after 1000 cycles at 2 A g−1, Cu2−xSe@C@NCNFs demonstrated a specific capacity of 74 mAh g−1. The outstanding electrochemical performance shows that “from micro to macro” Cu2−xSe@C@NCNFs is a potential electrode material for effective sodium storage.

Entropy‐Change Driven Highly Reversible Sodium Storage for Conversion‐Type Sulfide

AbstractTransition metal sulfides (TMSs) are reported to be efficient sodium storage anode materials due to their rich redox chemistry and good electronic conductivity features. However, the issues of poor reaction reversibility and cyclability, caused by structure degradation and volume expansion during repeated (de)sodiation processes, have far limited the applicability of these materials. Herein, a high‐entropy configuration strategy is reported for Cu4MnFeSnGeS8 anodes for advanced sodium ion batteries. In this high‐entropy material, the homogeneously dispersed cations can effectively suppress the continuous coarseness of Sn nanoparticles and maintain valid interface contact between M0 and Na2S, thus achieving highly reversible sodium storage. Moreover, the highly reversible crystalline‐phase transformation of high‐entropy Cu4MnFeSnGeS8 and highly inherent mechanical stability can effectively relieve the persistently accumulated mechanical stress, thus restraining continuous breakage of the solid electrolyte interphase film and pulverization of the electrode, and improving cycling stability. Furthermore, when coupled with a Na3V2(PO4)3 cathode, the full cell shows a high energy density (264 Wh kg–1), which makes the high‐entropy‐stabilized sulfide a promising anode candidate for SIBs.

Electron-Injection and Atomic-Interface Engineering toward Stabilized Defected 1T-Rich MoS2 as High Rate Anode for Sodium Storage.

1T-phase MoS2 is a promising electrode material for electrochemical energy storage due to its metallic conductivity, abundant active sites, and high theoretical capacity. However, because of the habitual conversion of metastable 1T to stable 2H phase via restacking, the poor rate capacity and cycling stability at high current densities hamper their applications. Herein, a synergetic effect of electron-injection engineering and atomic-interface engineering is employed for the formation and stabilization of defected 1T-rich MoS2 nanoflowers. The 1T-rich MoS2 and carbon monolayers are alternately intercalated with each other in the nanohybrids. The metallic 1T-phase MoS2 and conductive carbon monolayers are favorable for charge transport. The expanded interlayer spacing ensures fast electrolyte diffusion and the decrease of the ion diffusion barrier. The obtained defected 1T-rich MoS2/m-C nanoflowers exhibit high Na-storage capacity (557 mAh g-1 after 80 cycles at 0.1 A g-1), excellent rate capacity (411 mAh g-1 at 10 A g-1), and long-term cycling performance (364 mAh g-1 after 1000 cycles at 2 A g-1). Furthermore, a Na-ion full cell composed of the 1T-rich MoS2/m-C anode and Na3V2(PO4)3/C cathode maintains excellent cycling stability at 0.5 A g-1 during 400 cycles. Theoretical calculations are also performed to evaluate the phase stability, electronic conductivity, and Na+ diffusion behavior of 1T-rich MoS2/m-C. The energy storage performance demonstrates its excellent application prospects.