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1.
Sodium‐ion batteries (SIBs) are considered promising next‐generation energy storage devices. However, a lack of appropriate high‐performance anode materials has prevented further improvements. Here, a hierarchical porous hybrid nanosheet composed of interconnected uniform TiO2 nanoparticles and nitrogen‐doped graphene layer networks (TiO2@NFG HPHNSs) that are synthesized using dual‐functional C3N4 nanosheets as both the self‐sacrificing template and hybrid carbon source is reported. These HPHNSs deliver high reversible capacities of 146 mA h g?1 at 5 C for 8000 cycles, 129 mA h g?1 at 10 C for 20 000 cycles, and 116 mA h g?1 at 20 C for 10 000 cycles, as well as an ultrahigh rate capability up to 60 C with a capacity of 101 mA h g?1. These results demonstrate the longest cyclabilities and best rate capability ever reported for TiO2‐based anode materials for SIBs. The unprecedented sodium storage performance of the TiO2@NFG HPHNSs is due to their unique composition and hierarchical porous 2D structure.  相似文献   

2.
Flexible power sources have shown great promise in next‐generation bendable, implantable, and wearable electronic systems. Here, flexible and binder‐free electrodes of Na3V2(PO4)3/reduced graphene oxide (NVP/rGO) and Sb/rGO nanocomposites for sodium‐ion batteries are reported. The Sb/rGO and NVP/rGO paper electrodes with high flexibility and tailorability can be easily fabricated. Sb and NVP nanoparticles are embedded homogenously in the interconnected framework of rGO nanosheets, which provides structurally stable hosts for Na‐ion intercalation and deintercalation. The NVP/rGO paper‐like cathode delivers a reversible capacity of 113 mAh g?1 at 100 mA g?1 and high capacity retention of ≈96.6% after 120 cycles. The Sb/rGO paper‐like anode gives a highly reversible capacity of 612 mAh g?1 at 100 mA g?1, an excellent rate capacity up to 30 C, and a good cycle performance. Moreover, the sodium‐ion full cell of NVP/rGO//Sb/rGO has been fabricated, delivering a highly reversible capacity of ≈400 mAh g?1 at a current density of 100 mA g?1 after 100 charge/discharge cycles. This work may provide promising electrode candidates for developing next‐generation energy‐storage devices with high capacity and long cycle life.  相似文献   

3.
In this work, expanded MoS2 nanosheets grown on nitrogen‐doped branched TiO2/C nanofibers (NBT/C@MoS2 NFs) are prepared through electrospinning and hydrothermal treatment method as anode materials for sodium‐ion batteries (SIBs). The continuous 1D branched TiO2/C nanofibers provide a large surface area to grow expanded MoS2 nanosheets and enhance the electronic conductivity and cycling stability of the electrode. The large surface area and doping of nitrogen can facilitate the transfer of both Na+ ions and electrons. With the merits of these unique design and extrinsic pseudocapacitance behavior, the NBT/C@MoS2 NFs can deliver ultralong cycle stability of 448.2 mA h g?1 at 200 mA g?1 after 600 cycles. Even at a high rate of 2000 mA g?1, a reversible capacity of 258.3 mA h g?1 can still be achieved. The kinetic analysis demonstrates that pseudocapacitive contribution is the major factor to achieve excellent rate performance. The rational design and excellent electrochemical performance endow the NBT/C@MoS2 NFs with potentials as promising anode materials for SIBs.  相似文献   

4.
Ultrathin Co3O4 nanosheets grown on the reduced graphene oxide (Co3O4/rGO) was synthesized by a simple hydrothermal method and was investigated as a cathode in a Li-O2 battery. Benefited from the synergistic effect between Co3O4 and rGO, the hybrid exhibits a high initial capacity of 10,528 mAh g?1 along with a high coulombic efficiency (84.4%) at 100 mA g?1. In addition, the batteries show an enhanced cycling stability and after 113 cycles, the cut-off discharge voltage remains above 2.5 V. The outstanding performance is intimately related to the high surface area of rGO, which not only provide carbon skeleton for the uniform distribution of Co3O4 nanosheets but also facilitate the reversible formation and decomposition of insoluble Li2O2. The results of electrochemical tests confirm that the Co3O4/rGO hybrid is a promising candidate for the Li-O2 batteries.  相似文献   

5.
Sodium‐ion batteries (SIBs) are promising energy storage devices, but suffer from poor cycling stability and low rate capability. In this work, carbon doped Mo(Se0.85S0.15)2 (i.e., Mo(Se0.85S0.15)2:C) hierarchical nanotubes have been synthesized for the first time and serve as a robust and high‐performance anode material. The hierarchical nanotubes with diameters of 300 nm and wall thicknesses of 50 nm consist of numerous 2D layered nanosheets, and can act as a robust host for sodiation/desodiation cycling. The Mo(Se0.85S0.15)2:C hierarchical nanotubes deliver a discharge capacity of 360 mAh g−1 at a high current density of 2000 mA g−1 and keep a 81.8% capacity retention compared to that at a current density of 50 mA g−1, showing superior rate capability. Comparing with the second cycle discharge capacities, the nanotube anode can maintain capacities of 102.2%, 101.9%, and 97.8% after 100 cycles at current densities of 200, 500, and 1000 mA g−1, respectively. This work demonstrates the best cycling performance and high‐rate sodium storage capabilities of MoSe2 for SIBs to date. The hollow interior, hierarchical organization, layered structure, and carbon doping are beneficial for fast Na+‐ion and electron kinetics and are responsible for the stable cycling performance and high rate capabilities.  相似文献   

6.
Multivalent transition metal oxides (MOx) containing redox centers which can theoretically accept more than one electron have been suggested as promising anode materials for high‐performance lithium ion batteries (LIBs). The Li‐storage mechanism of these oxides is suggested to involve an unusual conversion reaction leading to the formation of metallic nanograins and Li2O; however, a full‐scale conversion reaction is seldom observed in molybdenum dioxide (MoO2) at room temperature due to slow kinetics. Herein, a full‐scale multi‐electron conversion reaction, leading to a high reversible capacity (974 mA h g?1 charging capacity at 60 mA g?1) in LIBs, is realized in a hybrid consisting of reduced graphene oxide (rGO) sheet‐wrapped MoO2 porous nanobelts (rGO/MoO2 NBs). The rGO wrapping layers stabilize the nanophase transition in MoO2 and alleviate volume swing effects during lithiation/delithiation processes. This enables the hybrid to exhibit great cycle stability (tested to around 1900 cycles) and ultrafast rate capability (tested up to 50 A g?1).  相似文献   

7.
Exploitation of high‐performance anode materials is essential but challenging to the development of sodium‐ion batteries (SIBs). Among all proposed anode materials for SIBs, sulfides have been proved promising candidates due to their unique chemical and physical properties. In this work, a facile solvothermal method to in situ decorate cobalt sulfide (CoS) nanoplates on reduced graphene oxide (rGO) to build CoS@rGO composite is described. When evaluated as anode for SIBs, an impressive high specific capacity (540 mAh g?1 at 1 A g?1), excellent rate capability (636 mAh g?1 at 0.1 A g?1 and 306 mAh g?1 at 10 A g?1), and extraordinarily cycle stability (420 mAh g?1 at 1 A g?1 after 1000 cycles) have been demonstrated by CoS@rGO composite for sodium storage. The synergetic effect between the CoS nanoplates and rGO matrix contributes to the enhanced electrochemical performance of the hybrid composite. The results provide a facile approach to fabricate promising anode materials for high‐performance SIBs.  相似文献   

8.
Research on sodium‐ion batteries (SIBs) has recently been revitalized due to the unique features of much lower costs and comparable energy/power density to lithium‐ion batteries (LIBs), which holds great potential for grid‐level energy storage systems. Transition metal dichalcogenides (TMDCs) are considered as promising anode candidates for SIBs with high theoretical capacity, while their intrinsic low electrical conductivity and large volume expansion upon Na+ intercalation raise the challenging issues of poor cycle stability and inferior rate performance. Herein, the designed formation of hybrid nanoboxes composed of carbon‐protected CoSe2 nanoparticles anchored on nitrogen‐doped carbon hollow skeletons (denoted as CoSe2@C∩NC) via a template‐assisted refluxing process followed by conventional selenization treatment is reported, which exhibits tremendously enhanced electrochemical performance when applied as the anode for SIBs. Specifically, it can deliver a high reversible specific capacity of 324 mAh g?1 at current density of 0.1 A g?1 after 200 cycles and exhibit outstanding high rate cycling stability at the rate of 5 A g?1 over 2000 cycles. This work provides a rational strategy for the design of advanced hybrid nanostructures as anode candidates for SIBs, which could push forward the development of high energy and low cost energy storage devices.  相似文献   

9.
It is of great importance to exploit electrode materials for sodium‐ion batteries (SIBs) with low cost, long life, and high‐rate capability. However, achieving quick charge and high power density is still a major challenge for most SIBs electrodes because of the sluggish sodiation kinetics. Herein, uniform and mesoporous NiS2 nanospheres are synthesized via a facile one‐step polyvinylpyrrolidone assisted method. By controlling the voltage window, the mesoporous NiS2 nanospheres present excellent electrochemical performance in SIBs. It delivers a high reversible specific capacity of 692 mA h g?1. The NiS2 anode also exhibits excellent high‐rate capability (253 mA h g?1 at 5 A g?1) and long‐term cycling performance (319 mA h g?1 capacity remained even after 1000 cycles at 0.5 A g?1). A dominant pseudocapacitance contribution is identified and verified by kinetics analysis. In addition, the amorphization and conversion reactions during the electrochemical process of the mesoporous NiS2 nanospheres is also investigated by in situ X‐ray diffraction. The impressive electrochemical performance reveals that the NiS2 offers great potential toward the development of next generation large scale energy storage.  相似文献   

10.
Rational synthesis of flexible electrodes is crucial to rapid growth of functional materials for energy‐storage systems. Herein, a controllable fabrication is reported for the self‐supported structure of CuCo2O4 nanodots (≈3 nm) delicately inserted into N‐doped carbon nanofibers (named as 3‐CCO@C); this composite is first used as binder‐free anode for sodium‐ion batteries (SIBs). Benefiting from the synergetic effect of ultrasmall CuCo2O4 nanoparticles and a tailored N‐doped carbon matrix, the 3‐CCO@C composite exhibits high cycling stability (capacity of 314 mA h g?1 at 1000 mA g?1 after 1000 cycles) and high rate capability (296 mA h g?1, even at 5000 mA g?1). Significantly, the Na storage mechanism is systematically explored, demonstrating that the irreversible reaction of CuCo2O4, which decomposes to Cu and Co, happens in the first discharge process, and then a reversible reaction between metallic Cu/Co and CuO/Co3O4 occurrs during the following cycles. This result is conducive to a mechanistic study of highly promising bimetallic‐oxide anodes for rechargeable SIBs.  相似文献   

11.
As anodes of Li‐ion batteries, copper oxides (CuO) have a high theoretical specific capacity (674 mA h g?1) but own poor cyclic stability owing to the large volume expansion and low conductivity in charges/discharges. Incorporating reduced graphene oxide (rGO) into CuO anodes with conventional methods fails to build robust interaction between rGO and CuO to efficiently improve the overall anode performance. Here, Cu2O/CuO/reduced graphene oxides (Cu2O/CuO/rGO) with a 3D hierarchical nanostructure are synthesized with a facile, single‐step hydrothermal method. The Cu2O/CuO/rGO anode exhibits remarkable cyclic and high‐rate performances, and particularly the anode with 25 wt% rGO owns the best performance among all samples, delivering a record capacity of 550 mA h g?1 at 0.5 C after 100 cycles. The pronounced performances are attributed to the highly efficient charge transfer in CuO nanosheets encapsulated in rGO network and the mitigated volume expansion of the anode owing to its robust 3D hierarchical nanostructure.  相似文献   

12.
Intimately coupled carbon/transition‐metal‐based hierarchical nanostructures are one of most interesting electrode materials for boosting energy conversion and storage applications owing to the strong synergistic effect between the two components and appealing structural stability. Herein, a universal method is reported for making hierarchical hollow carbon nanospheres (HCSs) with intimately coupled ultrathin carbon nanosheets and Mo‐based nanocrystals. The in situ and confined reaction of the synthetic strategy can not only allow the aggregation of the nanocrystals to be impeded, but also endows extremely intimate coupled interaction between the conductive carbon nanosheets and the nanocrystals MoM (M = P, S, C and O). As a proof of concept, the as‐prepared MoP/C HCSs exhibit extraordinary hydrogen evolution reaction electrocatalytic activity with small overpotential and robust durability in both acidic and alkaline solutions. In addition, the unique sheet‐on‐sheet MoS2/C HCSs as an anode demonstrate high capacity, great rate capabilities, and long‐term cycles for sodium‐ion batteries (SIBs). The capacity can be maintained at 410 mA h g?1 even after 1000 cycles even at a high current density of 4 A g?1, one of the best reported values for MoS2‐based electrode materials for SIBs. The present work highlights the importance of designing and fabricating functional strongly coupled hybrid materials for enhancing energy conversion and storage applications.  相似文献   

13.
Rechargeable magnesium batteries (rMBs) are promising as the most ideal further energy storage systems but lack competent cathode materials due to sluggish redox reaction kinetics. Herein, developed is an anionic Se‐substitution strategy to improve the rate capability and the cycling stability of 2D CuS1?xSex nanosheet cathodes through an efficient microwave‐induced heating method. The optimized CuS1?xSex (X = 0.2) nanosheet cathode can exhibit high reversible capacity of 268.5 mAh g?1 at 20 mA g?1 and good cycling stability (140.4 mAh g?1 at 300 mA g?1 upon 100 cycles). Moreover, the CuS1?xSex (X = 0.2) nanosheet cathode can deliver remarkable rate capability with a reversible capacity of 119.2 mAh g?1 at 500 mA g?1, much higher than the 21.7 mAh g?1 of pristine CuS nanosheets. The superior electrochemical performance can be ascribed to the enhanced reaction kinetics, enriched cation storage active sites, and shortened ion diffusion pathway of the CuS1?xSex nanosheet. Therefore, tuning anionic chemical composition demonstrates an effective strategy to develop novel cathode materials for rMBs.  相似文献   

14.
Potassium‐ion batteries (KIBs) are receiving increasing interest in grid‐scale energy storage owing to the earth abundant and low cost of potassium resources. However, their development still stays at the infancy stage due to the lack of suitable electrode materials with reversible depotassiation/potassiation behavior, resulting in poor rate performance, low capacity, and cycling stability. Herein, the first example of synthesizing single‐crystalline metallic graphene‐like VSe2 nanosheets for greatly boosting the performance of KIBs in term of capacity, rate capability, and cycling stability is reported. Benefiting from the unique 2D nanostructure, high electron/K+‐ion conductivity, and outstanding pseudocapacitance effects, ultrathin VSe2 nanosheets show a very high reversible capacity of 366 mAh g?1 at 100 mA g?1, a high rate capability of 169 mAh g?1 at 2000 mA g?1, and a very low decay of 0.025% per cycle over 500 cycles, which are the best in all the reported anode materials in KIBs. The first‐principles calculations reveal that VSe2 nanosheets have large adsorption energy and low diffusion barriers for the intercalation of K+‐ion. Ex situ X‐ray diffraction analysis indicates that VSe2 nanosheets undertake a reversible phase evolution by initially proceeding with the K+‐ion insertion within VSe2 layers, followed by the conversion reaction mechanism.  相似文献   

15.
Golden bristlegrass‐like unique nanostructures comprising reduced graphene oxide (rGO) matrixed nanofibers entangled with bamboo‐like N‐doped carbon nanotubes (CNTs) containing CoSe2 nanocrystals at each node (denoted as N‐CNT/rGO/CoSe2 NF) are designed as anodes for high‐rate sodium‐ion batteries (SIBs). Bamboo‐like N‐doped CNTs (N‐CNTs) are successfully generated on the rGO matrixed nanofiber surface, between rGO sheets and mesopores, and interconnected chemically with homogeneously distributed rGO sheets. The defects in the N‐CNTs formed by a simple etching process allow the complete phase conversion of Co into CoSe2 through the efficient penetration of H2Se gas inside the CNT walls. The N‐CNTs bridge the vertical defects for electron transfer in the rGO sheet layers and increase the distance between the rGO sheets during cycles. The discharge capacity of N‐CNT/rGO/CoSe2 NF after the 10 000th cycle at an extremely high current density of 10 A g?1 is 264 mA h g?1, and the capacity retention measured at the 100th cycle is 89%. N‐CNT/rGO/CoSe2 NF has final discharge capacities of 395, 363, 328, 304, 283, 263, 246, 223, 197, 171, and 151 mA h g?1 at current densities of 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, and 20 A g?1, respectively.  相似文献   

16.
SnS2 has been widely studied as an anode material for sodium‐ion batteries (SIBs) based on the high theoretical capacity and layered structure. Unfortunately, rapid capacity decay associated with volume variation during cycling limits practical application. Herein, SnS2/Co3S4 hollow nanocubes anchored on S‐doped graphene are synthesized for the first time via coprecipitation and hydrothermal methods. When applied as the anode for SIBs, the sample delivers a distinguished charge specific capacity of 1141.8 mAh g?1 and there is no significant capacity decay (0.1 A g?1 for 50 cycles). When the rate is increased to 0.5 A g?1, it presents 845.7 mAh g?1 after cycling 100 times. Furthermore, the composite also exhibits an ultrafast sodium storage capability where 392.9 mAh g?1 can be obtained at 10 A g?1 and the charging time is less than 3 min. The outstanding electrochemical properties can be ascribed to the enhancement of conductivity for the addition of S‐doped graphene and the existence of p–n junctions in the SnS2/Co3S4 heterostructure. Moreover, the presence of mesopores between nanosheets can alleviate volume expansion during cycling as well as being beneficial for the migration of Na+.  相似文献   

17.
A one‐step multipurpose strategy is developed to realize a sophisticated design that simultaneously integrates three desirable components of nitrogen dopant, 3D graphene, and 1D mesoporous metal oxide nanowires into one hybrid material. This facile synthetic strategy includes a one‐step hydrothermal reaction followed by topotactic calcination. The utilization of urea as the starting reagent enables the precipitation of precursor nanowires and concurrent doping of nitrogen heteroatoms on graphene during hydrothermal reaction, while at the same time the graphene nanosheets are self‐assembled to afford a 3D scaffold. Detailed characterizations on the final calcined product are conducted to confirm the phase purity, porosity, nitrogen composition, and morphology. The integration of two building blocks, i.e., flexible graphene nanosheets and Co3O4 nanowires, enables various intertwining behaviors such as seaming, bridging, hooping, bundling, and sandwiching, of which synergistic effect substantially enhances electrical and electrochemical properties of the resultant hybrid. For lithium ion battery application of the hybrid, a remarkably high capacity more than 1200 mA h g?1 (at 100 mA g?1) is stabilized over 100 cycles with coulombic efficiency higher than 97%. Even during rapid discharge/charge processes (1000 mA g?1), a reversible charge capacity of 812 mA h g?1 is still retained after 230 cycles.  相似文献   

18.
Fe2O3 is regarded as a promising anode material for lithium‐ion batteries (LIBs) and sodium‐ion batteries (SIBs) due to its high specific capacity. The large volume change during discharge and charge processes, however, induces significant cracking of the Fe2O3 anodes, leading to rapid fading of the capacity. Herein, a novel peapod‐like nanostructured material, consisting of Fe2O3 nanoparticles homogeneously encapsulated in the hollow interior of N‐doped porous carbon nanofibers, as a high‐performance anode material is reported. The distinctive structure not only provides enough voids to accommodate the volume expansion of the pea‐like Fe2O3 nanoparticles but also offers a continuous conducting framework for electron transport and accessible nanoporous channels for fast diffusion and transport of Li/Na‐ions. As a consequence, this peapod‐like structure exhibits a stable discharge capacity of 1434 mAh g?1 (at 100 mA g?1) and 806 mAh g?1 (at 200 mA g?1) over 100 cycles as anode materials for LIBs and SIBs, respectively. More importantly, a stable capacity of 958 mAh g?1 after 1000 cycles and 396 mAh g?1 after 1500 cycles can be achieved for LIBs and SIBs, respectively, at a large current density of 2000 mA g?1. This study provides a promising strategy for developing long‐cycle‐life LIBs and SIBs.  相似文献   

19.
Sodium‐ion batteries (SIBs) offer a promise of a scalable, low‐cost, and environmentally benign means of renewable energy storage. However, the low capacity and poor rate capability of anode materials present an unavoidable challenge. In this work, it is demonstrated that surface phosphorylated TiO2 nanotube arrays grown on Ti substrate can be efficient anode materials for SIBs. Fabrication of the phosphorylated nanoarray film is based on the electrochemical anodization of Ti metal in NH4F solution and subsequent phosphorylation using sodium hypophosphite. The phosphorylated TiO2 nanotube arrays afford a reversible capacity of 334 mA h g?1 at 67 mA g?1, a superior rate capability of 147 mA h g?1 at 3350 mA g?1, and a stable cycle performance up to 1000 cycles. In situ X‐ray diffraction and transmission electron microscopy reveal the near‐zero strain response and robust mechanical behavior of the TiO2 host upon (de)sodiation, suggesting its excellent structural stability in the Na+ storage application.  相似文献   

20.
Sodium‐ion batteries (SIBs) have been recognized as the promising alternatives to lithium‐ion batteries for large‐scale applications owing to their abundant sodium resource. Currently, one significant challenge for SIBs is to explore feasible anodes with high specific capacity and reversible pulverization‐free Na+ insertion/extraction. Herein, a facile co‐engineering on polymorph phases and cavity structures is developed based on CoMo‐glycerate by scalable solvothermal sulfidation. The optimized strategy enables the construction of CoMoOxSy with synergized partially sulfidized amorphous phase and yolk–shell confined cavity. When developed as anodes for SIBs, such CoMoOxSy electrodes deliver a high reversible capacity of 479.4 mA h g?1 at 200 mA g?1 after 100 cycles and a high rate capacity of 435.2 mA h g?1 even at 2000 mA g?1, demonstrating superior capacity and rate capability. These are attributed to the unique dual merits of the anodes, that is, the elastic bountiful reaction pathways favored by the sulfidation‐induced amorphous phase and the sodiation/desodiation accommodatable space benefits from the yolk–shell cavity. Such yolk–shell nano‐battery materials are merited with co‐tunable phases and structures, facile scalable fabrication, and excellent capacity and rate capability in sodium storage. This provides an opportunity to develop advanced practical electrochemical sodium storage in the future.  相似文献   

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