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1.
To develop high‐performance anode materials of lithium‐ion batteries (LIBs) instead of commercial graphite for practical applications, herein, a layer of silicon has been well‐anchored onto a 3D graphene/carbon nanotube (CNT) aerogels (CAs) framework with face‐to‐face contact and balanced open void by a simple chemical vapor deposition strategy. The engineered contact interface between CAs and Si creates high‐efficiency channels for the rapid electrons and lithium ions transport, and meanwhile, the balanced open‐void allows the free expansion of Si during cycling while maintaining high structural integrity due to the robust mechanical strength of 3D CAs framework. As a consequence, the as‐synthesized Si/CAs nanohybrids are highly stable anode materials for LIBs with a high reversible discharge capacity (1498 mAh g?1 at 200 mA g?1) and excellent rate capability (462 mAh g?1 at 10 000 mA g?1), which is much better than Si/graphene‐CNTs‐mixture (51 mAh g?1 at 10 000 mA g?1). More significantly, it is found that the Si/CAs nanohybrids display no obvious capacity decline even after 2000 cycles at a high current density of 10 000 mA g?1. The present Si/CAs nanohybrids are one of the most stable Si‐based anode materials ever reported for LIBs to date.  相似文献   

2.
Metal oxide‐based nanomaterials are widely studied because of their high‐energy densities as anode materials in lithium‐ion batteries. However, the fast capacity degradation resulting from the large volume expansion upon lithiation hinders their practical application. In this work, the preparation of walnut‐like multicore–shell MnO encapsulated nitrogen‐rich carbon nanocapsules (MnO@NC) is reported via a facile and eco‐friendly process for long‐cycling Li‐ion batteries. In this hybrid structure, MnO nanoparticles are uniformly dispersed inside carbon nanoshells, which can simultaneously act as a conductive framework and also a protective buffer layer to restrain the volume variation. The MnO@NC nanocapsules show remarkable electrochemical performances for lithium‐ion batteries, exhibiting high reversible capability (762 mAh g?1 at 100 mA g?1) and stable cycling life (624 mAh g?1 after 1000 cycles at 1000 mA g?1). In addition, the soft‐packed full batteries based on MnO@NC nanocapsules anodes and commercial LiFePO4 cathodes present good flexibility and cycling stability.  相似文献   

3.
High‐capacity lithium‐ion battery anode materials, such as transition metal oxides, Sn and Si, suffer from large volume expansion during lithiation, which causes capacity decay. Introducing sufficient void space to accommodate the volume change is essential to achieve prolonged cycling stability. However, excessive void space may significantly compromise the volumetric energy density. Herein, a method to control the void size in iron oxide@carbon (FeOx@C) yolk–shell structures is developed and the relationship between the void space and electrochemical performance is demonstrated. With an optimized void size, the FeOx@C yolk–shell structure exhibits the best cycling performance. A high reversible capacity of ≈810 mA h g?1 is obtained at 0.2 C, maintaining 790 mA h g?1 after 100 cycles. This contrasts with FeOx@C materials having either smaller or larger void sizes, in which significant capacity fading is observed during cycling. This contribution provides an effective approach to alleviate the volume expansion problem, which can be generally applied to other anode materials to improve their performance in LIBs.  相似文献   

4.
Lithium ion battery is the predominant power source for portable electronic devices, electrical vehicles, and back‐up electricity storage units for clean and renewable energies. High‐capacity and long‐life electrode materials are essential for the next‐generation Li‐ion battery with high energy density. Here bimetal‐organic‐frameworks synthesis of Co0.4Zn0.19S@N and S codoped carbon dodecahedron is shown with rooted carbon nanotubes (Co‐Zn‐S@N‐S‐C‐CNT) for high‐performance Li‐ion battery application. Benefiting from the synergetic effect of two metal sulfide species for Li‐storage at different voltages, mesoporous dodecahedron structure, N and S codoped carbon overlayer and deep‐rooted CNTs network, the product exhibits a larger‐than‐theoretical reversible Li‐storage capacity of 941 mAh g?1 after 250 cycles at 100 mA g?1 and excellent high‐rate capability (734, 591, 505 mAh g?1 after 500 cycles at large current densities of 1, 2, and 5 A g?1 , respectively).  相似文献   

5.
Sponge‐like composites assembled by cobalt sulfides quantum dots (Co9S8 QD), mesoporous hollow carbon polyhedral (HCP) matrix, and a reduced graphene oxide (rGO) wrapping sheets are synthesized by a simultaneous thermal reduction, carbonization, and sulfidation of zeolitic imidazolate frameworks@GO precursors. Specifically, Co9S8 QD with size less than 4 nm are homogenously embedded within HCP matrix, which is encapsulated in macroporous rGO, thereby leading to the double carbon‐confined hierarchical composites with strong coupling effect. Experimental data combined with density functional theory calculations reveal that the presence of coupled rGO not only prevents the aggregation and excessive growth of particles, but also expands the lattice parameters of Co9S8 crystals, enhancing the reactivity for sodium storage. Benefiting from the hierarchical porosity, conductive network, structural integrity, and a synergistic effect of the components, the sponge‐like composites used as binder‐free anodes manifest outstanding sodium‐storage performance in terms of excellent stable capacity (628 mAh g?1 after 500 cycles at 300 mA g?1) and exceptional rate capability (529, 448, and 330 mAh g?1 at 1600, 3200, and 6400 mA g?1). More importantly, the synthetic method is very versatile and can be easily extended to fabricate other transition‐metal‐sulfides‐based sponge‐like composites with excellent electrochemical performances.  相似文献   

6.
As an anode material for lithium‐ion batteries, titanium dioxide (TiO2) shows good gravimetric performance (336 mAh g?1 for LiTiO2) and excellent cyclability. To address the poor rate behavior, slow lithium‐ion (Li+) diffusion, and high irreversible capacity decay, TiO2 nanomaterials with tuned phase compositions and morphologies are being investigated. Here, a promising material is prepared that comprises a mesoporous “yolk–shell” spherical morphology in which the core is anatase TiO2 and the shell is TiO2(B). The preparation employs a NaCl‐assisted solvothermal process and the electrochemical results indicate that the mesoporous yolk–shell microspheres have high specific reversible capacity at moderate current (330.0 mAh g?1 at C/5), excellent rate performance (181.8 mAh g?1 at 40C), and impressive cyclability (98% capacity retention after 500 cycles). The superior properties are attributed to the TiO2(B) nanosheet shell, which provides additional active area to stabilize the pseudocapacity. In addition, the open mesoporous morphology improves diffusion of electrolyte throughout the electrode, thereby contributing directly to greatly improved rate capacity.  相似文献   

7.
Nitrogen‐rich porous carbons (NPCs) are the leading cathode materials for next‐generation Zn–air and Li–S batteries. However, most existing NPC suffers from insufficient exposure and harnessing of nitrogen‐dopants (NDs), constraining the electrochemical performance. Herein, by combining silica templating with in situ texturing of metal–organic frameworks, a new bifunctional 3D nitrogen‐rich carbon photonic crystal architecture of simultaneously record‐high total pore volume (13.42 cm3 g?1), ultralarge surface area (2546 m2 g?1), and permeable hierarchical macro‐meso‐microporosity is designed, enabling sufficient exposure and accessibility of NDs. Thus, when used as cathode catalysts, the Zn–air battery delivers a fantastic capacity of 770 mAh gZn?1 at an unprecedentedly high rate of 120 mA cm?2, with an ultrahigh power density of 197 mW cm?2. When hosting 78 wt% sulfur, the Li–S battery affords a high‐rate capacity of 967 mAh g?1 at 2 C, with superb stability over 1000 cycles at 0.5 C (0.054% decay rate per cycle), comparable to the best literature value. The results prove the dominant role of highly exposed graphitic‐N in boosting both cathode performances.  相似文献   

8.
Sodium‐ion batteries (SIBs) are considered as a promising alternative to lithium‐ion batteries, due to the abundant reserves and low price of Na sources. To date, the development of anode materials for SIBs is still confronted with many serious problems. In this work, encapsulation‐type structured MoSe2@hollow carbon nanosphere (HCNS) materials assembled with expanded (002) planes few‐layer MoSe2 nanosheets confined in HCNS are successfully synthesized through a facile strategy. Notably, the interlayer spacing of the (002) planes is expanded to 1.02 nm, which is larger than the intrinsic value of pristine MoSe2 (0.64 nm). Furthermore, the few‐layer nanosheets are space‐confined in the inner cavity of the HCNS, forming hybrid MoSe2@HCNS structures. When evaluated as anode materials for SIBs, it shows excellent rate capabilities, ultralong cycling life with exceptional Coulombic efficiency even at high current density, maintaining 501 and 471 mA h g?1 over 1000 cycles at 1 and 3 A g?1, respectively. Even when cycled at current densities as high as 10 A g?1, a capacity retention of 382 mA h g?1 can be achieved. The expanded (002) planes, 2D few‐layer nanosheets, and unique carbon shell structure are responsible for the ultralong cycling and high rate performance.  相似文献   

9.
Bismuth (Bi) is an attractive material as anodes for both sodium‐ion batteries (NIBs) and potassium‐ion batteries (KIBs), because it has a high theoretical gravimetric capacity (386 mAh g?1) and high volumetric capacity (3800 mAh L?1). The main challenges associated with Bi anodes are structural degradation and instability of the solid electrolyte interphase (SEI) resulting from the huge volume change during charge/discharge. Here, a multicore–shell structured Bi@N‐doped carbon (Bi@N‐C) anode is designed that addresses these issues. The nanosized Bi spheres are encapsulated by a conductive porous N‐doped carbon shell that not only prevents the volume expansion during charge/discharge but also constructs a stable SEI during cycling. The Bi@N‐C exhibits unprecedented rate capability and long cycle life for both NIBs (235 mAh g?1 after 2000 cycles at 10 A g?1) and KIBs (152 mAh g?1 at 100 A g?1). The kinetic analysis reveals the outstanding electrochemical performance can be attributed to significant pseudocapacitance behavior upon cycling.  相似文献   

10.
Graphdiyne (GDY), an emerging type of carbon allotropes, possesses fascinating electrical, chemical, and mechanical properties to readily spark energy applications in the realm of Li‐ion and Na‐ion batteries. Nevertheless, rational design of GDY architectures targeting advanced K‐ion storage has rarely been reported to date. Herein, the first example of synthesizing GDY frameworks in a scalable fashion to realize superb potassium storage for high‐performance K‐ion battery (KIB) anodes is showcased. To begin with, first principles calculations provide theoretical guidances for analyzing the intrinsic potassium storage capability of GDY. Meanwhile, the specific capacity is predicted to be as high as 620 mAh g?1, which is considerably augmented as compared with graphite (278 mAh g?1). Experimental tests then reveal that prepared GDY framework indeed harvests excellent electrochemical performance as a KIB anode, achieving high specific capacity (≈505 mAh g?1 at 50 mA g?1), outstanding rate performance (150 mAh g?1 at 5000 mA g?1) and favorable cycling stability (a high capacity retention of over 90% after 2000 cycles at 1000 mA g?1). Furthermore, kinetic analysis reveals that capacitive effect mainly accounts for the K‐ion storage, with operando Raman spectroscopy/ex situ X‐ray photoelectron spectroscopy identifying good electrochemical reversibility of GDY.  相似文献   

11.
Hollow structures are often used to relieve the intrinsic strain on metal oxide electrodes in alkali‐ion batteries. Nevertheless, one common drawback is that the large interior space leads to low volumetric energy density and inferior electric conductivity. Here, the von Mises stress distribution on a mesoporous hollow bowl (HB) is simulated via the finite element method, and the vital role of the porous HB structure on strain‐relaxation behavior is confirmed. Then, N‐doped‐C coated mesoporous α‐Fe2O3 HBs are designed and synthesized using a multistep soft/hard‐templating strategy. The material has several advantages: (i) there is space to accommodate strains without sacrificing volumetric energy density, unlike with hollow spheres; (ii) the mesoporous hollow structure shortens ion diffusion lengths and allows for high‐rate induced lithiation reactivation; and (iii) the N‐doped carbon nanolayer can enhance conductivity. As an anode in lithium‐ion batteries, the material exhibits a very high reversible capacity of 1452 mAh g?1 at 0.1 A g?1, excellent cycling stability of 1600 cycles (964 mAh g?1 at 2 A g?1), and outstanding rate performance (609 mAh g?1 at 8 A g?1). Notably, the volumetric specific capacity of composite electrode is 42% greater than that of hollow spheres. When used in potassium‐ion batteries, the material also shows high capacity and cycle stability.  相似文献   

12.
Nanowire aerogels (NWAs) are highly versatile and used in many applications. However, most synthesized NWAs are composed of single components that may produce unsatisfactory aggregated performance in mechanical strength, conductivity, and electrochemistry. To address this issue, a reticulate dual‐nanowire aerogel (rDNWA) composed of FeS2 nanowires and carbon nanotubes (CNTs) via a simple solvothermal method is synthesized. The rDNWA possesses excellent compressibility (modulus of 1.32 MPa), good conductivity (0.65 S cm?1), and high porosity (>98%). It can be applied as a high‐performance strain sensor with good sensitivity (Gauge Factor = 1.69) and enhanced stability. It can be densified to yield a high areal capacity of 10.0 mAh cm?2 and a high mass loading of 14.4 mg cm?2 after 100 cycles. As a freestanding anode for lithium ion battery (LIB), it exhibits a high specific mass capacity of 1031 mAh g?1 after 100 cycles at a current density of 100 mA g?1 and retains it to 729 mAh g?1 at a current density of 500 mA g?1 after 400 cycles. The outstanding overall performance of the hybrid aerogel is derived from the synergistic effect of intertwined CNTs and FeS2 nanowires and can be extended to fabricate NWAs with novel multifunctional capabilities.  相似文献   

13.
All‐solid‐state lithium metal batteries (ASSLMBs) have attracted significant attention due to their superior safety and high energy density. However, little success has been made in adopting Li metal anodes in sulfide electrolyte (SE)‐based ASSLMBs. The main challenges are the remarkable interfacial reactions and Li dendrite formation between Li metal and SEs. In this work, a solid‐state plastic crystal electrolyte (PCE) is engineered as an interlayer in SE‐based ASSLMBs. It is demonstrated that the PCE interlayer can prevent the interfacial reactions and lithium dendrite formation between SEs and Li metal. As a result, ASSLMBs with LiFePO4 exhibit a high initial capacity of 148 mAh g?1 at 0.1 C and 131 mAh g?1 at 0.5 C (1 C = 170 mA g?1), which remains at 122 mAh g?1 after 120 cycles at 0.5 C. All‐solid‐state Li‐S batteries based on the polyacrylonitrile‐sulfur composite are also demonstrated, showing an initial capacity of 1682 mAh g?1. The second discharge capacity of 890 mAh g?1 keeps at 775 mAh g?1 after 100 cycles. This work provides a new avenue to address the interfacial challenges between Li metal and SEs, enabling the successful adoption of Li metal in SE‐based ASSLMBs with high energy density.  相似文献   

14.
Potassium‐ion batteries have been regarded as the potential alternatives to lithium‐ion batteries (LIBs) due to the low cost, earth abundance, and low potential of K (?2.936 vs standard hydrogen electrode (SHE)). However, the lack of low‐cost cathodes with high energy density and long cycle life always limits its application. In this work, high‐energy layered P2‐type hierarchical K0.65Fe0.5Mn0.5O2 (P2‐KFMO) microspheres, assembled by the primary nanoparticles, are fabricated via a modified solvent‐thermal method. Benefiting from the unique microspheres with primary nanoparticles, the K+ intercalation/deintercalation kinetics of P2‐KFMO is greatly enhanced with a stabilized cathodic electrolyte interphase on the cathode. The P2‐KFMO microsphere presents a highly reversible potassium storage capacity of 151 mAh g?1 at 20 mA g?1, fast rate capability of 103 mAh g?1 at 100 mA g?1, and long cycling stability with 78% capacity retention after 350 cycles. A full cell with P2‐KFMO microspheres as cathode and hard carbon as anode is constructed, which exhibits long‐term cycling stability (>80% of retention after 100 cycles). The present high‐performance P2‐KFMO microsphere cathode synthesized using earth‐abundant elements provides a new cost‐effective alternative to LIBs for large‐scale energy storage.  相似文献   

15.
Na‐ion Batteries have been considered as promising alternatives to Li‐ion batteries due to the natural abundance of sodium resources. Searching for high‐performance anode materials currently becomes a hot topic and also a great challenge for developing Na‐ion batteries. In this work, a novel hybrid anode is synthesized consisting of ultrafine, few‐layered SnS2 anchored on few‐layered reduced graphene oxide (rGO) by a facile solvothermal route. The SnS2/rGO hybrid exhibits a high capacity, ultralong cycle life, and superior rate capability. The hybrid can deliver a high charge capacity of 649 mAh g?1 at 100 mA g?1. At 800 mA g?1 (1.8 C), it can yield an initial charge capacity of 469 mAh g?1, which can be maintained at 89% and 61%, respectively, after 400 and 1000 cycles. The hybrid can also sustain a current density up to 12.8 A g?1 (≈28 C) where the charge process can be completed in only 1.3 min while still delivering a charge capacity of 337 mAh g?1. The fast and stable Na‐storage ability of SnS2/rGO makes it a promising anode for Na‐ion batteries.  相似文献   

16.
A yolk–shell Sn@C nanobox composite with controllable structures has been synthesized using a facile approach. The void space is engineered to fit the volume expansion of Sn during cycling. It is demonstrated that the shell thickness of carbon nanobox has substantial influence on both nanostructures and the electrochemical performance. With an optimized shell thickness, a high reversible capacity of 810 mA h g?1 can be maintained after 500 cycles, corresponding to 90% retention of the second discharge capacity. For Sn@C materials with either thinner or thicker carbon shells, significant capacity decay or a decreased specific capacity are observed during cycling. The present study sheds light on the rational design of nanostructured electrode materials with enhanced electrochemical performance for next‐generation lithium ion batteries.  相似文献   

17.
Despite their high theoretical specific capacity (1675 mA h g?1), the practical application of Li–S batteries remains limited because the capacity rapidly degrades through severe dissolution of lithium polysulfide and the rate capability is low because of the low electronic conductivity of sulfur. This paper describes novel hierarchical yolk–shell microspheres comprising 1D bamboo‐like N‐doped carbon nanotubes (CNTs) encapsulating Co nanoparticles (Co@BNCNTs YS microspheres) as efficient cathode hosts for Li–S batteries. The microspheres are produced via a two‐step process that involves generation of the microsphere followed by N‐doped CNTs growth. The hierarchical yolk–shell structure enables efficient sulfur loading and mitigates the dissolution of lithium polysulfides, and metallic Co and N doping improves the chemical affinity of the microspheres with sulfur species. Accordingly, a Co@BNCNTs YS microsphere‐based cathode containing 64 wt% sulfur exhibits a high discharge capacity of 700.2 mA h g?1 after 400 cycles at a current density of 1 C (based on the mass of sulfur); this corresponds to a good capacity retention of 76% and capacity fading rate of 0.06% per cycle with an excellent rate performance (752 mA h g?1 at 2.0 C) when applied as cathode hosts for Li–S batteries.  相似文献   

18.
Silicon nanoparticles (Si NPs) have been considered as promising anode materials for next‐generation lithium‐ion batteries, but the practical issues such as mechanical structure instability and low volumetric energy density limit their development. At present, the functional energy‐storing architectures based on Si NPs building blocks have been proposed to solve the adverse effects of nanostructures, but designing ideal functional architectures with excellent electrochemical performance is still a significant challenge. This study shows that the effective stress evolution management is applied for self‐assembled functional architectures via cross‐scale simulation and the simulated stress evolution can be a guide to design a scalable self‐assembled hierarchical Si@TiO2@C (SA‐SiTC) based on core–shell Si@TiO2 nanoscale building blocks. It is found that the carbon filler and TiO2 layer can effectively reduce the risk of cracking during (de)lithiation, ensuring the stability of the mechanical structure of SA‐SiTC. The SA‐SiTC electrode shows long cycling stability (842.6 mAh g?1 after 1000 cycles at 2 A g?1), high volumetric capacity (174 mAh cm?3), high initial Coulombic efficiency (80.9%), and stable solid‐electrolyte interphase (SEI) layer. This work provides insight into the development of the structural stable Si‐based anodes with long cycle life and high volumetric energy density for practical energy applications.  相似文献   

19.
Lithium‐oxygen (Li‐O2) batteries are one of the most promising candidates for high‐energy‐density storage systems. However, the low utilization of porous carbon and the inefficient transport of reactants in the cathode limit terribly the practical capacity and, in particular, the rate capability of state‐of‐the‐art Li‐O2 batteries. Here, free‐standing, hierarchically porous carbon (FHPC) derived from graphene oxide (GO) gel in nickel foam without any additional binder is synthesized by a facile and effective in situ sol‐gel method, wherein the GO not only acts as a special carbon source, but also provides the framework of a 3D gel; more importantly, the proper acidity via its intrinsic COOH groups guarantees the formation of the whole structure. Interestingly, when employed as a cathode for Li‐O2 batteries, the capacity reaches 11 060 mA h g?1 at a current density of 0.2 mA cm?2 (280 mA g?1); and, unexpectedly, a high capacity of 2020 mA h g?1 can be obtained even the current density increases ten times, up to 2 mA cm?2 (2.8 A g?1), which is the best rate performance for Li‐O2 batteries reported to date. This excellent performance is attributed to the synergistic effect of the loose packing of the carbon, the hierarchical porous structure, and the high electronic conductivity of the Ni foam.  相似文献   

20.
A covalently tethered polyoxometalate (POM)–pyrene hybrid (Py–SiW11) is utilized for the noncovalent functionalization of single‐walled carbon nanotubes (SWNTs). The resulting SWNTs/Py–SiW11 nanocomposite shows that both SiW11 and pyrene moieties could interact with SWNTs without causing any chemical decomposition. When used as anode material in lithium‐ion batteries, the SWNTs/Py–SiW11 nanocomposite exhibits higher discharge capacities, and better rate capacity and cycling stability than the individual components. When the current density is 0.5 mA cm?2, the nanocomposite exhibits the initial discharge capacity of 1569.8 mAh g?1, and a high discharge capacity of 580 mAh g?1 for up to 100 cycles.  相似文献   

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