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1.
ACS Appl Mater Interfaces ; 12(2): 2390-2399, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31846287

RESUMO

Sodium/Potassium-ion batteries (SIBs/PIBs) have recently received tremendous attention because of their particular features of cost-effectiveness and promising energy density, which hold great potential for large-scale applications. Nevertheless, it still has a common bottleneck issue that is the sluggish kinetics of Na+/K+ intercalation, which raises more rigorous requirement on the electrode candidates regarding the morphology, dimension, and architecture. Herein, we have constructed unique MoSe2-based hybrid nanotubes with wall structures composed of highly disordered MoSe2 layers embedded in phosphorus and nitrogen co-doped carbon matrix (denoted MoSe2⊂PNC-HNTs), by a facile two-step strategy using Se nanorods as the dual-functional template, i.e., shape-directed agent and in situ selenization resources. Benefitting from the combined features of the one-dimensional (1D) hollow interior, hybrid wall structure with high disorder, and the phosphorus and nitrogen co-doping-induced abundant defect sites in the carbon matrix, the MoSe2⊂PNC-HNT anode exhibits high specific capacities of 280 and 262 mA h g-1 over 200 cycles at the current density of 0.1 A g-1 for Na+ and K+ storage, respectively, and achieves remarkable capacity retention rates of 87.0% at 2 A g-1 over 3500 cycles for Na-ion storage and 80.1% at 1 A g-1 after 500 cycles for K-ion storage.

2.
Angew Chem Int Ed Engl ; 59(9): 3505-3510, 2020 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-31880025

RESUMO

Lithium metal is an ideal electrode material for future rechargeable lithium metal batteries. However, the widespread deployment of metallic lithium anode is significantly hindered by its dendritic growth and low Coulombic efficiency, especially in ester solvents. Herein, by rationally manipulating the electrolyte solvation structure with a high donor number solvent, enhancement of the solubility of lithium nitrate in an ester-based electrolyte is successfully demonstrated, which enables high-voltage lithium metal batteries. Remarkably, the electrolyte with a high concentration of LiNO3 additive presents an excellent Coulombic efficiency up to 98.8 % during stable galvanostatic lithium plating/stripping cycles. A full-cell lithium metal battery with a lithium nickel manganese cobalt oxide cathode exhibits a stable cycling performance showing limited capacity decay. This approach provides an effective electrolyte manipulation strategy to develop high-voltage lithium metal batteries.

3.
Chem Commun (Camb) ; 55(95): 14375-14378, 2019 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-31720603

RESUMO

It is significantly challenging to stabilize sodium metal anodes in carbonate electrolytes. Here, we report that a sodium metal anode can achieve a high coulombic efficiency of up to ∼97% over 400 cycles at 0.1 mA cm-2 in a carbonate electrolyte with NaAsF6 as an additive. It is revealed that the SEI layer contains a large amount of NaF and O-As-O polymer which enables the stable cycling of sodium metal anodes.

4.
Chem Commun (Camb) ; 55(87): 13176-13178, 2019 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-31620730

RESUMO

Atom diffusion processes govern the structure and composition of core-shell nanomaterial, which play a crucial role in determining their properties. By using aberration-corrected high-resolution transmission electron microscopy and X-ray absorption near-edge structure spectroscopy in combination with in situ X-ray diffraction, we confirm that single-atom diffusion of Au to Ag2S occurs, and that the transition from the Au@Ag2S core-shell nanostructure to AuAgS-AuAgx or Ag3AuS2-AuAgx heterostructures was observed. Moreover, the phase of the ternary sulfide induced by Au single-atom diffusion in Ag2S is determined by the ratio of Au and Ag, thus exhibiting a significant difference in the photocatalytic activity performance.

5.
Small ; 15(42): e1902881, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31433124

RESUMO

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.

6.
Chemistry ; 25(57): 13094-13098, 2019 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-31298763

RESUMO

Sodium-ion batteries have attracted tremendous attention due to their much lower cost and similar working principle compared with lithium-ion batteries, which have been invited great expectation as energy storage devices in grid-level applications. The sodium superionic conductor Na3 V2 (PO4 )3 has been considered as a promising cathode candidate; however, its intrinsic low electronic conductivity results in poor rate performance and unsatisfactory cycling performance, which severely impedes its potential for practical applications. Herein, we developed a facile one-pot strategy to construct dual carbon-protected hybrid structure composed of carbon coated Na3 V2 (PO4 )3 nanoparticles embedded with carbon matrix with excellent rate performance, superior cycling stability and ultralong lifespan. Specifically, it can deliver an outstanding rate performance with a 51.5 % capacity retention from 0.5 to 100 C and extraordinary cycling stability of 80.86 % capacity retention after 6000 cycles at the high rate of 20 C. The possible reasons for the enhanced performance could be understood as the synergistic effects of the strengthened robust structure, facilitated charge transfer kinetics, and the mesoporous nature of the Na3 V2 (PO4 )3 hybrid structure. This work provides a cost-effective strategy to effectively optimize the electrochemical performance of a Na3 V2 (PO4 )3 cathode, which could contribute to push forward the advance of its practical applications.

7.
Adv Mater ; 31(23): e1901139, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30972836

RESUMO

Metal-organic frameworks (MOFs) have attracted tremendous interest due to their promising applications including electrocatalysis originating from their unique structural features. However, it remains a challenge to directly use MOFs for oxygen electrocatalysis because it is quite difficult to manipulate their dimension, composition, and morphology of the MOFs with abundant active sites. Here, a facile ambient temperature synthesis of unique NiCoFe-based trimetallic MOF nanostructures with foam-like architecture is reported, which exhibit extraordinary oxygen evolution reaction (OER) activity as directly used catalyst in alkaline condition. Specifically, the (Ni2 Co1 )0.925 Fe0.075 -MOF-NF delivers a minimum overpotential of 257 mV to reach the current density of 10 mA cm-2 with a small Tafel slope of 41.3 mV dec-1 and exhibits high durability after long-term testing. More importantly, the deciphering of the possible origination of the high activity is performed through the characterization of the intermediates during the OER process, where the electrochemically transformed metal hydroxides and oxyhydroxides are confirmed as the active species.

8.
ACS Appl Mater Interfaces ; 10(24): 20635-20642, 2018 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-29799182

RESUMO

Transition-metal diselenides have been extensively studied as desirable anode candidates for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) because of their high theoretical capacities. However, it is of great challenge to achieve satisfactory cycling performance, especially for larger sodium ion storage, originated from electrode deterioration upon large volume change. Herein, we reported the construction of hierarchical tubular hybrid nanostructures through encapsulating CoSe2 nanoparticles into MoSe2/C composite shells via a simple two-step strategy including a hydrothermal method followed by vapor-phase selenization process. The unique tubular structure enables the highly reversible Li/Na storage with high specific capacity, enhanced cycling stability, and superior rate performance. It is indicated that the contribution of partial pseudocapacitive behavior greatly improves the rate capability for SIBs, where a high capacity retention of 81.5% can be obtained when the current densities range from 0.1 to 3 A g-1 (460 mA h g-1 at 0.1 A g-1 vs 379 mA h g-1 at 3 A g-1). This work provides an effective design rationale on transition-metal diselenide-based tubular nanostructures as superior hosts for both Li and Na ions, which could push forward the development of practical applications of transition-metal diselenide-based anodes in LIBs and SIBs.

9.
Chemistry ; 24(6): 1253-1258, 2018 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-29205591

RESUMO

Sodium-ion batteries (SIBs) have been considered as promising energy storage devices in grid-level applications, owing to their largely reduced cost compared with that of lithium-ion batteries. However, the practical application of SIBs has been seriously hindered because of the lack of appropriate anode materials, limited by the thermodynamics perspective, which is one of the central task at current stage. Herein, we have developed a general one-pot strategy for the synthesis of transition-metal phosphide (TMP) based hybrid nanosheets composed of carbon-coated TMP nanoparticles anchored to the surface of nitrogen-doped carbon nanosheets. This facile and cost-effective method is quite universal and holds potential to be further extended to other metal phosphide materials. Significantly, the hybrid nanosheet electrode possesses excellent sodium storage properties as anodes for SIBs, including high specific capacity, an ultra-long cycle life and a remarkable rate performance. This work makes a significant contribution to not only the synthetic methodology of TMP-carbon two-dimensional hybrid nanostructures, but also the application of TMP-based anodes for high-energy SIBs.

10.
Sci Rep ; 5: 16052, 2015 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-26527570

RESUMO

We demonstrate that laser peening coupled with sintering of CdTe nanowire films substantially enhances film quality and charge transfer while largely maintaining basic particle morphology. During the laser peening phase, a shockwave is used to compress the film. Laser sintering comprises the second step, where a nanosecond pulse laser beam welds the nanowires. Microstructure, morphology, material content, and electrical conductivities of the films are characterized before and after treatment. The morphology results show that laser peening can decrease porosity and bring nanowires into contact, and pulsed laser heating fuses those contacts. Multiphysics simulations coupling electromagnetic and heat transfer modules demonstrate that during pulsed laser heating, local EM field enhancement is generated specifically around the contact areas between two semiconductor nanowires, indicating localized heating. The characterization results indicate that solely laser peening or sintering can only moderately improve the thin film quality; however, when coupled together as laser peen sintering (LPS), the electrical conductivity enhancement is dramatic. LPS can decrease resistivity up to a factor of ~10,000, resulting in values on the order of ~10(5) Ω-cm in some cases, which is comparable to CdTe thin films. Our work demonstrates that LPS is an effective processing method to obtain high-quality semiconductor nanocrystal films.

11.
Angew Chem Int Ed Engl ; 53(46): 12590-3, 2014 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-25124735

RESUMO

While the synthesis of TiO2 hollow structures is well-established, in most cases it is particularly difficult to control the crystallization of TiO2 in solution or by calcination. As a result, TiO2 hollow structures do not really exhibit enhanced lithium storage properties. Herein, we report a simple and cost-effective template-assisted method to synthesize anatase TiO2 hollow spheres composed of highly crystalline nanocrystals, in which carbonaceous (C) spheres are chosen as the removable template. The release of gaseous species from the combustion of C spheres may inhibit the growth of TiO2 crystallites so that instead small TiO2 nanocrystals are generated. The small size and high crystallinity of primary TiO2 nanoparticles and the high structural integrity of the hollow spheres gives rise to significant improvements in the cycling stability and rate performance of the TiO2 hollow spheres.


Assuntos
Lítio/química , Nanopartículas/química , Titânio/química , Cristalização , Fontes de Energia Elétrica , Nanopartículas/ultraestrutura , Nanotecnologia
12.
Angew Chem Int Ed Engl ; 53(34): 9041-4, 2014 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-24962932

RESUMO

Complex hollow structures of transition metal oxides, especially mixed metal oxides, could be promising for different applications such as lithium ion batteries. However, it remains a great challenge to fabricate well-defined hollow spheres with multiple shells for mixed transition metal oxides. Herein, we have developed a new "penetration-solidification-annealing" strategy which can realize the synthesis of various mixed metal oxide multi-shelled hollow spheres. Importantly, it is found that multi-shelled hollow spheres possess impressive lithium storage properties with both high specific capacity and excellent cycling stability. Specifically, the carbon-coated CoMn2O4 triple-shelled hollow spheres exhibit a specific capacity of 726.7 mA h g(-1) and a nearly 100 % capacity retention after 200 cycles. The present general strategy could represent a milestone in design and synthesis of mixed metal oxide complex hollow spheres and their promising uses in different areas.


Assuntos
Lítio/química , Metais/química , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Óxidos/química
13.
Nano Lett ; 14(6): 3466-73, 2014 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-24798806

RESUMO

Solution-synthesized thermoelectric nanostructured materials have the potential to have lower cost and higher performance than materials synthesized by solid-state methods. Herein we present the synthesis of ultrathin PbTe nanowires, which are compressed by spark plasma sintering at various temperatures in the range of 405-500 °C. The resulting discs possess grains with sizes of 5-30 µm as well as grains with sizes on the order of the original 12 nm diameter PbTe nanowires. This micro- and nanostructure leads to a significantly reduced thermal conductivity compared to bulk PbTe. Careful electron transport analysis shows suppressed electrical conductivity due to increased short-range and ionized defect scatterings, while the Seebeck coefficient remains comparable to the bulk value. The PbTe nanowire samples are found unintentionally p-type doped to hole concentrations of 2.16-2.59 × 10(18) cm(-3). The maximum figure of merit achieved in the unintentionally doped spark plasma sintered PbTe nanowires is 0.33 at 350 K, which is among the highest reported for unintentionally doped PbTe at low temperatures.

14.
Adv Mater ; 26(15): 2408-12, 2014 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-24338831

RESUMO

Strongly coupled NiCo2 O4 -rGO hybrid nanosheets are syntheiszed through a cost-effective two-step strategy involving a facile polyol process and subsequent thermal annealing treatment in air. The hybrid nanosheets exhibit impressive electrocatalytic performance for the oxygen reduction reaction (ORR) with a current density and onset potential comparable to those of commercial Pt/C catalyts, while having perfect tolerance to methanol..

16.
Adv Mater ; 25(18): 2589-93, 2013 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-23553828

RESUMO

Hierarchical tubular structures constructed by ultrathin carbon-coated SnO(2) nanoplates are rationally designed and synthesized. This interesting structure simultaneously integrates the structural and compositional design rationales for high-energy anode materials based on low-dimensional ultrathin nanoplates, a hollow tubular structure, and a carbon nanocoating. When evaluated as an anode material for lithium-ion batteries, the as-synthesized SnO(2)-carbon hybrid structure manifests high specific capacity and excellent cycling stability.

17.
Sci Rep ; 3: 1470, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23503561

RESUMO

Two one-dimensional hierarchical hybrid nanostructures composed of NiCo2O4 nanorods and ultrathin nanosheets on carbon nanofibers (CNFs) are controllably synthesized through facile solution methods combined with a simple thermal treatment. The structure of NiCo2O4 can be easily controlled to be nanorods or nanosheets by using different additives in the synthesis. These two different nanostructures are evaluated as electrodes for high performance supercapacitors, in view of their apparent advantages, such as high electroactive surface area, ultrathin and porous features, robust mechanical strength, shorter ion and electron transport path. Their electrochemical performance is systematically studied, and both of these two hierarchical hybrid nanostructures exhibit high capacitance and excellent cycling stability. The remarkable electrochemical performance will undoubtedly make these hybrid structures attractive for high-performance supercapacitors with high power and energy densities.

18.
Chem Commun (Camb) ; 49(2): 137-9, 2013 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-23169236

RESUMO

An advanced integrated electrode for high-performance supercapacitors has been designed by growing hierarchical NiCo(2)O(4)@MnO(2) core-shell heterostructured nanowire arrays on nickel foam. Such unique array nanoarchitectures exhibit remarkable electrochemical performance with high capacitance and desirable cycle life at high rates.


Assuntos
Cobalto/química , Compostos de Manganês/química , Nanofios/química , Níquel/química , Óxidos/química , Capacitância Elétrica , Eletrodos
19.
Adv Mater ; 25(7): 976-9, 2013 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-23225205

RESUMO

Mesoporous NiCo(2) O(4) nanosheets can be directly grown on various conductive substrates, such as Ni foam, Ti foil, stainless-steel foil and flexible graphite paper, through a general template-free solution method combined with a simple post annealing treatment. As a highly integrated binder- and conductive-agent-free electrode for supercapacitors, the mesoporous NiCo(2) O(4) nanosheets supported on Ni foam deliver ultrahigh capacitance and excellent high-rate cycling stability.

20.
Nanoscale ; 5(3): 877-81, 2013 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-23238333

RESUMO

One-dimensional hierarchical hollow nanostructures composed of NiO nanosheets are successfully synthesized through a facile carbon nanofiber directed solution method followed by a simple thermal annealing treatment. With the advantages of high electro-active surface area, carbon nanofiber supported robust structure and short ion and electron transport pathways, the hierarchical hybrid nanostructures deliver largely enhanced capacitance with excellent cycling stability when evaluated as electrode materials for supercapacitors. More specifically, a high capacitance of 642 F g(-1) is achieved when the charge-discharge current density is 3 A g(-1) and the total capacitance loss is only 5.6% after 1000 cycles.


Assuntos
Capacitância Elétrica , Fontes de Energia Elétrica , Eletrodos , Nanopartículas Metálicas/química , Nanopartículas Metálicas/ultraestrutura , Níquel/química , Desenho de Equipamento , Análise de Falha de Equipamento , Tamanho da Partícula
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