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1.
Nanoscale ; 2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31993622

RESUMO

Lithium ion capacitors (LICs) are regarded as one of the most promising energy storage devices since they can bridge the gap between lithium ion batteries and supercapacitors. However, the mismatches in specific capacity, high-rate behavior, and cycling stability between the two electrodes are the most critical issues that need to be addressed, severely limiting the large energy density and long cycling life of LICs while delivering high-power density output. Herein, quinone and ester-type oxygen-modified carbon has been successfully obtained by chemical activation with alkali, which is beneficial to the absorption of PF6- together with lithium ions, which would largely improve the electrode kinetics. In particular, the cathode capacity is considerably enhanced with the increase in the amount of oxygen functional groups. Moreover, for the full carbon LIC device, an energy density of 144 W h kg-1 is exhibited at the power density of 200 W kg-1. Surprisingly, even after 10 000 cycles at 20 000 W kg-1, a capacity retention of 70.8% is successfully achieved. These remarkable results could be ascribed to the enhancement of cathode capacity and the acceleration of anode kinetics. Furthermore, the density functional theory (DFT) calculations prove that the oxygen functional groups can deliver enhanced electrochemical activity for lithium storage through surface-induced redox reactions. This elaborate study may open an avenue for resolving the issues with the electrode materials of LICs and deepen the understanding on the surface engineering strategies for incorporating oxygen-functional groups.

2.
Small ; 16(5): e1905842, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31916666

RESUMO

Rechargeable Zn/MnO2 batteries using mild aqueous electrolytes are attracting extensive attention due to their low cost, high safety, and environmental friendliness. However, the charge-storage mechanism involved remains a topic of controversy so far. Also, the practical energy density and cycling stability are still major issues for their applications. Herein, a free-standing α-MnO2 cathode for aqueous zinc-ion batteries (ZIBs) is directly constructed with ultralong nanowires, leading to a rather high energy density of 384 mWh g-1 for the entire electrode. Greatly, the H+ /Zn2+ coinsertion mechanism of α-MnO2 cathode for aqueous ZIBs is confirmed by a combined analysis of in situ X-ray diffractometry, ex situ transmission electron microscopy, and electrochemical methods. More interestingly, the Zn2+ -insertion is found to be less reversible than H+ -insertion in view of the dramatic capacity fading occurring in the Zn2+ -insertion step, which is further evidenced by the discovery of an irreversible ZnMn2 O4 layer at the surface of α-MnO2 . Hence, the H+ -insertion process actually plays a crucial role in maintaining the cycling performance of the aqueous Zn/α-MnO2 battery. This work is believed to provide an insight into the charge-storage mechanism of α-MnO2 in aqueous systems and paves the way for designing aqueous ZIBs with high energy density and long-term cycling ability.

3.
ACS Appl Mater Interfaces ; 12(2): 2432-2444, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31845791

RESUMO

Discovering cathode materials composed of earth-abundant elements has become the current priority for developing sodium-ion batteries (SIBs) to meet the ever-increasing demand of large-scale energy storage. Herein, for the first time, layered NaxMO2 (M = Cu, Fe, Mn) cathodes are successfully prepared by directly using concentrated chalcopyrite ores as precursors. Greatly, impurity elements like Si and Ca are found to be crucial to tailoring the phase structure of as-obtained layered oxides as a P2 or O3 type, which removes the traditional concern that the impurities may restrict the utilization of natural ores. More interestingly, a certain amount of the Ca elements remaining in the Na sites through a self-doping process endows the P2-type products with enhanced structural stability. In half-cells, P2-type NaxMO2 with self-doped Ca elements shows superior rate capability and cycling stability (56 mAh g-1 at 5 C and 90% capacity retention after 100 cycles at 1 C). In contrast, less impurity elements are favorable for O3-type oxides to achieve a high capacity of 107 mAh g-1 at 0.1 C and 84% capacity retention after 200 cycles at 2 C. This new strategy would efficiently shorten the process for preparing electrode materials and open a feasible route to construct cheap and durable SIBs.

4.
ACS Appl Mater Interfaces ; 11(47): 44170-44178, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31674753

RESUMO

Well-tailored sulfur-doped anatase titanium dioxide nanoparticles anchored on a large-area carbon sheet are designed, where the in situ sulfur-doped titanium dioxide directly comes from titanium oxysulfate and the large-area carbon sheet is derived from glucose. When applied as an anode material for sodium-ion batteries, it exhibits an excellent electrochemical performance including a high capacity [256.4 mA h g-1 at 2 C (1 C = 335 mA h g-1) after 500 cycles] and a remarkable rate of cycling stability (100.5 mA h g-1 at 30 C after 500 cycles). These outstanding sodium storage behaviors are ascribed to the nanosized particles (about 8-12 nm), good electronic conductivity promoted by the incorporation of carbon sheet and sulfur, as well as the unique chemical bond based on the electrostatic interaction.

5.
ACS Appl Mater Interfaces ; 11(49): 45596-45605, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31714055

RESUMO

The sluggish kinetics and large overpotential of the oxygen reduction reaction (ORR) severely limit the widespread production and application of metal-air batteries. Herein, a conductive three-dimensional (3D) porous spiral-like polyhedron structure composed of nitrogen-doped carbon nanosheets (L/D-SPNC) was utilized as catalysts with combination of 3D hierarchical porous properties and distinguishing intrinsic properties of two-dimensional (2D) nanosheets for ORR. The chiral template, l/d-tartaric acid, induces the self-assembly of the supramolecule and the formation of an orderly array of carbon with spiral-like surface feature on a molecular scale. The resulting L/D-SPNC exhibits a small wall thickness (2.5 nm), large specific surface area (2034.2 m2/g), and high conductivity (155.76 S/m), which indicates that the properties of 2D nanosheets building blocks are kept in 3D mode. As catalysts for ORR, the optimized L-SPNC-950-1 exhibits a more positive onset potential of 1.03 V compared with those of Pt/C (1.00 V) and a half-wave potential of 0.87 V is also comparable to those of Pt/C (0.87 V). Al-air battery discharge data demonstrate that the spiral-like structure facilitates the diffusion of the electrolyte and oxygen on a three-phase interface, causing weak polarization. Density functional theory (DFT) calculations prove that the twisted surface aggravates the differential charge distribution between C-C/C-N bonds.

6.
Adv Sci (Weinh) ; 6(20): 1901433, 2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31637171

RESUMO

Lithium metal is the most ideal anode for next-generation lithium-ion batteries. However, the formation of lithium dendrites and the continuous consumption of electrolyte during cycling lead to a serious safety problems. Developing stable lithium metal anode with uniform lithium deposition is highly desirable. Herein, a nitrogen plasma strengthening strategy is proposed for copper oxide nanosheet-decorated Cu foil as an advanced current collector, and deep insights into the plasma regulating mechanism are elaborated. The plasma-treated electrode can maintain a high coulombic efficiency of 99.6% for 500 cycles. The symmetric cell using the lithium-plated electrode can be cycled for more than 600 h with a low-voltage hysteresis (23.1 mV), which is much better than those of electrodes without plasma treatment. It is well confirmed that this plasma-induced nitrogen doping method can provide sufficient active sites for lithium nucleation to enhance the stability of lithium deposition on copper oxide nanosheets decorated on Cu foil and improve the electrical conductivity to greatly reduce the overpotential of the lithium nucleation, which can be extended to other modified current collectors for stable lithium metal anode.

7.
ACS Nano ; 13(9): 10787-10797, 2019 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-31442023

RESUMO

Transition-metal selenides have captured sustainable research attention in energy storage and conversion field as promising anodes for sodium-ion batteries. However, for the majority of transition metal selenides, the potential windows have to compress to 0.5-3.0 V for the maintenance of cycling and rate capability, which largely sacrifices the capacity under low voltage and impair energy density for sodium full batteries. Herein, through introducing diverse metal ions, transition-metal selenides consisted of different composition doping (CoM-Se2@NC, M = Ni, Cu, Zn) are prepared with more stable structures and higher conductivity, which exhibit superior cycling and rate properties than those of CoSe2@NC even at a wider voltage range for sodium ion batteries. In particular, Zn2+ doping demonstrates the most prominent sodium storage performance among series materials, delivering a high capacity of 474 mAh g-1 after 80 cycles at 500 mA g-1 and rate capacities of 511.4, 382.7, 372.1, 339.2, 306.8, and 291.4 mAh g-1 at current densities of 0.1, 0.5, 1.0, 1.4, 1.8, and 2.0 A g-1, respectively. The composition adjusting strategy based on metal ions doping can optimize electrochemical performances of metal selenides, offer an avenue to expand stable voltage windows, and provide a feasible approach for the construction of high specific energy sodium-ion batteries.

8.
Angew Chem Int Ed Engl ; 58(44): 15841-15847, 2019 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-31437348

RESUMO

Rechargeable aqueous zinc-ion batteries have been considered as a promising candidate for next-generation batteries. However, the formation of zinc dendrites are the most severe problems limiting their practical applications. To develop stable zinc metal anodes, a synergistic method is presented that combines the Cu-Zn solid solution interface on a copper mesh skeleton with good zinc affinity and a polyacrylamide electrolyte additive to modify the zinc anode, which can greatly reduce the overpotential of the zinc nucleation and increase the stability of zinc deposition. The as-prepared zinc anodes show a dendrite-free plating/stripping behavior over a wide range of current densities. The symmetric cell using this dendrite-free anode can be cycled for more than 280 h with a very low voltage hysteresis (93.1 mV) at a discharge depth of 80 %. The high capacity retention and low polarization are also realized in Zn/MnO2 full cells.

9.
Inorg Chem ; 58(9): 6410-6421, 2019 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-31009210

RESUMO

Given its competitive theoretical capacity, Bi2MoO6 is deemed as a promising anode material for the realization of efficient Li storage. Considering the severe capacity attenuation caused by the lithiation-induced expansion, it is essential to introduce effective modification. Remarkably, in this work, Bi2MoO6 microsphere with double-layered spherical shells are successfully prepared, and the polyaniline are coated on both inner and outer surfaces of double-layered spherical shells, working as buffer layers to strain the volume expansion during electrochemical cycling. Inspiringly, when utilized as anode in LIBs, the specific capacity of Bi2MoO6@PANI is maintained at 656.3 mAh g-1 after 200 cycles at 100 mA g-1, corresponding to a high capacity of 82%. However, the counterpart of individual Bi2MoO6 is only 36%. This result confirms that the polyaniline layer can dramatically promote stable cycling performances. Supported by in situ EIS and ex situ technologies followed by detailed analysis, the enhanced pseudocapacitance-dominated contributions and electron/ion transfer rate, benefiting from the combination with polyaniline, are further proved. This work confirms the significant effect of polyaniline on the ultrastable energy storage, further providing an in-depth sight on the impacts of polyaniline coating to the electrical conductivity as well as the resistances of electron/ion transport.

10.
Small ; 15(32): e1804908, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30740883

RESUMO

A novel electrochemistry method using stochastic collision of particles at microelectrode to study their performance in single-particle scale has obtained remarkable development in recent years. This convenient and swift analytical method, which can be called "nanoimpact," is focused on the electrochemical process of the single particle rather than in complex ensemble systems. Many researchers have applied this nanoimpact method to investigate various kinds of materials in many research fields, including sensing, electrochemical catalysis, and energy storage. However, the ways how they utilize the method are quite different and the key points can be classified into four sorts: sensing particles at ultralow concentration, theory optimization, kinetics of mediated catalytic reaction, and redox electrochemistry of the particles. This review gives a brief overview of the development of the nanoimpact method from the four aspects in a new perspective.

11.
Waste Manag ; 85: 529-537, 2019 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-30803608

RESUMO

Recycling lithium and graphite from spent lithium-ion battery plays a significant role in mitigation of lithium resources shortage, comprehensive utilization of spent anode graphite and environmental protection. In this study, spent graphite was firstly collected by a two-stage calcination. Secondly, under the optimal conditions of 1.5 M HCI, 60 min and solid-liquid ratio (S/L) of 100 g·L-1, the collected graphite suffers simple acid leaching to make almost 100% lithium, copper and aluminum in it into leach liquor. Thirdly, 99.9% aluminum and 99.9% copper were removed from leach liquor by adjusting pH first to 7 and then to 9, and thenthe lithium was recovered by adding sodium carbonate in leach liquor to form lithium carbonate with high purity (>99%). The regenerated graphite is found to have high initial specific capacity at the rate of 37.2 mA·g-1 (591 mAh·g-1), 74.4 mA·g-1 (510 mAh·g-1) and 186 mA·g-1 (335 mAh·g-1), and with the high retention ratio of 97.9% after 100 cycles, it also displays excellent cycle performance at high rate of 372 mA·g-1. By this process, copper and lithium can be recovered and graphite can be regenerated, serving as a sustainable approach for the comprehensive utilization of anode material from spent lithium-ion battery.


Assuntos
Grafite , Lítio , Fontes de Energia Elétrica , Eletrodos , Reciclagem
12.
ACS Appl Mater Interfaces ; 11(11): 10829-10840, 2019 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-30801168

RESUMO

As an anode for lithium-ion batteries, metallic bismuth (Bi) can provide a superb volumetric capacity of 3800 mA h cm-3, showing perspective value for application. It is a pity that the severe volume swelling during the lithiation process leads to the dramatic deterioration of the cycling performances. To overcome this issue, Bi nanorods encapsulated in N-doped carbon nanotubes (yolk-shell Bi@C-N) are elaborately designed through in situ thermal reduction of Bi2S3@polypyrrole nanorods. In comparison with the commercial Bi, the lithium storage capacities of Bi@C-N are significantly enhanced, and it presents a stable volumetric capacity of 1700 mA h cm-3 over 500 cycles at a high current density of 1.0 A g-1, nearly 2.2 times that of graphite. The N-doped carbon nanotube and the cavity between the carbon wall and Bi jointly contribute to this superior performance. Especially, the failure mechanism of Bi nanorods and the protective effect of the carbon shell are revealed by ex situ TEM, which illuminates the decreasing tendency in the initial 10-20 cycles and the subsequent stable trend of cyclic performance.

13.
BMC Infect Dis ; 19(1): 106, 2019 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-30717702

RESUMO

BACKGROUND: To investigate the status of anti-tuberculosis treatment in critically ill patients, and to explore the value of APACHE-II score in guiding anti-tuberculosis treatment. METHODS: This analysis included critically ill patients with tuberculosis. The utility of APACHE-II score for predicting drug withdrawal was evaluated using receiver operating characteristic (ROC) curve analysis. RESULTS: Among 320 patients enrolled (58 ± 22 years; 256 males), 147 (45.9%) had drugs withdrawn. The drug withdrawal group had higher APACHE-II score (median [interquartile range]: 21 [3-52] vs. 17 [4-42] points), higher CD4%, lower hemoglobin level, higher rates of chronic obstructive pulmonary disease (COPD) and chronic renal failure, and lower rate of extrapulmonary tuberculosis (P < 0.05). Logistic regression identified APACHE-II score > 18 (odds ratio [95% confidence interval]: 2.099 [1.321-3.334], P < 0.01), COPD (1.913 [1.028-3.561], P < 0.05) and hemoglobin level (0.987 [0.977-0.997], P < 0.05) as independent factors associated with drug withdrawal. At an optimal cutoff of 18.5, the sensitivity, specificity, positive predictive value and negative predictive value of APACHE-II score for predicting drug withdrawal was 59.2, 61.8, 56.9 and 64.1%, respectively. CONCLUSIONS: APACHE-II score > 18 points might predict patient tolerance of anti-tuberculosis treatment.


Assuntos
Antituberculosos/efeitos adversos , Estado Terminal , Tuberculose/diagnóstico , Tuberculose/tratamento farmacológico , APACHE , Adulto , Idoso , Idoso de 80 Anos ou mais , Antituberculosos/uso terapêutico , Comorbidade , Estado Terminal/epidemiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Retrospectivos , Sensibilidade e Especificidade , Tuberculose/complicações , Tuberculose/epidemiologia , Suspensão de Tratamento/estatística & dados numéricos
14.
ACS Appl Mater Interfaces ; 11(6): 6154-6165, 2019 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-30645091

RESUMO

Compared to chemosynthetic CuFeS2, natural chalcopyrite (CuFeS2) can be regarded as a promising anode material for exploring ultrafast and stable Li-ion batteries benefiting from it being firsthand, eco-friendly, and resource-rich. Considering the nonuniform size distribution in it and the fact that homogeneous grain distributions can effectively restrain the aggregation of active materials, the engineering of size is deemed an effective strategy to achieve excellent Li-storage performances. Herein, varisized natural CuFeS2 are obtained by facial mineral processing technology and outstanding Li-storage performances are exhibited. Along with the decreasing of size, the contribution of pseudocapacitive as well as the ion transfer rates are significantly boosted. As expected, even at 1 A g-1, a remarkable capacity of 1009.7 mA h g-1 is displayed by the sample with the smallest size and most uniform distributions even after 500 cycles. Furthermore, supported by the detailed analysis of in situ X-ray diffraction and kinetic features, a hybrid of multiple lithium-metal sulfur systems and the major origin of the enhanced capacity upon long cycles are confirmed. Remarkably, this work is expected to increase the far-ranging applications of natural chalcopyrite as a firsthand anode material for lithium-ion batteries (LIBs) and inform the readers about the effects of particle size on Li-storage performances.

15.
Adv Mater ; 31(3): e1806092, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30430659

RESUMO

Exploring high-rate electrode materials with excellent kinetic properties is imperative for advanced sodium-storage systems. Herein, novel cubic-like XFe (X = Co, Ni, Mn) Prussian blue analogs (PBAs), as cathodes materials, are obtained through as-tuned ionic bonding, delivering improved crystallinity and homogeneous particles size. As expected, Ni-Fe PBAs show a capacity of 81 mAh g-1 at 1.0 A g-1 , mainly resulting from their physical-chemical stability, fast kinetics, and "zero-strain" insertion characteristics. Considering that the combination of elements incorporated with carbon may increase the rate of ion transfer and improve the lifetime of cycling stability, they are expected to derive binary metal-selenide/nitrogen-doped carbon as anodes. Among them, binary Ni0.67 Fe0.33 Se2 coming from Ni-Fe PBAs shows obvious core-shell structure in a dual-carbon matrix, leading to enhanced electron interactions, electrochemical activity, and "metal-like" conductivity, which could retain an ultralong-term stability of 375 mAh g-1 after 10 000 loops even at 10.0 A g-1 . The corresponding full-cell Ni-Fe PBAs versus Ni0.67 Fe0.33 Se2 deliver a remarkable Na-storage capacity of 302.2 mAh g-1 at 1.0 A g-1 . The rational strategy is anticipated to offer more possibilities for designing advanced electrode materials used in high-performance sodium-ion batteries.

16.
Nanoscale ; 11(1): 16-33, 2018 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-30525147

RESUMO

Unlike zero-dimensional quantum dots, one-dimensional nanowires/nanorods, and three-dimensional networks or even their bulk counterparts, the charge carriers in two-dimensional (2D) materials are confined along the thickness while being allowed to move along the plane. They have distinct characteristics like strong quantum confinement, tunable thickness, and high specific surface area, which makes them a promising candidate in a wide range of applications such as electronics, topological spintronic devices, energy storage, energy conversion, sensors, biomedicine, catalysis, and so on. After the discovery of the extraordinary properties of graphene, other graphene-like 2D materials have attracted a great deal of attention. Like graphene, to realize their potential applications, high efficiency and low cost industrial scale methods should be developed to produce high-quality 2D materials. The electrochemical methods usually performed under mild conditions are convenient, controllable, and suitable for mass production. In this review, we introduce the latest and most representative investigations on the fabrication of 2D monoelemental Xenes, 2D transition-metal dichalcogenides, and other important emerging 2D materials such as organic framework (MOF) nanosheets and MXenes through electrochemical exfoliation. The electrochemical exfoliation conditions of the bulk layered materials are discussed. The numerous factors which will affect the quality of the exfoliated 2D materials, the possible exfoliating mechanism and potential applications are summarized and discussed in detail. A summary of the discussion together with perspectives and challenges for the future of this emerging field is also provided in the last section.

17.
J Chem Inf Model ; 58(12): 2420-2427, 2018 12 24.
Artigo em Inglês | MEDLINE | ID: mdl-30457872

RESUMO

The specific surface area (SSA) of ABO3-type perovskite is one of the important properties associated with photocatalytic ability. In this work, data mining methods were used to explore the relationship between the SSA (in the range of 1-60 m2 g-1) of perovskite and its features, including chemical compositions and technical parameters. The genetic algorithm-support vector regression method was used to screen the main features for modeling. The correlation coefficient ( R) between the predicted and experimental SSAs reached as high as 0.986 for the training data set and 0.935 for leave-one-out cross-validation. ABO3-type perovskites with higher SSA can be screened out using the Online Computation Platform for Materials Data Mining (OCPMDM) developed in our laboratory. Further, an online web server has been developed to share the model for the prediction of SSA of ABO3-type perovskite, which is accessible at http://118.25.4.79/material_api/csk856q0fulhhhwv .


Assuntos
Compostos de Cálcio/química , Mineração de Dados , Aprendizado de Máquina , Óxidos/química , Titânio/química , Algoritmos , Bases de Dados de Compostos Químicos , Estrutura Molecular , Propriedades de Superfície
18.
ACS Appl Mater Interfaces ; 10(50): 43669-43681, 2018 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-30489056

RESUMO

The transition-metal sulfide, CuS, is deemed a promising material for energy storage, mainly derived from its good chemisorption and conductivity, although serious capacity fading limits its advancement within reversible lithium storage. Learning from the gold extraction method utilizing the lime-sulfur-synthetic-solution, a CuS@S hybrid utilizing CaS x as both sulfur resource and reductant-oxidant is prepared, which is an efficient approach to apply the metallurgy for the preparation of electrode materials. Regulating the amount of CuCl2, the CuS@S is induced to reach a molecular-level hybrid. When utilized as an anode within a lithium-ion battery, it presents the specific capacity of 514.4 mA h g-1 at 0.1 A g-1 over 200 cycles. Supported by the analyses of pseudo-capacitive behaviors, it is confirmed that the CuS matrix with the suitable content of auxiliary sulfur could improve the durability of the CuS-based anode. Expanding the wider application within lithium-sulfur batteries, the synchronous growth of CuS@S exhibits stronger chemisorption with polysulfides than the mechanical mixture of CuS and S. A suite of in situ electrochemical impedance spectroscopy studies further investigates the stable resistances of the CuS@S within the charge/discharge process, corresponding to the reversible structure evolution. This systematic work may provide a practical fabricating route of metal sulfides for scalable energy storage applications.

19.
Nanoscale ; 10(39): 18786-18794, 2018 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-30276389

RESUMO

Transition metal sulfides (TMSs) have been extensively studied as electrode materials for sodium-ion batteries by virtue of their high theoretical capacity. However, the poor cyclability limits the practical application of TMSs in sodium ion batteries. In this study, N-rich carbon-coated Co3S4 ultrafine nanocrystal (Co3S4@NC) was prepared by utilizing ZIF-67 as a precursor through continuous carbonization and sulfuration processes, exhibiting ultrafine nanocrystals with a diameter of about 5 nm. When utilized as the anode for sodium ion batteries, the nanohybrid material exhibits remarkable cycling performance with a high specific capacity of 420.9 mA h g-1 at the current density of 100 mA g-1 after 100 cycles, indicating that the cycling performance is strengthened by the nitrogen-doped carbon coating. Impressively, the obtained material shows good rate performances with reversible specific capacities of 386.7, 284.0, and 151.2 mA h g-1 at 400, 1000, and 1400 mA g-1, respectively, due to the high surface-capacitance contribution and porous structure inherited from the precursor, which finally results in the increase in infiltration of electrolyte and the accelerating diffusion rate of Na+. This study sheds light on the routes to improve the performance of TMSs@nitrogen-doped carbon nanohybrid materials for sodium ion batteries.

20.
Front Chem ; 6: 389, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30211157

RESUMO

Restricted by the dissatisfied capacity of traditional materials, lithium-ion batteries (LIBs) still suffer from the low energy-density. The pursuing of natural electrode resources with high lithium-storage capability has triggered a plenty of activities. Through the hydro-refining process of raw molybdenite ore, containing crushing-grinding, flotation, exfoliation, and gradient centrifugation, 2D molybdenum disulfide (MoS2) with high purity is massively obtained. The effective tailoring process further induce various sizes (5, 2, 1 and 90 nm) of sheets, accompanying with the increasing of active sites and defects. Utilized as LIB anodes, size-tuning could serve crucial roles on the electrochemical properties. Among them, MoS2-1 µm delivers an initial charge capacity of 904 mAh g-1, reaching up to 1,337 mAh g-1 over 125 loops at 0.1 A g-1. Even at 5.0 A g-1, a considerable capacity of 682 mAh g-1 is remained. Detailedly analyzing kinetic origins reveals that size-controlling would bring about lowered charge transfer resistance and quicken ions diffusion. The work is anticipated to shed light on the effect of different MoS2 sheet sizes on Li-capacity ability and provides a promising strategy for the commercial-scale production of natural mineral as high-capacity anodes.

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