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1.
Artigo em Inglês | MEDLINE | ID: mdl-32150377

RESUMO

A gentle method is used to treat the precursor to induce the doping of SO42- and Ni2+. The doped SO42- induces the formation of oxygen vacancies and defects, which are beneficial for inhibition of the loss of O2-, stabilization of the structure, and amelioration of voltage decay, and the doped Ni2+ increases the degree of lithium nickel mixing and significantly increases the midvoltage. After modification, the specific discharge capacity reaches 305.20 mAh g-1, with a Coulombic efficiency of 86.20% (the specific discharge capacity and Coulombic efficiency of the original material are only 276.50 mAh g-1 and 77.30%, respectively). In addition, the cycle performance is also significantly improved, and the discharge midvoltage is dramatically increased from 2.74 to 3.00 V after 350 cycles at a large current density of 1C due to the dual-ion synergistic effect. In summary, these results show that the materials exhibit not only a more stable structure but also better electrochemical performance after modification.

2.
Artigo em Inglês | MEDLINE | ID: mdl-32103602

RESUMO

The deployment of high-energy-density lithium (Li) metal batteries has been greatly impeded by the Li dendrite growth and the safety concerns originating from flammable liquid electrolytes. Herein, we report a stable quasi-solid-state Li metal battery employing a deep eutectic solvent (DES)-based self-healing polymer (DSP) electrolyte. This electrolyte was facilely fabricated via in situ copolymerizing (2-(3-(6-methyl-4-oxo-1,4-dihydropyrimidin-2-yl)ureido)ethyl methacrylate) (UPyMA) and pentaerythritol tetraacrylate (PETEA) monomers in a DES-based electrolyte containing fluoroethylene carbonate (FEC) additive. The well-designed DSP electrolyte simultaneously possesses non-flammability, high ionic conductivity and electrochemical stability, and dendrite-free Li plating. When applied in Li metal batteries with LiMn 2 O 4 cathode, the DSP electrolyte effectively suppresses manganese dissolution from the cathode, and enables high capacity and long lifespan at room and elevated temperatures.

3.
ACS Nano ; 2020 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-31927976

RESUMO

Lithium (Li) metal anode has attracted tremendous attention for its highest capacity (3860 mAh g-1). Herein, we report that the formation of dead Li can be effectively suppressed through Li plating on porous lithiated graphite lamina (PLGL). A lithiophilic carbon layer was decorated on the lithiophobic basal plane of porous graphite lamina (PGL) with an industry-scalable slurry-coating strategy. Moreover, the higher delithiation potential of PLGL will ensure the complete stripping of the plated Li before its delithiation, thus dramatically enhancing the average Coulombic efficiency (ACE) of Li plating/stripping to 98.5% at a high Li plating/stripping capacity of 2 mAh cm-2 (∼1100 mAh g-1) at 2 mA cm-2. Even at an ultrahigh current density of 4 mA cm-2 (with Li capacity of 4 mAh cm-2 (∼1900 mAh g-1)), the ACE could still be maintained at 96.2% in an ordinary carbonate electrolyte.

4.
J Colloid Interface Sci ; 560: 659-666, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31704000

RESUMO

Rechargeable aqueous Zn-ion batteries have shown considerable potential for stationary grid-scale energy storage systems owing to their characteristics of low cost and non-pollution. Nevertheless, the development of high-performance cathode materials is still a formidable challenge. In this work, for the first time, we report a superior silver vanadate (ß-AgVO3) cathode for Zn-ion batteries, and demonstrate the fundamental Zn2+ storage mechanism in detail. In sharp contrast to the previously-reported layered vandium-based materials, the ß-AgVO3 cathode experiences an initial phase transition to form a layered Zn3V2O7(OH)2·2H2O through a displacement/reduction reaction of Zn2+/Ag+ in the first discharge process. The in situ generated Ag0 along with the residual Ag+ and structural water within the framework afford high electronic/ionic conductivity, thus enabling enhanced Zn2+ intercalation/deintercalation kinetics in the layered phase. As a consequence, the cathode can deliver remarkable rate performance (103 mAh g-1 at 5000 mA g-1) and long-term cycling stability (95 mAh g-1 after 1000 cycles at 2000 mA g-1). The present study offers a totally new insight into the exploration of non-layered-structured vandium-based cathodes for high performance Zn-ion batteries.

5.
ACS Appl Mater Interfaces ; 11(49): 45578-45585, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31742373

RESUMO

Potassium-ion batteries (PIBs) are considered to be potential alternatives to the conventional lithium-ion batteries (LIBs) due to the similar working mechanism and abundant potassium (K) resource. However, it still remains challenging to directly apply commercial graphite anodes for PIBs owing to the large K ions, which may impede the electrochemical intercalation of K ions into the graphite interlayer and result in a poor cyclic stability and rate capability. Reduced graphene oxide (rGO) has shown remarkable electrochemical performance as an anode material for PIBs due to the fact that rGO possesses more active sites with an enlarged interlayer distance. Understanding the microstructure of rGO is crucial for optimizing its K-ion storage capabilities. Herein, it is revealed that the K-ion storage behavior of rGO is strongly dependent on the thermal treatment temperature on account of the difference in microstructure. rGO graphitized at 2500 °C exhibits a superior long-term cyclic stability for 2500 cycles due to the expanded interlayer distance and the unique graphite-like structure in a long range, enabling it to endure the huge volume change during uninterrupted K-ion intercalation/deintercalation processes.

6.
Nanoscale ; 11(47): 22899-22906, 2019 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-31763640

RESUMO

All-inorganic perovskite CsPbBr3-Cs4PbBr6 composite nanocrystals (NCs) were synthesized via a convenient solution process without inert gas protection and systematically studied as green phosphors for light emitting diode (LED) applications. While colloidal composite NCs emit green color with an emission peak at around 515 nm, their thin films on top of blue GaN chips exhibit a redshift of ∼15-20 nm due to subsequential aggregation in solid state. The Commission Internationale De I'eclairage (CIE) chromaticity coordinates of the green LEDs assembled by composite NCs reached (0.201, 0.746) with nearly 100% green ratio. Moreover, the pure green LED displayed a luminous efficiency of 45 lm W-1 under 10 mA driving current. The colloidal CsPbBr3-Cs4PbBr6 composite NCs have the photoluminescence quantum yield (PLQY) as high as 74%. The high PLQY originates from cubic CsPbBr3 NCs well passivated by the zero-dimensional Cs4PbBr6 matrix, substantially suppressing the nonradiative recombination. The comparison between the green LEDs fabricated with pure and composite perovskites imply that the CsPbBr3-Cs4PbBr6 composites with higher quantum yield could be an effective way to get the brightness and the stability of pure green LEDs.

7.
ACS Appl Mater Interfaces ; 11(49): 45709-45716, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31729859

RESUMO

Herein, we successfully prepared one-dimensional nanowire with carbon-coated selenium (Se@CW) by using a simple wet chemical method and obtained a one-dimensional hollow Se@C nanotube (Se@CT) after the subsequent calcination treatment. We have formed a new Al-Se secondary battery by using Se@CT as the cathode and metal aluminum as the anode in the AlCl3/[EMIm]Cl electrolyte. It is believed that the oxidation intermediate of Se in Al-Se batteries may not only have Se22+, but there may be other oxidation intermediates, such as Se4+, Se2+, and Se82+. Therefore, Se@CT exhibits excellent charge-discharge performance in Al-Se batteries. Its initial discharge capacity reaches 447.2 mA h g-1 at 200 mA g-1, and the operating voltage is above 1.6 V. Its energy density approaches 708.8 W h k g-1, the capacity is still 162.9 mA h g-1 after 200 cycles at 500 mA g-1, and the corresponding capacity retention rate is up to 83.5%. In addition, its electrochemical performance is far superior to that of Se@CMK-3 in Al-Se batteries and the electrochemical properties of carbon materials, oxides, and sulfide electrode materials in some aluminum-ion batteries, which will open up a new direction for the development of new secondary aluminum-based batteries.

8.
Chem Commun (Camb) ; 55(83): 12555-12558, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31576844

RESUMO

A facile, low-cost precipitation method, utilizing an autogenously protective atmosphere without the assistance of an inert atmosphere, is proposed to synthesize nano-sized Prussian white K1.62Fe[Fe(CN)6]0.92·0.33H2O. The cathode delivers a high capacity of 120.9 mA h g-1 at 50 mA g-1 and an ultrahigh capacity retention of 98.2% after 100 cycles.

9.
Adv Mater ; 31(48): e1904991, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31549760

RESUMO

Lithium metal anodes with high energy density are important for further development of next-generation batteries. However, inhomogeneous Li deposition and dendrite growth hinder their practical utilization. 3D current collectors are widely investigated to suppress dendrite growth, but they usually occupy a large volume and increase the weight of the system, hence decreasing the energy density. Additionally, the nonuniform distribution of Li ions results in low utilization of the porous structure. A lightweight, 3D Cu nanowire current collector with a phosphidation gradient is reported to balance the lithiophilicity with conductivity of the electrode. The phosphide gradient with good lithiophilicity and high ionic conductivity enables dense nucleation of Li and its steady deposition in the porous structure, realizing a high pore utilization. Specifically, the homogenous deposition of Li leads to the formation of an oriented texture on the electrode surface at high capacities. A high mass loading (≈44 wt%) of Li with a capacity of 3 mAh cm-2 and a high average Coulombic efficiency of 97.3% are achieved. A lifespan of 300 h in a symmetrical cell is obtained at 2 mA cm-2 , implying great potential to stabilize lithium metal.

10.
Small ; : e1902843, 2019 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-31550082

RESUMO

Developing electrochemical energy storage devices with high energy-power densities, long cycling life, as well as low cost is of great significance. Sodium-ion capacitors (NICs), with Na+ as carriers, are composed of a high capacity battery-type electrode and a high rate capacitive electrode. However, unlike their lithium-ion analogues, the research on NICs is still in its infancy. Rational material designs still need to be developed to meet the increasing requirements for NICs with superior energy-power performance and low cost. In the past few years, various materials have been explored to develop NICs with the merits of superior electrochemical performance, low cost, good stability, and environmental friendliness. Here, the material design strategies for sodium-ion capacitors are summarized, with focus on cathode materials, anode materials, and electrolytes. The challenges and opportunities ahead for the future research on materials for NICs are also proposed.

11.
Nat Commun ; 10(1): 4244, 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31534125

RESUMO

Sodium metal batteries have potentially high energy densities, but severe sodium-dendrite growth and side reactions prevent their practical applications, especially at high temperatures. Herein, we design an inorganic ionic conductor/gel polymer electrolyte composite, where uniformly cross-linked beta alumina nanowires are compactly coated by a poly(vinylidene fluoride-co-hexafluoropropylene)-based gel polymer electrolyte through their strong molecular interactions. These  beta alumina nanowires combined with the gel polymer layer create dense and homogeneous solid-liquid hybrid sodium-ion transportation channels through and along the nanowires, which promote uniform sodium deposition and formation of a stable and flat solid electrolyte interface on the sodium metal anode. Side reactions between the sodium metal and liquid electrolyte, as well as sodium dendrite formation, are successfully suppressed, especially at 60 °C. The sodium vanadium phosphate/sodium full cells with composite electrolyte exhibit 95.3% and 78.8% capacity retention after 1000 cycles at 1 C at 25 °C and 60 °C, respectively.

12.
Adv Mater ; 31(43): e1902432, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31513318

RESUMO

Gelation is an effective way to realize the self-assembly of nanomaterials into different macrostructures, and in a typical use, the gelation of graphene oxide (GO) produces various graphene-based carbon materials with different applications. However, the gelation of MXenes, another important type of 2D materials that have different surface chemistry from GO, is difficult to achieve. Here, the first gelation of MXenes in an aqueous dispersion that is initiated by divalent metal ions is reported, where the strong interaction between these ions and OH groups on the MXene surface plays a key role. Typically, Fe2+ ions are introduced in the MXene dispersion which destroys the electrostatic repulsion force between the MXene nanosheets in the dispersion and acts as linkers to bond the nanosheets together, forming a 3D MXene network. The obtained hydrogel effectively avoids the restacking of the MXene nanosheets and greatly improves their surface utilization, resulting in a high rate performance when used as a supercapacitor electrode (≈226 F g-1 at 1 V s-1 ). It is believed that the gelation of MXenes indicates a new way to build various tunable MXene-based structures and develop different applications.

13.
Nanomaterials (Basel) ; 9(9)2019 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-31540315

RESUMO

Two-dimensional (2D) tungsten disulfide (WS2) has inspired great efforts in optoelectronics, such as in solar cells, light-emitting diodes, and photodetectors. However, chemical vapor deposition (CVD) grown 2D WS2 domains with the coexistence of a discontinuous single layer and multilayers are still not suitable for the fabrication of photodetectors on a large scale. An emerging field in the integration of organic materials with 2D materials offers the advantages of molecular diversity and flexibility to provide an exciting aspect on high-performance device applications. Herein, we fabricated a photodetector based on a 2D-WS2/organic semiconductor materials (mixture of the (Poly-(N, N'-bis-4-butylphenyl-N, N'-bisphenyl) benzidine and Phenyl-C61-butyric acid methyl ester (Poly-TPD/PCBM)) heterojunction. The application of Poly-TPD/PCBM organic blend film enhanced light absorption, electrically connected the isolated WS2 domains, and promoted the separation of electron-hole pairs. The generated exciton could sufficiently diffuse to the interface of the WS2 and the organic blend layers for efficient charge separation, where Poly-TPD was favorable for hole carrier transport and PCBM for electron transport to their respective electrodes. We show that the photodetector exhibited high responsivity, detectivity, and an on/off ratio of 0.1 A/W, 1.1 × 1011 Jones, and 100, respectively. In addition, the photodetector showed a broad spectral response from 500 nm to 750 nm, with a peak external quantum efficiency (EQE) of 8%. Our work offers a facile solution-coating process combined with a CVD technique to prepare an inorganic/organic heterojunction photodetector with high performance on silicon substrate.

14.
ACS Nano ; 13(10): 11891-11900, 2019 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-31542919

RESUMO

Although the lithium-rich cathode material Li1.2Mn0.54Ni0.13Co0.13O2, as a promising cathode material, has a high specific capacity, it suffers from capacity decay and discharge voltage decay during cycling. In this work, the specific capacity and discharge voltage of Li1.2Mn0.54Ni0.13Co0.13O2 are stabilized by surface-functionalized LiCeO2 coating. We have conducted LiCeO2 coating via a mild synchronous lithium strategy to protect the electrode surface from electrolyte attack. This optimized LiCeO2 coating has high Li+ conductivity and abundant oxygen vacancies. The results demonstrate that 3% LiCeO2-coated Li1.2Mn0.54Ni0.13Co0.13O2 exhibits the highest capacity retention rate at 1, 2, and 5 C after 200 cycles, which were 84.3%, 85.4%, and 86.3%, respectively. The discharge specific capacity was almost 1.3, 1.4, and 1.4 times that of the pristine electrode. In addition, the 3% LiCeO2 electrode exhibited the least voltage decay of 0.409, 0.497, and 0.494 V at 1, 2, and 5 C, which was only about half of the pristine electrode. It should not be overlooked that the 3% LiCeO2 electrode still exhibits a high capacity at high current densities of 1250 mA g-1 (5 C) and 2500 mA g-1 (10 C), and its specific discharge capacities are 190.5 and 160.6 mAh g-1, respectively. These outstanding electrochemical properties benefit from surface-functionalized LiCeO2 coatings. To better understand the mechanism of oxygen loss of lithium-rich materials, we propose the lattice oxygen migration path of the LiCeO2-coated electrodes during the cycle. Our research provides a possible solution to the poor rate capability and cycle performance of cathode materials through surface-functionalized coatings.

15.
ACS Appl Mater Interfaces ; 11(40): 37357-37364, 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31532614

RESUMO

Li4Ti5O12 (LTO) as the anode of lithium (Li) ion batteries has high interfacial side reactivity with the electrolyte, which leads to severe gassing behavior and poor cycling stability. Herein, the capacity loss mechanism of the high-tap density LTO microsphere anode under different temperatures (25, 45, and 60 °C) and charge/discharge rates (1 and 5 C) is systematically investigated. The capacity retentions of the LTO/Li cell after 500 cycles at 1 C are 95.6, 90.0, and 87.1% under three temperatures, which drop to 91.9, 58.3, and 20.9% when cycling at 5 C, respectively. Results show that the high temperature and rate almost do not damage the structure of LTO, but greatly affect the thickness and components of the solid electrolyte interface (SEI), and consequently reduce the performance of the LTO/Li cells. An SEI mainly consisting of inorganic species forms on LTO after 500 cycles at 1 C, while organic compounds are observed after 500 cycles at 5 C. The capacity of cycled LTO cannot recover again because of the thick SEI although using new Li metal anodes, separators, and electrolytes. This work demonstrates that it is of great significance for LTO to construct a stable SEI for achieving excellent cycling performance at a high rate and temperature.

16.
Small ; : e1902603, 2019 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-31389177

RESUMO

Sodium-ion batteries (SIBs) are promising for large-scale energy storage systems and carbon materials are the most likely candidates for their electrodes. The existence of defects in carbon materials is crucial for increasing the sodium storage ability. However, both the reversible capacity and efficiency need to be further improved. Functionalization is a direct and feasible approach to address this issue. Based on the structural changes in carbon materials produced by surface functionalization, three basic categories are defined: heteroatom doping, grafting of functional groups, and the shielding of defects. Heteroatom doping can improve the electrochemical reactivity, and the grafting of functional groups can promote both the diffusion-controlled bulk process and surface-confined capacitive process. The shielding of defects can further increase the efficiency and cyclic stability without sacrificing reversible capacity. In this Review, recent progresses in the ways to produce surface functionalization are presented and the related impact on the physical and chemical properties of carbon materials is discussed. Moreover, the critical issues, challenges, and possibilities for future research are summarized.

17.
Chem Commun (Camb) ; 55(68): 10084-10087, 2019 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-31380530

RESUMO

Pd-encapsulated porous carbon materials (Pd-PCMs) were prepared from the coupling polymerization of an aryl halide and aryl alkyne under mild conditions. Combining its porous microstructure and encapsulated Pd nanoparticles, Pd-PCMs with high sulfur loading reach a capacity of 920 mA h g-1 after 200 cycles at 0.3C.

18.
ACS Appl Mater Interfaces ; 11(33): 29993-30000, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31353902

RESUMO

Designing composite structures of active materials is critical for high-performance lithium-ion batteries, as it determines the reversibility of lithium-ion insertion and extraction of the electrodes. The V2O3 anode has a high specific capacity but presents poor cycling stability due to a large volume change. Herein, a novel C@V2O3-Li4Ti5O12 composite with ultrastable cycling stability is constructed. In this composite structure, the interconnected ultrasmall V2O3 and Li4Ti5O12 nanoparticles (5-10 nm) construct robust interfaces in the carbon matrix. The Li4Ti5O12 nanoparticles with excellent cycling stability and a minor volume change act as fixtures that effectively restrict the volume change of V2O3 nanoparticles and improve the cycling stability of the C@V2O3-Li4Ti5O12 composite. The C@V2O3-Li4Ti5O12 composite maintains no degradation during 500 cycles under a current density of 100 mA g-1. The results demonstrate that constructing a highly stable interface between the active nanoparticles with smaller and larger volume changes is of great significance to suppress their pulverization and achieve high reversibility. This work contributes to a new strategy to design the structure of long-cycling anode materials for highly stable lithium-ion batteries.

19.
Nano Lett ; 19(7): 4601-4607, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31185572

RESUMO

Uncontrollable dendrite growth is one of the major problems that hinders the application of lithium (Li) metal anode in rechargeable Li batteries. Achieving uniform Li deposition is the key to tackle this intractable problem. Herein, we report the highly dispersed Cu2O nanoparticles (NPs) in situ anchored on partially reduced graphene oxide via a low-temperature pyrolysis process could serve as seeds for the Li metal deposition. The lithiophilic nature of Cu2O NPs reduces the overpotential of Li nucleation and relieves the electrode polarization, enabling uniform Li nucleation and smooth plating, thus effectively eliminating dendritic and dead Li. As a result, the resulted Li metal electrodes deliver a high Coulombic efficiency of 95.6% after 140 cycles at a current density of 2 mA cm-2 and a prolonged lifespan (800 h at 1 mA cm-2) for the symmetrical cell.

20.
J Biomed Nanotechnol ; 15(7): 1532-1545, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31196356

RESUMO

Not only dose oral administration have the highest safety, convenience and patient compliance, but also can improve patients' quality of life and reduce health care costs in many cases when compared to the parenteral route. However, many drugs, especially most anticancer drugs such as paclitaxel (PTX), are not orally bioavailable, which is attributed to low aqueous solubility, poor intestinal permeability, and the high level of P-glycoprotein (P-gp) efflux. In this study, we developed a nano-porous silica aerogel delivery system for oral administration of PTX that improved the bioavailability, reduced the side effects of the drug and inhibited tumor growth. The advantages of nano-porous silica aerogel include very high porosities, vast specific surface areas, high drug-loading rate, high biological safety, excellent biocompatibility, and biological inertia, which can also be applied to a variety of drugs. The aerogel delivery system is a universal pharmaceutical system that has huge potential in the field of pharmacy.


Assuntos
Paclitaxel/química , Administração Oral , Materiais Biocompatíveis , Disponibilidade Biológica , Sistemas de Liberação de Medicamentos , Humanos , Porosidade , Qualidade de Vida , Dióxido de Silício
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