Effect of high-temperature crystallization on the electrochemical properties of LiNi<Subscript>0.5</Subscript>Co<Subscript>0.2</Subscript>Mn<Subscript>0.3</Subscript>O<Subscript>2</Subscript> synthesized from a lithiated transition metal oxide precursor

The lithiated transition metal oxide precursor (LNCMO) with typical α-NaFeO₂ structure and imperfect crystallinity, obtained from a hydrothermal process, was pretreated at 500 °C and then subjected to sintering at 800–920 °C to synthesize the ternary layered LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523). X-ray diffraction (XRD), scanning electron microscope (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge/discharge testing were used for investigating the effect of the high-temperature crystallization on the properties of the NCM523 cathode materials. The results show that the materials heated at 880–900 °C possess superior cation ordering, perfect crystallinity, and excellent electrochemical performances, among which the material heated at 900 °C delivers better performances, with the initial discharge capacity of 152.6 mAh g^?1 at 0.5 C over 3.0 to 4.3 V and the capacity retention of 95.5% after 50 cycles. Furthermore, the effect of the high-temperature crystallization on the Li⁺ diffusion coefficient, potential polarization, and electrochemical resistance are discussed.     

Electrosprayed NiCo<Subscript>2</Subscript>O<Subscript>4</Subscript> nanoparticles for long cycle life and high-power Li-ion battery anode

Electrospraying-based synthesis of NiCo₂O₄ (NCO-ES) nanoparticles that exhibit long cycle life and high rate capability is reported. The results are compared with a conventionally prepared NiCo₂O₄ sample by direct annealing (NCO-DA). The structure and morphology of NCO-ES and NCO-DA nanoparticles have been characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy to confirm the size, morphology, structure, and surface chemistry of the as-prepared samples. Electrochemical testing established that the NCO-ES sample displayed enhanced Li-ion storage performance. The NCO-ES delivered a discharge capacity of almost 370 mAh/g at the end of 50 cycles at 1C rate (890 mA/g) while only 180 mAh/g was retained for the NCO-DA sample at the same condition. At a high rate of 5C (4450 mA/g), NCO-ES electrodes delivered a stabilized specific capacity of 225 mAh/g with almost 100% Coulombic efficiency over 1000 cycles. Its rate capability and cycle life were found to be superior to NCO-DA electrodes. The nanoscale grain boundaries in the NCO-ES sample enhanced the lithium-ion diffusion and enabled high rate capability. The impedance analysis at different stages of lithiation/delithiation indicates a lower impedance and better kinetics as one of the reasons for better performance of the NCO-ES sample.     

Improving the rate performance and stability of LiNi<Subscript>0.6</Subscript>Co<Subscript>0.2</Subscript>Mn<Subscript>0.2</Subscript>O<Subscript>2</Subscript> in high voltage lithium-ion battery by using fluoroethylene carbonate as electrolyte additive

Fluoroethylene carbonate (FEC) is investigated as the electrolyte additive to improve the electrochemical performance of high voltage LiNi_0.6Co_0.2Mn_0.2O₂ cathode material. Compared to LiNi_0.6Co_0.2Mn_0.2O₂/Li cells in blank electrolyte, the capacity retention of the cells with 5 wt% FEC in electrolytes after 80 times charge-discharge cycle between 3.0 and 4.5 V significantly improve from 82.0 to 89.7%. Besides, the capacity of LiNi_0.6Co_0.2Mn_0.2O₂/Li only obtains 12.6 mAh g^?1 at 5 C in base electrolyte, while the 5 wt% FEC in electrolyte can reach a high capacity of 71.3 mAh g^?1 at the same rate. The oxidative stability of the electrolyte with 5 wt% FEC is evaluated by linear sweep voltammetry and potentiostatic data. The LSV results show that the oxidation potential of the electrolytes with FEC is higher than 4.5 V vs. Li/Li⁺, while the oxidation peaks begin to appear near 4.3 V in the electrolyte without FEC. In addition, the effect of FEC on surface of LiNi_0.6Co_0.2Mn_0.2O₂ is elucidated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The analysis result indicates that FEC facilitates the formation of a more stable surface film on the LiNi_0.6Co_0.2Mn_0.2O₂ cathode. The electrochemical impedance spectroscopy (EIS) result evidences that the stable surface film could improve cathode electrolyte interfacial resistance. These results demonstrate that the FEC can apply as an additive for 4.5 V high voltage electrolyte system in LiNi_0.6Co_0.2Mn_0.2O₂/Li cells.     

Hierarchical Co<Subscript>3</Subscript>O<Subscript>4</Subscript>@C hollow microspheres with high capacity as an anode material for lithium-ion batteries

Three-dimensional hierarchical Co₃O₄@C hollow microspheres (Co₃O₄@C HSs) are successfully fabricated by a facile and scalable method. The Co₃O₄@C HSs are composed of numerous Co₃O₄ nanoparticles uniformly coated by a thin layer of carbon. Due to its stable 3D hierarchical hollow structure and uniform carbon coating, the Co₃O₄@C HSs exhibit excellent electrochemical performance as an anode material for lithium-ion batteries (LIBs). The Co₃O₄@C HSs electrode delivers a high reversible specific capacity, excellent cycling stability (1672 mAh g^?1 after 100 cycles at 0.2 A g^?1 and 842.7 mAh g^?1 after 600 cycles at 1 A g^?1), and prominent rate performance (580.9 mAh g^?1 at 5 A g^?1). The excellent electrochemical performance makes this 3D hierarchical Co₃O₄@C HS a potential candidate for the anode materials of the next-generation LIBs. In addition, this simple synthetic strategy should also be applicable for synthesizing other 3D hierarchical metal oxide/C composites for energy storage and conversion.     

Gluonic Distribution in the Constituent Quark and Nucleon Induced by the Instantons

Abstract Instanton effects can give large contribution to strong interacting processes, especially at the energy scale where perturbative QCD is no longer valid. However instanton contribution to the gluon contribution in constituent quark and nucleon has never been calculated before. Based on both the constituent quark picture and the instanton model for QCD vacuum, we calculate the unpolarized and polarized gluon distributions in the constituent quark and in the nucleon for the first time. We find that the pion field plays an important role in producing both the unpolarized and the polarized gluon distributions.     

Spectral and Mechanistic Investigation of Oxidation of Rizatriptan by Silver Third Periodate Complex in Aqueous Alkaline Medium

The oxidation of Rizatriptan by diperiodatoargentate(III) has been studied by spectrophotometry at neutral pH. The kinetics of the reaction of Rizatriptan has been shown to principle of non-complementary oxidation steps. The initial step involves the deprotonated of the diperiodatoargentate(III) with the alkali; this rearranges during the displacement of a ligand to give free periodate and takes up another ligand monoperiodateargentate(III), combines with a substrate to endow with an intermediate complex which decomposes within a slow step to provide the final product in the following step with a first-order rate constant. The main product was identified by spot test, Fourier- transform infrared spectroscopy, Nuclear magnetic resonance and Liquid chromatography-mass spectrometry spectrum. A conceivable mechanism including pre equilibrium of adducts development between the complex and reductant was planned from the kinetics study. The rate conditions got from system can clarify all exploratory phenomena, and the activation parameters alongside rate constants of the rate determining step were ascertained.     

One-dimensional backreacting holographic <Emphasis Type="Italic">p</Emphasis>-wave superconductors

We analytically and numerically study the properties of one-dimensional holographic p-wave superconductors in the presence of backreaction. We employ the Sturm–Liouville eigenvalue problem for the analytical calculation and the shooting method for the numerical investigations. We apply the \(\hbox {AdS}_{{3}}\)/\(\hbox {CFT}_{{2}}\) correspondence and determine the relation between the critical temperature \(T_{c}\) and the chemical potential \(\mu \) for different values of the mass m of a charged spin-1 field \(\rho _{\mu }\) and backreacting parameters. We observe that the data of both analytical and numerical studies are in good agreement. We find that increasing the backreaction and the mass parameter causes the greater values for \({T_{c}}/{\mu }\). Thus, it makes the condensation harder to form. In addition, the analytical and numerical approaches show that the value of the critical exponent \( \beta \) is 1 / 2, which is the same as in the mean field theory. Moreover, both methods confirm the existence of a second order phase transition.     

The smallest absorption refrigerator: the thermodynamics of a system with quantum local detailed balance

We study the thermodynamics of a quantum system interacting with different baths in the repeated interaction framework. In an appropriate limit, the evolution takes the Lindblad form and the corresponding thermodynamic quantities are determined by the state of the full system plus baths. We identify conditions under which the thermodynamics of the open system can be described only by system properties and find a quantum local detailed balance condition with respect to an equilibrium state that may not be a Gibbs state. The three-qubit refrigerator introduced in Linden et al. [Phys. Rev. Lett. 105, 130401 (2010)] and Skrzypczyk et al. [J. Phys. A: Math. Theory 44, 492002 (2011)] is an example of such a system. From a repeated interaction microscopic model we derive the Lindblad equation that describes its dynamics and discuss its thermodynamic properties for arbitrary values of the internal coupling between the qubits. We find that external power (proportional to the internal coupling strength) is required to bring the system to its steady state, but once there, it works autonomously as discussed in Linden et al. [Phys. Rev. Lett. 105, 130401 (2010)] and Skrzypczyk et al. [J. Phys. A: Math. Theory 44, 492002 (2011)].