Relatively small hysteresis in voltage, appropriate electromotive force and low average delithiation voltage make MnO, among many transition metal oxides. MnO/reduced graphene oxide sheet (MnO/RGOS) ...hybrid is synthesized by a two-step electrode design consisting of liquid phase deposition of MnCO3 nanoparticles on the surface of graphene oxide sheets followed by heat treatment in flowing nitrogen. As an anode for Li-ion batteries, the MnO/RGOS hybrid electrode shows a reversible capacity of 665.5 mA h g−1 after 50 cycles at a current density of 100 mA g−1 and delivers 454.2 mA h g−1 at a rate of 400 mA g−1, which is obviously better than that of bare MnO electrode. Those reasons for such enhanced electrochemical properties are investigated by galvanostatic intermittent titration technique (GITT) as well as electrochemical impedance spectroscopy (EIS). The probable origins, in the term of thermodynamic and kinetic factors, for the marked hysteresis in voltage observed between charge and discharge are also discussed.
► MnO/RGOS hybrid is synthesized by a two-step electrode design. ► As an anode material, it displays superior lithium storage performance. ► Reasons for such enhanced performance are investigated by TEM, GITT and EIS. ► The probable origins of hysteresis in voltage are discussed.
LiF is successful used to modify the surface of layered LiNi1/3Co1/3Mn1/3O2 via a wet chemical method followed by an annealing process. The lattice structure of LiNi1/3Co1/3Mn1/3O2 is not changed ...distinctly after modification and part of F− dopes into the surface lattice of the oxide. The LiF-modified oxide exhibits capacity retentions of 97.5% at 0.1 C at room temperature and 93.5% at 1 C at 60 °C after 50 cycles, and delivers a high discharge capacity of 137 mAh g−1 at 10 C at room temperature. Furthermore, it has reversible capacities of 124.4 mAh g−1 at 1 C at 0 °C and 85.6 mAh g−1 at 0.1 C at −20 °C, respectively. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) tests show that the LiF-modified layer can reduce the dissolution of metal ions in the electrode and enhance the conductivity of the oxide surface through partly F-substitution. LiF modification will be promising for the application of layered oxide for lithium ion batteries.
► LiNi1/3Co1/3Mn1/3O2 is modified with LiF by a wet chemical method. ► Discharge capacity of 137 mAh g−1 is obtained at 10 C (2800 mA g−1). ► Capacity retention of 93.5% is obtained at 1 C at 60 °C after 50 cycles. ► Reversible capacity of 124.4 mAh g−1 is obtained at 1 C at 0 °C. ► Even at −20 °C, discharge capacity of 85.6 mAh g−1 is obtained at 0.1 C.
► We synthesize a hierarchically porous NiO film. ► The hierarchically porous NiO film possesses large surface area (196.8
m
2
g
−1). ► A specific capacitance of 200
F
g
−1 can be obtained at a ...discharging current of 20
A. ► 87% of capacitance is retained when the current density changes from 2 to 20
A
g
−1.
A hierarchically porous NiO film on nickel foam substrate is prepared by a facile ammonia-evaporation method. The self-assembled film possesses a structure consisting of NiO triangular prisms and randomly porous NiO nanoflakes. The pseudocapacitive behaviors of the porous NiO film are investigated by cyclic voltammograms and galvanostatic charge–discharge tests in 1
M KOH. The hierarchically porous NiO film exhibits a high discharge capacitance and excellent rate capability with 232
F
g
−1, 229
F
g
−1, 213
F
g
−1 and 200
F
g
−1 at 2, 4, 10, and 20
A
g
−1, respectively. The specific capacitance of 87% is maintained from 2
A
g
−1 to 20
A
g
−1. The porous NiO film also shows rather good cycling stability and exhibits a specific capacitance of 348
F
g
−1 after 4000 cycles.
All the Li metal anode-based batteries suffer from a high propensity to form Li dendrites. To prevent the formation of dendritic lithium on the electrodes, amorphous carbon coatings are deposited ...onto the surface of metallic lithium foil by magnetron sputtering technique. The electrochemical performances of the amorphous carbon-coated lithium (Li/C) electrodes are investigated by galvanostatic charge/discharge tests, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The compact carbon coatings on the surface of lithium foil can suppress the growth of dendritic lithium during charge–discharge process. The thickness of amorphous carbon coating affects the electrode from two aspects; the thick coating can prevent the formation of dendritic lithium much efficiently, but lead to a large impedance of Li+ transfer.
•Amorphous carbon coatings were deposited onto the surface of metallic lithium.•The formation of dendritic can be prevented according to the SEM photograph.•The electrochemical performance is promoted due to the existence of a-C coating.•The thickness of a-C coating affects the electrode performance from two aspects.
NiO films were prepared by chemical bath deposition and electrodeposition method, respectively, using nickel foam as the substrate. The films were characterized by scanning electron microscopy (SEM) ...and the images showed that their morphologies were distinct. The NiO film prepared by chemical bath deposition was highly porous, while the film prepared by electrodeposition was dense, and both of their thickness was about 1
μm. As anode materials for lithium ion batteries, the porous NiO film prepared by chemical bath deposition exhibited higher coulombic efficiency and weaker polarization and its specific capacity after 50 cycles was 490
mAh
g
−1 at the discharge–charge current density of 0.5
A
g
−1, and 350
mAh
g
−1 at 1.5
A
g
−1, higher than the electrodeposited film (230
mAh
g
−1 at 0.5
A
g
−1, and 170
mAh
g
−1 at 1.5
A
g
−1). The better electrochemical performances of the film prepared by chemical bath deposition are attributed to its highly porous morphology, which shorted diffusion length of lithium ions, and relaxed the volume change caused by the reaction between NiO and Li
+.
Mass excesses of short-lived A ¼ 2Z 1 nuclei 63Ge, 65As, 67Se, and 71Kr have been directly measured to be 46 921ð37Þ, 46 937ð85Þ, 46 580ð67Þ, and 46 320ð141Þ keV, respectively. The deduced proton ...separation energy of 90ð85Þ keV for 65As shows that this nucleus is only slightly proton unbound. X-ray burst model calculations with the new mass excess of 65As suggest that the majority of the reaction flow passes through 64Ge via proton capture, indicating that 64Ge is not a significant rp-process waiting point.
The WO3/PANI core/shell nanowire array is prepared by the combination of solvothermal and electropolymerization methods. The core/shell nanowire array film shows remarkable enhancement of the ...electrochromic properties. In particular, a significant optical modulation (59% at 700nm), fast switching speed, high coloration efficiency (86.3cm2C−1 at 700nm) and excellent cycling stability are achieved for the core/shell nanowire array film. The improved electrochromic properties are mainly attributed to the formation of the donor–acceptor system, and the porous space among the nanowires, which can make fast ion diffusion and provide larger surface area for charge-transfer reactions. The data indicate great promise for the WO3/PANI core/shell nanowire array as a potential multicolor electrochromic material.
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•The WO3/PANI core/shell nanowire array is successfully prepared.•The dual-electrochromism effect is obtained for the core/shell nanowire array.•The core/shell structure exhibits large optical modulation and fast switching speed.•High CE and excellent cycling stability are achieved for the core/shell structure.
Li-rich layered oxide LiLi0.2Mn0.54Ni0.13Co0.13O2 is synthesized by combustion reaction using alcohol as both solvent and fuel. X-ray diffraction (XRD), scanning electron microscopy (SEM) and ...transmission electron microscopy (TEM) show that the oxide synthesized at 800 °C exhibits perfect crystallinity and lattice ordering, and has particle sizes of 50–150 nm. The layered oxide delivers an initial discharge capacity of 290.1 mAh g−1 at a current density of 20 mA g−1 after activation, and exhibits improved rate capability with high discharge capacities of 238.6 and 165.0 mAh g−1 at current densities of 200 and 2000 mA g−1 in the voltage range of 2.0–4.8 V, respectively. Low Li-ion diffusion coefficient of 1.07 × 10−14−1.01 × 10−16 cm2 s−1 is calculated by galvanostatic intermittent titration technique (GITT) during the initial discharge process, indicating that the improved rate capability is mainly attributed to the small particle sizes of the Li-rich oxide.
► Cathode material LiLi0.2Mn0.54Ni0.13Co0.13O2 is synthesized by combustion method. ► Alcohol is adopted as both solvent and fuel. ► Initial discharge capacity of 290.1 mAh g−1 is obtained at 20 mA g−1. ► High discharge capacity of 165.0 mAh g−1 is obtained at 2000 mA g−1. ► Diffusion coefficients of Li+ of 1.07 × 10−14–1.01 × 10−16 cm2 s−1 is obtained by GITT.
Cube-like and plate-like LiLi0.2Mn0.54Ni0.13Co0.13O2 particles are obtained after treated in LiCl and KCl molten salts at 800 °C, respectively, comparing to the ball-like original particles calcined ...in air. The oxide treated in KCl molten salt with large specific area of 17.05 m2 g−1 delivers high discharge capacities of 254.1 mAh g−1 and 168.5 mAh g−1 at current densities of 200 mA g−1 and 2000 mA g−1, respectively. In addition, enhanced cycle stability with capacity retention of 94.9% after 80 cycles at charge–discharge current densities of 200 mA g−1 is obtained for the oxide treated in LiCl molten salt with sacrifice of a little capacity. Such electrochemical performance change is proved to be independent of Li+ diffusion coefficient. It appears that the treatment in molten salts can effectively reform the electrochemical performances of LiLi0.2Mn0.54Ni0.13Co0.13O2 cathode materials for various applications.
•Cube and plate-like particles are obtained after treated in LiCl and KCl molten salts.•Oxide treated in KCl molten salt has large specific area of 17.05 m2 g−1.•And discharge capacity of 168.5 mAh g−1 is obtained at 10 C.•Oxide treated in LiCl molten salt has enhanced capacity retention of 94.9%.
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