Search

Abstract: A fully dense nanocrystalline (nc) Ni film on the brass substrate was fabricated by a simple electrodeposition from a choline chloride-based ionic liquid (choline chloride–ethylene glycol) at working voltage (between the two electrodes) of 1.0V and room temperature. It is found that the nc Ni with an average grain size of about 6nm has a face-centered cubic crystal structure. At the film/substrate interface, the epitaxial growth of some nc Ni grains on brass grains can be evidenced by the high resolution transmission electron microscope. The 6nm grain sized Ni exhibits a high strain rate sensitivity (m =0.051) and enhanced hardness values in the range of 7.6–9.7GPa. The deformation mechanism of the nc Ni under indentation is also discussed with the theoretical model fitting. The potentiodynamic polarization curve shows that the nc Ni film exhibits a much negative corrosion potential, which provides a sacrificial anode protection for the brass substrate. [Copyright &y& Elsevier]

Lithium metal has always been considered as a “Holy Grail” of anode materials for high-energy-density batteries owing to its extremely high theoretical gravimetric capacity of 3860 mAh g −1 and the lowest electrochemical potential of −3.04 V. Unfortunately, huge challenges including unlimited dendrite growth and complex interfacial reaction accompanied with relatively low Coulombic efficiency have extremely restricted its practical applications for decades. In this review, we discuss recently exciting achievements in modifying Li metal anodes, particularly regarding porous structure design, surface modification, heterogeneous seed strategy, potential substitutes including Li powder, and pre-lithiated composite. Although each improvement method has its own advantage, we believe appropriate combination of them will yield more promising results. Finally, we discuss core issues and potential opportunities of Li metal anode, expecting to shed new light on future research in this field. [ABSTRACT FROM AUTHOR]

To meet the design requirements for high-rate battery electrodes, self-supporting hierarchical rGO@Ni nanosheet@Co 3 O 4 nanowire array film with light weight is synthesized via a series of controllable fabrication processes. Due to modifying the highly conductive nickel nanosheets onto the surface of rGO film, the energy storage performance of this hybrid film is enhanced, especially in rate capability. The whole high-rate battery, which is fabricated by using this film as the positive electrode, manifests the maximum energy density of 20.3 Wh kg −1 at a power density of 326 W kg −1 along with excellent capacity retention of 81.4% after 5000 cycles. Therefore, the rGO-Ni-Co 3 O 4 hybrid film is a promising electrode material for flexible long-life cycling high-rate batteries. [ABSTRACT FROM AUTHOR]

Construction of high-capacity anode is highly important for the development of next-generation high-performance lithium ion batteries (LIBs). Herein we fabricate Si/Ag nanowires/reduced graphene oxide (Si/Ag NWs/rGO) integrated composite film by introducing binary conductive networks (Ag NWs and rGO) into Si active materials with the help of a facile vacuum-filtration method. Active Si nanoparticles are homogeneously encapsulated by binary Ag NWs-rGO conductive network, in which Ag NWs are interwoven among the rGO sheets. The electrochemical properties of the integrated Si/Ag NWs/rGO composite film are thoroughly characterized as anode of LIBs. Compared to the Si/rGO composite film, the integrated Si/Ag NWs/rGO composite film exhibits enhanced electrochemical performances with higher capacity, better high-rate capability and cycling stability (1269 mAh g −1 at 50 mA g −1 up to 50 cycles). The binary conductive network plays a positive role in the enhancement of performance due to its faster ion/electron transfer, and better anti-structure degradation caused by volume expansion during the cycling process. [ABSTRACT FROM AUTHOR]

A novel 2Li 3 V 2 (PO 4 ) 3 ·LiV 3 O 8 composite with short rod and thin plate shapes is synthesized through sol–gel method followed by hydrothermal and solid–state reaction. LiV 3 O 8 is used as an additive to improve the capacity of Li 3 V 2 (PO 4 ) 3 . In the composite cathode, active impurity phase Li 0.3 V 2 O 5 is also present, which has little impact on the whole electrochemical properties. The 2Li 3 V 2 (PO 4 ) 3 ·LiV 3 O 8 composite delivers a high initial capacity of 162.8 mAh g −1 at a current density of 100 mA g −1 in the voltage range of 2.0–4.3 V. Furthermore, the composite with high crystallinity also shows high electrochemical reversibility and good rate capability. The diffusion coefficient of Li ions in the composite is in the range of 10 −11 –10 −9 cm 2 s −1 obtained from galvanostatic intermittent titration technique. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

A porous Co3O4 nanoflake array film grown on nickel foam is prepared by a hydrothermal synthesis for pseudo-capacitor application. The pseudocapacitive behavior of the Co3O4 nanoflake array is investigated by cyclic voltammograms (CV), galvanostatic charge–discharge tests and electrochemical impedance spectroscopy (EIS) in 2 M KOH at different temperatures. The specific capacity is 210, 289 and 351 F g−1 at 2 A g−1 tested at −5 °C, 25 °C and 60 °C, respectively, corresponding to that of 184, 243 and 242 F g−1 at 20 A g−1. After 4000 cycles at 2 A g−1, the remaining specific capacity is 187, 342 and 124 F g−1 tested at −5 °C, 25 °C and 60 °C. It shows that with increasing the temperature from −5 °C to 60 °C, the specific capacity increases, while the cycling stability becomes worse. The operation temperature has a pronounced influence on the pseudocapacitive performance of Co3O4 nanoflake array. [ABSTRACT FROM AUTHOR]

Abstract: LiVO3 materials are synthesized by combustion method with oxalic acid as fuel. Owing to its relatively low crystallization and small particle size, the LiVO3 calcined at 450 °C for 2 h displays optimal electrochemical performances, delivering a high discharge capacity of 298.4 mAh g−1 and 262.5 mAh g−1 between 1.0 and 3.5 V at a current density of 50 mA g−1 and 500 mA g−1 respectively, and exhibiting good cyclic stability. In this work, the chemical diffusion coefficient of Li+ (D Li+) in the LiVO3 electrode is determined by electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT). The value calculated by EIS is in the range of 10−9–10−8 cm2 s−1, while it calculated by GITT is 10−9.5–10−8 cm2 s−1. [Copyright &y& Elsevier]

Highlights: [•] MnCo2O4 nanowire array is prepared by a fast and facile hydrothermal method. [•] MnCo2O4 nanowire array exhibits noticeable pseudocapacitive properties. [•] The as-prepared nanowire array is also a promising material for Li-ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: Surface modified-LiV3O8 cathode materials with Al2O3 are successfully synthesized via a facile thermolysis process. The 0.5 wt.% Al2O3-coated LiV3O8 exhibits an enhanced cyclic stability at various charge–discharge current densities. At a current density of 100 mA g−1, it delivers an initial specific discharge capacity of 283.1 mAh g−1 between 2.0 and 4.0 V. Moreover, high capacities of 139.4 and 118.5 mAh g−1 are obtained at the 100th cycle at current densities of 2000 and 3000 mA g−1, respectively. The improved electrochemical performance is attributed to the Al2O3 coating, which can hinder the irreversible phase transformation and act as a protective layer to prevent the active material from direct contact with electrolyte. Furthermore, the formation of a Li–V–Al–O solid solution at the LiV3O8/Al2O3 interface provides a fast Li+ diffusion path which is of benefit to the electrochemical behaviors. [Copyright &y& Elsevier]

Abstract: Cube-like and plate-like Li[Li0.2Mn0.54Ni0.13Co0.13]O2 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 Li[Li0.2Mn0.54Ni0.13Co0.13]O2 cathode materials for various applications. [Copyright &y& Elsevier]

Abstract: Li-rich layered oxide Li[Li0.2Mn0.54Ni0.13Co0.13]O2 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. [Copyright &y& Elsevier]

Abstract: Li3V2(PO4)3/C cathode material was synthesized by using a freeze-drying method followed by carbon-thermal reduction. This as-prepared material has a uniform particle size distribution and a well carbon coating on the surface of Li3V2(PO4)3 particles. The Li3V2(PO4)3/C exhibits good electrochemical performance and cycling stability. Between 3.0 and 4.3V, the composite delivered a reversible capacity of 125.2mAhg−1 at a charge–discharge rate of 1.48C (1C=133mAg−1) and without obviously capacity fading after 100 cycles. Even at 14.8C and 29.6C rates, it can still deliver discharge capacities of 105.6mAhg−1 and 93.3mAhg−1, and the discharge capacities of 84.5 and 60.5mAhg−1 are sustained after 500 cycles, respectively. [Copyright &y& Elsevier]

Abstract: Ball-like LiMn0.4Ni0.4Co0.2O2 particles composed of flakes were synthesized by a simplified co-precipitation method followed by a solid-state reaction at temperatures of 600–900°C. The relationship between the flake thickness and the electrochemical performance of the layered oxides was investigated in this work. The layered oxide with a flake thickness of 80–100nm synthesized at 800°C has the best electrochemical performance among these cathode materials, especially the rate capability. An initial discharge capacity of 160mAhg−1 was obtained at 5C (1400mAg−1) in the voltage range of 2.5–4.5V, and the capacity retention was 80% after 50 cycles. The excellent rate capability is attributed to the well formed structure, short diffusion distance and good crystallinity. In addition, a detailed study of diffusion coefficient of Li+ was carried out to further understand this material. The value of calculated is in the range of 10−11 to 10−12 cm2 s−1. [Copyright &y& Elsevier]

Abstract: 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 1M KOH. The hierarchically porous NiO film exhibits a high discharge capacitance and excellent rate capability with 232Fg−1, 229Fg−1, 213Fg−1 and 200Fg−1 at 2, 4, 10, and 20Ag−1, respectively. The specific capacitance of 87% is maintained from 2Ag−1 to 20Ag−1. The porous NiO film also shows rather good cycling stability and exhibits a specific capacitance of 348Fg−1 after 4000 cycles. [Copyright &y& Elsevier]

Abstract: Li3V2(PO4)3/C cathode material is synthesized by a carbon-thermal reduction method using polyvinyl alcohol as carbon source at 700°C. The Li3V2(PO4)3/C electrode presents a high initial discharge capacity of 84.3, 111.1, 128.7, 129.2 and 132.1mAhg−1 at −20, 0, 25, 40 and 65°C between 3.0 and 4.3V, and 118.9, 132.1, 187.6, 180.3 and 172.2mAhg−1 between 3.0 and 4.8V at 0.1C, respectively. However, the electrode only delivers small discharge capacities at −20°C at 10C rate. The capacity fade at low temperatures is mainly attributed to the reduced ionic and electronic conductivity of the electrolyte, the increased impendence of solid electrolyte interface (SEI) and charge-transfer resistance on the electrolyte–electrode interfaces. At higher temperatures, the capacity increases with increasing temperature between 3.0 and 4.3V, but decreases between 3.0 and 4.8V. In the potential range of 3.0–4.8V, the larger crystal structural distortion and non-uniformity of SEI layer at high temperatures may be the main reasons for the capacity loss. [Copyright &y& Elsevier]

Abstract: Spherical Li3V2(PO4)3/C composites are synthesized by a soft chemistry route using hydrazine hydrate as the spheroidizing medium. The electrochemical properties of the materials are investigated by galvanostatic charge–discharge tests, cyclic voltammograms and electrochemical impedance spectrum. The porous Li3V2(PO4)3/C spheres exhibit better electrochemical performances than the solid ones. The spherical porous Li3V2(PO4)3/C electrode shows a high discharge capacity of 129.1 and 125.6mAhg−1 between 3.0 and 4.3V, and 183.8 and 160.9mAhg−1 between 3.0 and 4.8V at 0.2 and 1C, respectively. Even at a charge–discharge rate of 15C, this material can still deliver a discharge capacity of 100.5 and 121.5mAhg−1 in the potential regions of 3.0–4.3V and 3.0–4.8V, respectively. The excellent electrochemical performance can be attributed to the porous structure, which can make the lithium ion diffusion and electron transfer more easily across the Li3V2(PO4)3/electrolyte interfaces, thus resulting in enhanced electrode reaction kinetics and improved electrochemical performance. [Copyright &y& Elsevier]

Abstract: A nanosized LiFePO4/C composite with a complete and thin carbon-shell is synthesized via a ball-milling route followed by solid-state reaction using poly(vinvl alcohol) as carbon source. The LiFePO4/C nanocomposite delivers discharge capacities of 159, 141, 124 and 112mAhg−1 at 1C, 5C, 15C and 20C, respectively. Even at a charge–discharge rate of 30C, there is still a high discharge capacity of 107mAhg−1 and almost no capacity fading after 1000 cycles. Based on the analysis of cyclic voltammograms, the apparent diffusion coefficients of Li ions in the composite are in the region of 2.42×10−11 cm2 s−1 and 2.80×10−11 cm2 s−1. Electrochemical impedance spectroscopy and galvanostatic intermittent titration technique are also used to calculate the diffusion coefficients of Li ions in the LiFePO4/C electrode, they are in the range of 10−11–10−14 cm2 s−1. In addition, at −20°C, it can still deliver a discharge capacity of 122mAhg−1, 90mAhg−1 and 80mAhg−1 at the charge–discharge rates of 0.1C, 0.5C and 1C, respectively. [Copyright &y& Elsevier]

Abstract: The multi-walled carbon nanotubes (MWCNTs) modified Li3V2(PO4)3/C composite is synthesized by polyvinyl alcohol (PVA) based carbon-thermal reduction method using MWCNTs as a highly conductive agent. PVA mainly supplies a reductive atmosphere to reduce V5+ and provides a network of carbon to inhibit the aggregation of Li3V2(PO4)3 particles. The amorphous carbon coating and MWCNTs co-modified composite shows excellent high-rate lithium intercalation/deintercalation property and cycling performance between 3.0 and 4.3V. The discharge capacities of 131.7 and 122.9mAhg−1 are obtained at rates of 1C and 10C, respectively, for the Li3V2(PO4)3/(C+MWCNTs). These improvements are attributed to the valid conducting networks of C+MWCNTs and the reduced Li3V2(PO4)3 particle size by the network carbon from the pyrolysis of PVA. [Copyright &y& Elsevier]