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The utility of TiO 2 as an anode for lithium-ion storage is hindered by low conductivity and sluggish ionic diffusion. Here, the 2D N-doped carbon-wrapped TiO 2 (TiO 2 @NC) composite with a thickness of 5.5 nm derived from the 2D metal-organic framework was designed. This composite consisting of TiO 2 nanoparticles embedded in ultrathin N-doping carbon was used to address the rate and cyclability of Li-ion batteries. The 2D nanosheet morphology obtained from Ti 8 O 8 (OH) 4 (BDC-NH 2) 6 （NH 2 -MIL-125 (Ti)）effectively increases the specific surface area and shortens the electron/ion transport pathway. The chemical bond of Ti-C-O between TiO 2 nanocrystals and N-doping carbon further improve conductivity. Due to its unique structure, the produced TiO 2 @NC composite shows excellent cyclability with a reversible capacity of 110 mAh g–1 after 2000 cycles at 0.5 A g–1. Furthermore, the 2D TiO 2 @NC exhibits outstanding rate performance (71 mAh g–1 at 5 A g–1) compared to bulk TiO 2 @NC. This general concept can be extended to the development of metal oxide materials based on insertion mechanisms, such as Nb 2 O 5. • The 2D TiO 2 @N-doping carbon composite with a thickness of 5.5 nm is prepared. • Solvent-dependent variation of morphology NH 2 -MIL-125(Ti) MOF is investigated. • The TiO 2 nanocrystals embedded in ultrathin N-doping carbon nanosheets via chemical bonding. • The TiO 2 @N-doping carbon composite shows excellent lithium-ion storage performances. [ABSTRACT FROM AUTHOR]

The electrochemical properties of NCM cathodes with various conductive additives have been comparatively studied in this work. The conductive additives are porous graphene/carbon black (SG), carbon black/conductive graphite (SK), carbon black (SC), and conductive graphite (KS), respectively. The results suggest that the NCM electrode with SG conductive additive shows the best rate performance, which exhibits a discharge capacity of 78 mAh g −1  at the current density of 2000 mA g −1 in the voltage range of 2.5–4.1 V versus lithium electrode, that is ∼1.7 times higher than that of NCM electrode with SK additive. The electrochemical impedance spectra (EIS) results reveal that the NCM electrode with SG addition has the lowest charge transfer resistance. On this basis, the structural evolution of NCM material with SG conductive additive in the first charge process has been studied via an in situ synchrotron X-ray diffraction technique (XRD). The XRD patterns show that a thorough phase transition from hexagonal H1 to hexagonal H2 occurs at the voltage of 4.3 V, and the diffraction peaks of (0 1 8)/(1 1 0) splits gradually, representing the extraction of lithium from the ordered layer-structured NCM materials. [ABSTRACT FROM AUTHOR]

• Ni(Co)MoO 4 hybrid electrode with a mixed structure was synthesized on nickel foam. • The hybrid electrode exhibits a remarkable cycling performance due to the mixed morphology. • The asymmetric supercapacitor shows a high energy density of 55.71 Wh kg−1 at the power density of 375 W kg−1. [Display omitted] In this work, the Ni(Co)MoO 4 (NMO-Co) hybrid materials with nanoneedle and nanosheet structure were prepared on nickel foam (NF) by the hydrothermal method for high-stability supercapacitors. The effect of Co presence on the structure and electrochemical properties of NMO-Co was investigated. As the molar of Cobalt increased, more nanoneedles grew on the surface of NiMoO 4 /NF. The combination of the Ni-doped CoMoO 4 nanoneedles and Co-doped NiMoO 4 nanosheets was irregularly arranged on the surface of NF, which emerged an improvement of the cycling performance. When the molar ratio of Co: Ni: Mo was 0.5: 1: 1, the capacitance retention of the hybrid electrode was 80.1% after 10,000 cycles at 10 A g−1, while the pure NiMoO 4 electrode was 53.1%. Moreover, an asymmetric supercapacitor device displayed high energy density and power density. The maximum energy density and power density could reach 55.71 Wh kg−1 and 14,999 W kg−1, respectively. The hybrid electrode's good electrochemical performance is due to the combination of mutual doping of Ni and Co with a mixed morphology. [ABSTRACT FROM AUTHOR]

• NF/ZnCo 2 O 4 @NiCo 2 O 4 heterostructures electrodes are fabricated via facile two-step methods. • The impact of all components in integrated electrode was investigated and discussed. • The integrated electrode exhibits excellent specific capacitance and cycling stability. • The hybrid supercapacitor delivers high energy and power densities. [Display omitted] The hierarchical core-shell heterostructures ZnCo 2 O 4 @NiCo 2 O 4 on Ni foam (NF) for supercapacitors were prepared via two-step hydrothermal and electrodeposition reactions followed by two post-annealing treatments. The effect of deposition time on its morphology and electrochemical performance was investigated in detail. Combining high electric conductivity of ZnCo 2 O 4 with high stability of NiCo 2 O 4 as well as synergistic effect, the NF/ZnCo 2 O 4 @NiCo 2 O 4 -100 (NF/ZCO@NCO-100) integrated electrode exhibited high specific capacitance of 1728.1 F g−1 (240.0 mAh g−1) at 1 A g−1, and excellent long-term stability with 97.8% capacitance retention after 10,000 cycles. The assembled hybrid supercapacitor (HSC) delivered the specific capacitance of 133.6 F g−1 (55.7 mAh g−1) at 1 A g−1 and high energy density of 40.58 Wh kg−1 at 745.62 W kg−1 as well as the outstanding long-term stability of 91.3% capacitance retention after 10,000 cycles. These results provide insights into the rational design of transition metal compound composite materials to construct integrated electrodes for high performance supercapacitors. [ABSTRACT FROM AUTHOR]

Abstract: A blue-white emitting Sr2CeO4 phosphor with orthorhombic structure was synthesized via a simple ethylenediaminetetraacetic acid (EDTA)-complexing process using strontium nitrate and cerous nitrate as raw materials at a relatively low temperature. The crystalline phase, microstructure and morphology of the resulting particles were studied by X-ray diffraction, Raman spectra and transmission electron microscopy. The obtained Sr2CeO4 powders consisted of uniform crotch-like grains with size of ca. 100nm. The interplanar distance of d 111 was 0.297nm. Photoluminescence studies at room temperature showed strong luminescent behavior for the superfine particles. Two excitation bands were located at ∼280 and ∼345nm, respectively. The intensity of the latter excitation band exceeded that of the former while the precursors were calcined at 1000°C. The emission spectrum was a broad band at 472nm, which was suitable for the doping of rare earth ions. [Copyright &y& Elsevier]

SnO 2 /NiFe 2 O 4 /Graphene (SNG) nanocomposites have been fabricated by a one-step hydrothermal synthesis method for Lithium ion batteries. Due to the synergetic effect between graphene, NiFe 2 O 4 and SnO 2 nanoparticle, the nanocomposites show good electrochemical performance. It is found that the electrochemical performance was enhanced with increasing content of SnO 2. Typically, the nanocomposite with 50 wt% SnO 2 exhibits a high reversible capacity of 731.5 mA h/g at a current density of 200 mA/g after 50 cycles, which can remain 80.9% of the first cycle. The material also exhibits a relatively high discharge capacity of 613 mA h/g at 800 mA/g after 100 cycles. These improved electrochemical performances are attributed to the capacity of NiFe 2 O 4 /SnO 2 and the SnO 2 buffer layers impede the pulverization of electrode material during lithium insertion/extraction. Furthermore, graphene sheet can enhance electrical conductivity and accommodate the volume change in some extent, which can keep the structure integrate, and then improving the cycling stability and rate capability. SnO 2 /NiFe 2 O 4 /Graphene (SNG) nanocomposites are fabricated by one-step hydrothermal method and the materials are utilized as anode material for high-performance Lithium ion batteries. Image 1 • One step hydrothermal synthesis of SnO 2 /NiFe 2 O 4 /Graphene for Lithium ion batteries. • NiFe 2 O 4 /SnO 2 contributes to the high capacity of SnO 2 /NiFe 2 O 4 /Graphene. • SnO 2 has cushioning effect on the insertion and release of lithium ions. • Graphene provides high surface to slow down the volume change. [ABSTRACT FROM AUTHOR]

Abstract: Ultrafine Er2Ti2O7 was synthesized at 700°C within 2h by a soft-chemistry route named citric acid sol–gel method (CAM). The obtained Er2Ti2O7 with high dispersibility was square-like and the average size was about 70nm. The prepared Er2Ti2O7 nanocrystals in 6M KOH aqueous solutions were investigated as a hydrogen storage material. It was found that the Er2Ti2O7 powders would function as electrochemical hydrogen storage, showed fair electrochemical reversibility, and considerably high charge–discharge capacity. The reversible discharge capacity of the Er2Ti2O7 electrode was found to exceed 320mAh/g and adsorption capability of hydrogen is up to 1.27% at a current rate of 100mA/g. In addition, the cycling ability and high rate capability of the Er2Ti2O7 electrode are fairly good with only 4% capacity decay after 25 cycles. Cyclic voltammograms (CVs) were carried out to further examine the electrochemical hydrogen storage mechanism of Er2Ti2O7. [Copyright &y& Elsevier]