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Solid-state Li-ion batteries (SSBs) are believed the new future of electrochemical energy storage, while the solid electrolyte membrane is the core part. The development of new electrolyte membrane with easy densification, high stability and high conductivity is crucial for the widespread application of SSBs. In this study, tuning the conductivity and sintering behavior of perovskite-type La 2/3-x Li 3x TiO 3 (LLTO) membranes through a co-doping strategy was proposed and systematically investigated. Specifically, the membranes with the nominal compositions of Li 0.33-y+x La 0.557-x M x Ti 1-y N y O 3 (M = Sr, Ba, Ca, N = Ta) were designed and investigated. The results demonstrated that replacement of La3+ by smaller Ca2+ decreased the bulk Li+ conductivity while substitution of La3+ by Sr2+ or Ba2+ with larger ionic radii increased the bulk Li+ conductivity. Besides, Ta5+ and Sr2+ co-doped LLTO with optimized Ta/Sr molar ratio could improve the membrane densification involving the relative density and grain size. Accordingly, a high total Li+ conductivity (1.4 × 10−4 S cm−1) with low electronic conductivity (3.2 × 10−8 S cm−1) could be achieved, and the as-prepared Li 0.33 La 0.457 Sr 0.1 Ti 0.9 Ta 0.1 O 3 membrane presented prominent electrochemical performance with a high capacity retention (89%) and Coulombic efficiency of 97% for 80 cycles, thus promised co-doping strategy for developing superior perovskite Li-ion conducting membranes for SSBs. • Perovskite Li 0.33-y+x La 0.557-x M x Ti 1-y N y O 3 (M = Sr, Ba, Ca, N = Ta) membranes were prepared systematically. • Ta5+ and Sr2+ co-doped membrane exhibited high membrane densification and low grain boundary resistance. • Li 0.33 La 0.457 Sr 0.1 Ti 0.9 Ta 0.1 O 3 showed a total Li-ion conductivity of 1.4 × 10−4 S cm−1 at room temperature. • The membrane could be cycled in solid-state Li-ion battery with a capacity retention of 89% after 80 cycles. [ABSTRACT FROM AUTHOR]

• (Bi 2) m (Bi 2 Te 3) n nanotubular architectures were fabricated via the Kirkendall effect. • Tellurium precursor played a crucial role in the formation of nanoscale tubular structure. • (Bi 2) m (Bi 2 Te 3) n contains four custom-built composition of Bi 2 Te 3 , Bi 4 Te 3 , BiTe, and Bi 2 Te 3 -Te. • The results were verified by XRD, SEM, EDX, HR-TEM, SAED, and ICP-OES. The (Bi 2) m (Bi 2 Te 3) n series, as well-studied thermoelectric materials, have also attracted worldwide attention for their unique topological insulator property. However, only one of several compounds in the Bi-Te systems is synthesized, especially for one-dimensional structures. Herein, a two-step solvothermal process has been designed to synthesize nanotubular (Bi 2) m (Bi 2 Te 3) n series (i.e., Bi 2 Te 3 , Bi 4 Te 3 , BiTe, and Bi 2 Te 3 -Te) by optimizing the concentration of Bi agent and altering the microstructure of Te precursors during the reaction process regarding "Kirkendall effect". The results were verified by powder X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscope (EDS), high-resolution transmission electron microscope (HR-TEM), selected area electron diffraction (SAED), and inductively coupled plasma optical emission spectrometer (ICP-OES). A possible growth mechanism was proposed based on experimental results. This work provides a feasible way to selectively synthesize (Bi 2) m (Bi 2 Te 3) n compounds with tunable composition and structure. [Display omitted]. [ABSTRACT FROM AUTHOR]

Abstract: We demonstrate a promising method to fabricate highly adhesive silver nanoparticle coating on glass carbon electrode with good dispersity by using gas phase cluster beam deposition. The fabricated nanoparticles have clean surface and show enhanced electrocatalytic activity toward the reduction of H2O2 with a considerably decreased overpotential. A nonenzyme sensing platform for stable detection of H2O2 with a very rapid response time (less than 1s), high sensitivity (63μA/mM) as well as a low detection limit (1.3μM) is realized from the silver nanoparticle based electrode with a optimized nanoparticle coverage. [Copyright &y& Elsevier]

Abstract: Few-layer graphene sheets were prepared by splitting expanded graphite using high-power sonication. Atomic-level calibrated scanning transmission electron microscopy was used to obtain efficient layer statistics, enabling optimization of the experimental conditions. This resulted in a two-step splitting mechanism in which the mean number of layers was first reduced to less than 20 by heating to 1100°C and then to a few-layer region by a 5-min104 WL−1 – power-density sonication. Raman spectroscopic analysis confirms the above mechanism and demonstrates that the sheets are largely free of defects and functional groups. [Copyright &y& Elsevier]

Abstract: In this paper, we reported the successful synthesis of hierarchical Ni11(HPO3)8(OH)6 superstructures based on nanorods via a facile hydrothermal route, employing NiCl2·6H2O and NaH2PO2·H2O as the reactants in the presences of polyvinylpyrrolidone (PVP) and CH3COONa·3H2O. The reaction was carried out at 170°C for 10h. HPO3 2− ions were provided via the dismutation reaction of H2PO2 − ions in a weak basic solution. The as-obtained products were characterized by X-ray powder diffraction (XRD), energy dispersive spectrometry (EDS), field emission scanning electron microscopy (SEM), selected area electron diffraction (SAED) and high resolution transmission electron microscopy (HRTEM). Some factors influencing the morphology of the hierarchical Ni11(HPO3)8(OH)6 nanorods, such as the reaction temperature, time, the amounts of PVP and CH3COONa, and the initial concentration of Ni2+ ions, were systematically investigated. A possible growth mechanism was proposed based on experimental results. [Copyright &y& Elsevier]

Abstract Poor electrical conductivity of sulfur, sluggish redox kinetics, dissolution of intermediate polysulfides, and expansion in volume upon cycling are the main drawbacks that hamper the practical application of Li-S batteries. By taking advantages of the high conductivity and favorable catalytic activity of RuO 2 , we design a 3D carbon nanotube film with embedded RuO 2 nanoparticles as a freestanding type of chemisorptive and catalyst-like cathode for Li-S batteries, which can be facilely prepared by a surfactant-assisted vacuum infiltration method. Both experimental and theoretical results reveal the excellent capability of RuO 2 for anchoring polysulfides and accelerating the kinetics of polysulfides catalytic redox reactions. Besides, the 3D freestanding cathode is beneficial to overcoming pulverization during volume changes, especially for long-term cycling. At a high areal sulfur loading of 2 mg cm−2, favorable initial capacities of 750 and 1060 mA h g−1 respectively at 2 and 0.5 C are achieved. More attractively, the capacity after 1000 cycles maintains 405 mA h g−1 at 0.5 C with a loss in capacity of only 0.06% per cycle. Additionally, such freestanding cathode allows the batteries to be tested under various bending stages, hence encouraging more research works on fabrication of other 3D nanostructure families as high-performance cathodes for Li-S batteries. Graphical abstract A 3D free-standing catalyst-like cathode is designed and prepared for Li-S battery through a surfactant-assisted infiltration approach. Favorable high-rate performances and stabilities are delivered for Li-S battery with the as-prepared cathode due to the excellent chemisorption, high conductivity and for various redox reactions of RuO 2. The 3D free-standing catalyst-like cathode provides an inspirational model for promising flexible energy storage devices. Image 1 Highlights • A free-standing porous RuO 2 -embedded 3D CNT film is fabricated. • The freestanding film can overcome the pulverization of sulfur cathode. • Conductive RuO 2 shows favorable catalytic activity for polysulfides. • The cross-linked CNT enables the electron transport in whole cathode. • The Li-S battery with the freestanding cathode operates over 1000 cycles. [ABSTRACT FROM AUTHOR]

A sol-gel method with ethylene diamine tetraacetic acid and citric acid as co-chelates is employed for the synthesis of P2-type Na 2/3 Mn 1/2 Fe 1/4 Co 1/4 O 2 as cathode material for sodium-ion batteries. Among the various calcination temperatures, the Na 2/3 Mn 1/2 Fe 1/4 Co 1/4 O 2 with a pure P2-type phase calcined at 900 °C demonstrates the best cycle capacity, with a first discharge capacity of 157 mA h g −1 and a capacity retention of 91 mA h g −1 after 100 cycles. For comparison, the classic P2-type Na 2/3 Mn 1/2 Fe 1/2 O 2 cathode prepared under the same conditions shows a comparable first discharge capacity of 150 mA h g −1 but poorer cycling stability, with a capacity retention of only 42 mA h g −1 after 100 cycles. Based on X-ray photoelectron spectroscopy, the introduction of cobalt together with sol-gel synthesis solves the severe capacity decay problem of P2-type Na 2/3 Mn 1/2 Fe 1/2 O 2 by reducing the content of Mn and slowing down the loss of Mn on the surface of the Na 2/3 Mn 1/2 Fe 1/4 Co 1/4 O 2 , as well as by improving the activity of Fe 3+ and the stability of Fe 4+ in the electrode. This research is the first to demonstrate the origin of the excellent cycle stability of Na 2/3 Mn 1/2 Fe 1/4 Co 1/4 O 2 , which may provide a new strategy for the development of electrode materials for use in sodium-ion batteries. [ABSTRACT FROM AUTHOR]

Considering the abundance and low price of sodium, sodium-ion batteries (SIBs) are of particular attractiveness for large-scale electrochemical energy storage. Layered P2–Na 2/3 Mn 1/2 Fe 1/4 Co 1/4 O 2 (NMFC) is a promising cathode material for SIBs because of its large theoretical capacity, however, its high air sensitivity and poor cycling stability seriously limits the practical use. Here, we report nanometre-thick Al 2 O 3 coating of NMFC electrode through atomic layer deposition (ALD) technique can effectively alleviate such deficiencies to obtain an air-insensitive electrode, which was realized by effectively preventing the direct exposure of NMFC to H 2 O and CO 2 present in the air atmosphere. Interestingly, the ultrathin Al 2 O 3 coating did not cause a block for sodium ion intercalation, and a high capacity of 217.9 mA h g−1 at a high cut-off potential of 4.5 V was achieved. More attractively, a capacity retention rate as high as 84.8% was obtained after cycling at a current density of 0.5C over 100 cycles, demonstrating improved electrochemical stability. Based on CV and EIS characterizations, such good cycling stability is associated with the use of the Al 2 O 3 coating layer as well, which effectively avoided the side reactions at the interface of the liquid electrolyte and the active material under high potential. Display Omitted • Layered P2-type Na 2/3 Mn 1/2 Fe 1/4 Co 1/4 O 2 (NMFC) oxide was synthesized by solid-state method. • Ultrathin Al 2 O 3 layer was successfully coated on NMFC by atomic layer deposition. • The air sensitivity of NMFC was reduced. • The cycling stability of NMFC was improved. [ABSTRACT FROM AUTHOR]