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Three unsymmetrical tetradentate Schiff base ligands, H2salipn, H2salipn-Br4 and H2salipn-Cl2, have been synthesized from the typical condensation reactions of treating 1,2-diaminopropane with salicylaldehyde, 3,5-dibromosalicylaldehyde and 5-chlorosalicylaldehyde, respectively. Treatment of [RuCl2(PPh3)3] with one equivalent of H2salipn or H2salipn-Br4 in the presence of triethylamine in tetrahydrofuran (THF) afforded the corresponding ruthenium(III) complexes [RuIIICl(PPh3)(salipn)] (1) and [RuIIICl(PPh3)(salipn-Br4)] (2). Interaction of [RuHCl(CO)(PPh3)3] with one equivalent of H2salipn-Cl2 or H2salipn-Br4 under the same conditions led to isolation of ruthenium(II) complexes [RuII(CO)(PPh3)(salalipn-Cl2)] (3) and [RuII(CO)(PPh3)(salalipn-Br4)] (4), respectively, in which one of the imine bonds was nucleophilically attacked by hydride to result in the formation of a mixed imine-amine ligand. The molecular structures of 1⋅1.5CH2Cl2, 2, 3⋅0.5CH2Cl2 and 4 have been determined by single-crystal X-ray crystallography. The electrochemical properties of 1–4 were also investigated. Their cyclic voltammograms displayed quasi-reversible Ru(IV)/Ru(III) and Ru(III)/Ru(II) couples with Eo ranging from 0.67 to 1.05 V and 0.74 to 0.80 V vs. Ag/AgCl (0.1 M), respectively. [ABSTRACT FROM AUTHOR]

Transformation-type anodes such as Fe3O4 and other transition-metal oxides are gaining popularity in rechargeable Li-ion batteries, but the poor cycling performance and low poor Coulombic efficiency seriously influence their practical applications. Herein, we design a facile method to prepare well-defined yolk-shell Fe3O4@C nanocomposites, and test the nanocomposites as anode material for Li-ion battery. Due to the protection of carbon shell and the loose interspace structure, the capacity of this yolk-shell Fe3O4@C nanocomposites electrode is approximately 860 mAh g−1 after 300 cycles at 200 mA g−1 charge/discharge current density with 2 mg cm−1 loading. The first Coulombic efficiency is about 73.2% and the average Coulombic efficiency is 99% in the following cycles. The remarkably high specific capacity and excellent cycle performance endow the yolk-shell Fe3O4@C nanocomposites as a great potential anode for the Li-ion batteries application. [ABSTRACT FROM AUTHOR]

The garnet-type solid Li-ion conductor, Li6.4La3Zr1.4Ta0.6O12, is viewed as a promising solid-state electrolyte for the next-generation high-performance Li-ion battery because of its high ionic conductivity and stability. The previous researches, in order to avoid Li volatilization loss during solid-state reaction of sintering, mother powder with the same composition as green bodies was usually used to cover the samples, it would waste the expensive raw materials and increase the fabrication cost. In this study, a new method was proposed to prepare the Li6.4La3Zr1.4Ta0.6O12 ceramic solid-state electrolyte where the Li loss is compensated by the outside Li2CO3. Samples prepared by this method have pure garnet phase and compact micromorphology with few pores. These samples have a high Li-ion conductivity of 2.9×10−4 S/cm and a low activation energy of 0.37 eV at room temperature. The electronic conductivity is 1.08×10−8 S/cm, which can be neglected for solid-state electrolyte. [ABSTRACT FROM AUTHOR]

A facile and scalable strategy, based on a hydrothermal route, has been applied to fabricate potassium vanadate (KVO) nanowires on Ti fabric. The morphology, crystal structure, chemical composition of the prepared sample are tested and presented in detail. When tested as cathode materials for lithium-ion batteries, the flexible KVO electrode has a high reversible capacity of 270 mAh g −1 at a current density of 100 mA g −1 after 300 cycles. Furthermore, the KVO delivers outstanding rate behavior, even at 960 mA g −1 , a reversible capacity as high as 214.1 mAh g −1 can be retained. The superior electrochemical performance suggests that the KVO nanowires on Ti fabric can be as a potential cathode candidate for flexible rechargeable lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: Solid carbon electrooxidation is the anode reaction of a direct carbon fuel cell. In this study, electrooxidation of graphite in molten carbonates containing transition metal oxides (Fe2O3, Co3O4, NiO, and MnO2) is investigated. It is demonstrated that, by dissolving transition metal oxides into the molten Li2CO3–K2CO3, the onset potential for graphite oxidation is significantly shifted to negative value and the oxidation current density is remarkably increased. At 750 °C, NiO causes a negative shift of onset oxidation potential by around 0.3 V and a current density (at −0.4 V) increase by 4.5 times. The coulombic efficiency of graphite oxidation remains above 94% with and without metal oxides. The apparent activation energy is reduced by more than 40 kJ mol−1 by the addition of metal oxides. The working mechanism of the transition metal oxides is interpreted by electronegativity of metal cations, the concentration of oxygen anions and the indirect oxidation pathway via preceding chemical reaction-following electrochemical reaction. [Copyright &y& Elsevier]

We present herein the vertical step‐growth polymerization of a monomer A‐B through individual A–A or B–B coupling driven by electrochemical switching of positive and negative bias on a self‐assembled A or B electrode. The monomer RuII(bda)AB (bda=2,2′‐bipyridine‐6,6′‐dicarboxylate), in which A and B are pyridine moieties with pendant carbazolyl and vinyl groups, could be dimerized at oxidative (ca. 1.0 V vs. Ag/Ag+) or reductive potential (ca. −1.8 V) to give a self‐assembled RuII(bda)PA or RuII(bda)PB monolayer (P=pyridine with a pendant phosphonic acid) on ITO glass. This polymerization enabled the sequence‐ and topology‐controlled synthesis of surface‐confined molecular wires with single‐molecule precision on an electrode. The electrocatalytic performance of the vertically orientated molecular wires for water oxidation increased with increasing molecular length and exceeded that of both the self‐assembled monolayer and a randomly electropolymerized film, which have previously been studied as typical models. A step up: Vertical step‐growth polymerization of a monomer A‐B through individual A–A and B–B coupling reactions driven by electrochemically positive and negative bias on a self‐assembled A or B electrode enabled the sequence‐ and topology‐controlled synthesis of molecular wires with single‐molecule precision (see picture). The resulting surface‐confined molecular wires showed fast electron transfer and excellent electrocatalytic performance. [ABSTRACT FROM AUTHOR]

Abstract: A multi‐state and multi‐stimuli‐responsive oxazine molecular switch that combines an electro‐base property and sensitive base/acid‐responsive properties was designed and synthesized. The multi‐state structures of the molecular switch, with different colors, were predicted by comparing the optical properties with reference molecules and confirmed by using NMR spectroscopy. The color‐switching mechanism under stimulation with acids and bases was investigated by using DFT calculations. Three single states can be obtained and the switching is unidirectional under acid and base stimulation. The electrochromic phenomenon of the molecular switch, which combines its electro‐base and base‐sensitive properties, was demonstrated. An electrochromic device that exhibited good electrochromic properties with excellent reversibility (2000 cycles) and high coloration efficiency (804 cm2 C−1) was successfully constructed. [ABSTRACT FROM AUTHOR]

Cubic perovskite–type oxide Li 3/8 Sr 7/16 Hf 1/4 Ta 3/4 O 3 (LSHT) is a promising solid electrolyte material for next–generation Li–ion batteries such as all–solid–state Li batteries and Li–redox flow batteries due to its high room–temperature Li–ion conductivity and good chemical compatibility with commercial organic liquid electrolyte. High relative density is another important requirement for these applications. Here we investigate the influence of sintering additives (Li 3 BO 3 , Li 4 SiO 4 , LiF) on the density, the total Li–ion conductivity, the interfacial conductivity against commercial liquid electrolyte, and the cycling performance of the hybrid Li-ion cells. The results show that comparing with other additives, LSHT sintered with 2 wt% LiF shows the highest Li–ion conductivity (3.3 × 10 −4 S cm −1 ) and the smallest interfacial resistance (125 Ω cm 2 ) against organic electrolyte at room temperature; Li/LiFePO 4 batteries with LSHT pellets fired with 2 wt% LiF have the best cyclability and the highest coulombic efficiency (99.6 ± 0.04%) in 50 cycles. [ABSTRACT FROM AUTHOR]

The electrochemical behavior of aqueous processing lithium cobalt oxide (LiCoO2) cathodes used hydrogen peroxide (H2O2)-treated vapor-grown carbon fibers (VGCFs) as a conductive agent for lithium-ion batteries has been investigated and improved. The sedimentation experiments show that the dispersibility in water of H2O2-treated VGCFs is better than that of KS-6 (flaky graphite) or as-received VGCFs. This improvement is due to the surface chemistry of H2O2-treated VGCFs has become more hydrophilic that was evidenced by its significant shift of iso-electric point (I.E.P) from pH 6.7 to 5.0. As a result, the H2O2-treated VGCFs can be well-dispersed in the LiCoO2 electrode which was observed by scanning electron microscope. Furthermore, the rate capability results of electrodes show that addition with H2O2-treated VGCFs has better performance than that with KS-6 or as-received VGCFs. [ABSTRACT FROM AUTHOR]