Search

All-solid-state Li-ion batteries (ASSLIBs) are promising but face several challenges, especially regarding Li-metal anodes prone to dendrite formation and Si-based anodes with limited performance. To address this issue, we propose a self-stabilizing Sn-based anode. While Sn anodes suffer from agglomeration during cycling, transition metal-Sn anodes, specifically FeSn2anodes, self-stabilize during cycling by exhibiting uniformity and densification without cycling-induced agglomeration, owing to their unique electrochemical-cycling-induced size reduction and distinctive mechanical properties. A full cell with an FeSn2anode, a LiNi0.6Co0.2Mn0.2O2cathode, and a Li6PS5Cl solid electrolyte exhibits highly reversible areal capacity (15.54 mAh cm−2at 100 mg cm−2cathode loading), excellent rate capability (74.5%/83.2% retention over 1,000 cycles at 10/20 C), and exceptional energy density at high current densities. The self-stabilizing FeSn2anodes offer high energy density, compatibility with solid electrolytes, safety, wide operating temperature range, cost effectiveness, and scalability, thereby accelerating the realization of superior ASSLIBs.

Graphical abstract:

Four main anode types are generally considered as typical anodes for Li-ion batteries (LIBs): Li-metal, carbon-based, alloy-based, and oxide-based anodes. Although they exhibit satisfactory electrochemical performance as LIB anodes, they cannot simultaneously satisfy all key requirements for LIB anodes: high reversible capacity, high initial Coulombic efficiency (ICE), long cycle life, fast rate capability, structural stability, and no safety concerns. Here, we suggest Li-compound anodes as a promising class of high-performance LIB anodes. Three binary (LiSn, Li2Sb, and LiBi) and three ternary (Li2ZnSb, Li5GeP3, and Li5SnP3) Li compounds were introduced as Li-compound anodes. LiSn and Li5SnP3were selected and further modified into their nanocomposites by solid-state synthetic routes using carbon sources for high-performance LIB anodes. The Li-compound nanocomposite anodes exhibited excellent performance and simultaneously fulfilled all the key requirements for high-performance LIB anodes. Therefore, Li-compound anodes are expected to be a promising and innovative category of high-performance LIB anodes.

We describe the electrochemical α-amidoalkylation of γ-lactams based on transition-metal-free cross-coupling via hydrogen atom transfer. The highly selective hydrogen atom transfer process allows for a broad substrate scope including both inter- and intramolecular reactions. Also, the construction of quaternary centers was realized by a double hydrogen atom transfer protocol to afford spirocycles. Detailed mechanistic studies including experimental and computational studies are provided to support the reaction pathway.

Electrocatalysts with dramatically enhanced water splitting efficiency, derived from controlled structures, phase transitions, functional activation, etc., have been developed recently. Herein, we report an in situobservation of graphene-based self-healing, in which this functional activation is induced by a redox reaction. Specifically, graphene on stainless steel (SUS) switches between graphene (C–C) and graphene oxide (C–O) coordination via an electrical redox reaction to activate water splitting. A heterostructure comprising Pt-NiO thin films on single-layer graphene directly grown on a SUS substrate (Pt-NiO/Gr-SUS) was also synthesized by electrodeposition. Pt-NiO/Gr-SUS exhibited water splitting activity with low Pt loading (<1 wt %). The findings provide valuable insight for designing robust electrodes based on reversible redox-induced self-healable graphene to develop more efficient catalysts.

The synthesis of versatile scaffold indolopyrans based on C–C radical–radical cross-coupling under metal-free conditions is described. The reaction involving single electron transfer between coupling partners followed by cage collapse allows highly selective cross-coupling while employing only equimolar amounts of coupling partners. Moreover, the mechanistic manifold was expanded for the functionalization of enamines to give the stereoselective synthesis of 2,3-dihydrofurans. This iodine-mediated oxidative coupling features mild conditions and fast reaction kinetics.

To design a high-performance sodium-ion battery anode, binary zinc phosphides (ZnP2and Zn3P2) were synthesized by a facile solid-state heat treatment process, and their Na storage characteristics were evaluated. The Na reactivity of ZnP2was better than that of Zn3P2. Therefore, a C-modified ZnP2-based composite (ZnP2-C) was fabricated to achieve better electrochemical performance. To investigate the electrochemical reaction mechanism of ZnP2-C during sodiation/desodiation, various ex situ analytical techniques were employed. During sodiation, ZnP2in the composite was transformed into NaZn13and Na3P phases, exhibiting a one-step conversion reaction. Conversely, Zn and P in NaZn13and Na3P, respectively, were fully recombined to the original ZnP2phase during desodiation. Owing to the one-step conversion/recombination of ZnP2in the composite during cycling, the ZnP2-C showed high electrochemical performance with a highly reversible capacity of 883 mA h g–1after 130 cycles with no capacity deterioration and a fast C-rate capability of 500 mA h g–1at 1 C and 350 mA h g–1at 3 C.

Metal phosphides are attractive candidates for use as anodes in high-performance Li/Na–ion batteries (LIBs/NIBs) owing to their high theoretical capacities and low operating potentials. In this study, CoP2-C hollow nanoboxes (HNBs), that is, CoP2nanocrystallites (~5–10 nm) embedded in N-doped carbon HNBs, were produced using a simple two-step method and utilized as LIB/NIB anodes. Various cutting-edge ex situtechniques were used to analyze the phase transition mechanism of the CoP2-C HNBs during the Li/Na reaction. The CoP2-C HNBs anode exhibited high initial reversible capacities (LIB: 1082 mAh g−1, NIB: 507 mAh g−1), high-rate capabilities (LIB: 926 mAh g−1at 3C, NIB: 370 mAh g−1at 2C), and excellent cycling performance at a high 1C rate (LIB: ~91 % capacity retention over 100 cycles, NIB: ~100 % capacity retention over 100 cycles), respectively. The excellent anode performance of LIBs/NIBs was attributed to the uniformly embedded CoP2nanocrystallites in the robust N-doped carbon HNBs and the electrochemically driven recombination reaction of CoP2. Therefore, we believe that CoP2-C HNBs are promising high-capacity anodes for LIBs/NIBs, and that this unique HNBs architecture is highly suitable for various energy storage and conversion systems.

To design an easily manufactured, large energy density, highly reversible, and fast rate-capable Li-ion battery (LIB) anode, Co–Sn intermetallics (CoSn2, CoSn, and Co3Sn2) were synthesized, and their potential as anode materials for LIBs was investigated. Based on their electrochemical performances, CoSn2was selected, and its C-modified nanocomposite (CoSn2/C) as well as Ti- and C-modified nanocomposite (CoSn2/a-TiC/C) was straightforwardly prepared. Interestingly, the CoSn2, CoSn2/C, and CoSn2/a-TiC/C showed conversion/nonrecombination, conversion/partial recombination, and conversion/full recombination during Li insertion/extraction, respectively, which were thoroughly investigated using ex situX-ray diffraction and extended X-ray absorption fine structure analyses. As a result of the interesting conversion/full recombination mechanism, the easily manufactured CoSn2/a-TiC/C nanocomposite for the Sn-based Li-ion battery anode showed large energy density (first reversible capacity of 1399 mAh cm–3), high reversibility (first Coulombic efficiency of 83.2%), long cycling behavior (100% capacity retention after 180 cycles), and fast rate capability (appoximately 1110 mAh cm–3at 3Crate). In addition, degradation/enhancement mechanisms for high-capacity and high-performance Li-alloy-based anode materials for next-generation LIBs were also suggested.

The complexity of Alzheimer’s disease (AD) stems from the inter-relation of multiple pathological factors upon initiation and progression of the disease. To identify the involvement of metal-bound amyloid-β (metal-Aβ) aggregation in AD pathology, among the pathogenic features found in the AD-affected brain, small molecules as chemical tools capable of controlling metal–Aβ aggregation were developed. Herein, we report a new class of 2,2′-bipyridine (bpy) derivatives (1–4) rationally designed to be chemical modulators toward metal–Aβ aggregation over metal-free Aβ analogue. The bpyderivatives were constructed through a rational design strategy employing straightforward structural variations onto the backbone of a metal chelator, bpy: (i) incorporation of an Aβ interacting moiety; (ii) introduction of a methyl group at different positions. The newly prepared bpyderivatives were observed to bind to metal ions [i.e., Cu(II) and Zn(II)] and interact with metal–Aβ over metal-free Aβ to varying degrees. Distinguishable from bpy, the bpyderivatives (1–3) were indicated to noticeably modulate the aggregation pathways of Cu(II)–Aβ and Zn(II)–Aβ over metal-free Aβ. Overall, our studies of the bpyderivatives demonstrate that the alteration of metal binding properties as well as the installation of an Aβ interacting capability onto a metal chelating framework, devised via the rational structure-based design, were able to achieve evident modulating reactivity against metal–Aβ aggregation. Obviating the need for complicated structures, our design approach, presented in this work, could be appropriately utilized for inventing small molecules as chemical tools for studying desired metal-related targets in biological systems.

A cubic crystal-structured Sn-based compound, SnTe, was easily synthesized using a solid-state synthetic process to produce a better rechargeable battery, and its possible application as a Sn-based high-capacity anode material for Li-ion batteries (LIBs) and Na-ion batteries (NIBs) was investigated. The electrochemically driven phase change mechanisms of the SnTe electrodes during Li and Na insertion/extraction were thoroughly examined utilizing various ex situanalytical techniques. During Li insertion, SnTe was converted to Li4.25Sn and Li2Te; meanwhile, during Na insertion, SnTe experienced a sequential topotactic transition to NaxSnTe (x≤ 1.5) and conversion to Na3.75Sn and Na2Te, which recombined into the original SnTe phase after full Li and Na extraction. The distinctive phase change mechanisms provided remarkable electrochemical Li- and Na-ion storage performances, such as large reversible capacities with high Coulombic efficiencies and stable cyclabilities with fast C-rate characteristics, by preparing amorphous-C-decorated nanostructured SnTe-based composites. Therefore, SnTe, with its interesting phase change mechanisms, will be a promising alternative for the oncoming generation of anode materials for LIBs and NIBs.

Tin selenides with layered crystal structures, SnSe and SnSe2, were synthesized by a solid-state method and electrochemically tested for use as Li-ion battery anodes. The phase change mechanisms of these compounds were thoroughly evaluated by ex situ X-ray diffraction and Se K-edge extended X-ray absorption fine structure techniques. SnSe showed better electrochemical reversibility of Li insertion/extraction than SnSe2, which was attributed to remarkable conversion/recombination reactions of the former compound during lithiation/delithiation. Additionally, the electrochemical performance of SnSe was further enhanced by preparing carbon-modified nanocomposites using two different methods, that is, heat treatment (HT) for producing a carbon coating using polyvinyl chloride as a precursor and high-energy ball milling (BM) using carbon black powder. The SnSe/C electrode produced by BM showed a highly reversible initial capacity of 726 mA h g–1with a good initial Coulombic efficiency of ∼82%, excellent cycling behavior (626 mA h g–1after 200 cycles), and a fast C-rate performance (580 mA h g–1at 2C rate).

Among the various liquid metals, Ga has unique properties, such as a low melting temperature, fluidity, and non-toxicity. In addition, Ga can alloy with Li to form a Li2Ga phase, which can be applied to high-capacity anodes for Li-ion batteries (LIBs). However, Ga-based materials readily melt and agglomerate during lithiation/delithiation owing to their low melting temperature and high surface energy, resulting in poor cycling stability. In this study, two structural types of Ga, crystalline and amorphous, were selected and electrochemically investigated as LIB anodes. Subsequently, to address the melting and agglomeration issues of the Ga anode, an optimized Ga-based nanocomposite was developed using a novel synthetic concept, namely a solid-state alloying–dealloying process. This process involves an alloying reaction of Ga and Ti to form various Ga–Ti compounds, such as Ga3Ti, Ga2Ti, and Ga3Ti2, and a dealloying reaction with amorphous C to form a nanocomposite comprising evenly dispersed amorphous Ga and Li-inactive TiC in the amorphous C matrix. The Li-inactive TiC and amorphous C matrix in the nanocomposite effectively confined amorphous Ga, thereby preventing the problems caused by its melting and agglomeration during cycling. In addition, an interesting transformation behavior of amorphous Ga into electrochemically stabilized Ga nanocrystallites (approximately 2–3 nm) was demonstrated during cycling, contributing to the high electrochemical performance. The Ga-based nanocomposite exhibited a superior electrochemical performance. This study proposes a better understanding of high-performance Ga-based anodes for LIBs as well as an effective fabrication method for high-performance nanocomposites by solid-state alloying–dealloying.

To achieve high-performance Ga anodes for alkali-ion batteries, the electrochemical Li/Na/K-ion reaction pathways in Ga are thoroughly elucidated using ex situanalytical tools. Ga exhibits a high Li-ion storage reaction owing to the formation of Li2Ga (theoretical capacity: 769 mAh g−1). However, it exhibits poor Na- and K-ion storage reactions owing to the formation of NaGa4(theoretical capacity: 96 mAh g−1) and K3Ga13(theoretical capacity: 89 mAh g−1), respectively. The high Li-ion storage reaction in Ga demonstrates its potential as an anode for Li-ion batteries (LIBs). Therefore, we fabricate an amorphous Ga composite (Ga/C) comprising amorphous Ga homogeneously distributed in an amorphous carbon using a simple one-pot solid-state mechanical process. Ga/C exhibits high reversible capacity, long-term Li-ion storage stability, and high rate capability. In addition, three-step confinement of amorphous Ga in the composite during continuous cycling is demonstrated and suggested as an enhancement mechanism for high-performance Ga/C anodes for LIBs. The interesting Li-ion storage reaction in Ga and high-performance amorphous Ga composites are expected to be highly applicable to LIB anodes.

A layered GeS2material was assessed as an electrode material in the fabrication of superior rechargeable Li-ion batteries. The electrochemical Li insertion/extraction behavior of the GeS2electrode was investigated from extended X-ray absorption measurements as well as by cyclic voltammetry and differential capacity plots to better understand its Li insertion/extraction behavior. Using the Li insertion/extraction reaction mechanism of the GeS2electrode, an interesting amorphous GeS2-based composite was developed and tested for use as a high-performance electrode. Interestingly, the amorphous GeS2-based composite electrode exhibited highly reversible discharging and charging reactions, which were attributed to a conversion/recombination reaction. The amorphous GeS2-based composite electrode exhibited highly reversible and outstanding electrochemical performances, a highly reversible capacity (first charge capacity: 1298 mAh g–1) with a high first Coulombic efficiency (83.3%), rapid rate capability (ca. 800 mAh g–1at a high current rate of 700 mA g–1), and long capacity retention over 180 cycles with high capacity (1100 mAh g–1) thanks to its interesting electrochemical reaction mechanism. Overall, this layered GeS2and its amorphous GeS2/C composite are novel alternative anode materials for the potential mass production of rechargeable Li-ion batteries with excellent performance.

Supplemental digital content is available in the text.

The development of an electrode material for rechargeable Li-ion batteries (LIBs) and the understanding of its reaction mechanism play key roles in enhancing the electrochemical characteristics of LIBs for use in various portable electronics and electric vehicles. Here, we report a three-dimensional (3D) crystalline-framework-structured silicon diphosphide (SiP2) and its interesting electrochemical behaviors for superior LIBs. During Li insertion in the SiP2, a three-step electrochemical reaction mechanism, sequentially comprised of a topotactic transition (0.55–2 V), an amorphization (0.25–2 V), and a conversion (0–2 V), was thoroughly analyzed. On the basis of the three-step electrochemical reaction mechanism, excellent electrochemical properties, such as high initial capacities, high initial Coulombic efficiencies, stable cycle behaviors, and fast-rate capabilities, were attained from the preparation of a nanostructured SiP2/C composite. This 3D crystalline-framework-structured SiP2compound will be a promising alternative anode material in the realization and mass production of excellent, rechargeable LIBs.

Among the various existing layered compounds, silicon diselenide (SiSe2) possesses diverse chemical and physical properties, owing to its large interlayer spacing and interesting atomic arrangements. Despite the unique properties of layered SiSe2, it has not yet been used in energy applications. Herein, we introduce the synthesis of layered SiSe2through a facile solid-state synthetic route and demonstrate its versatility as a sulfide solid electrolyte (SE) additive for all-solid-state batteries (ASSBs) and as an anode material for Li-ion batteries (LIBs). Li-argyrodites with various compositions substituted with SiSe2are synthesized and evaluated as sulfide SEs for ASSBs. SiSe2-substituted Li-argyrodites exhibit high ionic conductivities, low activation energies, and high air stabilities. In addition, when using a sulfide SE, the ASSB full cell exhibits a high discharge/charge capacity of 202/169 mAh g–1with a high initial Coulombic efficiency (ICE) of 83.7% and stable capacity retention at 1C after 100 cycles. Furthermore, the Li-storage properties of SiSe2as an anode material for LIBs are evaluated, and its Li-pathway mechanism is explored by using various cutting-edge ex situanalytical tools. Moreover, the SiSe2nanocomposite anode exhibits a high Li- insertion/extraction capacity of 950/775 mAh g–1, a high ICE of 81.6%, a fast rate capability, and stable capacity retention after 300 cycles. Accordingly, layered SiSe2and its versatile applications as a sulfide SE additive for ASSBs and an anode material for LIBs are promising candidates in energy storage applications as well as myriad other applications.

We aimed to determine whether the controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) technique could improve the image quality of the hepatic arterial phase of gadoxetic acid–enhanced liver magnetic resonance (MR) imaging.

We present a display-based visual stimulator for psychophysical and electrophysiological visual sensitivity measurements. The stimulator offers various psychophysical visual stimuli and transfers the signals from external devices along with the stimulation signals to an electrophysiological recorder. As an experimental demonstration, we perform a visual sensitivity experiment in the mesopic vision range by using the display-based stimulator. The intensity of the steady-state visual evoked potential is observed to correlate with the luminance of the flickering visual stimulation. For the psychophysically determined detection thresholds, we determine the mesopic luminance, showing agreement with the perceived brightness within the uncertainty of the luminance measurement.

Functionalization of enamidesunder Heck conditions has been limited to those with unsubstituted vinyl groups. By tuning reaction parameters that allow for the balance between stability and reactivity of reactants, the oxidative Heck cross‐coupling to produce highly substituted enamides in good to excellent yields was achieved (see scheme).

The manipulation of the bandgap of graphene by various means has stirred great interest for potential applications. Here we show that treatment of graphene with xenon difluoride produces a partially fluorinated graphene (fluorographene) with covalent C−F bonding and local sp3-carbon hybridization. The material was characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, electron energy loss spectroscopy, photoluminescence spectroscopy, and near edge X-ray absorption spectroscopy. These results confirm the structural features of the fluorographane with a bandgap of 3.8 eV, close to that calculated for fluorinated single layer graphene, (CF)n. The material luminesces broadly in the UV and visible light regions, and has optical properties resembling diamond, with both excitonic and direct optical absorption and emission features. These results suggest the use of fluorographane as a new, readily prepared material for electronic, optoelectronic applications, and energy harvesting applications.

The stereoselective diazo transferreaction with oxime ethers offers an efficient route to the corresponding α‐diazo oxime ethers. The utility of these compounds has been demonstrated by the synthesis of highly substituted pyrroles through a [3+2] cycloaddition of α‐oximino carbenoids with enamines (see scheme).

A highly oriented nanostructure of poly(styrene)-b-(ethylene-alt-propylene)-b-(ethylene) (PS/PEP/PE) semicrystalline terblock copolymer was deformed under tensile loading. Roll casting process oriented the microdomains of the terpolymer. Hexagonally ordered PS cylinders subsequently guided the crystallization of the PE block occurring in between the PS cylinders, resulting in the molecular chain orientation of the PE blocks perpendicular to the PS cylinder axis. The structure change of the terblock copolymer under deformation was monitored using Simultaneous Wide Angle X-ray Scattering (WAXS) and Small Angle X-ray Scattering (SAXS). The samples with the load parallel and perpendicular to the cylindrical axis of the PS show their mechanical failures at the strain of approximate 100 % and 210%, respectively. The anisotropic mechanical behavior was interpreted by interplay of the different types of the nano scale domains

The first metastable phase Ag, ZnS: α-In2S3QDs were synthesized by ultrafast light-material interaction. The multiple irradiation of millisecond flash pulses facilitated thermodynamic non-equilibrium superheating and quenching for metastable QD formation, as well as sequential self-formation of α-In2S3QD nucleation, Ag-doping and ZnS-passivation by photo-responsive ionic kinetics. Upon multiple illumination of flash pulses, the synthesis mechanism of Ag, ZnS: α-In2S3QD was experimentally proved by atomic-resolution transmission electron microscopy (AR-TEM), scanning TEM (STEM) and diverse spectral analysis. To verify the metastable phase QD formation by superheating/quenching in reaction solution, the localized surface plasmon (LSP) properties and instantaneous temperature increment were theoretically calculated using finite-difference time-domain (FDTD) method. Finally, optoelectronic performance and long-term stability of as-synthesized QDs were evaluated by demonstrating the broad wavelength metal-semiconductor-metal (MSM) photoelectric device.

Developing sensing approaches that can exploit visible light for the detection of low-concentration hydrogen at room temperatures has become increasingly important for the safe use of hydrogen in many applications. In this study, heterostructures composed of monolayer MoS2and Pd nanoclusters (Pd/MoS2) acting as photo- and hydrogen-sensitizers are successfully fabricated in a facile and scalable manner. The uniform deposition of morphologically isotropic Pd nanoclusters (11.5 ± 2.2 nm) on monolayer MoS2produces a plethora of active heterojunctions, effectively suppressing charge carrier recombination under light illumination. The dual photo- and hydrogen-sensitizing functionality of Pd/MoS2can enable its use as an active sensing layer in optoelectronic hydrogen sensors. Gas-sensing examinations reveal that the sensing performance of Pd/MoS2is enhanced three-fold under visible light illumination (17% for 140 ppm of H2) in comparison with dark light (5% for 140 ppm of H2). Photoactivation is also found to enable excellent sensing reversibility and reproducibility in the obtained sensor. As a proof-of-concept, the integration of Pd nanoclusters and monolayer MoS2can open a new avenue for light-induced hydrogen gas sensing at room temperature.

Representative Ge-rich binary Co–Ge compounds (CoGe, Co5Ge7, and CoGe2) are synthesized by facile solid-state reactions and apply as Li-ion battery (LIB) anode materials. Among the binary Co–Ge compounds studied, CoGe2shows the highest Li reversibility. Thus, a CoGe2-decorated carbon composite (CoGe2@C) is prepared to improve the electrochemical performance of CoGe2. Ex situanalysis results of X-ray diffraction and extended X-ray absorption fine structure demonstrate that the CoGe2@C has an interesting mechanism of conversion/recombination during Li insertion/extraction. Owing to this continual conversion/recombination mechanism during cycling, the CoGe2@C shows superior electrochemical performance. Specifically, CoGe2@C shows high reversible capacity (1,106 and 973 mAh/cm3 at current density of 50 and 100 mA/g, respectively), stable cycling behavior (93.3% and 98.8% capacity retention at a cycling rate of 50 mA/g and 100 mA/g, respectively, after 100 cycling), and fast rate capability with stable cycling behavior (~700 mAh/cm3 at 1C rate over 200 cycles). Therefore, CoGe2@C can be used as a high-performance LIB anode material.

To obtain anodes with a high reversible capacity, high initial coulombic efficiency (ICE), long cycle durability, and fast rate-capability for Li-ion batteries (LIBs), a nanostructured Si-based composite comprising Si, a Li-inactive FeSi2matrix, and carbonaceous matrices was developed by combination of simple solid-state synthetic methods. Firstly, various FexSiyalloys with different atomic compositions were synthesized by simple high-energy ball milling (HEBM) and their potential as LIB anodes was investigated. Among these FexSiyalloys, the Fe10Si90alloy (comprising Si-FeSi2) exhibited the highest first reversible capacity of 2609 mAh g−1and ICE of ∼91%. To further enhance the electrochemical performance of the Si-FeSi2alloy, a graphite-modified (Fe10Si90-graphite (Si-FeSi2-G)) composite was synthesized by using the physical force generated during HEBM, and the Si-FeSi2-G composite was further hierarchically carbon-coated (Fe10Si90-graphite-C (Si-FeSi2-G-C)) with polyvinyl chloride (PVC) by pyrolysis. The final product (Si-FeSi2-G-C composite) was comprised of well-dispersed nanocrystalline Si (active for Li) and FeSi2(inactive for Li) within the graphite and amorphous carbon matrices. The Si-FeSi2-G-C composite exhibited excellent electrochemical performance with a high first reversible capacity of 1045 mA h g−1, a high ICE of 87%, a long cycle durability of 925 mAh g−1over 80 cycles, and fast rate-capability of 700 and 550 mAh g−1at 1.2C and 2C rates, which meets the requirements for commercial use as a high-capacity Si-based anode for LIBs.

CoSn2/SnO2/C nanocomposites were synthesized by a simple mechanical solid-state synthesis method using a disproportionation reaction of SnO and a stable formation of CoSn2. The synthesized CoSn2/SnO2/C nanocomposites were composed of small CoSn2(5–10 nm) and SnO2(∼5 nm) nanocrystallites within amorphous C matrices, whose electrochemical performances were tested for use as Li-ion battery anodes. Additionally, the electrochemical reaction mechanism during Li insertion/extraction was characterized thoroughly using ex situ extended X-ray absorption fine structure analyses. The CoSn2/SnO2/C nanocomposites showed high electrochemical performances with a high reversible initial capacity of 803 mAh g−1, an excellent cycling behavior (571 mAh g−1after 500 cycles), and a fast C-rate performance (approximately 645 mAh g−1at 1C rate and 560 mAh g−1at 3C rate). The high electrochemical performance of CoSn2/SnO2/C nanocomposites demonstrated its promise as a new high-performance Li-ion battery anode.

A nanocrystalline-Zn-embedded TiOx–amorphous carbon composite was prepared using a two-step high-energy mechanical milling (HEMM) process. First, the starting ZnO was reduced to Zn by Ti incorporation via HEMM. The resulting Zn–TiOxcomposite was then placed in an amorphous carbon matrix via a second milling step, resulting in a Zn–TiOx–C nanocomposite. The samples were analyzed by X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy; the results confirmed the formation of metallic Zn and amorphous TiOxphases in the composite. The nanocrystalline-Zn-embedded phase and its distribution were observed by high-resolution transmission electron microscopy. The electrochemical reaction mechanism of the Zn–TiOx–C nanocomposite with Li+during the first cycle was investigated by ex situ XRD analysis. The results demonstrated the reaction sequence of the nanocrystalline Zn phase with Li+and the electrochemical reactivities of the amorphous TiOxand carbon phases toward Li+. In the electrochemical tests, the Zn–TiOx–C composite showed greatly improved electrochemical properties compared to those of pure Zn. This improvement was attributed to the microstructure of the composite, in which the nanocrystalline Zn was uniformly dispersed, to the TiOxphases, and to the amorphous carbon matrix functioning as buffers against the large volume changes of Zn.

Sb2Te3and its amorphous carbon-modified nanocomposite (Sb2Te3–C) are synthesized by simple solid-state synthetic methods, and their potential as anode materials for rechargeable Na-ion batteries (NIBs) is evaluated. Ex situ X-ray diffraction and high-resolution transmission electron microscopy clearly demonstrate the sodiation/desodiation reaction mechanism of the Sb2Te3and Sb2Te3–C nanocomposite electrodes. In both electrodes, Sb2Te3is converted into Na3Sb and Na2Te during Na insertion. However, Na3Sb and Na2Te in only the Sb2Te3–C nanocomposite electrode recombine into the original Sb2Te3phase after full Na extraction. As a consequence of its interesting conversion/recombination reaction during sodiation/desodiation reaction, the Sb2Te3–C nanocomposite electrode exhibits a long cycle life with highly reversible gravimetric and volumetric capacity (373 mAh g−1and 765 mAh cm−3over 50 cycles) and fast rate capability (1 C: 391 mAh g−1and 802 mAh cm−3; 2 C: 377 mAh g−1and 773 mAh cm−3).

The electrochemical reaction mechanisms of the tin oxides, SnO and SnO2, were investigated to obtain a fundamental understanding of their Li insertion/extraction behaviors using ex situ X-ray diffraction, X-ray absorption near edge structure, X-ray absorption fine structure, and high-resolution transmission electron microscopy analyses along with differential capacity plots. The results of the analyses thoroughly demonstrated partial recombination reactions of SnO and SnO2.

Sn/In2O3/C nano composite was prepared from SnO, In and amorphous carbon (Super P) using thermal reduction followed by high-energy mechanical milling. The nanocomposite consisted of nanosize Sn and In2O3crystallites, which were randomly distributed in the amorphous carbon matrix. The electrochemical performances of the nanocomposite were evaluated and the reaction mechanism of the composite during cycling was investigated using an X-ray diffractometer (XRD) and high-resolution transmission electron microscopy (HRTEM). The cycle performance of the nanocomposite was greatly enhanced when compared to each component of the composite. The nanocomposite exhibited charge capacity of ca. 600 mAh g−1over 100 cycles, with a first-cycle Coulombic efficiency of 71%.

Conditions for the oxidative Heck cross‐coupling of enamides are developed.

α‐Oximino diazo compounds such as (I), (IV) and (VII) can serve as carbenoid precursors furnishing access to 2‐isoxazolines and 2H‐azirines under rhodium catalysis.

A stereoselective diazo transfer reaction with oxime ethers offers an efficient route to the corresponding α‐diazo oxime ethers which are subsequently used for the synthesis of highly substituted pyrroles through a [3+2] cycloaddition with enamines.

Review: 313 refs.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Intermetallic TiSb2and Sb/TiC/C nanocomposites were prepared by alloying and dealloying reactions, respectively, and their potential as anode materials for rechargeable Li-ion batteries was investigated. The Sb/TiC/C nanocomposite was composed of nanocrystalline Sb and TiC, which were distributed uniformly in an amorphous carbon matrix. The reaction mechanism of intermetallic TiSb2with Li was examined by ex situ X-ray diffraction and high resolution transmission electron microscopy. The Sb/TiC/C nanocomposite exhibited good electrochemical performance, such as a high initial coulombic efficiency of 87% and a long cycle retention of 83% after 100 cycles.

The electrochemical behavior of Ag with Li was investigated with various particle sizes and under different current densities. When tested at a current of 10mAg−1, the electrochemical behavior of a nano-Ag electrode showed a highly reversible reaction with Li, with the first discharge and charge capacities being 1158 and 727mAhg−1, respectively. The electrochemical reaction mechanism of Ag alloying/dealloying with Li was revealed by ex situ X-ray diffraction analyses combined with a differential capacity plot of the nano-Ag electrode.

The electrochemical reaction mechanism of germanium with lithium at room temperature was investigated. Two distinct voltage plateaus corresponding to the formation of Li9Ge4and Li7Ge2were observed, and the final products were identified as a mixture of Li15Ge4and Li22Ge5phases. A three-step reaction mechanism of germanium with lithium was suggested. Carbon-coated germanium composites prepared by mechanical milling and pyrolysis were evaluated as anode materials for lithium-ion batteries. The composite materials, Ge–mesocarbon microbeads and Ge–poly(vinyl alcohol), showed good cyclability and retained fairly large capacities of 473 and 579mAh∕g, respectively, up to 50 cycles when cycled within a limited voltage window.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Abstract not Available.

Antimony (Sb)/carbon nanocomposite and Sb/carbon/graphite composite were prepared by high-energy mechanical milling and were investigated as an anode material for Li rechargeable batteries. X-ray diffraction and high-resolution transmission electron microscopy revealed that the Sb/carbon nanocomposite is composed of nanosized Sb and amorphous carbon, and the electrochemical tests showed that it exhibited good electrochemical reversibility and enhanced cyclability. Moreover, the cyclic performance and high-rate capability can be further enhanced by controlling the voltage range or discharge capacity. Also, Sb/carbon/graphite composite showed a high capacity with very good cyclic performance.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.