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The reduction of ketones or alkenes is an attractive and challenging task in organic chemistry and has widespread applications in the production of fine chemicals, fragrances, pharmaceuticals, vitamins, and functional materials. Classical reduction methods usually require the use of potentially dangerous hydrogen and the reaction under high temperature and pressure conditions, so environmentally friendly, economical, simple, and safe reduction methods are urgently needed. This paper innovatively reports a method for the electrochemical reduction of diarylketones or aryl alkenes in a mixed solvent system of CH3CN/THF. The reaction proceeds smoothly, and the corresponding products are obtained in high yields. The mechanistic study shows that the reaction is a free radical reaction, and reveals the necessity of CH3CN solvent, which plays the three roles of solvent, proton donors, and reactant at the same time. Furthermore, the high yield of the gram‐scale experiment successfully confirmed the potential industrial application of this electrochemical method. [ABSTRACT FROM AUTHOR]

Rechargeable batteries are considered one of the most effective energy storage technologies to bridge the production and consumption of renewable energy. The further development of rechargeable batteries with characteristics such as high energy density, low cost, safety, and a long cycle life is required to meet the ever‐increasing energy‐storage demands. This Review highlights the progress achieved with halide‐based materials in rechargeable batteries, including the use of halide electrodes, bulk and/or surface halogen‐doping of electrodes, electrolyte design, and additives that enable fast ion shuttling and stable electrode/electrolyte interfaces, as well as realization of new battery chemistry. Battery chemistry based on monovalent cation, multivalent cation, anion, and dual‐ion transfer is covered. This Review aims to promote the understanding of halide‐based materials to stimulate further research and development in the area of high‐performance rechargeable batteries. It also offers a perspective on the exploration of new materials and systems for electrochemical energy storage. [ABSTRACT FROM AUTHOR]

Abstract: Fiber‐shaped rechargeable batteries hold promise as the next‐generation energy storage devices for wearable electronics. However, their application is severely hindered by the difficulty in fabrication of robust fiber‐like electrodes with promising electrochemical performance. Herein, yolk–shell NiS2 nanoparticles embedded in porous carbon fibers (NiS2⊂PCF) are successfully fabricated and developed as high‐performance fiber electrodes for sodium storage. Benefiting from the robust embedded structure, 3D porous and conductive carbon network, and yolk–shell NiS2 nanoparticles, the as‐prepared NiS2⊂PCF fiber electrode achieves a high reversible capacity of about 679 mA h g−1 at 0.1 C, outstanding rate capability (245 mA h g−1 at 10 C), and ultrastable cycle performance with 76% capacity retention over 5000 cycles at 5 C. Notably, a flexible fiber‐shaped sodium battery is assembled, and high reversible capacity is kept at different bending states. This work offers a new electrode‐design paradigm toward novel carbon fiber electrodes embedded with transition metal oxides/sulfides/phosphides for application in flexible energy storage devices. [ABSTRACT FROM AUTHOR]

Abstract: Herein we report the proof-of-principle of a new concept of rechargeable batteries based on chloride shuttle, i.e., chloride ion batteries. This system includes the metal chloride/metal electrochemical couple and an electrolyte composed of binary ionic liquids allowing chloride ion transfer at room temperature. [Copyright &y& Elsevier]

A key challenge of chloride ion batteries is to develop cathode materials that are stable in the electrolytes. Metal oxychlorides are presented as such a cathode material. The electrochemical performance and the reaction mechanisms of the BiOCl and FeOCl cathode were investigated. Both cathodes showed reversible reactions, including a major conversion reaction and a minor intercalation process, by chloride ion transfer during cycling. [ABSTRACT FROM AUTHOR]

Abstract: Elemental substitution of part Ti by Zr has been carried out for Ti2Ni alloy to form Ti2−x Zr x Ni (x = 0, 0.2, 0.4) alloys. Mechanical milling and subsequent heat treatment have been used to prepare non-equilibrium Ti–Zr–Ni alloys. The effects of Zr addition on the structure and discharge properties of Ti2Ni alloy were investigated. The addition of Zr could enhance the discharge capacity of the non-equilibrium Ti2Ni alloy at electrolyte temperatures of 313 and 333 K. For instance, the non-equlibrium Ti1.6Zr0.4Ni alloy had a stable discharge capacity of about 210 mAh/g at 313 K. However, the protective surface layer formed during heat treatment was destroyed at a high electrolyte temperature of 333 K, and thus a severe capacity loss during cycling. [Copyright &y& Elsevier]

Abstract: Cu2O/Cu composite particles were synthesized by a novel and facile chemical reduction method without any template or surfactant. X-ray diffraction (XRD) results showed that the product mainly consisted of the Cu2O phase coexisting with a few Cu phases. Typical FE-SEM images indicated that the particles with an octahedral shape were Cu2O. In addition, the electrochemical performance of the Cu2O/Cu particles as the working electrode material in alkaline solution was systematically investigated. The particles showed a maximum discharge capacity of 222.9mAhg−1 at a discharge current density of 60mAg−1 and a high value of 109.1mAhg−1 after 50 charge–discharge cycles. The results of cyclic voltammetry demonstrated that the reaction between Cu2O and Cu is the major electrochemical reaction during the charging and discharging process. The results of electrochemical impedance spectroscopy indicated that the formation of Cu2O on the surface of Cu particles significantly increased the contact resistance and the charge transfer resistance of the electrode during the discharging process. [Copyright &y& Elsevier]

Abstract: The AB5 alloy and Co powders have been mixed at various weight ratios to form AB5–Co composite electrodes. The discharge properties such as discharge capacity, discharge plateau, and cycling stability are investigated by charge and discharge testing using Arbin battery testing equipment. Synergistic effects in the composite electrodes contribute to significant improvements of the discharge behavior. For instance, the composite AB5–25%Co electrode shows a high discharge capacity of 395.1mAh/g, which is significantly higher than that of AB5 or Co electrode, and good cycling stability. The discharge process is also characterized by electrochemical impedance spectroscopy. Moreover, the electrochemical discharge mechanism is discussed. [Copyright &y& Elsevier]

Abstract: Mechanical alloying has been carried out to synthesize a hydrogen storage alloy by milling titanium hydride and nickel. The structure and electrochemical properties such as discharge capacity, charge-transfer, and hydrogen diffusion of the milled powders were investigated. The results of X-ray diffraction showed that an amorphous phase was formed after ball milling. The electrode potentials of the milled powders were −0.989, −0.878 and −0.941V (vs. Hg/HgO) in the electrolyte of 6M KOH when the milling periods were 20, 40, and 60h, respectively. The Ti–Ni–H powders milled for 60h had a maximum discharge capacity of 102.2mAh/g at a discharge current density of 60mA/g. The results of the linear polarization showed that the exchange current density decreased as the hydrogen concentration within the powders decreased. The electrochemical impedance spectroscopy (EIS) demonstrated the same consequence and presented that the hydrogen diffusion decreased by decreasing the hydrogen concentration. [Copyright &y& Elsevier]

Abstract: The structure and electrochemical properties of titanium-based hydrogen storage alloy prepared by solid phase sintering at 1123K were investigated. The result of X-ray diffraction (XRD) showed that the sintered alloy mainly consists of Ti2Ni phase coexisting with TiNi, TiNi3 and Ni phases. The alloy had a maximum discharge capacity of 205mAh/g at a discharge current density of 60mA/g and showed a discharge capacity of 146mAh/g at 150mA/g. The results of linear polarization (LP) and potential-step measurement presented that the exchange current density and hydrogen diffusion efficient of the alloy were 100mA/g and 4.2×10−9 cm2/s, respectively. The electrochemical performance of the alloy could be effectively improved by using solid phase sintering. [Copyright &y& Elsevier]

Abstract: Surface treatment by the fluorination treatment with an aqueous solution of KF and HF with a little addition of KBH4 followed by electroless Ni–P plating has been carried out to modify the surface structure and electrochemical properties of the La–Ni–Al hydrogen storage alloy. The results of scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) show that a Ni-rich and Al-poor layer forms after fluorination treatment. The electroless plating results in the precipitation of the nanometer-scale Ni–P particles with homogeneous distribution on the alloy surface. Both the treatments contribute to an increase in exchange current density, a decrease in charge-transfer resistance and the facility of hydrogen diffusion within the bulk alloy, leading to significant improvements on high rate dischargeability (HRD) of the alloy. The alloy treated by the composite treatment of the fluorination treatment and the following electroless plating possesses best overall electrode performance. [Copyright &y& Elsevier]

The desalination battery is regarded as a promising high‐efficiency technology for seawater desalination on account of the reversible salt‐ion storage in the bulk of the battery electrodes. Herein, polypyrrole is used as a new electrode to store chloride ions in seawater desalination. The as‐prepared polypyrrole composite electrode shows good electrochemical reversibility in chloride‐ion storage and removal in the aqueous NaCl electrolyte. When this chloride electrode is incorporated with a sodium electrode of sodium manganese oxide, a desalination battery that can capture chloride and sodium ions from the electrolyte through the electrochemical redox reactions is obtained. A stable and reversible capacity of 40 mAh g−1 of the desalination battery is achieved after 200 cycles. [ABSTRACT FROM AUTHOR]

The chloride ion battery has been developed as one of the alternative battery chemistries beyond lithium ion, toward abundant material resources and high energy density. Its application, however, is limited by the dissolution of electrode materials and side reactions in the liquid electrolyte. Herein, a solid polymer electrolyte allowing chloride ion transfer and consisting of poly(ethylene oxide) as the polymer matrix, tributylmethylammonium chloride as the chloride salt, and succinonitrile as the solid plasticizer is reported. The as‐prepared polymer electrolyte shows conductivities of 10−5–10−4 S cm−1 in the temperature range of 298–343 K. When it is assembled with the iron oxychloride/lithium electrode system, reversible electrochemical redox reactions of FeOCl/FeO at the cathode side and Li/LiCl at the anode side are realized, demonstrating the first all‐solid‐state rechargeable chloride ion battery. An all‐solid‐state rechargeable chloride ion battery is developed by employing a ternary solid polymer electrolyte, which is composed of a polyethylene oxide (PEO) polymer matrix, a quaternary ammonium chloride salt, and a solid succinonitrile plasticizer. The electrochemical redox reaction mechanisms and the chloride ion transport in the as‐assembled battery are revealed. [ABSTRACT FROM AUTHOR]

Abstract Iron oxychloride has been regarded as a promising cathode material for chloride ion batteries (CIBs). However, it suffers a severe capacity decay during repeated conversion reactions based on chloride ion transfer. Herein, we report an iron oxychloride composite material with a polypyrrole coating (FeOCl@PPy), which is prepared by a facile and efficient chemical vapor phase polymerization method, as cathode for CIB. The as-prepared FeOCl@PPy cathode material with drastically enhanced charge transfer and chloride ion diffusion shows a stable core-shell structure, which can prevent the FeOCl particles from pulverization during cycling. As a result, a maximum capacity of 187 mA h g−1 and significantly improved cycling stability with 82.9% capacity retention after 30 cycles are obtained. In contrast, the neat FeOCl cathode fades fast and shows only 13.2% capacity retention. Highlights • FeOCl@PPy material was prepared by a chemical vapor phase polymerization method. • PPy coating enhances the charge transfer and ion diffusion of FeOCl cathode. • Stable core-shell structure of FeOCl@PPy cathode contributes to significant improvement in cycling stability. [ABSTRACT FROM AUTHOR]

Finding and optimizing the appropriate cathode materials in the electrolyte are critical to the development of chloride ion batteries. Herein, chloride ion-doped polyaniline/carbon nanotubes (PANI/CNTs) composite materials, which were prepared by an in situ chemical oxidative polymerization method using FeCl 3 ·6H 2 O as the oxidant, have been developed as new cathodes for chloride ion battery. The PANI/CNTs cathode showed reversible electrochemical energy storage through redox reactions of nitrogen species and chloride ion transfer, as confirmed by the results of the electrochemical testing and X-ray photoelectron spectroscopy. The structural configuration of PANI by the incorporation of conductive CNT carrier contributed to significant improvement in the electrochemical properties. More than 80 mAh g −1 stable capacity and a high Coulombic efficiency of about 99% were delivered. This work offers a promising strategy for designing chloride ion storage electrode and novel electrochemical systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • The polyaniline/graphene material is first employed as the faradaic electrode in the desalination system. • The as-prepared polyaniline-based electrode delivers a high reversible capacity of 126 mA h g−1. • Competitive chloride ion storage performance of the polyaniline electrode is achieved. The use of anion storage materials has played an important role in the development of electrochemical energy storage systems and water desalination. Herein, the graphene-supported polyaniline (PANI/GN) nanomaterial is developed as a new chloride ion storage electrode in aqueous sodium chloride solution. The as-prepared PANI/GN electrode exhibits highly reversible electrochemical stability in both a three-electrode system and a full desalination battery using a sodium ion storage electrode. Competitive electrochemical properties with a reversible capacity of 126 mA h g−1, a coulombic efficiency of more than 95 % and a high rate capability are achieved for the PANI/GN electrode compared to the previously reported electrodes of metals, antimony oxychloride, and polypyrrole. The anionic chloride species instead of covalent chloride species in the as-prepared PANI/GN is demonstrated to be electrochemically active. [ABSTRACT FROM AUTHOR]