Acrylic acid-based copolymers are synthesized by polymerization of acrylic acid with a small portion of crosslinker, diallyl ethers. The obtained copolymers are soluble in water, and viscosity of their aqueous solution incrementally varies with increase in the amount of crosslinker and neutralization degree of -COOH groups with NaOH. The copolymers are examined as binders for silicon/graphite composite electrodes for lithium-ion batteries. Reversibility and lithiation capacity of the composite are highly improved by the selection of copolymers, which is due to better homogeneity and mechanical durability of the composite electrodes. © The Author Electrochemical lithiation has been extensively studied and discussed for application in lithium-ion batteries. Generally, active materials with higher-capacity lithiation suffers from repeated volume change during lithiation/delithiation especially in lithium silicide system. 1 Si-based electrodes demonstrate high-capacity lithiation, however, capacity fade inevitably arises from the huge volume change. The lithiation of Si-based electrodes is improved by binder selection, e.g. carboxymethylcellulose, 2 polyimide, polyacrylate, 3,4 compared to conventional fluorinated binders.Poly(acrylic acid) (PAH), commodity chemicals used in industry, improves mechanical stability of composite electrodes against the volume change. 5,6 Because poly(acrylic acid) is weak polyacid, its conformation in water is modulated by neutralization with alkali hydroxides, which is capable to adjust the slurry rheology and leads to better electrode performance. 6 The capacity retention of the Si-based composite was highly improved with 80% neutralized polyacrylate binders because of self-forming porous structure of the composite. 5Furthermore, PAH binders with cross-linkage between two carboxylic groups with polycarbodiimide efficiently improved the lithiation performance of Si.7 The cross-linkage proceeded in organic solvent during slurry process. In this study, we prepare a new water-soluble crosslinked binder, synthesized by copolymerization of acrylic acid with coexistence of crosslinker, diallyl ether, and demonstrate the battery performance of silicon-graphite electrodes with the copolymers. ExperimentalCross-linked poly(acrylic acid)s were synthesized by copolymerization of acrylic acid with different amount of dially ether as a crosslinker, H 2 C=CH-CH 2 -(O-CH 2 -CH 2 ) n -O-CH 2 -CH=CH 2 (n = 1 ∼ 4) as shown in Fig. 1a.8 Acrylic acid monomers were polymerized with different amounts of the crosslinker, 0, 0.007, 0.07, 0.14, and 0.7 mol% and the obtained polymers are hereafter denoted as PAH, 1CLPAH, 10CLPAH, 20CLPAH, and 100CLPAH, respectively. The polymers were dissolved in water to prepare 1 wt% binder solution, and further neutralized by dropping 1 mol dm −3 NaOH (titration up to pH 6.7) to convert 80% of -COOH into -COONa, 6 and they are similarly denoted as PAH 0.2 Na 0.8 , 1CLPAH 0.2 Na 0.8 , 10CLPAH 0.2 Na 0.8 , 20CLPAH 0.2 Na 0.8 , and 100CLPAH 0.2 Na 0.8 . Viscosity measurement o...

Various substituted nitroaromatics were successfully hydrogenated to the corresponding N-aryl hydroxylamines in excellent yields (up to 99%) using supported platinum catalysts such as Pt/SiO 2 under a hydrogen atmosphere (1 bar) at room temperature. The key to the fast and highly selective formation of hydroxylamines is the addition of small amounts of amines such as triethylamine and dimethyl sulfoxide; amines promote the conversion of nitroaromatics, while dimethyl sulfoxide inhibits further hydrogenation of hydroxylamines to anilines. The promotive effect depends on which type of amine and primary amine was most effective. The hydrogenation efficiently proceeded in common organic solvents, including isopropanol, diethyl ether, and acetone. This methodology should extend the application range of conventional solid catalysts to fine chemicals synthesis.

Quaternary ammonium- and amino-functionalized silica catalysts have been prepared for the selective synthesis of cyclic sulfites from epoxides and sulfur dioxide, demonstrating the effects of immobilizing the homogeneous catalysts on silica. The cycloaddition of sulfur dioxide to various epoxides was conducted under solvent-free conditions at 100 °C. The quaternary ammonium- and amino-functionalized silica catalysts produced cyclic sulfites in high yields (79-96 %) that are comparable to those produced by the homogeneous catalysts. The functionalized silica catalysts could be separated from the product solution by filtration, thereby avoiding the catalytic decomposition of the cyclic sulfite products upon distillation of the product solution. Heterogenization of a homogeneous catalyst by immobilization can, therefore, improve the efficiency of the purification of crude reaction products. Despite a decrease in catalytic activity after each recycling step, the heterogeneous pyridine-functionalized silica catalyst provided high yields after as many as five recycling processes.

The high anodic stability of electrolytes for rechargeable magnesium batteries enables the use of new positive electrodes, which can contribute to an increase in energy density. In this study, novel Ph3COMgCl-, Ph3SiOMgCl-, and B(OMgCl)3-based electrolytes were prepared with AlCl3 in triglyme. The Ph3COMgCl-based electrolyte showed anodic stability over 3.0 V vs. Mg but was chemically unstable, whereas the Ph3SiOMgCl-based electrolyte was chemically stable but featured lower anodic stability than the Ph3COMgCl-based electrolyte. Advantageously, the B(OMgCl)3-based electrolyte showed both anodic stability over 3.0 V vs. Mg (possibly due to the Lewis acidic nature of B in B(OMgCl)3) and chemical stability (possibly due to the hard acid character of B(OMgCl)3). B(OMgCl)3, which was prepared by reacting boric acid with a Grignard reagent, was characterized by nuclear magnetic resonance (NMR) spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and X-ray absorption spectroscopy (XAS). The above analyses showed that B(OMgCl)3 has a complex structure featuring coordinated tetrahydrofuran molecules. 27Al NMR spectroscopy and Al K-edge XAS showed that when B(OMgCl)3 was present in the electrolyte, AlCl3 and AlCl2+ species were converted to AlCl4−. Mg K-edge XAS showed that the Mg species in B(OMgCl)3-based electrolytes are electrochemically positive. As a rechargeable magnesium battery, the full cell using the B(OMgCl)3-based electrolyte and a Mo6S8 Chevrel phase cathode showed stable charge-discharge cycles. Thus, B(OMgCl)3-based electrolytes, the anodic stability of which can be increased to ~3 V by the use of appropriate battery materials, are well suited for the development of practical Mg battery cathodes.

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