Preparation of P(AN-MMA) gel electrolyte for Li-ion batteries

Phase inversion technique was used to prepare poly(acrylonitrile-methyl methacrylate) [P(AN-MMA)]-based microporous gel electrolyte with addition of SiO₂ via in-situ composition for Li-ion batteries. The P(AN-MMA) was synthesized by emulsion polymerization and was dissolved into N,N-dimethylformamide (DMF) to form a uniform solution, while tetraethyl orthosilicate (TEOS) was added into the solution and was hydrolyzed by catalysis of alkali ammonia solution to form SiO₂. Then the solution was cast onto a glass plate using a doctor blade and exposed to humidified atmosphere produced by ultrasonic humidifier, followed by washing, rinsing, and drying, successively. The gel electrolyte was obtained by putting the P(AN-MMA) microporous membrane in a liquid electrolyte. The gelled microporous membrane sucked with 755 wt% of liquid electrolyte vs the dried membrane. It had a porosity of 70%, about 1∼5 μm of pores, and presented an ionic conductivity of 0.94 × 10⁻³ S/cm at room temperature. Electrochemical stability window of the porous gel polymer electrolyte was determined by running a linear sweep voltammetry. The decomposition voltage of the polymer electrolyte exceeds 4.5 V vs Li. The coin test cell with the microporous gel electrolyte showed a good cycling performance. The discharge capacity retention was above 87% at 0.1 C for 45 cycles.     

A novel composite anode for LIB prepared via template-like-directed electrodepositing Cu–Sn alloy process

A novel composite anode material consisted of electrodeposited Cu–Sn alloy dispersing in a conductive micro-porous carbon membrane coated on Cu current collector was investigated. The composite material was prepared by template-like-directed electrodepositing Cu–Sn alloy process and then annealing. The template-like microporous membrane electrode was obtained as follows: (1) casting a polyacrylonitrile (PAN) solution on a copper foil, (2) then immersing the copper foil into deionized water for phase inversion, and (3) drying the membrane electrode. This method provided the composite material with high decentralization of Cu–Sn alloy and supporting medium function of conductive carbon membrane deriving from pyrolysis of PAN. SEM, XRD, and EDS analysis confirmed this structure. The characteristic structure was beneficial to inhibit the aggregation among Cu–Sn microparticles, to relax the volume expansion during cycling, and to improve the cycle ability of electrode. The reversible charge/discharge capacity of the composite material remained more than 426.6 and 445.1 mAh g⁻¹, respectively, after 70 cycles, while that of the electrode prepared by electrodepositing Cu–Sn on a bare Cu foil decreased seriously to only 11.3 mAh g⁻¹. These results show that the novel preparing anode process for LIB is a promising method and can achieve composite materials with larger specific capacity and long cycle life.     

重费米子化合物LiV2O4电子结构的第一性原理研究

用第一性性原理的FP-LMTO能带计算方法研究了重费米子化合物LiV2O4的电子结构。结果表明：费米面附近的导带是由V原子的3d电子形成的宽度为2.5eV的窄能带,是3d态在立方晶体场中具有t2g对称性的子带;它与O的2p轨道构成的能带有近1.9eV的能隙。计算得出的费米能处电子态密度和线性电子比热系数分别是11.1states/eV f.u.和26.7mJ/molK^2。费米面处的能带色散具有电子型和空穴型和空穴型两种,呈现出一种复杂的费米面结构。LSDA以及LDA+GGA计算表明,LiV2O4有一个磁矩为每个钒原子1.13μB,总能比LDA基态低约148meV/f.u.的铁磁性基态。由目前的能带结构计算的结构无法确定这一类Kondo体系的局域磁矩的来源,表明这一化合物中的重费米子行为可能有别于在含有4f和5f稀土的重费米子合金中观察到的局域磁矩与传导电子的交换作用机制,其中存在量子相变的可能。     

复合材料结构几何非线性分析

本文采用退化的等参壳元分析了复合材料板、壳结构的几何非线性特性。数值计算表明：与各向同性材料不同,即使在很小的载荷和挠度下,几何非线性对复合材料结构的影响也是相当显著的。     

各向异性矩形悬臂板稳态热传导解析

应用各向异性稳态热传导解析解分析了三边对流换热、另一边给定不均匀温度的各向异性矩形悬臂板温度场。讨论了各向异性角对温度场分布的影响。各向异性角的增大加剧了温度梯度。数值结果表明各向异性角为0°的悬臂板内温度梯度最小。     

锂离子电池合金负极材料的研究进展

本文综述了锂离子电池合金负极材料的研究现状,对比了各种合金负极材料的制备方法,并指出了合金负极材料目前面临的主要问题及现有的解决方案,最后提出纳米锂合金复合物将是合金负极材料发展的最终出路.     

Promoting Piezocatalytic H2O2 Production in Pure Water by Loading Metal-Organic Cage-Modified Gold Nanoparticles on Graphitic Carbon Nitride

Piezocatalytic hydrogen peroxide (H₂O₂) production is a green synthesis method, but the rapid complexation of charge carriers in piezocatalysts and the difficulty of adsorbing substrates limit its performance. Here, metal-organic cage-coated gold nanoparticles are anchored on graphitic carbon nitride (MOC-AuNP/g-C₃N₄) via hydrogen bond to serve as the multifunctional sites for efficient H₂O₂ production. Experiments and theoretical calculations prove that MOC-AuNP/g-C₃N₄ simultaneously optimize three key parts of piezocatalytic H₂O₂ production: i) the MOC component enhances substrate (O₂) and product (H₂O₂) adsorption via host–guest interaction and hinders the rapid decomposition of H₂O₂ on MOC-AuNP/g-C₃N₄, ii) the AuNP component affords a strong interfacial electric field that significantly promotes the migration of electrons from g-C₃N₄ for O₂ reduction reaction (ORR), iii) holes are used for H₂O oxidation reaction (WOR) to produce O₂ and H⁺ to further promote ORR. Thus, MOC-AuNP/g-C₃N₄ can be used as an efficient piezocatalyst to generate H₂O₂ at rates up to 120.21 μmol g⁻¹ h⁻¹ in air and pure water without using sacrificial agents. This work proposes a new strategy for efficient piezocatalytic H₂O₂ synthesis by constructing multiple active sites in semiconductor catalysts via hydrogen bonding, by enhancing substrate adsorption, rapid separation of electron-hole pairs and preventing rapid decomposition of H₂O₂.     

含有氟代溶剂或含氟添加剂的锂离子电解液

随着大型移动设备（如新能源汽车等）、储能电站及其他便携式充电设备的日益普及,锂离子电池正逐步占领化学电源市场的主导地位。电解液是锂离子电池的重要组成部分,对电池的许多性能如输出电压、能量密度、输出功率、寿命、温度适用范围和安全性能等具有重要的影响。氟具有很强的电负性和弱极性,氟代溶剂或含氟添加剂具有低熔点、高闪点和高氧化分解电压等优点。氟代溶剂与电极材料之间的润湿性也较好,在高电压电解液、高安全性电解液、宽温度窗口电解液以及其他特殊功能电解液的开发中具有深入的研究和广泛的应用。本文综述了近年来氟代溶剂或添加剂在锂离子电池电解液中的不同应用,分析阐述了其对电池性能提升的机理,总结了以氟代碳酸乙烯酯（FEC）为代表的氟代溶剂的合成方法,最后对用于锂离子电池电解液的氟代溶剂或含氟添加剂的研发方向和发展趋势进行了展望。