太阳能驱动的氢-冷-热-电综合能源系统性能分析

基于可再生能源的综合能源系统具有清洁低碳与安全高效的特点。提出一种以抛物面槽式太阳能集热器驱动的综合能源系统,该系统包括质子交换膜电解池、有机朗肯循环和吸收式制冷子系统。根据能量梯级利用原理和热力学分析理论,建立综合能源系统的稳态数学模型,分析热力参数变化对系统性能的影响规律。结果表明,在设计条件下,质子交换膜电解槽制氢效率、有机朗肯循环发电效率和吸收式制冷效率分别为58.65%、12.20%、36.93%,制氢功冷联供总效率为55.58%。系统总效率随着涡轮机入口温度升高先增加后减少;随着发生器出口温度升高而增加。另外,增加工作压力和膜厚度会导致电解槽电压升高和电解槽效率下降。研究结果可为以抛物面槽式太阳能集热器驱动的多联供系统的建立和评价提供参考。     

Electrochemical stripping features of graphite and its products characterization

A stable dispersion in mixed solvent of water and N,N-dimethyl formamide (DMF) of graphene was synthesized by one-step electrochemical approach. Here we demonstrate about electrochemical stripping graphite to prepare graphene influence by different electrolytes. The physical and chemical properties of the stripping product had been characterized by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), UV-Vis spectrophotometer (UV-Vis), Scanning electron microscopy (SEM), Transmission Electron Microscope (TEM) . The characteristic results of XRD showed that it could improve the efficiency of graphite stripping when H₂SO₄ was used as electrolyte mother liquid and amount of HNO₃ was doped in electrolyte; XPS and FTIR results indicate that the electrochemical stripping products preserve the intrinsic structure of graphene. The results of SEM and TEM shown that the surface morphology of the as-prepared graphene was folded lamellar structure and have good transparency;its thickness varies from 0.8 nm to a few nanometers.     

环氧季铵盐对明胶的阳离子化改性

碱性条件下,环氧季铵盐1,2-环氧丙基二甲基十二烷基氯化铵(EPQA)与明胶侧链的伯胺基、羟基反应,得到阳离子改性明胶EPQA-GE,核磁共振(~(13)C-NMR、~1H-NMR)及元素分析结果表明,精氨酸、赖氨酸的氨基以及羟脯氨酸的羟基参与了反应,季铵阳离子基团成功引入了明胶结构中。X射线衍射及差示扫描量热分析结果表明,明胶的微观相结构受阳离子含量的影响较大,引入的季铵离子越多,EPQA-GE的近程有序度越高。以水和乙二醇为标准液,测定了阳离子化程度不同的EPQA-GE膜的接触角,并应用Owens-Wendt方程计算了表面自由能,结果显示阳离子基团的引入增加了明胶的亲水性,且随着阳离子化程度增加,膜表面的亲水性增强。抗菌实验结果表明阳离子的引入增加了明胶的抗菌性,EPQA-GE对革兰氏阳性菌的抗菌效果优于对革兰氏阴性菌的抗菌性。     

Highly Uniform Resistive Switching Properties of Solution‐Processed Silver‐Embedded Gelatin Thin Film

The silver‐embedded gelatin (AgG) thin film produced by the solution method of metal salts dissolved in gelatin is presented. Its simple fabrication method ensures the uniform distribution of Ag dots. Memory devices based on AgG exhibit good device performance, such as the ON/OFF ratio in excess of 10⁵ and the coefficient of variation in less of 50%. To further investigate the position of filament formation and the role of each element, current sensing atomic force microscopy (CSAFM) analysis as well as elemental line profiles across the two different conditions in the LRS and HRS are analyzed. The conductive and nonconductive regions in the current map of the CSAFM image show that the conductive filaments occur in the AgG layer around Ag dots. The migration of oxygen ions and the redox reaction of carbon are demonstrated to be the driving mechanism for the resistive switching of AgG memory devices. The results show that dissolving metal salts in gelatin is an effective way to achieve high‐performance organic–electronic applications.     

Electrochemical corrosion behavior of 2A02 Al alloy under an accelerated simulation marine atmospheric environment

The corrosion behavior of 2A02 Al alloy under simulated marine atmospheric environment has been studied using mass-gain, scanning electron microscope/energy dispersive spectroscopy (SEM/EDS), laser scanning confocal microscopy, X-ray diffraction spectroscopy and localized electrochemical methods. The results demonstrate that the relationship between the corrosion induced mass-gain and the corrosion time is in accordance with the power rule. The mass-gain increases gradually during the corrosion time, while the corrosion rate decreases. With ongoing of the corrosion, corrosion products film changed from a porous to a compact structure. The various spectroscopic data show that the corrosion products films composed mainly of Al(OH)₃, Al₂O₃ and AlCl₃. The electrochemical corrosion behavior of the 2A02 Al alloy was studied by electrochemical impedance spectroscopy (EIS).     

Performance Evaluation of Composite Electrolyte with GQD for All-Solid-State Lithium Batteries

The use a stabilized lithium structure as cathode material for batteries could be a fundamental alternative in the development of next-generation energy storage devices. However, the lithium structure severely limits battery life causes safety concerns due to the growth of lithium (Li) dendrites during rapid charge/discharge cycles. Solid electrolytes, which are used in high-density energy storage devices and avoid the instability of liquid electrolytes, can be a promising alternative for next-generation batteries. Nevertheless, poor lithium ion conductivity and structural defects at room temperature have been pointed out as limitations. In this study, through the application of a low-dimensional graphene quantum dot (GQD) layer structure, stable operation characteristics were demonstrated based on Li⁺ ion conductivity and excellent electrochemical performance. Moreover, the device based on the modified graphene quantum dots (GQDs) in solid state exhibited retention properties of 95.3% for 100 cycles at 0.5 C and room temperature (RT). Transmission electron microscopy analysis was performed to elucidate the Li⁺ ion action mechanism in the modified GQD/electrolyte heterostructure. The low-dimensional structure of the GQD-based solid electrolyte has provided an important strategy for stably-scalable solid-state lithium battery applications at room temperature. It was demonstrated that lithiated graphene quantum dots (Li-GQDs) inhibit the growth of Li dendrites by regulating the modified Li⁺ ion flux during charge/discharge cycling at current densities of 2.2–5.5 mA cm, acting as a modified Li diffusion heterointerface. A full Li GQD-based device was fabricated to demonstrate the practicality of the modified Li structure using the Li–GQD hetero-interface. This study indicates that the low-dimensional carbon structure in Li–GQDs can be an effective approach for stabilization of solid-state Li matrix architecture.     

液体电解质氧传感器输出特性研究

对液体电解质氧传感器在不同氧体积分数、氧分压下的输出特性进行研究.测量氧传感器在不同氧体积分数、氧分压下的输出值,利用最小二乘法对输出值进行处理,得到氧传感器的输出特性曲线.对特性曲线进行分析,结果表明:液体电解质氧传感器对氧体积分数、氧分压的测量具有良好的线性度.压力冲击对传感器工作电极造成损害从而影响传感器性能,加入粉末冶金层能够克服这一问题,但传感器的响应时间有所增长.     

The function of vinylene carbonate as a thermal additive to electrolyte in lithium batteries

The role of vinylene carbonate (VC) as a thermal additive to electrolytes in lithium ion batteries is studied in two aspects: the protection of liquid electrolyte species and the thermal stability of the solid electrolyte interphase (SEI) formed from VC on graphite electrodes at elevated temperatures. The nuclear magnetic resonance (NMR) spectra indicate that VC can not protect LiPF₆ salt from thermal decomposition. However, the function of VC on SEI can be observed via impedance and electron spectroscopy for chemical analysis (ESCA). These results clearly show VC-induced SEI comprises polymeric species and is sufficiently stable to resist thermal damage. It has been confirmed that VC can suppress the formation of resistive LiF, and thus reduce the interfacial resistance.     

CeO_2基极限电流氧传感器的研究

采用Gd掺杂的CeO2(Ce0.8Gd0.2O1.9,CGO)粉体,干压成型后于空气气氛下1450℃烧结4 h。通过物理特性分析,发现在该烧结制度下烧结成型的样品基本满足氧传感器对敏感材料的要求。制备了一种新型结构的致密扩散障型极限电流氧传感器。经测试,发现该传感器在较高氧体积分数范围内有较好的极限电流特性,并为此建立了相关的理论模型,较好地解释了此类传感器极限电流和氧体积分数的关系。     

MAGA-WNN模型在明胶浓度软测量中的应用

胶液浓度的测量在明胶的生产过程中是一项很重要的任务,为解决明胶浓度胶液手工检测中存在的滞后时间长、测量误差大等实际问题,将软测量技术应用到明胶的浓度测量中。通过对明胶生产工艺的分析,采用小波神经网络建立软测量模型,利用混合变异自适应遗传算法对模型参数进行优化。用现场采集并归一化后的120组数据做仿真实验,其中80组作为训练,40组作为预测。仿真结果表明,该算法迭代67次后误差平方和低于0.01并趋于稳定。证明混合变异自适应遗传算法可增强小波神经网络模型的鲁棒性和提高收敛速度。所以该算法用于明胶浓度的软测量中是可行的。