高电压磷酸钴锂正极材料性能调控研究

高性能、高安全储能电池的迫切需求加速了橄榄石型高电压正极材料的研究步伐。为了改善高电压磷酸钴锂(LiCoPO₄)的综合电化学性能,采用溶剂热法研究了溶剂比、过渡元素(Fe、Mn)单掺杂和双掺杂(掺杂元素总量占10%)对正极材料形貌、尺寸、反位缺陷和电化学性能的影响。结果表明,当溶剂比为2.3时,未掺杂LiCoPO₄在0.1C下表现出163.1 mAh·g^-1的最高理论比容量;双掺杂LiCo_0.9Mn_0.05Fe_0.05PO₄正极材料具有突出的循环性能,在0.5C电流密度下,循环100圈后的容量保持率为78.9%,循环稳定性得到明显改善。     

Acceptor-rich bulk heterojunction polymer solar cells with balanced charge mobilities

In this work, we reported efficient polymer solar cells with balanced hole/electron mobilities tuned by the acceptor content in bulk heterojunction blend films. The photovoltaic cells were fabricated with two new wide band-gap D-A polymers PBDDIDT and PBDDIDTT as the donor material. The molecular conformations of new polymers are carefully evaluated by theoretical calculations. The results of photovoltaic studies show that two devices reach their optimal conditions with rich PC₇₁BM content up to 80% in blend films, which is uncommon with most of reported PSCs. The as-cast devices based on PBDDIDT and PBDDIDTT reveal good photovoltaic performance with PCE of 7.04% and 6.40%, respectively. The influence of PC₇₁BM content on photovoltaic properties is further detailed studied by photoluminescence emission spectra, charge mobilities and heterojunction morphology. The results exhibit that more efficient charge transport between donor and acceptor occurs in rich PC₇₁BM blend films. Meanwhile, the hole and electron mobilities are simultaneously enhanced and afford a good balance in rich PC₇₁BM blend films (D/A, 1:4) which is critical for the improvement of current density and fill factors.     

Effects of thin film processing on pentacene/C60 bilayer solar cell performance

Solar cells based on pentacene/C₆₀ bilayer heterojunctions have been fabricated with a structure of ITO/poly(styrenesulfonate) (PEDOT:PSS)/pentacene (40 nm)/fullerene (C₆₀)(40 nm)/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) (10 nm)/Al. The effect of pentacene crystalline domain size on performance was investigated by controlling the pentacene deposition rate. The devices show improved light-to-electricity conversion efficiencies from 0.49% to 1.12% under an AM 1.5 solar simulator (100 mW/cm²), when the pentacene evaporation rate is in a range of 5 Å/s–0.5 Å/s. Atomic force microscopy (AFM) measurements show that the pentacene films deposited by a slow evaporation rate have larger crystalline domains and a fewer amorphous domains, compared to films obtained by faster evaporation rates. Upon thermal annealing at 200 °C for 1 min, there is merging of pentacene crystalline domains. These changes in film morphology impact the charge separation at the donor/acceptor interface and the hole and electron mobilities, and hence, directly affect the device performance.     

WS2 sensitized mesoporous TiO2 for efficient photocatalytic hydrogen production from water under visible light irradiation

Nanosized WS₂ sensitized mesoporous titanium dioxide (TiO₂) was prepared to extend the adsorption of the wide band gap TiO₂ into visible light region. Compared with TiO₂ substrate without mesopores, it was found that the mesoporous substrate is beneficial for larger amount of WS₂ loading and inhibition of the light-induced detachment of WS₂ particles from the substrate during photocatalytic reaction, which leads to higher photocatalytic activity and better stability. We also found that the rate-determining step for photocatalytic hydrogen production is the transfer of electrons from TiO₂ substrate to H⁺ in solution, when the recombination between electrons and holes within TiO₂ could be neglected. In this case, deposition of Pt at the surface of semiconductor is indispensable for efficient hydrogen production.     

高熵合金涂层研究进展

制备各类涂层对材料表面进行强化是提高材料服役性能的重要途径,可根据服役环境要求,在不影响基体性能的前提下,通过调控工艺改变涂层成分、组织结构,从而改善其性能,延长部件的使用寿命.高熵合金及其涂层是近年来材料领域的研究热点,具有优异的强度、韧性、耐蚀性、耐磨性等特点,在表面工程领域的应用发展迅速.通过设计不同体系的高熵合...     

氨基酸改性碳纤维电极电化学及海洋电场响应性能

碳纤维表面引入含氧、含氮官能团,可提高其电化学性能和电场响应性能。将谷氨酸、甘氨酸、赖氨酸作为含氧、含氮官能团载体,在碳纤维表面接枝一层分子膜,通过扫描电子显微镜、红外吸收光谱等手段进行表面表征,并结合循环伏安曲线、电化学阻谱和电场响应曲线等测试方法,探究其电化学性能和电场响应性能变化。结果表明,改性后碳纤维电极具有较大的双电层电容和较低的低频容抗;配对碳纤维电极电位差漂移量均在5 mV/d以下,电化学自噪声均小于5 nV/Hz;配对碳纤维电极能较好地响应1 mV、1 mHz正弦交流电场信号,其中谷氨酸改性组线性度为0.058%,在改性组中最低,这与其特殊的双电层结构有关。本研究可为高性能海洋电场传感器研究提供新的技术路线和理论依据。     

环氧树脂涂层表面亲水性对微藻黏附性能的影响

在固体材料表面黏附成膜是微藻细胞的一种生理特性。近些年基于微藻生物膜的生物过程，如生物膜贴壁培养和防附着技术受到了很多关注。微藻在固体材料表面的黏附受藻细胞与材料表面之间的相互作用的影响，建立黏附强度与材料表面性质参数间的关系对于通过材料选择来强化或控制微藻生物膜具有非常重要的意义。本工作的目的是揭示和明确材料亲疏水性对微藻黏附的影响，提出了一种双酚A环氧(EP)树脂表面亲疏水改性的方法。通过将亲水性的二乙醇胺(DEA)或疏水性的聚甲基聚硅氧烷(PMHS)加入到EP树脂中反应，EP树脂表面水接触角在36.80?~98.34?范围内可通过加入不同量的DEA或PMHS实现任意可调，材料的表面水接触角与DEA或PMHS加入量之间有线性关系。重要的是这种改性方法获得的材料，其形貌、结构、表面粗糙度等表面性质几乎没有变化，从而在研究和关联微藻黏附量与材料表面亲疏水性(表面水接触角)之间的关系时可以排除亲疏水性之外的其他表面性质的影响；其次，考察了小球藻和栅藻在不同亲疏水性材料表面的黏附行为，结果表明小球藻和栅藻在亲水性和疏水性材料表面均能黏附成膜，但在亲水性材料表面黏附更多更快；建立了微藻最大黏附容量与材料表面接触角之间关联关系，表明微藻最大黏附容量随材料表面水接触角的增大而线性降低，栅藻的表面黏附容量比小球藻大。     

Hydrophobic organic coating based water--solid TENG for water-flow energy collection and self-powered cathodic protection

Water–solid triboelectric nanogenerators (TENGs), as new energy collection devices, have attracted increasing attention in ocean energy harvesting and self-powered sensing. Polyacrylic acid (PAA) coating, usually used on the surface of marine equipment, has the property of anti-aging and anti-wear but limits triboelectrical output when used with TENGs. In this paper, polyacrylic acid coating was modified with fluorinated polyacrylate resin (F-PAA) to increase its triboelectrical output, by 6 times, and also to increase its anti-corrosion property. In addition, the corrosion resistance property can be further enhanced by cathodic protection using the electrical output generated by the water-flow triboelectrical energy transfer process. Given their easy fabrication, water-flow energy harvesting, and corrosion resistance, PAA/F-PAA coating-based TENGs have promising applications in river and ocean energy collection and corrosion protection.     

Stability of n-type doped conducting polymers and consequences for polymeric microelectronic devices

Present polymeric microelectronic devices are typically unipolar devices, based on p-type semiconducting polymers. Bipolar devices stable under ambient conditions are desirable, but have not yet been reported due to a lack of stable n-type doped conducting polymers. Starting from the standard redox potentials of, especially, water and oxygen, stability requirements on electrode potentials of n-type doped conducting polymers are derived. The predictions are then compared with experimental data on stability of conducting polymers. A good agreement is obtained. An electrode potential of about 0 to + 0.5 V (SCE) is required for stable n-type doped polymers, similar to the requirement on the electrode potential for stable undoped p-type polymers. Consequences for bipolar devices are analysed. Huge overpotentials for the redox reaction with wet oxygen are required in order to realize thermodynamically stable bipolar devices from known doped p-type and n-type conducting polymers. Finally, possible solutions, accepting thermodynamic instability, are discussed.