涂碳铝箔对磷酸铁锂电池性能影响研究

本文研究了使用涂碳铝箔作为正极集流体磷酸铁锂电池的性能。研究对比了使用普通铝箔和涂层铝箔的10 Ah软包磷酸铁锂电池的主要性能。研究表明:使用涂层铝箔不但可以提高磷酸铁锂材料的粘结性,而且使用导电涂层可以有效降低正极材料和集流体的接触内阻,从而减小电池内阻,提高电池倍率性能。与使用普通铝箔作为集流体相比,通过使用涂碳铝箔可以使得电池的内阻降低65%左右,但是,磷酸铁锂正极材料的克容量却偏低约5~10 mAh·g-1,首次效率也偏低4%左右;在快速放电15C倍率下,使用涂碳铝箔的电芯比使用普通铝箔容量提高约15%左右,10C放电倍率下,平台增加0.3~0.4 V;使用涂碳铝箔电芯的常温自放电率较高,但容量恢复率也较高;550周循环下,使用涂碳铝箔可以使得电池的循环性能提高约1%。而在电池低温性能方面,使用涂碳铝箔对低温性能并无改善。     

液相色谱-串联质谱法检测血清中15种甾体激素的动态变化

建立了用液相色谱-串联质谱检测血清中15种甾体激素的方法。在血清样品中加入含内标的乙腈沉淀蛋白质后,用100 mmol/L盐酸羟胺衍生,经Agilent-C18柱(50 mm×3.0 mm,2.7μm)分离,内标法定量。质谱分析采用电喷雾电离(ESI)正离子扫描,多反应监测(MRM)模式检测。数据显示,13种激素在0.05~20 ng/mL范围内线性关系良好(相关系数(R2)不小于0.995 6),检出限不大于1 ng/mL;皮质醇及脱氢表雄酮硫酸酯在50~2 000ng/mL范围内线性关系良好(R2不小于0.997 9),检出限不大于0.5 ng/mL。将该方法应用于女性月经周期激素变化规律的研究,结果表明,15种甾体激素在一个完整的月经周期内有不同特征的动态变化,其中雄激素在滤泡期的后期达到最高值,孕(雌)激素在黄体期达到最高值,而皮质激素则波动不明显。该方法灵敏度高、重复性好,为临床诊疗提供了参考。     

Simultaneous Stabilization of Potassium Metal and Superoxide in K–O2 Batteries on the Basis of Electrolyte Reactivity

In superoxide batteries based on O₂/O₂^? redox chemistry, identifying an electrolyte to stabilize both the alkali metal and its superoxide remains challenging owing to their reactivity towards the electrolyte components. Bis(fluorosulfonyl)imide (FSI^?) has been recognized as a “magic anion” for passivating alkali metals. The KFSI–dimethoxyethane electrolyte passivates the potassium metal anode by cleavage of S?F bonds and the formation of a KF‐rich solid–electrolyte interphase (SEI). However, the KFSI salt is chemically unstable owing to nucleophilic attack by superoxide and/or hydroxide species. On the other hand, potassium bis(trifluorosulfonyl)imide (KTFSI) is stable to KO₂, but results in mossy potassium deposits and irreversible plating and stripping. To circumvent this dilemma, we developed an artificial SEI for the metal anode and thus long‐cycle‐life K–O₂ batteries. This study will guide the development of stable electrolytes and artificial SEIs for metal–O₂ batteries.     

量子简并性对气体斯特林制冷循环性能的影响

基于理想量子气体的状态方程，分析了量子气体斯特林制冷循环中的回热特征，推导出循环的制冷系数一般表达式.获得了在强简并和弱简并条件下循环的制冷系数，对全面理解气体斯特林制冷机的性能有所帮助. 关键词： 量子简并性 斯特林制冷循环     

长循环寿命结晶@非结晶金属硫化物复合电极材料的制备及其混合电容器性能

通过乙二醇诱导策略成功地设计和构建了结晶@非结晶NiCo₂S₄@MoS₂(v-NCS@MS)纳米结构,利用非结晶MoS₂壳层的柔性保护和带缺陷的内部核 NiCo₂S₄的高比容量,使 v-NCS@MS电极具有高比容量(1 A·g^-1时 1 034 mAh·g^-1)和出色的倍率性能。此外,以v-NCS@MS为正极、活性炭(AC)为负极组装的混合超级电容器在219 W·kg^-1的比功率下可获得111 Wh·kg^-1的高比能量,在不同电流密度下循环15 000次后容量保持率高达80.5%。     

On the Characterization of Maximal Planar Graphs with a Given Signed Cycle Domination Number

Let G =(V, E) be a simple graph. A function f : E → {+1,-1} is called a signed cycle domination function(SCDF) of G if ∑_(e∈E(C))f(e) ≥ 1 for every induced cycle C of G. The signed cycle domination number of G is defined as γ'_(sc)(G) = min{∑_(e∈E)f(e)| f is an SCDF of G}. This paper will characterize all maximal planar graphs G with order n ≥ 6 and γ'_(sc)(G) = n.     

Significance of a volcano relation of fajans for hydration energies

A volcano-shaped relation between heats of solution of a series of salts and the difference of hydration energy of the ions of the salt was noted by Fajans. This relation has a maximum when the difference of hydration energy of the cation and anion approaches zero. A rationalization of this type of relation is proposed on the basis of sums of reciprocal radii terms which represent the dependence of electrostatic hydration energy on ion size. The general trend of heats of solution with ionic size in series of salts with either a common cation or a common anion is discussed.     

Biotransformation of 20(R)-panaxatriol by the fungus Aspergillus flavus Link AS 3.3950

Microbial transformation of 20(R)-panaxatriol by the fungus Aspergillus flavus Link AS 3.3950 was performed. Four new (1–4), along with two previously reported metabolites (5 and 6), were obtained. Their chemical structures were elucidated on the basis of extensive spectroscopic analyses. Furthermore, the inhibitory effects of those compounds on K562/ADR, Du-145, Hela, MCF-7 and HepG2 cell lines were evaluated by MTT assay. Among them, compound 15β-hydroxy-20(R)-panaxatriol (4) exhibited selective inhibitory effects on human leukaemic progenitor cells K562/ADR through arresting cell cycle, which was associated with obvious decrease of cyclin B1, cyclin D1 and cyclin-dependent kinase (CDK) 1/2/4/6 protein expression.     

锂离子电池硅负极循环稳定性研究进展

硅是已知质量比容量最高的锂离子电池负极材料,研究人员希望通过制造可靠的高容量硅负极,生产高能量密度的锂离子电池. 但由于充放电过程中锂在硅材料中嵌入与释放,硅材料发生巨大的体积变化,以致破碎,并从负极上脱落下来. 硅负极容量随着充放循环次数的增加而迅速下降,是其应用进程中受到的最大制约. 本文结合锂离子电池硅负极研究现状,从硅材料本体结构、整体负极结构两方面介绍几种不同的提高硅负极循环稳定性的方法,并对各种方法的稳定性、成本、制备方法等进行比较,提出对未来硅负极材料研究的展望.