A Theoretical Study of Reactions between Polysulfides and Organic Carbonates and Raman Spectra in Lithium-Sulfur Battery

锂硫电池具有更高能量密度比，近年来锂硫电池研究备受关注。作为电池主要构成的一部分，电解液会显著影响电池的电化学行为。在锂硫电池工作中，如果可溶的多硫阴离子与电解液发生化学反应，将严重影响电池的循环性能。 有机碳酸酯类材料中的碳酸乙烯酯(EC)和碳酸丙烯酯(PC)常作为电解液用于电池。然而，其作为锂离子电池电解液时具有优良的循环性能，但在作为锂硫电池电解液时却使电池循环性能变差。不同的研究者对此现象的认识存在较大的分歧，其主要的分歧在于多硫阴离子(Sn2-)与碳酸酯类电解液反应时进攻碳酸酯类分子的羰基碳还是烷基碳。随着谱学电化学技术的不断发展，电化学工作者已有望获得界面电化学反应的分子水平信息...The rechargeable lithium-sulfur battery is receiving a great deal of interest at the present time because, theoretically, it can store 3-5 times more energy than current lithium-ion batteries. Conventional Li-S cells consist of a lithium metal anode, an organic electrolyte,and a sulfur composite cathode.The known problems include low volumn ratio, low efficiency of sulfur and low short cycle life....学位：理学硕士院系专业：化学化工学院_物理化学学号：2052012115154

新工科背景下高校人工智能实训课程的改革与创新

随着科技的飞速发展，人工智能时代已经到来，这对中国的教育行业来说更是提供了很多的机遇和挑战。在新工科背景的要求下，高等院校纷纷展开了一系列的创新和创业教育。为了促进教育有效性的进一步提升，高校开始加强人工智能实训课程的改革和创新。截止到 2019 年 12 月底，已经有 38 所高校开设了人工智能学院，并集合较多的科学力量和师资力量展开人工智能实训课程的教育，不仅符合国家要求的创新驱动发展策略，还帮助建设实际综合的一流性大学做出了巨大的贡献。</jats:p

Theoretical Study of Reactions Between Polysulfides and Ethylene Carbonate and Raman Spectra in Lithium-sulfur Battery

通过密度泛函理论(dfT)计算了锂硫电池中多硫阴离子(S2-n)和碳酸乙烯酯(EC)的2种反应机理,并对其反应物和主要产物的拉曼光谱进行了理论分析.计算结果表明,2种反应路径中,S2-n进攻EC分子烷基碳所需活化能和gIbbS自由能均较低.多硫基团有很强的拉曼特征谱峰,与EC分子相关的部分拉曼谱亦发生显著变化.锂离子的存在影响反应产物的结构和拉曼光谱.密度泛函理论计算提供了锂硫电池中锂、多硫阴离子和电解液反应前后的结构变化和反应信息.Two mechanisms of the reaction between polysulfides( S2-n,n = 2—4) and ethylene carbonate( EC) and Raman spectra of the reactants and main products were investigated by density functional theory( DFT) method.The results showed that the reaction of polysulfides attacking the ethyl carbon of EC is more favorable than that attacking the carbonyl carbon of EC in terms of the activation energies and Gibbs free energies.Sulfur groups in polysulfides display strong Raman signals,so that simulated Raman spectra of the products of the S2-n+ EC reaction significantly change after the reaction.The coordination effect of Li+cation also influenced the simulated Raman spectra of reaction products.DFT results and Raman spectroscopic analysis provide a new insight on structural stability of polysulfides and EC electrolyte in the lithium sulfur battery.国家自然科学基金(批准号:21373172;21321062); 国家基础科学人才培养基金(批准号:J1310024)资助~

STUDY ON PHYSIOLOGICAL ECOLOGY of SONNERATIA APETALA INTRODUCED IN DIFFERENT AREAS IN FUJIAN PROVINCE

采用乙醇提取法、纳氏比色法、钼锑抗显色法及f-C法分别研究了人工引种于福建省漳浦、集美、泉港、连江无瓣海桑(SOnnErATIA APETAlA)成熟叶片的生理指标:叶绿素、氮、磷及总酚含量。结果表明,4个地区叶片叶绿素A含量在(1.44±0.54)—(2.52±0.94)Mg/g之间波动,叶绿素b含量范围在(0.54±0.02)—(0.94±0.11)Mg/g之间,叶绿素A/b随着纬度的升高有增大趋势,表明随纬度升高无瓣海桑对蓝紫光需求比例增大;各地点无瓣海桑氮、磷含量均无显著差异,且n:P比值均小于14,表明均存在n限制;总酚含量随着纬度的升高而逐步升高,可能与无瓣海桑生长条件随纬度的上升而受到外界环境胁迫增大有关。In this paper, we analyzed the concentration of chlorophyll, nitrogen (N), phosphorus (P), and total polyphenol of the mature leaves of Sonneratia apetala which were introduced from Lianjiang, Quangang, Jimei and Zhangpu, using ethanol extract, Nessler's Reagent Spectrophotometry, Mo anti-antimony colorimetry and Folin-Ciocalteu respectively.The concentration of chlorophyll-a ranged from (1.44±0.54) to (2.52±0.94)mg/g, and the concentration of chlorophyll-b was from (0.54±0.02) to (0.94±0.11)mg/g.The concentrations of chlorophyll-a/b increased along with the increasing of the latitude, which demonstrated that the growing demand of blue-purple light by S.apetala.There was no significant difference between nitrogen and phosphorus in 4 sample areas.The N : P ratios were less than 14, which indicates N limited exists in these four sample areas.The concentration of polyphenol increased gradually with the latitude, which could be explained by the increasing environment stress.福建省科技计划重点项目;2009Y0036号;集美大学创新团队资助基金资助;2010A004