Uncovering the solid-phase conversion mechanism via a new range of organosulfur polymer composite cathodes for lithium-sulfur batteries

The sulfur cathodes operating via solid phase conversion of sulfur have natural advantages in suppressing polysulfide dissolution and lowering the electrolyte dosage,and thus realizing significant improvements in both cycle life and energy density.To realize an ideal solid-phase conversion of sulfur,a deep understanding of the regulation path of reaction mechanism and a corresponding intentional material and/or cathode design are highly essential.Herein,via covalently fixing of sulfur onto the triallyl isocyanurate,a series of S-triallyl isocyanurate organosulfur polymer composites(STIs) are developed.Relationship between the structure and the electrochemical conversion behavior of STIs is systematically investigated.It is found that the structure of STIs varies with the synthetic temperature,and correspondingly the electrochemical redox of sulfur can be controlled from conventional "solid-liquid-solid" conversion to the "solid-solid" one.Among the STI series,the STI-5 composite realizes an ideal solid-phase conversion and demonstrates great potential for building a Li-S battery with high-energy density and long-cyclelife:it realizes stable cycling over 1000 cycles in carbonate electrolyte,with a degradation rate of0.053% per cycle;the corresponding pouch cell shows almost no capacity decay for 125 cycles under the conditions of high sulfur loading(4.5 mg cm^(-2)) and lean electrolyte(8 μL mg_s^(-1)).In addition,the tailoring strategy of STI can also apply to other precursors with allyl functional groups to develop new organosulfur polymers for "solid-solid" sulfur cathodes.The vulcanized triallyl phosphate(STP) and triallylamine(STA) both show great lithium storage potential.This strategy successfully develops a new family of organosulfur polymers as cathodes for Li-S batteries via solid-phase conversion of sulfur,and brings insights to the mechanism study in Li-S batteries.

Simultaneous Removal of H_2S and Organosulfur Compounds from Liquefied Petroleum Gas Using Formulated Solvents: Solubility Parameter Investigation and Industrial Test

The performance of four formulated solvents(labeled as UDS-I, UDS-II, UDS-III, and UDS-IV) for removing methyl mercaptan from liquefied petroleum gas was predicted based on a two-dimensional solubility parameter theory. The calculation results show that UDS-IV has the closest solubility parameter to that of methyl mercaptan as compared with other tested solvents, indicating the strongest affinity and the highest solubility for methyl mercaptan. The industrial tests at a plant for desulfurization of LPG produced from the delayed coker have shown that the UDS solvents have the excellent performance for removal of organosulfur compounds(mainly methyl mercaptan). Although the sulfur loading dramatically increases, the total sulfur content of LPG treated with UDS-IV can be reduced by about 50% in comparison with N-methyl diethanolamine. In addition, UDS-IV has superior regeneration performance and selectivity for sulfur compounds over hydrocarbons. The industrial test and the solubility parameter calculation results are in good agreement with each other.

Insight into the reaction mechanism of sulfur chains adjustable polymer cathode for high-loading lithium-organosulfur batteries

Small molecules with adjustable sulfur atoms in the confined structure were acted as precursor for the synthesis of polymer cathodes for lithium-organosulfur batteries.Among them,poly(diallyl tetrasulfide)(PDATtS)delivered a high capacity of 700 mAh g^(-1),stable capacity retention of 85%after 300 cycles,high areal capacity~4 m Ah cm^(-2) for electrode with up to 10.3 mg cm^(-2) loading.New insight into the reaction mechanism of PDATtS electrode that radicals arisen from the homolytic cleavage of S-S bond in PDATtS reacted with Li+to generate thiolates(RSLi)and insoluble lithium sulfides(Li_(2)S)or lithium disulfide(Li_(2)S_(2))was clearly verified by in-situ UV/Vis spectroscopy,nuclear magnetic resonance(NMR)studies and density-functional theory(DFT)calculations.Therefore,based on the unique reaction mechanism,problems of rapid capacity fading due to the formation of soluble polysulfide intermediates and their serious shuttle effect in conventional lithium-sulfur(Li-S)batteries was totally avoided,realizing the dendrite-free lithium sulfur batteries.This study sets new trends for avenues of further research to advance Li-S battery technologies.

Synthesis and Characterization of a One-dimensional Coordination Polymer Generated from Unsymmetrical Bridging Organosulfur Ligand

A new one-dimensional（1D） coordination polymer [Zn（MMTA）2]n（MMTA=5-mercapto-l-methyl-tetrazole） was synthesized under solvothermal conditions and characterized by single crystal X-ray diffraction. This compound crystallizes in the monoclinic space group C2/c, with cell parameters： a=1.4938（7） nm, b=1.3599（5） nm, c=1.2180（4） nm, fl=120.84（3）^＊, V=2.1243（2） nm^3, and Z=8. The deprotonated HMMTA molecule as a/a2-1igand links the zinc center, forming ID chains, which are luther linked by weak C--H...N hydrogen bonds, forming a three-dimensional supramolecular framework. The compound exhibits intense photoluminescence at room temperature. On the basis of the results of TG/DTA analyses, the structure is thermally stable up to -280 ℃.

Low-temperature Li-S batteries enabled by all amorphous con version process of organosulfur cathode

The high degree of crystallinity of discharging in termediates of Li-S batteries(Li_(2)S_(2)/Li_(2)S)causes a severe capacity attenuation at low temperatures.Herein,a sulfur-rich polymer is fabricated,which enables all the discharging in termediates to exist in an amorphous state without long-range order,promoti ng the substantial conversion of discharging intermediates and enhancing Li-S batteries'performance at low temperatures greatly.This cathode material exhibits excellent performance both at room and low temperatures.Even under an extremely low temperature(-40℃),the discharge capacity can remain 67% of that at room temperature.Besides,in-situ UV/Vis spectroscopy and density functional theory calculations reveal that this organosulfur cathode undergoes a new mechanism during discharge.Li_(2)S_(6) and Li_(2)S_(3) are the primary discharging intermediates that are quite different from conventional Li-S batteries.These results provide a new directi on for a broader range of applications of Li-S batteries.

Sulfur-accumulating Model of Superhigh Organosulfur Coal From Guiding, China

Superhigh organosulfur coal has received considerable attention 'chemically as well as geologically,because from it we could get much useful chemical information for removing organosulfur from coal.By studying it, we could also find out the factors af-

A non-aqueous Li/organosulfur semi-solid flow battery

Non-aqueous flow batteries have attracted extensive attention due to the advantages of wide voltagewindow, high energy density and wide operating temperature and so on. Herein, tetramethylthiuramdisulfide （TMTD） with high intrinsic capacity （223 mAh/g） and high solubility （-1 mol/L in chloroform） isinvestigated as the positive active material of the non-aqueous LiJdisulfide semi-solid flow battery. Theelectrochemical activity and reversibility are investigated by cyclic voltammetry and linear scanvoltammetry. This Li/TMTD battery with a high cell voltage of 3.36 V achieves coulombic efficiency of 99%,voltage efficiency of 73% and energy efficiency of 72% at the current density of 5 mA/cm2 with activematerial concentration of 0.1 mol/L. Moreover, the LiJTMTD battery can operate for 100 cycles withoutobvious efficiency decay, indicating good stability.

Microbial reduction of organosulfur compounds at cathodes in bioelectrochemical systems

Organosulfur compounds,present in e.g.the pulp and paper industry,biogas and natural gas,need to be removed as they potentially affect human health and harm the environment.The treatment of organosulfur compounds is a challenge,as an economically feasible technology is lacking.In this study,we demonstrate that organosulfur compounds can be degraded to sulfide in bioelectrochemical systems(BESs).Methanethiol,ethanethiol,propanethiol and dimethyl disulfide were supplied separately to the biocathodes of BESs,which were controlled at a constant current density of 2 A/m^(2) and 4 A/m^(2).The decrease of methanethiol in the gas phase was correlated to the increase of dissolved sulfide in the liquid phase.A sulfur recovery,as sulfide,of 64% was found over 5 days with an addition of 0.1 mM methanethiol.Sulfur recoveries over 22 days with a total organosulfur compound addition of 1.85 mM were 18% for methanethiol and ethanethiol,17% for propanethiol and 22% for dimethyl disulfide.No sulfide was formed in electrochemical nor biological control experiments,demonstrating that both current and microorganisms are required for the conversion of organosulfur compounds.This new application of BES for degradation of organosulfur components may unlock alternative strategies for the abatement of anthropogenic organosulfur emissions.

有机硫化物在可充电电池中的研究进展

近年来,有机硫化物因具有结构灵活、种类繁多、资源丰富和环境友好的特点而在储能领域得到广泛应用,并展示出较大的发展前景.有机硫化物在充放电过程中会发生硫-硫(S—S)键的可逆断裂和形成,分子中S—S键的数目决定了电子转移的多少,而有机基团可以影响电池的电化学行为.本文综合评述了有机硫化物在可充电电池中的研究进展,主要包括有机硫小分子和聚合物正极材料在可充电锂电池中的应用,有机硫电解液添加剂对锂-硫(Li-S)和锂-硒(Li-Se)电池性能的影响及有机硫材料在其它可充电电池中的应用等4个方面.这些结构可调的有机硫化物展示出优异的循环稳定性,改变了传统Li-S和Li-Se电池的氧化-还原路径,参与正负极固体电解质界面的形成,能抑制多硫化物的穿梭效应,阻止锂枝晶的生长.最后,讨论了有机硫化物在可充电电池领域未来研究发展中面临的挑战.

高硫含量正极在锂硫电池中的研究进展

锂硫电池具有高能量密度、原料储量丰富、低成本和环境友好等优点,有望发展为下一代实用化二次电池体系之一。然而锂硫电池中活性物质硫导电性差、多硫化物的溶解与穿梭效应及充放电过程中的体积膨胀等问题阻碍了其商业化进程。通过采用载体材料将硫限域、封装,可以一定程度上解决锂硫电池面临的以上问题。但是传统复合硫正极材料中硫含量和活性物质利用率较低,限制了高能量密度锂硫电池的发展。因此,开发具有高性能和高硫含量的复合硫正极是实现锂硫电池实用化的有效手段。本文从提高复合材料硫含量入手,综述了近年来碳-硫复合材料、过渡金属化合物-硫复合材料和有机硫三种高硫正极材料在锂硫电池中的研究进展,重点讲述了高硫材料的合成方法及其结构对硫和多硫化物的限制与动力学加速作用,并对高硫含量正极材料的未来发展方向进行了展望。

有机硫化合物在锂硫电池中的应用

锂硫电池具有理论能量密度高、环境友好和成本低等优点,有望成为替代锂离子电池的新一代储能系统。然而,锂硫电池充放电产物的绝缘性、可溶性多硫化锂的穿梭效应、硫正极体积膨胀及锂枝晶的不可控生长,严重影响了锂硫电池的实际容量发挥和循环稳定性。为解决上述问题,采用有机硫化合物来替代单质硫作为正极材料是有前途的策略。调控有机硫化合物的硫链、碳链及其相互作用,可改变其电化学反应过程,提高离子/电子电导,抑制穿梭效应。有机硫化合物作为电解液添加剂,可调控硫正极的反应过程并保护金属锂负极,作为聚合物电解质的改性链段可加速锂离子传导。本综述对有机硫化合物在锂硫电池的正极、电解液添加剂和固态电解质中的应用研究进展进行详细的阐述。将有机硫化合物的结构、反应机理和电化学性质联系起来,为解决锂硫电池存在的问题提供见解。最后,提出高性能有机硫化合物的设计合成和机理研究思路,以期实现可实用化的锂硫电池。

直接进样气相色谱法测定密闭环境中有机硫化合物

建立了直接进样气相色谱-硫化学发光法测定密闭环境空气中微痕量有机硫化合物的方法。密闭环境空气通过直接进样、DB-SULFUR毛细管色谱柱分离、硫化学发光检测器进行检测,实现了对密闭环境空气中二硫化碳、甲硫醇等8种有机硫化物完全分离并准确测定。以目标组分的色谱峰面积响应值对相应质量浓度进行线性回归,计算线性方程和相关系数。建立的8种有机硫化物标准曲线线性良好,相关系数达0.999,加标回收率为96.4%~111.2%,测定结果的相对标准偏差不大于3%(n=6),方法检出限为0.003~0.008 mg/m^(3),部分有机硫化物的检出限低于人体嗅觉阈值。

大蒜有机硫化物对药物代谢酶和转运体影响的研究进展

近年来,大蒜有机硫化物(GOSCs)及其活性代谢产物在慢性阻塞性肺疾病(COPD)的治疗中表现出低毒高效的效果,且可减少布地奈德等药物的不良反应,因此GOSCs具有单独开发和与现有药物复方开发的巨大潜力。为发现可能存在的药物相互作用,我们需明确GOSCs及活性代谢产物对药物代谢酶和转运体的影响。通过查阅PubMed、中国知网及万方数据等数据库,检索到GOSCs药理作用相关文献46篇,GOSCs代谢转运和生物转化机制相关文献46篇及COPD相关文献6篇。作者对主要的GOSCs及活性代谢物的药理活性、生物转化机制,对主要的药物Ⅰ相、Ⅱ相代谢酶及药物转运体的调控机制进行综述,并结合目前主流COPD治疗药物的代谢机制,推测了药物联用可能发生的药物相互作用,以期为GOSCs的进一步开发和临床合理用药提供理论基础。

气袋采样-预浓缩-GC-MS同时测定污染源废气中8种有机硫化物

建立了气袋采样-预浓缩进样-GC-MS同时测定污染源废气中8种有机硫化物的分析方法。方法线性良好,相关系数均大于0.998,检出限在0.002~0.004 mg/m3,RSD为0.8%~3.2%,加标回收率在94.0%~125%,完全满足定性定量分析要求。

可见光催化有机硫化合物的绿色合成

含硫官能团是一类重要的有机官能团,发展绿色、高效和选择性可控的方法制备有机硫化合物具有重要意义.可见光催化因其温和、绿色和原子经济等优点,已逐渐发展成为构建有机硫化合物的一种强有力工具,也是近年来有机合成领域的热点研究之一.本文综述了近三年来本课题组基于可见光催化制备有机硫化合物的研究工作.

合山超高有机硫煤中Fe-Mn-Hg-Zn-Ni-Cr-V的赋存状态及意义

采用逐级化学提取方法,研究了广西合山超高有机硫煤中Hg,Ni,Zn,Mn,Cr,V等有害元素赋存状态.解结果表明:超高有机硫煤中与无机质结合的Ni,Cr,V,Zn,Hg,Mn均大于90%,而有机结合状态硫小于10%.酸在各种无机结合态中,硫化物结合态、铁锰氧化物结合态或铝硅酸盐结合态为主要赋存状态;如,Ni和Zn主要与硫化物和铝硅酸盐结合;Hg主要与硫化物结合;Cr和Mn主要与硫化物和铁锰氧化物结合;V主要与铝硅酸盐和铁锰氧化物结合;Fe主要与硫化物和铁锰氧化物结合.因此,从煤的洁净利用角度看,超高有机硫煤中的这些有害元素有可能通过洗选来脱除.特殊的局限碳酸盐台地成煤环境决定了合山超高有机硫煤中Fe,Ni,Cr,V,Zn,Hg,Mn的上述赋存特征.

碱热活化过硫酸盐降解柴油精制废水中的有机硫化合物

利用碱热活化过硫酸盐降解水中有机硫化合物。通过对比发现,碱热活化过硫酸钠对有机硫化合物的降解效果优于单一碱活化或热活化方式。废水的碱性特征为碱热活化提供了有利条件,可减少调节pH的药剂费用。此外,考察了过硫酸钠投加量、初始pH及温度对降解效果的影响,并通过监测过硫酸根残留率,分析了以上各因素对过硫酸钠利用率的影响。结果表明,在碱性条件下对有机硫化合物的降解效果优于中性、酸性条件,增加过硫酸钠投加量或提高温度均可提高其降解效果。在初始pH=9.0、50℃、过硫酸钠投加量60mg/L时,有机硫化合物降解率高于98%。

不同沉积环境成因煤显微组分的有机硫分布

运用扫描电镜能谱微区测试对不同沉积环境成因煤的有机显微组分进行有机硫含量的系统测定，结果表明在不同类型的煤中某一类显微组分的有机硫含量存在明显差异；同一煤中不同亚显微组分的有机硫含量也不同。综合分析发现煤显微组分有机硫含量主要受聚煤环境、组分凝胶化程度、氧化程度的影响，而聚煤环境为主导影响因素。

贵定超高有机硫煤中的细菌体及其意义

运用透射电镜（ＴＥＭ）观察贵定超高有机硫煤的镜质组，识别出了多种形态的有机体似的细菌物体，其大，１～２μｍ，内部具层圈状结构或不均一状物质分布，与之共生有大量的０．１～１μｍ大小的超微类脂体。实验还发现，镜质组中细菌体与超微类脂体越富集，有机硫含量就越高，荧光性越强。这意味着细菌活动是导致煤性质异常变化的原因之一。

大蒜有机硫化合物药理活性的研究进展

大蒜的主要药理活性成分是有机硫化合物。大蒜有机硫化合物能通过多种途径抑制肿瘤生长,诱导肿瘤细胞凋亡,并具有抗菌消炎、提高机体免疫力、预防和治疗心血管疾病等药理作用。本文对大蒜有机硫化合物药理活性的研究进展做一综述。