基于烯碳酸盐的电解质中超氧化物诱导的环开放的机械洞察,使用现场表面增强红外光谱
J Padmanabhan Vivek1, Neil Berry1, Georgios Papageorgiou2
1Department of Chemistry, University of Liverpool , Liverpool L69 7ZD, United Kingdom.
Journal of the American Chemical Society
|February 25, 2016
概括
氧 (Li-O2) 电池中碳酸盐 (PC) 的超氧化物诱导降解是依赖于阴离子的. ((+) 协调可显著降低PC环开启的激活能量障碍,影响电解质稳定性.
科学领域:
- 电化学
- 材料科学
- 物理化学
背景情况:
- 稳定的电解质对于开发高性能氧 (Li-O2) 电池至关重要.
- 溶剂降解,特别是超氧化物降解,是限制2电池寿命的一个主要挑战.
- 了解电解质分解的机制是设计强大的电池系统的关键.
研究的目的:
- 阐明氧电池电解质中超氧化物诱导的溶剂降解的机制细节.
- 研究电解质在碳酸盐 (PC) 分解中的作用.
- 评估在现场减弱的全反射面增强红外吸收光谱 (ATR-SEIRAS) 对于研究界面反应的有用性.
主要方法:
- 现场减弱的全反射面增强红外吸收光谱 (ATR-SEIRAS) 用于监测电化学反应期间的界面变化.
- 在与2电池相关的条件下,研究了碳酸盐 (PC) 在模型电极表面的分解.
- 使用计算建模来研究PC降解的反应途径和激活能量障碍.
主要成果:
- SEIRAS研究表明,电解质中的阴离子决定了超氧化物诱导PC环开放的途径.
- 与四乙 (TEA) 相比,当Li(+) 是反时,计算模型显示PC分解的激活能量障碍明显较低.
- 的协调与碳酸盐的功能被确定为减少激活能量的原因.
结论:
- 在二氧化电池中,二氧化对二氧化电解质的稳定性起着至关重要的作用.
- (+) 协调增强PC降解,强调电解质成分对电池性能的重要性.
- 该技术是研究界面电化学反应的强大工具,并指导合理选择2电池电解质.
相关概念视频
01:17Thermal Electrocyclic Reactions: Stereochemistry
2.7K
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
2.7K
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
3.2K
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
3.2K
01:26Photochemical Electrocyclic Reactions: Stereochemistry
2.4K
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
2.4K
01:16Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)
3.3K
Ring-opening metathesis polymerization or ROMP involves strained cycloalkenes as starting materials. The mechanism of ROMP proceeds by reacting cycloalkene with Grubbs catalyst to give metallacyclobutane intermediate which undergoes a ring-opening reaction to form new carbene. The new carbene reacts with another molecule of cycloalkene. Repetition of these steps leads to the formation of an unsaturated open-chain polymer product. All these steps are reversible, however, relieving the ring...
3.3K
02:26Base-Catalyzed Ring-Opening of Epoxides
11.0K
Due to their highly strained structures, epoxides can readily undergo ring-opening reactions through nucleophilic substitution, either in the presence of an acid or a base. The nucleophilic substitution reactions in the presence of acid are called acid-catalyzed ring-opening reactions, and nucleophilic substitution reactions in the presence of a base are called base-catalyzed ring-opening reactions. Epoxides undergo base-catalyzed ring-opening reactions in the presence of a strong nucleophile...
11.0K
02:24Acid-Catalyzed Ring-Opening of Epoxides
9.7K
Epoxides that are three-membered ring systems are more reactive than other cyclic and acyclic ethers. The high reactivity of epoxides originates from the strain present in the ring. This ring strain acts as a driving force for epoxides to undergo ring-opening reactions either with halogen acids or weak nucleophiles in the presence of mild acid. The acid catalyst converts the epoxide oxygen, a poor leaving group, into an oxonium ion, a better leaving group, making the reaction feasible. The...
9.7K