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Through-Space Charge Modulation Overriding Substituent Effect: Rise of the Redox Potential at 3.35 V in a Lithium-Phenolate Stereoelectronic Isomer
Chemistry of Materials ( IF 7.2 ) Pub Date : 2020-11-25 , DOI: 10.1021/acs.chemmater.0c02989
Louis Sieuw 1 , Alae Eddine Lakraychi 1 , Darsi Rambabu 1 , Koen Robeyns 1 , Alia Jouhara 2 , Gheorghe Borodi 3 , Cristian Morari 3 , Philippe Poizot 2 , Alexandru Vlad 1
Affiliation  

Raising the operating potential of the organic positive electrode materials is a crucial challenge if they are to compare with lithium-ion inorganic counterparts. Although many efforts have been directed on tuning through substituent electronic effect, the chemistries than can operate above 3 V vs Li+/Li0, and thus be air stable in the Li-reservoir form (alike the conventional inorganic Li-ion positive electrode materials) remain finger-counted. Herein, we report on a new n-type organic Li-ion positive electrode material—the tetralithium 2,5-dihydroxy-1,4-benzenediacetate—with a remarkably high redox potential of 3.35 V vs Li+/Li0 attained notably in the solid phase. The origin of the high-energy content in this quinone derivative is found in a stereoelectronic chameleonic effect with an intramolecular conformation change and charge modulation leading to a redox potential increase of 650 mV in the solid state as compared to the same chemistry tested in solution (2.70 V vs Li+/Li0). The conformational dependent electroactivity rationale is supported by electrochemical and crystallography analysis, comparative infrared spectroscopy, and DFT calculation. We identify and make a linear correlation between the enolate vibrational modes and the redox potential, with general applicability for possibly other phenolate redox chemistries. Owing to these effects, this lithiated quinone is stable in ambient air and can be processed and handled alike the conventional inorganic Li-ion positive electrode materials. Whereas intrinsic to high voltage operation stability issues remain to be solved for practical implementation, our fundamental in nature and proof-of-concept study highlights the strong amplitude of through-space charge modulation effects in designing new organic Li-ion positive electrode chemistries with practical operating potential.

中文翻译:

通过空间电荷调制的替代取代效应:苯甲酸锂立体电子异构体中3.35 V时氧化还原电势的升高

如果要将有机正电极材料与锂离子无机对应物进行比较,则提高它们的工作潜力是一项至关重要的挑战。尽管已经进行了许多努力来通过取代基电子效应进行调节,但化学物质仍能在高于3 V vs. Li + / Li 0的条件下运行,因此在Li储层形式下是空气稳定的(类似于常规的无机Li离子正电极材料)保持手指数。在此,我们报道了一种新型的n型有机锂离子正极材料,即2,5,2-二羟基-1,4-苯二乙酸四锂,其氧化还原电势相对于Li + / Li 0非常高,为3.35 V在固相中显着达到。与在溶液中测试的相同化学物质相比,该醌衍生物中高能含量的起因是具有分子内构象变化和电荷调节的立体电子Chaleleonic效应,导致固态氧化还原电势增加了650 mV( 2.70 V vs锂+ /锂0)。依赖于构象的电活性原理受到电化学和晶体学分析,比较红外光谱和DFT计算的支持。我们确定了烯醇式振动模式与氧化还原电位之间的线性关系,并可能适用于其他酚盐氧化还原化学物质。由于这些作用,这种锂化的醌在环境空气中是稳定的,并且可以像常规的无机锂离子正极材料一样进行加工和处理。高压操作稳定性所固有的问题仍有待实际解决,
更新日期:2020-12-08
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