Bendadesse Ezzoubair, Morozov Anatolii V, Abakumov Artem M, Perrot Hubert, Tarascon Jean-Marie, Sel Ozlem
Chimie du Solide et de l'Energie, UMR 8260, Collège de France, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France.
Réseau sur le Stockage Electrochimique de l'Energie (RS2E), CNRS FR 3459, 33 Rue Saint Leu, 80039 Amiens Cedex, France.
ACS Nano. 2022 Sep 27;16(9):14907-14917. doi: 10.1021/acsnano.2c05784. Epub 2022 Aug 19.
A major feature of the electrolyte/electrode interface (EEI) that affects charge storage in lithium-ion batteries is the electrical double layer (EDL), but most of the available experimental approaches for probing its structuration have limitations due to electrical field and redox reaction disturbances, hence explaining why it is frequently overlooked. Herein we show that this is no longer true by using an advanced electrochemical quartz crystal microbalance (EQCM)-based method in the form of -electrogravimetry. For proof of concept, we studied the effect of various solvent/salt combinations, differing in their dipole moment and size/weight, respectively, on the structure of the EDL forming at the EEI of LiMoO. We show that a significant amount of solvated lithium ions and anions contribute to charge compensation at the interface, and by varying the nature of the solvents (cyclic vs noncyclic), we provide a solid experimental proof of the direct relationship between the ions' solvation and solvent polarity. Moreover, we demonstrated a disappearance of the anionic motion in the less polar solvent (DMC) most likely due to plausible formation of contact ion pairs and agglomerates at the EDL level. Altogether, -electrogravimetry, when combined with classical EQCM, stands as an elegant and powerful method to experimentally assess the chemical structure and dynamics of the electrical double layer. We hope that the community will start to adopt it to better engineer interfaces of electrochemical energy storage devices.
影响锂离子电池电荷存储的电解质/电极界面（EEI）的一个主要特征是双电层（EDL），但由于电场和氧化还原反应干扰，大多数用于探测其结构的现有实验方法都存在局限性，这就解释了为什么它经常被忽视。在此，我们通过使用基于先进电化学石英晶体微天平（EQCM）的方法——电重量分析法表明情况并非如此。为了验证概念，我们研究了各种溶剂/盐组合（分别在偶极矩和尺寸/重量方面有所不同）对在LiMoO的EEI处形成的EDL结构的影响。我们表明，大量溶剂化锂离子和阴离子对界面处的电荷补偿有贡献，并且通过改变溶剂的性质（环状与非环状），我们提供了离子溶剂化与溶剂极性之间直接关系的可靠实验证据。此外，我们证明了在极性较小的溶剂（DMC）中阴离子运动的消失，这很可能是由于在EDL水平上可能形成了接触离子对和团聚体。总之，电重量分析法与经典EQCM相结合，是一种用于实验评估双电层化学结构和动力学的优雅而强大的方法。我们希望该领域的研究人员将开始采用它来更好地设计电化学储能装置的界面。
