Dawkins Jeremy I G, Ghavidel Mohammadreza Z, Chhin Danny, Beaulieu Isabelle, Hossain Md Sazzad, Feng Renfei, Mauzeroll Janine, Schougaard Steen B
Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Québec H3A 0B8, Canada.
Department of Chemistry, NanoQAM, Université du Québec à Montréal, Quebec Centre for Functional Materials, Case Postale 8888 Succ. Centre-Ville, Montréal, Québec H3C 3P8, Canada.
Anal Chem. 2020 Aug 18;92(16):10908-10912. doi: 10.1021/acs.analchem.0c02086. Epub 2020 Jul 29.
The trade-off between energy density and power capabilities is a challenge for Li-ion battery design as it highly depends on the complex porous structures that holds the liquid electrolyte. Specifically, mass-transport limitations lead to large concentration gradients in the solution-phase and subsequently to crippling overpotentials. The direct study of these solution-phase concentration profiles in Li-ion battery positive electrodes has been elusive, in part because they are shielded by an opaque and paramagnetic matrix. Herein we present a new methodology employing synchrotron hard X-ray fluorescence to observe the concentration gradient formation within Li-ion battery electrodes in . This methodology is substantiated with data collected on a model LiFePO/Li cell using a 1 M LiAsF in 1:1 ethylene carbonate/dimethyl carbonate (EC/DMC) electrolyte under galvanostatic and intermittent charge profiles. As such, the technique holds great promise for optimization of new composite electrodes and for numerical model validation.
能量密度与功率性能之间的权衡是锂离子电池设计面临的一项挑战，因为这在很大程度上取决于容纳液体电解质的复杂多孔结构。具体而言，传质限制会导致溶液相中出现较大的浓度梯度，进而导致严重的过电势。对锂离子电池正极中这些溶液相浓度分布的直接研究一直难以实现，部分原因是它们被不透明且顺磁性的基质所屏蔽。在此，我们提出一种新方法，利用同步加速器硬X射线荧光来观察锂离子电池电极内浓度梯度的形成。该方法通过在恒电流和间歇充电曲线下，使用1 M LiAsF于1:1碳酸乙烯酯/碳酸二甲酯（EC/DMC）电解质的LiFePO/Li模型电池收集的数据得到证实。因此，该技术在优化新型复合电极和数值模型验证方面具有很大的前景。
