Schleker P Philipp M, Grosu Cristina, Paulus Marc, Jakes Peter, Schlögl Robert, Eichel Rüdiger-A, Scheurer Christoph, Granwehr Josef
Institut für Grundlagen der Elektrochemie IEK-9, Forschungszentrum Jülich, Wilhelm-Johnen Straße, 52425, Jülich, Germany.
Institut für Chemie, Technische Universität München, 85748, Garching b, München, Germany.
Commun Chem. 2023 Jun 7;6(1):113. doi: 10.1038/s42004-023-00913-6.
It is of general interest to combine the faradaic processes based high energy density of a battery with the non-faradaic processes based high power density of a capacitor in one cell. Surface area and functional groups of electrode materials strongly affect these properties. For the anode material LiTiO (LTO), we suggest a polaron based mechanism that influences Li ion uptake and mobility. Here we show electrolytes containing a lithium salt induce an observable change in the bulk NMR relaxation properties of LTO nano particles. The longitudinal Li NMR relaxation time of bulk LTO can change by almost an order of magnitude and, therefore, reacts very sensitively to the cation and its concentration in the surrounding electrolyte. The reversible effect is largely independent of the used anions and of potential anion decomposition products. It is concluded that lithium salt containing electrolytes increase the mobility of surface polarons. These polarons and additional lithium cations from the electrolyte can now diffuse through the bulk, induce the observed enhanced relaxation rate and enable the non-faradaic process. This picture of a Li ion equilibrium between electrolyte and solid may help with improving the charging properties of electrode materials.
将基于法拉第过程的电池高能量密度与基于非法拉第过程的电容器高功率密度结合在一个电池单元中，这是一个普遍感兴趣的问题。电极材料的表面积和官能团强烈影响这些性能。对于阳极材料LiTiO（LTO），我们提出了一种基于极化子的机制，该机制会影响锂离子的吸收和迁移率。在这里，我们表明含有锂盐的电解质会引起LTO纳米颗粒体相NMR弛豫特性的可观察到的变化。块状LTO的纵向锂NMR弛豫时间可以改变近一个数量级，因此，对周围电解质中的阳离子及其浓度非常敏感。这种可逆效应在很大程度上与所使用的阴离子以及潜在的阴离子分解产物无关。可以得出结论，含锂盐的电解质会增加表面极化子的迁移率。这些极化子和来自电解质的额外锂阳离子现在可以扩散通过体相，诱导观察到的增强弛豫率，并实现非法拉第过程。这种电解质和固体之间锂离子平衡的情况可能有助于改善电极材料的充电性能。
