Technische Universität Clausthal, Institut für Metallurgie, AG Mikrokinetik, Robert-Koch-Str. 42, 38678 Clausthal-Zellerfeld, Germany.
Phys Chem Chem Phys. 2018 Sep 19;20(36):23480-23491. doi: 10.1039/c8cp03540g.
Operando neutron reflectometry measurements were carried out to study the insertion of lithium into amorphous silicon film electrodes during cyclic voltammetry (CV) experiments at a scan rate of 0.01 mV s-1. The experiments allow mapping of regions where significant amounts of Li are incorporated/released from the electrode and correlation of the results to modifications of characteristic peaks in the CV curve. High volume changes up to 390% accompanied by corresponding modifications of the neutron scattering length density (which is a measure of the average Li fraction present in the electrode) are observed during electrochemical cycling for potentials below 0.3 V (lithiation) and above 0.2 V (delithiation), leading to a hysteretic behaviour. This is attributed to result from mechanical stress as suggested in the literature. Formation and modification of a surface layer associated with the solid electrolyte interphase (SEI) were observed during cycling. Within the first lithiation cycle the SEI grows to 120 Å for potentials below 0.5 V. Afterwards a reversible and stable modification of the SEI between 70 Å (delithiated state) and 120 Å (lithiated state) takes place.
采用运行中中子反射测量技术，在扫描速率为 0.01 mV s-1 的循环伏安（CV）实验中研究了锂在非晶硅薄膜电极中的嵌入。实验允许对大量锂从电极中嵌入/释放的区域进行映射，并将结果与 CV 曲线特征峰的变化相关联。在电化学循环过程中，当电势低于 0.3 V（锂化）和高于 0.2 V（去锂化）时，观察到高达 390%的高体积变化，并伴有相应的中子散射长度密度的变化（这是电极中存在的平均 Li 分数的量度），导致滞后行为。这归因于文献中提出的机械应力的结果。在循环过程中观察到与固体电解质界面（SEI）相关的表面层的形成和修饰。在第一次锂化循环中，SEI 在低于 0.5 V 的电势下生长至 120 Å。之后，在 70 Å（去锂化状态）和 120 Å（锂化状态）之间，SEI 发生可逆且稳定的修饰。
