Huo Hanyu, Bai Yang, Benz Sebastian Leonard, Weintraut Timo, Wang Shuo, Henss Anja, Raabe Dierk, Janek Jürgen
Institute of Physical Chemistry, Justus Liebig University Giessen, Heinrich-Buff-Ring 17, D-35392, Giessen, Germany.
Center for Materials Research (ZfM), Justus Liebig University Giessen, Heinrich-Buff-Ring 16, D-35392, Giessen, Germany.
Adv Mater. 2025 Feb;37(7):e2415006. doi: 10.1002/adma.202415006. Epub 2024 Dec 20.
Silicon is a promising negative electrode material for solid-state batteries (SSBs) due to its high specific capacity and ability to prevent lithium dendrite formation. However, SSBs with silicon electrodes currently suffer from poor cycling stability, despite chemical engineering efforts. This study investigates the cycling failure mechanism of composite Si/LiPSCl electrodes by decoupling the effects of interface chemical degradation and mechanical cracking. Chlorine-rich LiPSCl suppresses interface chemical degradation when paired with silicon, while small-grained LiPSCl shows 4.3-fold increase of interface resistance due to large Si/LiPSCl contact area for interface degradation. Despite this, small-grained LiPSCl improves the microstructure homogeneity of the electrode composites, effectively alleviating the stress accumulation caused by the expansion/shrinkage of silicon particles. This minimizes bulk cracks in LiPSCl during the lithiation processes and interface delamination during the delithiation processes. Mechanical cracking shows a dominant role in increasing interface resistance than interface chemical degradation. Therefore, electrodes with small-grained LiPSCl show better cycling stability than those with LiPSCl. This work not only provides an approach to decouple the complex effects for cycling failure analysis but also provides a guideline for better use of silicon in negative electrodes of SSBs.
硅因其高比容量和防止锂枝晶形成的能力，是固态电池（SSB）中一种很有前景的负极材料。然而，尽管进行了化学工程方面的努力，目前含硅电极的固态电池仍存在循环稳定性差的问题。本研究通过解耦界面化学降解和机械开裂的影响，研究了复合Si/LiPSCl电极的循环失效机制。富含氯的LiPSCl与硅配对时可抑制界面化学降解，而小颗粒LiPSCl由于Si/LiPSCl界面降解的接触面积大，界面电阻增加了4.3倍。尽管如此，小颗粒LiPSCl改善了电极复合材料的微观结构均匀性，有效缓解了硅颗粒膨胀/收缩引起的应力积累。这使锂化过程中LiPSCl的体裂纹和脱锂过程中的界面分层最小化。机械开裂在增加界面电阻方面比界面化学降解起主导作用。因此，含小颗粒LiPSCl的电极比含LiPSCl的电极具有更好的循环稳定性。这项工作不仅提供了一种解耦循环失效分析中复杂影响的方法，还为在固态电池负极中更好地使用硅提供了指导。
