Azizi Jafar, Groß Axel, Euchner Holger
Institute of Theoretical Chemistry, Ulm University, Ulm D-89081, Germany.
Institute of Physical and Theoretical Chemistry, University of Tübingen, Tübingen 72076, Germany.
ACS Appl Mater Interfaces. 2025 Jun 11;17(23):33965-33974. doi: 10.1021/acsami.5c04287. Epub 2025 May 28.
Graphite and graphite derivatives, the standard anode materials for Li-ion batteries, are also of great interest for post-Li-ion technologies, such as potassium-ion batteries. However, certain aspects of the intercalation process in these systems, as well as the resulting consequences, still require a deeper understanding. In particular, the first steps of K intercalation in graphitic systems, i.e., at low concentrations, are fundamentally different from the case of Li. Herein, we use density functional theory to elucidate the early-stage intercalation of K in graphitic materials by seeking comparison to the behavior of Li and Na. Our results show the crucial role of the competition between the interlayer van der Waals interaction and the alkali metal-carbon bond formation for the initial stages of intercalation of large alkali metal atoms. As a consequence, and in contrast to the case of Li, K intercalation becomes energetically unfavorable at low concentrations. This is a significant finding, which can explain the origin of the differences observed for Li and K intercalation in graphitic materials. Hence, we identify the first steps of K intercalation as potential reasons for performance loss and battery failure and show that heteroatom doping can open pathways for solving these issues.
石墨及石墨衍生物作为锂离子电池的标准负极材料，对于后锂离子技术（如钾离子电池）也具有重要意义。然而，这些体系中嵌入过程的某些方面以及由此产生的后果，仍需要更深入的理解。特别是，石墨体系中钾嵌入的第一步，即在低浓度下，与锂的情况有着根本的不同。在此，我们运用密度泛函理论，通过与锂和钠的行为进行比较，来阐明钾在石墨材料中的早期嵌入过程。我们的结果表明，层间范德华相互作用与碱金属 - 碳键形成之间的竞争对于大碱金属原子嵌入的初始阶段起着关键作用。因此，与锂的情况不同，钾在低浓度下嵌入在能量上变得不利。这是一个重要发现，它可以解释在石墨材料中锂和钾嵌入所观察到的差异的起源。因此，我们将钾嵌入的第一步确定为性能损失和电池失效的潜在原因，并表明杂原子掺杂可以为解决这些问题开辟途径。
