Astles Thomas, McHugh James G, Zhang Rui, Guo Qian, Howe Madeleine, Wu Zefei, Indykiewicz Kornelia, Summerfield Alex, Goodwin Zachary A H, Slizovskiy Sergey, Domaretskiy Daniil, Geim Andre K, Falko Vladimir, Grigorieva Irina V
Department of Physics and Astronomy, University of Manchester, Manchester, UK.
National Graphene Institute, University of Manchester, Manchester, UK.
Nat Commun. 2024 Aug 13;15(1):6933. doi: 10.1038/s41467-024-51196-x.
The ongoing efforts to optimize rechargeable Li-ion batteries led to the interest in intercalation of nanoscale layered compounds, including bilayer graphene. Its lithium intercalation has been demonstrated recently but the mechanisms underpinning the storage capacity remain poorly understood. Here, using magnetotransport measurements, we report in-operando intercalation dynamics of bilayer graphene. Unexpectedly, we find four distinct intercalation stages that correspond to well-defined Li-ion densities. Transitions between the stages occur rapidly (within 1 sec) over the entire device area. We refer to these stages as 'in-plane', with no in-plane analogues in bulk graphite. The fully intercalated bilayers represent a stoichiometric compound CLiC with a Li density of ∼2.7·10cm, notably lower than fully intercalated graphite. Combining the experimental findings and DFT calculations, we show that the critical step in bilayer intercalation is a transition from AB to AA stacking which occurs at a density of ∼0.9·10cm. Our findings reveal the mechanism and limits for electrochemical intercalation of bilayer graphene and suggest possible avenues for increasing the Li storage capacity.
为优化可充电锂离子电池而持续开展的努力引发了人们对包括双层石墨烯在内的纳米级层状化合物插层的兴趣。其锂插层最近已得到证实，但支撑存储容量的机制仍知之甚少。在此，我们利用磁输运测量报告了双层石墨烯的原位插层动力学。出乎意料的是，我们发现了四个不同的插层阶段，它们对应于明确的锂离子密度。阶段之间的转变在整个器件区域内迅速发生（在1秒内）。我们将这些阶段称为“面内”阶段，在块状石墨中没有面内类似物。完全插层的双层代表一种化学计量化合物CLiC，锂密度约为2.7·10cm，明显低于完全插层的石墨。结合实验结果和密度泛函理论计算，我们表明双层插层中的关键步骤是从AB堆叠到AA堆叠的转变，这发生在密度约为0.9·10cm时。我们的发现揭示了双层石墨烯电化学插层的机制和极限，并提出了提高锂存储容量的可能途径。
