Wichmann Lennart, Jiang Shi-Kai, Thienenkamp Johannes Helmut, Mohrhardt Marvin, Hwang Bing Joe, Winter Martin, Brunklaus Gunther
Helmholtz-Institute Münster, IMD-4, Forschungszentrum Jülich GmbH, Münster, Germany.
Nano-electrochemistry Laboratory, Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan.
Nat Commun. 2025 Aug 5;16(1):7216. doi: 10.1038/s41467-025-62289-6.
Alloying coatings are widely accepted to boost the reversibility of lithium inventory in anode-free cell configurations. While diminished capacity losses are evident from electrochemical data, their impact beyond decreasing the nucleation overpotential remains elusive. Herein, in situ Li NMR spectroscopy is applied to differentiate capacity losses in pouch cells with representative electrochemical behavior. Next to an accelerated interphase formation, the alloying layer diminishes the formation of dead lithium deposits notably. In contrast to previous reports, the capacity lost to electronically insulated lithium deposits is not related to their tortuosity and surface area. Though alloy formation reduces the nucleation overpotential with coated copper, deconvolution of Li NMR spectra as well as scanning electron microscopy evidence predominantly compact lithium deposits in the initial cycles and a similar increase of high-surface area morphologies with bare and coated copper negative electrodes. Instead of improved lithium deposit morphology, the enhanced reversibility with the alloying layer is bestowed by improved interfacial transport towards the end of lithium dissolution. These insights add to the mechanistic understanding of dead lithium formation, exploiting impedance spectroscopy in the discharged state as a valuable tool to assess the ability to dissolve lithium metal from a given substrate.
合金涂层被广泛认为可提高无阳极电池结构中锂存储的可逆性。虽然从电化学数据中可以明显看出容量损失有所减少，但其除了降低成核过电位之外的影响仍不明确。在此，采用原位锂核磁共振光谱法来区分具有代表性电化学行为的软包电池中的容量损失。除了加速界面形成外，合金层还显著减少了死锂沉积物的形成。与之前的报道不同，电子绝缘锂沉积物导致的容量损失与它们的曲折度和表面积无关。尽管合金形成降低了涂覆铜的成核过电位，但锂核磁共振光谱的反褶积以及扫描电子显微镜证据表明，在初始循环中主要是致密的锂沉积物，并且裸铜和涂覆铜负极的高表面积形态的增加相似。合金层增强的可逆性并非源于锂沉积物形态的改善，而是由于在锂溶解末期界面传输得到了改善。这些见解有助于加深对死锂形成机理的理解，利用放电状态下的阻抗谱作为评估从给定基材中溶解锂金属能力的有价值工具。
