Abstrakt
Aqueous aluminum ion batteries are a promising candidate for substituting commonly used lithium-ion batteries [1]. The main drawbacks hindering their practical application are the formation of an aluminum oxide layer and hydrogen evolution side reactions [2]. An improvement of reversibility can be achieved by using lamellar Al-Al2Cu nanostructures, where Al2Cu lamellas serve as nanopatterns to guide dendrite-free Al plating [3]. Magnetron sputtering and subsequent annealing offer a convenient way to produce dendritic structures of α-Al and Al2Cu intermetallic phases.
Heterogeneous Al-Cu-Al structures were prepared by DC magnetron sputtering and gas aggregation source [4]. Cu nanoparticles (diameter ~15 nm) were sputtered on a thin Al-film and subsequently covered with another Al-layer. The microstructure evolution of the heterogeneous structures was analyzed during in situ annealing in a transmission electron microscope (TEM) using conventional TEM with selected area diffraction and scanning electron microscopy (STEM) with bright field, high angle annular dark field, and secondary electron detectors combined with energy dispersive X-ray spectroscopy. The dissolution of Cu nanoparticles and formation of new Cu-rich phases was observed during the annealing at temperatures below 600 oC. The observations in TEM were compared with the results of computer simulations.