Structure and composition of silicon microarrays subjected to cyclic insertion and extraction of lithium

Application of silicon zig-zag wall arrays for anodes of Li-ion batteries

“…This suggests that the amount of lithium introduced into the silicon walls depends on height. This finding is consistent with previously observed non-uniform changes in the morphology of high-aspect structures [17,18]. Table 2 also shows that sample 10-7 has a larger proportion of crystalline material than sample 10-6.…”

“…The Raman spectra of samples 10-6 and 10-7 support our previous data on non-uniform lithiation at different wall heights [17,18]. In our opinion, the reason for this phenomenon is that the surface potential at the interface with the electrolyte varies with increasing distance from the separator.…”

“…The walls of sample 10-7 retained their original structure, but we can see the peeling of an outer layer from the walls, just as it occurs on a planar silicon wafer subjected to electrochemical lithiation [26,27]. An EDX analysis demonstrated that, similar to the walls remaining under the outer layer, this layer mostly contains silicon (85% Si, 12% C and 3% O), whereas oxygen and carbon are predominant in the SEI [18].…”

“…In the anodes with low Si walls, a cavity was formed at the end of anodization [19]. In this way, the cavity served to separate the zigzag structure from the substrate after the copper plating [18]. For the structures with high walls, a membrane was first produced by substrate removal through grinding and polishing and then copper was deposited [24].…”

“…Anisotropic shaping of macropores makes it possible to obtain a variety of 3D configurations with monodisperse walls faceted by a single type of crystallographic plane [16]. Structures of this kind can serve as a good model object for studies of the cyclic lithiation/delithiation processes of single-crystal silicon particles [17,18]. The Föll group [12,19,20] focused their attention on the configuration of high-aspect silicon wires with a diameter of ∼1 μm and developed the optimized technique for the manufacture of anodes on a copper substrate [21].…”