We report on the scalable synthesis and characterization of novel architecture three-dimensional high-capacity amorphous Silicon Nanostructures (SiNSs)-based anodes, with focus on studying their electrochemical degradation mechanisms. By using our novel, low cost and high mass loading chemical vapor deposition (CVD) procedure we synthesized anodes that have shown stable cycle life for up to hundreds of cycles and provided capacities of up to 5.5mAh/cm², very low irreversible capacity and good compatibility with commercial cathodes such as NCA and LFP. Notably, it was found that the growth of the continuous solid electrolyte interphase (SEI) layer thickness, and its concomitant increase in resistivity, represents the major reason for the observed capacity loss of the SiNSs-based anodes. Since, according to our previous studies, artificial SEI layer may stabilize the SEI formation and growth, thin uniform coatings of Al₂O₃ was applied directly on the SiNS by a process of atomic layer deposition (ALD). The performance of alumina ALD coated SiNSs-based anodes is presented. Our data reveals that NSs-based anodes of novel architecture are expected to meet the requirements of lithium-ion batteries for both portable and electric-vehicle applications.