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Here, we report on the scalable synthesis and characterization of novel architecture three-dimensional (3D) high-capacity amorphous silicon nanowires (SiNWs)-based anodes with focus on studying their electrochemical degradation mechanisms. We achieved an unprecedented combination of remarkable performance characteristics, high loadings of 3-15 mAh/cm(2), a very low irreversible capacity (10% for the 3-4 mAh/cm(2) anodes), current efficiency greater than 99.5%, cycle stability (both in half cells and a LiFePO4 battery), a total capacity of 457 mAh/cm(2) over 204 cycles and fast charge-discharge rates (up to 2.7C at 20 mA/cm(2)). These SiNWs-based binder-free 3D anodes have been cycled for over 200 cycles, exhibiting a stable cycle life. Notably, it was found that the growth of the continuous SEI layer thickness, and its concomitant increase in resistivity, represents the major reason for the observed capacity loss of the SiNWs-based anodes. Importantly, these NWs-based anodes of novel architecture meet the requirements of lithium batteries for future portable, and electric-vehicle, applications.

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