Silicon-based supercapacitors are essential for consumer electronics due to their on-chip integration with established CMOS fabrication technology. Silicon nanowalls were carved on commercial silicon wafers using metal (silver)-assisted chemical etching. Electron microscopy revealed smooth, single-crystalline, vertically aligned nanowalls. Raman and ATR-FTIR spectroscopy confirmed Si–O–Si bonded structures. Cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) studies in organic electrolyte NEt4BF4/PC demonstrated redox peaks from silver-related deep-level traps and silicon oxidation. Effects of these redox peaks on capacitance and cycle life are discussed. © 2020 Elsevier B.V., All rights reserved.