Integrated on-chip energy storage is increasingly important in the fields of internet of things, energy harvesting, sensing, and wearables; capacitors being ideal for devices requiring higher powers or many thousands of cycles. This work demonstrates electrochemical capacitors fabricated using an electrolyte and porous silicon nanostructures with very high surface-to-volume ratios. Nanopore morphologies and passivation coatings for maximizing energy and power densities of porous-silicon based electrochemical capacitors are studied. Stability is achieved through atomic layer deposition (ALD) titanium nitride or chemical vapor deposition (CVD) carbon coatings. The use of silicon processing methods creates the potential for on-chip energy storage.