A cathode containing a metal substrate that possesses a micro-roughened surface imparted by spark anodization is provided. The surface is formed by contacting the substrate with an electrolytic solution and applying a voltage to form a dielectric sub-oxide layer. The voltage is raised to a sufficiently high level to initiate “sparking” at the surface of the substrate, which is believed to create high local surface temperatures sufficient to etch away the substrate. This results in the formation of a “micro-roughened” surface having a plurality elevated regions. These elevated regions can increase the effective surface area and thus allow for the formation of capacitors with increased cathode capacitance for a given size and/or capacitors with a reduced size for a given capacitance. The elevated regions may also exhibit excellent adhesion to additional electrochemically-active materials and provide enhanced stability in certain liquid electrolytes.