Described embodiments include a system and a method. A system includes a controllable electrochemical cell configured to output electric power. The controllable cell includes an electrolyte and a first working electrode configured to transfer electrons to or from the electrolyte. The controllable cell includes a second working electrode configured to transfer electrons to or from the electrolyte. The controllable cell includes a gating electrode spaced-apart from the second working electrode. The gating electrode is configured, if biased relative to the second working electrode, to modify an electric charge, field, or potential in the space between the electrolyte and the second working electrode. The controllable cell includes a control circuit coupled to the gating electrode of the controllable cell and configured to apply a biasing signal responsive to an electrical property of an external electrical load coupled to the controllable cell.