A static semi-solid filled energy storage system having a plurality of static cells, each cell comprising an ion permeable membrane separating positive and negative current collectors and positioned to define positive and negative electroactive zones. Electroactive material is delivered to the electroactive zones via a plurality of manifolds. The manifolds are injected with an electronically insulating barrier that is configured to seal each static cell from its neighboring static cell. Valves are used to allow gas created from the electrochemical reactions to be released from the system. Coolant may be introduced to dissipate heat from the system.