A novel silver-lithium-iodine solid-state energy device and system are disclosed. The rechargeable, self-assembled, dual-function, metal-iodide battery exhibits small size and high deliverable power. Inert until activation, the device may be stored for long periods of time. Upon activation, the device assembles the required electrochemical moieties for operation without external intervention. The device limits short-circuiting and self-discharge of the system by spontaneous reactions at the electrode / electrolyte interfaces, and thus is self-healing. By incorporating both silver and lithium in the same system, a dual function is achieved, whereby the characteristics of a lithium-based battery dominate at a low load and those of a silver-based battery dominate under a high load.