Calcium-ion Battery

An energy storage device configured to exchange energy with an external device includes a container having walls, a lid covering the container and having a safety pressure valve, a negative electrode disposed away from the walls of the container, a positive electrode in contact with at least a portion of the walls of the container, and an electrolyte contacting the negative electrode and the positive electrode at respective electrode/electrolyte interfaces. The negative electrode, the positive electrode and the electrolyte include separate liquid materials within the container at an operating temperature of the battery.