An electrochemical cell is provided, which includes a cathode comprising a three dimensional (3D) porous cathode structure, an anode, an electrolyte separator, comprised of a ceramic material, located between the cathode and the anode, and a cathode current collector, wherein the cathode is located between the cathode current collector and the electrolyte separator. The 3D porous cathode structure includes ionically conducting electrolyte strands extending through the cathode from the cathode current collector to the electrolyte separator, pores extending through the cathode from the cathode current collector to the electrolyte separator, and an electronically conducting network extending on sidewall surfaces of the pores from the cathode current collector to the electrolyte separator.