A brazing structure for an electrochemical cell is described. It includes a nickel or nickel alloy component; a ceramic component; a braze alloy layer, containing an active metal element, between the nickel and the ceramic component, and a barrier layer disposed between the nickel layer and the braze alloy layer. The barrier layer is capable of preventing or minimizing the diffusion of the active metal element into the nickel or nickel alloy component. Electrochemical cells that include such a brazing structure are also described, as are related methods for joining nickel components to ceramic components in the manufacture of thermal batteries.