According to the present invention, a stacked electrochemical conversion assembly is provided with an electrically and thermally insulating plate within one or both of the end unit assemblies of the stack. For example, in accordance with one embodiment of the present invention, the electrochemical conversion assembly includes at least one end unit assembly comprising an electrically conductive terminal plate and an electrically insulating plate interposed between the terminal plate and an end unit plate of the end unit assembly. The electrically insulating plate comprises an array of thermally insulating regions defined therein.