The instant disclosure provides an electrolysis cell, which includes: an anode; a cathode block; and a current collector bar configured to be at least partially disposed adjacent to and in electrical communication with the cathode block, wherein the bar comprises: at least one sidewall; an inner void enclosed by the sidewall; and an expandable material retained in the inner void via the at least one sidewall, wherein the expandable material is configured to exert pressure on the wall of the inner void while the bar is at operating temperature, such that the bar is conformed to the cathode block.