Secondary battery and secondary battery module

A secondary battery and a secondary battery module, the secondary battery including an electrode assembly (60), the electrode assembly (60) including a positive electrode (61), a negative electrode (62), and a separator (63) therebetween; a case (50) for accommodating the electrode assembly (60); a cap plate (40) for sealing the case (50); and a first terminal unit including a first electrode rivet (12) electrically connected to one of the electrodes of the electrode assembly (60) and formed of a first metallic material, a rivet terminal (22) formed of a second metallic material, the second metallic material being different from the first metallic material, and a clad unit (10) between the electrode rivet (12) and the rivet terminal (22).