The present disclosure is directed to providing an electrode assembly which improves the thermal safety of a battery by preventing shrinking of a separator adjacent to electrode tabs. The electrode assembly includes a positive electrode plate having a positive electrode tab at one end thereof, a negative electrode plate having a negative electrode tab at one end thereof, and a separator interposed between the positive electrode plate and the negative electrode plate, wherein the positive electrode plate and the negative electrode plate are stacked so that each of the tabs may be positioned in the same direction, and the separator has a gradient in thickness so that the thickness of one side having the electrode tabs are larger than that of the other side.