Secondary battery

A secondary battery comprising:

• a case;
• an electrode assembly housed in the case and comprising a first electrode, a second electrode, and a separator between the first electrode and the second electrode, the first electrode having a coating portion coated with a first active material and a non-coating portion absent the first active material;
• and
• first and second collector plates enmeshed together with the non-coating portion therebetween,
• wherein:
• the first collector plate comprises a first plate and a first protrusion, the first protrusion extending lengthwise from the first plate and extending with a first step height from the first plate;
• the second collector plate comprises a second plate and a second protrusion, the second protrusion extending lengthwise from the second plate and extending with a second step height from the second plate;
• the non-coating portion is between the first protrusion and the second protrusion;
• the non-coating portion is coupled to both the first protrusion and the second protrusion by a weld between the first and second protrusions;
• a first portion of the weld has a length extending in a direction along lengthwise edge portions of the first protrusion and the second protrusion;
• and
• the first portion of the weld has a width that is less than the length of the first portion of the weld.