Given the drawbacks of the conventional welding methods in joining the battery case and tab in the lithium-ion battery, the laser welding technique using the metal tube has been introduced for the weld. The metal tube is supposed to contribute a positive effect on protecting the outside structure by blocking the injection of the spatters. However, the use of the metal tube is believed to affect the intensity as well as the power distribution of the laser gaussian beam. Through the observation and analysis in this study, both advantages and disadvantages of the application of the metal tube on the weld have been clarified. The use of the metal tube prevents the ejection of the spatter to the outside of the welding zone, the gap between the battery case and tab in the weld is also minimized. Besides, the limitation of the intensity and the power energy distribution of the laser Gaussian beam has caused significant changes in the morphology, mechanical, and electrical properties of the weld.