Evaluation of welding joint methods for a prismatic battery cell module

Abstract: Prismatic battery cells swell due to a number of different factors, such as state of charge, temperature and irreversibly with charge cycling. Cell health can be improved by restricting the swelling of the cell, and therefore, the container which holds the cells, the module, should be able to restrict the swelling, and thus withstand the force exerted by the cells. This paper evaluates the use of three different welding techniques to use with a specified module frame constructed out of aluminium. The welding of the module will be performed with the cells in place and as of safety reasons to avoid the devastating effects of a thermal runaway, a maximum temperature requirement is set on the cell side of the welded parts. The three welding techniques evaluated in this report are, tungsten inert gas, friction stir, and laser welding. Which are evaluated on a basis of strength and maximum temperature development during the welding process. This paper focuses on comparing the three different methods relative each other. Calculations and simulations should not in any way be considered accurate or be used for dimensioning without extensive validation. The most promising welding method in this report is laser welding, as the research points toward a significant safety factor towards the maximum allowed temperatures on the cells. However, the strength requirement is not met with the use of the same alloys as suggested with the other techniques, but is promising with the use of alternative alloys.