I know Vapcell can add button tops for ordered cells upon request. And to my experience on their 18650’s, these button tops are by default simply fixed by the insulation stickers, not welded. Later they told me that was because some customers would like to remove these button tops in some situation. However the conductivity is really poor that way and makes the whole resistance much higher, especially when their cells are mostly high-drain ones.
But for this 10440 cell, Vapcell told me their button tops are installed directly by the cell manufacturer. Vapcell sourced these cells and rewrapped them, without any modifications.
So it appears that the cell manufacturer simply sent Vapcell another product without ever notice.
