And here are a couple of photos of my inflated K2 battery, which is literally THREE TIMES its original thickness (bulging the front and back surfaces of the K2 case, and splitting the case open on one side):
Battery serial number fuzzed, just to confuse amazon.
And the connector side. As you can see, the older kindles had four battery pins, unlike the three shown in the PW2/3 battery post above. On a K3 battery those middle pins actually have "clock" and "data" (or similar) labels printed on them. They are unlabelled on this K2 battery module.
What is not visible in these photos is that the center of the battery is inflated most, on both sides. The photos appear more inflated near the edges, just because of how the light is reflecting from the battery wrapper. The center is three times as thick as the corners.
In the future, I will remove the outer label, and take more photos of the inner circuit board and LiPo battery pack, and I will post them here.