sticky pad caused by swollen battery ???

I came to this forum for help for my sticky touch pad. So I learned about taking out the battery to try and clean it from the back side. As soon as the battery was removed the pad worked perfectly (just using the power cord and leaving the battery out). Tried to replace the battery and the problem returned - the pad wouldn't respond well and didn't make the slight click when touched. The battery also didn't fit well and bulged on both flat sides. For the last week the battery has not been charging and when the cord is removed the computer turns off immediately. This was an original battery and has been deteriorating in the charge it will hold - but it sure looks like it's swelling.

Just wondering do these batteries ever explode?

Yes, mine burst out of the titanium casing recently. I know the battery is gone, but I wonder about other problems in my MBPro. Also, the MBPro won't turn on with just the power cord attached.