Battery terminal completely corroded – can this be cleaned or do I need a new battery?

[keira_lancaster]

I opened my hood this morning to check why my 2014 Kia Rio was having trouble starting, and I found the positive battery terminal covered in that blue and white crusty corrosion. Like, really bad. There's so much of it that the cable clamp looks swollen. I tried cleaning it with baking soda and a wire brush but it's still not making good contact and the car barely starts. I live near Festival City and I'm looking for a Skilled 55D23L Battery Replacement in Festival City if the battery is toast, but I'm wondering if I can just replace the terminal clamp instead. I saw Amaron's battery page and they mentioned terminal cleaning and replacement as part of their service. Has anyone here had corrosion so bad that it ruined the battery post itself? Is there a way to tell if the battery casing is damaged or if it's just surface gunk? Also could the corrosion be caused by overcharging from the alternator? I don't want to put a new battery in if the alternator is going to kill it too. Any advice from someone who's dealing with severe corrosion would be great. I'm hoping I don't need a whole new battery but preparing for the worst. Thanks.