Per apples website
Your one-year warranty includes replacement coverage for a defective battery. You can extend your coverage to two years from the date of your iPhone purchase with the AppleCare Protection Plan for iPhone. During the plan’s coverage period, Apple will replace the battery if it drops below 50% of its original capacity. If it is out of warranty, Apple offers a battery replacement for $79, plus $6.95 shipping, subject to local tax. Apple disposes of your battery in an environmentally friendly manner.
A Verizon store can't do it, I would say take it directly to Apple, I didn't even know something like that was offered because the batteries aren't removable, good luck with everything.