Fancy Accordion is the best accordion module for Joomla, which supports Joomla contents, K2 contents and Joomla modules as well. That means, you can set Joomla articles as accordion, K2 contents as accordion, Joomla Modules as an accordion.
It comes with pre built 25 styles to choose from. Just select the style and its ready to go. Matches with all website themes and has got a lot of features.
Works very well on all types of Joomla templates. Highly configurable and backed with a 24×7 Customer Support package. This module is cross browser compatible and works on all the modern browsers.