Sure it's old, but it focuses entirely on graphite. The "Purpose of Work" and "Barriers" section are good bits of information to understand how overwhelming choosing a graphite for batteries can be.

http://energy.gov/sites/prod/files/2014/03/f12/merit08_jansen_1.pdf

What is encouraging is that Zenyatta was included in those two studies by ORNL. Given the complexity of graphite in battery, Zenyatta seemed to have been reviewed and selected rather quickly.