Lithium batteries a bad green investment?

One of the first Chevy Volt battery packs

Recently, hype about plug-in vehicles, such as the Chevy Volt, the Nissan Leaf or the Tesla Roadster has increased interest in the key to this technology, lithium-ion batteries.

Analysts in the sector, however, believe that retail investors - those with less than two years of investment experience - are fueling a surge of investment into this space in a overreaction to real world growth potential.

"I think (Sanyo shares) are overbought," said Osamu Hirose, an analyst at Tokai Tokyo Research Center, according to Reuters.

Moreover, "According to Thomson Reuters, no brokerage has a "buy" rating on Sanyo, which has a price-to-earnings ratio of 67 times its estimated earnings."

On the other hand, Tim Seymour of FastMoney called out a number of Asian companies, those with interests in hybrid and electric vehicle batteries as an investment play off the Chevy Volt.

What do you think? Are the battery makers of plug-in hybrids a worthy green investment, or has this game already been-overplayed? Even more interesting, is it retail investors that over-estimating the potential of plug-in hybrids, or are the professional investors under-estimating the potential of plug-ins?