For electric vehicles and plug-in hybrids to compete with gas-powered cars, battery prices need to drop by between 50 and 80 percent, according to recent estimates by the U.S. Department of Energy. Getting there might require inventing entirely new kinds of batteries, but there’s also a strong case that improvements to the lithium-ion batteries that power the current generation of electric vehicles may be enough.

 The United States could have the capacity by 2015 to produce enough battery packs for 500,000 cars. But this year, due to high prices, plug-in vehicle sales won’t even reach a tenth of that in the United States. As a result, advanced battery makers in the United States have struggled. A123 Systems went bankrupt. Dow said its battery joint venture Dow Kokam had dropped markedly. And an LG Chem factory meant to supply batteries for the Chevrolet Volt has been built, but the factory is sitting idle, waiting for demand to pick up.

Electric vehicles cost less to operate than gas-powered ones, but that economic advantage largely disappears in the face of expensive batteries. The battery pack for the Chevrolet Volt costs about $8,000. The larger battery in the Nissan Leaf costs about $12,000.