Cost is a major issue, says Dahn. “Batteries are about three to five times more expensive than what we want,” he says. But while there are energy and cost advantages to using iron sulfide, it can be problematic to use in manufacturing. “Iron sulfide is stable in air, but when you react it with lithium it loses this stability,” he says.

Qinetiq says it has solved this issue, although the company won’t go into details about how. Based on early estimates, using low volumes of materials, the new batteries should be half the cost of conventional nickel-metal hydride batteries, Mepsted says.

Developed as part of a $3.2 million two-year project in collaboration with Ricardo, based in Warwickshire, the battery has so far been tested under only limited conditions. In the lab, the cell has demonstrated 50 percent improvements in discharge rates. “There needs to be more development in the cell chemistry before it could be considered for production,” says Colin Wren, a researcher at Ricardo. But because it can be tailored for either high energy density or high power density, he says, the technology is suited to both plug-in electrics and hybrids.