Lithium Ion batteries have been the preferred storage medium in hybrid vehicles lately. Qinetiq, a UK-based defense technology company, is investing money in their new type of Li-Ion battery, that could be half cheaper than regular models being used today. Additionally, it should have up to 1.6 times the energy and 50% more power density.
Qinetiq changed the approach that they built their battery on: it is based on a lithium-iron-sulfide chemistry. Their new batteries are more attractive to the hybrid vehicles industry.
An issue that the scientists confronted with was safety. Unlike in small devices, in larger scales (like vehicles) the batteries have to behave well in case of mechanical shocks, that Jeff Dahn, a professor of physics and chemistry at Dalhousie University in Halifax, Canada, calls “abuse conditions”. Such conditions are overcharging and collisions that could cause the battery to combust or explode, worsening the survival chances for the car’s occupants.
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.
The lithium-ion iron-sulfide battery is part of a $3.2 million project that lasted two years. Qinetiq’s collaborator was Warwickshire-based Ricardo. The two companies only tested the prototype battery units in lab conditions, where they showed 50% improvement in discharge rates. Anyway, before the battery can be brought to the market and in PHEVs, their calculations and projects will have to undergo thorough developmental stages that would improve the cell’s chemistry.