Quest for the 800-kilometre electric car battery technology
The race is on to produce a rechargeable battery that can rival the driving range of a petrol tank. We’re more than two decades on from the release, by Sony and Asahi Kasei, of the first commercial lithium-ion (Li-ion) battery. And the electric car battery technology has improved since then to drive the market forward hugely.
electric car battery technology
The combined value of the market for electric car battery technology was $11.8 billion in 2010, and is set to grow to $53.7 billion in 2020.
The number of people moving over to electric cars is growing, and you can find plenty of information online about battery performance. It’s easy, for example, to compare the prices of automotive batteries and among the online range of batteries you can find good deals on Electric Vehicle Charging Stations.
Experts, though, say Li-ion cells are not the answer to the problem of how to give electric cars the 800-kilometre range of a petrol tank. Most researchers think only another 30 per cent energy by weight can be squeezed into Li-ion cells, so the challenge is to come up with the next generation of rechargeable batteries for cars.
In 2012, the US Department of Energy gave the Chicago-based Joint Center for Energy Storage Research (JCESR) $120 million to fund its project to develop cells that can be incorporated into commercial battery packs for electric cars. The challenge: to make cells five times more energy dense, and five times cheaper, in five years.
The goal is to hit 400 watt-hours per kilogram by 2017, which even JCESR director George Crabtree regards as “very aggressive”. Even the best estimates project that Li-ion batteries will fail to reach much above 300 watt-hours per kilogram.
The three main alternatives to Li-ion cells are magnesium-ion, lithium-sulphur and lithium-oxygen.
Lithium-oxygen is regarded as having the greatest potential, with some experts saying the technology could reach an energy density of 1,000 watt-hours per kilogram. These have been used in a project by IBM’s nanoscience and technology division in California that set out in 2009 to produce a car battery with an 800-kilometre range.
This type of “breathing” battery has a huge advantage over its rivals, being able to oxidise lithium with oxygen drawn from the air. But cost is a prohibitive factor at the moment and Winfried Wilcke, who headed the California team, now favours a cheaper breathing battery based on sodium. He believes sodium-oxygen (Na-O) batteries can get close to the commonly-agreed affordability goal of $100 per kilowatt-hour.
Li-sulphur batteries change the electrodes to solid lithium and chemically active sulphur, which could help to pack in more energy per kilogram.
Another solution, used in magnesium-ion batteries, is to redesign the electrodes and replace lithium with magnesium. Magnesium is cheaper than lithium, and this technology is regarded as having the potential to reach the goal of 400 watt-hours per kilogram.
Although magnesium ions carry two electrical charges at a time, compared to one with lithium, there are still challenges to overcome. The heavier ions carry more charge, and could double the energy carried per volume, so the JCESR team are pushing ahead with research into this technology.