With an energy density of about 1000Wh/kg, Chen’s battery already surpasses its commercial counterparts. ‘Lithium-ion batteries that are used in Tesla electric cars have only about 180Wh/kg,’ says Chen. And, he adds, even after 200 discharge–recharge cycles, they saw almost no drop in the battery’s capacity.
However, there are still challenges to overcome before a sodium–carbon dioxide battery will see the inside of an electric car. Chen admits that water is detrimental to the battery, it only works with pure carbon dioxide and their coin-sized setup is currently too small to power anything more than a tiny light emitting diode.