Electric vehicles are easier on the environment than their gasoline-powered counterparts, but their long charging times and the lack of readily available charging stations can make life hard for their eco-conscious drivers.

Yet, now a breakthrough is about to be made. Scientists are working to develop refillable, or as they call it 'flow' batteries that can be refueled in minutes and will be available at a large range of converted petrol stations. It is a shift that might make these EVs more attractive to buyers who were wary of long charging times.

“You drive 300 miles, drain your tank and pump in new [liquid] — as long as it would take to fill your car with gasoline — and drive off,” says John Cushman - a professor of earth and atmospheric sciences and mathematics at Purdue and a leading researcher on liquid battery technology.

Lee Cronin, a chemist at the University of Glasgow in Scotland and another leading researcher on the technology, agrees. He says flow batteries “would turn EVs into the cultural equivalent of a fuel car. And you have the existing pipe infrastructure for moving liquids around” — a reference to the service stations now in existence that could be retrofitted to pump the battery liquid instead of gasoline.

Like the lithium-ion batteries that power most electric vehicles today, these flow batteries release energy through chemical reactions between the ends of the battery and an electrolyte (Electrolysis). In a lithium-ion battery, you recharge the battery when the electrolyte runs out. In a flow battery, the electrolyte is pumped from a tank through the battery; when it finsihes, it can simply be swapped out for a fresh batch.

Modern flow batteries have been around since the 1980s. Their long lifespans and easy recharging mean they’re well suited for large-scale energy storage but they have always been too big and too heavy for use in vehicles.

A duo called Cushman and Croninare working to solve this problem, though their teams are taking very different approaches. Cronin’s team is working to increase the energy density of flow batteries by creating electrolyte with a high concentration of metal oxide. Cushman’s team announced on Feb. 7 that they had created a liquid battery with three to five times the usual energy density by pumping the electrolyte through multiple battery cells at high speed.

While some have uncertainties about whether it will be safe and easily available, scientists are working hard to find a solution. However, it’s unclear when flow battery-powered vehicles might come to the market. Cushman says he hopes to test the technology in cars in the next three years. Cronin expects to spend up to 18 months testing out the electrolyte his team developed.

Overall, signs have been made for improvement and there is soon to be a breakthrough which could provide the equivalent of a car evolution.