It is a misconception that charging times for electric vehicles are long. This belief holds many potential buyers back from purchasing an electric vehicle. However, the average charging time of an electric car at fast charging stations is already less than 20 minutes today.
Electric vehicles are rapidly gaining popularity, but some prospective buyers remain hesitant. One of the reasons is that charging EVs (electric vehicles) is slow compared to the classic addition of "diesel". While drivers today are used to filling up their fuel tank in under five minutes, EVs, depending on battery size and specifications, typically take between 20 and 30 minutes to reach 80 percent at the fastest charging stations. At the fastest charging stations, combined with the ability to charge the car, it is thus possible to add 100 kilometers of range in just a few minutes. Some even report a time of around 6 minutes.
The belief of non-electric vehicle owners is that they will always charge their electric vehicle battery to 80 percent or more while on the road. The fact is that drivers of electric vehicles at fast charging stations only "recharge" energy for the necessary distance to the home charging station. It means that, for example, on the way home from a trip longer than the range of the car, they only stand on the electric charger for about 10 minutes. Only as much as they need to the home "socket". The reason also lies in the fact that charging an electric car at the public infrastructure of charging stations is quite expensive, or several times more expensive than charging at home.
In five to 10 years, however, much faster charging would be possible. Which theoretically means a stop at a charging station for only a few minutes. Namely, companies are developing new materials for lithium-ion batteries, as well as new "solid state" batteries, which are more stable at a faster charging speed. Charging speeds of 15 minutes or less for a "full" classic battery charge are already within the technological reach today.
Meanwhile, a team of scientists recently designed a prototype lithium battery that can charge more than 50 percent of its capacity under laboratory conditions in just three minutes—and can do so thousands of times without significantly degrading its capacity. The researchers also report that it could pave the way for batteries that can be fully charged in just 10 minutes.
However, there are still scientific and engineering challenges to be overcome before ultra-fast charging EV batteries are technically feasible and, above all, affordable. Some experts question whether electric vehicles that can be charged so quickly are really the future we want – at least with the electric grid we have now. This could be an obstacle.
The basics of charging
The batteries in today's EVs are made up of thousands of lithium-ion cells with the ability to store and release energy thousands of times over. Each of these cells consists of two electrodes – a metal cathode and a graphite anode – separated by a liquid electrolyte. While the battery is charging, lithium ions flow through the liquid from the cathode to the anode, filling the spaces between the graphite layers. The rate at which lithium ions move from the cathode to the anode dictates how quickly the battery charges.
At high charging rates, lithium batteries can overheat, causing them to degrade over time. More problematically, lithium can start to accumulate on the surface of the anode instead of entering it - a phenomenon known as lithium plating. Not only can this drastically reduce battery capacity, lithium deposits eventually form filament-like structures known as dendrites. Once they begin to form, these dendrites can grow across the electrolyte, touch the cathode and create a short circuit, causing the battery to catch fire or explode.
Due to fast charging issues, all EV batteries have built-in charging speed limits. A very powerful 350-kilowatt fast charging station could theoretically charge the 95-kilowatt-hour battery of an SUV like the Audi E-tron in less than 16 minutes. But the battery itself can only handle a maximum of about 150 kilowatts of charging power, making its actual full charge speed limit closer to 40 minutes.
How quickly the battery will charge depends not only on the charger and how many kilowatts of power the battery is capable of receiving, but also on the size of the battery, how much it is charged and even on the weather - that is, the external temperatures and the battery's readiness to receive energy. Still, state-of-the-art fast charging stations can often charge an EV battery up to 80 percent, literally adding hundreds of miles of range in as little as 30 minutes (when the battery is 80 percent full, the charging rate slows down to avoid damaging the battery). Tesla owners can visit the "Tesla supercharger" station, which will add around 300 km of range in 15 minutes.
What is the future of ultra-fast charging?
Although adding 300 kilometers in just 15 minutes is really extremely fast, psychologically this is still far from what we need today to fill up a classic "diesel" tank with which we do 1000 kilometers. Those hoping for such an EV charging experience will have to wait another decade or so for the already known technology to be put into real practice. Even when EV batteries are capable of charging in less than 10 minutes, it is not clear whether ultra-fast charging will be possible. At 400 volts and more, which today's fast charging stations draw from the electrical network, the question of the sustainability of the infrastructure quickly arises.
But the fact is that we are asking the wrong things! Electric vehicle users use public infrastructure and fast charging stations only as an emergency exit. Most modern electric cars are able to travel a real 300 kilometers without recharging. In practice, this means that anyone from Ljubljana can easily get to Portorož and back. So to the home charging station - without intermediate stops. If you want a safe 100 kilometers of additional range, you can get the energy in less than 10 minutes at fast charging stations along the highways. This is a time that is comparable to a normal stop at a gas station. Both drivers of classic cars and electric cars suck.
Linked and adapted: natgeo, evdb, …
