Researchers at Penn State say they have found a way to make batteries for electric cars that can be smaller — which conserves the precious resources currently seeing massive price increases — and faster charging — which addresses the concern many people have that charging an electric car takes too long. The research was published on October 12 in the journal Nature.
Scientific research papers seldom make for light reading, but there are enough significant details in the study’s abstract to make it worth sharing with you.
Lithium ion batteries with nickel-rich layered oxide cathodes and graphite anodes have reached specific energies of 250–300 Wh kg and it is now possible to build a 90 kWh electric vehicle pack with a 300 mile cruise range. Unfortunately, using such massive batteries to alleviate range anxiety is ineffective for mainstream EV adoption owing to the limited raw resource supply and prohibitively high cost.
Ten minute fast charging enables downsizing of EV batteries for both affordability and sustainability, without causing range anxiety. However, fast charging of energy-dense batteries (more than 250 Wh kg or higher than 4 mAh cm) remains a great challenge. Here we combine a material agnostic approach based on asymmetric temperature modulation with a thermally stable dual salt electrolyte to achieve charging of a 265 Wh kg battery to 75% (or 70%) state of charge in 12 (or 11) minutes for more than 900 (or 2,000) cycles.
This is equivalent to a half million mile range in which every charge is a fast charge. Further, we built a digital twin of such a battery pack to assess its cooling and safety and demonstrate that thermally modulated 4C charging only requires air convection. This offers a compact and intrinsically safe route to cell-to-pack development. The rapid thermal modulation method to yield highly active electrochemical interfaces only during fast charging has important potential to realize both stability and fast charging of next-generation materials, including anodes like silicon and lithium metal.
Well, that is certainly a jargon-filled exposition. Let’s see if we can unpack some of the implications of this research based on a press release from Penn State and a report by Time. First the explanation from the university.
“The need for smaller, faster-charging batteries is greater than ever,” said Chao-Yang Wang, the lead author on the study. “There are simply not enough batteries and critical raw materials, especially those produced domestically, to meet anticipated demand.” [The reference to domestic production is especially relevant now that the Inflation Reduction Act has tied EV incentives to cars manufactured in America using materials sourced from North America or certain trading partners.]
By 2035, the largest auto market in the United States [California] will effectively retire the internal combustion engine, the press release states. If new car sales are going to shift to battery-electric vehicles, they will need to overcome two major drawbacks. First, they are too slow to recharge. Second, they are too large to be efficient and affordable.
“Our fast-charging technology works for most energy dense batteries and will open a new possibility to downsize electric vehicle batteries from 150 to 50 kWh without causing drivers to feel range anxiety,” said Wang. “The smaller, faster charging batteries will dramatically cut down battery cost and usage of critical raw materials such as cobalt, graphite, and lithium, enabling mass adoption of affordable electric cars.”
The technology relies on internal thermal modulation, an active method of temperature control to demand the best performance possible from the battery. Batteries operate most efficiently when they are hot, but not too hot. Keeping batteries consistently at just the right temperature has been a major challenge for battery engineers. Historically, they have relied on external, bulky heating and cooling systems to regulate battery temperature, which respond slowly and waste a lot of energy, Wang said.
Instead, the team decided to regulate the temperature from inside the battery. The researchers developed a new battery structure that adds an ultrathin nickel foil as the fourth component besides the anode, electrolyte, and cathode. Acting as a stimulus, the nickel foil self-regulates the battery’s temperature and reactivity which allows for 10 minute fast charging on just about any EV battery, Wang explained.
“True fast charging batteries would have immediate impact,” the researchers write. “Since there are not enough raw minerals for every internal combustion engine car to be replaced by a 150 kWh-equipped EV, fast charging is imperative for EVs to go mainstream.”
Batteries, Batteries, Batteries
Sharp eyed readers will instantly notice that 150 kWh batteries are not really the norm for electric cars, unless we are talking about behemoths like the Ford F-150 Lightning or Hummer EV from GM. The typical battery size for a normal EV today seems to be between 60 kWh and 80 kWh — half the size that Professor Wang talks about. Nevertheless, batteries that do more with less would be welcome news, particularly when it comes to making more affordable EVs.
Time explains it this way. “The technology can work for any size of battery, but perhaps the biggest benefit is that it will enable automakers to sell EVs with smaller batteries without triggering consumers’ range anxiety. The faster a battery can charge, the less need there is for big battery packs with long range, since stopping to charge will be no less an inconvenience than going to a gas station. And smaller battery packs also mean cheaper EVs.”
It points out that Professor Wang has been involved in battery research for several decades and contributed to development of the EV1, the groundbreaking electric car from GM. We reported on his research back in 2019, which just goes to show how long it takes for new ideas to make their way out of the lab and into production. Wang is the CTO of EC Power, which is seeking to commercialize the new technology for batteries. It is building a factory to produce the new batteries so they can be distributed to EV manufacturers to validate their suitability for production vehicles. It should be noted that StoreDot, an Israeli startup, also says it is working on batteries that can be recharged in 10 minutes or less.
Maybe the new batteries from EC Power will actually preform as promised and a paradigm shift will occur in the world of electric cars. While fast charging is certainly desirable, the elimination of bulky — and expensive — liquid cooling systems for battery packs could be just as important because it would help lower the cost of electric cars.
Who knows? It might also give a boost to battery swapping, which is being promoted by NIO, CATL, and BYD, because there will be no coolant lines to connect and disconnect. Installing a fully charged battery in place of a depleted one not only is fast, it also eliminates any owner concerns about battery degradation — a subject that is very much on the mind of people considering the purchase of an electric car.
The upshot is that the EV revolution is moving forward and there will be many innovations along the way, just as there were many innovations along the way as gasoline-powered cars gained popularity. Just think how the self starter changed the automobile experience! These are exciting times and there is a lot happening behind the scenes.
According to legend, on December 31, 1899, the head of the US Patent Office told people, “Everything that can be invented has now been invented.” For those who would like to see the EV revolution move forward more quickly, we can only offer this advice: “Patience, grasshopper.”
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