The Electric: Battery Hands Are Skeptical of Byd’s Claim of Five-Minute Charging
Last month, China’s Byd said it would soon release two electric vehicles capable of charging in five minutes—not much longer than the time it takes to fill a gas tank. The assertion caught rivals uncomfortably off guard, especially companies in the West, where the fastest competing EVs charge to 80% of capacity in roughly 20 minutes.
Byd’s claim is that its new EVs could deliver roughly 150 miles of driving range in five minutes. If that’s true, the company—already on an early pace to surpass Tesla as the world’s leading EV maker globally this year—seems likely to run away with the race. It would dramatically narrow the difference between EVs and gasoline-power vehicles.
Byd has released few details about its charging system and batteries, and it did not respond to emails. But Western battery industry veterans raise doubts about its claim. It’s long been possible to charge so quickly once, twice or perhaps even a handful of times over the 1,000-cycle lifetime of a typical EV battery with the 300-mile driving range most motorists demand, they said. But such a battery would burn up, and possibly catch fire, if subjected to consecutive five-minute charges for many hundreds of cycles, industry hands said.
Batteries are all about trade-offs between range, weight and charging time. Building a battery that can handle a huge jolt of electricity at once would limit the EV’s range to 100 or 150 miles. The reason is the balance between the electrodes. To enable lithium ions to move that fast into the negative electrode—the anode—it must be made ultrathin. But if you make the anode thinner, you have to make the positive electrode—the cathode—thinner, too, which reduces its capacity to hold energy. That decreases the driving range.
In addition, producing that huge jolt would require costly upgrades to charging stations and the power grid, which at the moment can’t meet such a demand. The cost to build a small four-charger station would be well over $1 million, according to Quincy Lee, CEO of Electric Era, a charging station company. Part of that cost is the large batteries the stations would require to buttress grid power.
The already strained power grid would need expensive upgrades to enable such stations. Byd said it will build 4,000 new charging stations capable of 1 megawatt bursts of power, roughly twice as much voltage as the current best transformers can theoretically supply. There currently appear to be no such transformers in the U.S. (or China) for passenger vehicles, though a few have been installed in depots to charge up gigantic batteries that power electric semitrucks.
A truly competitive new battery would charge in five minutes, go at least 300 miles on a charge, cost roughly the same as current batteries to produce and use conventional charging stations. It hardly seems worth the effort to get 150 miles of range, except for the global buzz generated by the announcement. “I think it’s amazing marketing—it’s a bang,” said Gene Berdichevsky, CEO of Sila Nanotechnologies, a California-based silicon anode developer.
Byd CEO and founder Wang Chuanfu made the fast-charging claim in a public event March 17 at the company’s headquarters in Shenzhen. The company’s new system, he said, would deliver around 150 miles of driving range in five minutes. He said in the presentation that the first two EVs powered by the system, the Han L sedan at $37,400 and the Tang L SUV at $38,500, will be available in April. They will only be sold in China.
Wang did not say the battery would charge in five minutes every time. But his manner suggested the new cars would be comparable to those currently on the road with 250 or 300 miles of range—except that they could charge a lot faster. It was a claimed breakthrough that, if true, would put serious pressure on rival EV makers, since plenty of Chinese buyers would then expect such capability in any EV.
By comparison, Tesla says its EVs can charge to a maximum of 170 miles in 15 minutes; Mercedes-Benz says its new CLA sedan can charge to 200 miles in 10 minutes.
Claims about the Han L in Chinese media in recent months have evolved. In January, prominent Chinese tech website IT Home reported that the Han L could charge from 16% to 80% of its battery capacity—around 144 miles—in 10 minutes. That makes sense because those capacity levels are the sweet spot of charging. Totally draining a battery can damage it, and batteries begin to resist more charge at about 80% of capacity.
Offering another clue, the Beijing-based publication Cars News China reported that the Han L and Tang L use large lithium-iron-phosphate batteries, which allow faster charging than nickel-based batteries. Byd uses LFP in all its cars. No one has reported the type of anode Byd’s new EVs use, but they are likely graphite because the alternative—silicon—doesn’t twin well with LFP cathodes.
Last year, StoreDot, an Israeli battery developer, claimed to have produced a battery that delivered 200 miles of driving range in 10 minutes, and said it would soon deliver a battery that provided 100 miles of charge in five minutes. Its cathodes are nickel based and its anodes are made of costly silicon, which allows much faster charging than graphite.
StoreDot CEO Doron Myersdorf told me that the key to the performance of StoreDot’s batteries is its electrolyte—the liquid that sits between the two electrodes. He said Byd might have improved its electrolyte as well, but that he remained skeptical of its claims.
“What BYD is claiming is really not so feasible, especially not with the infrastructure that we have today. Also, it’s very dangerous to put 1 megawatt into a vehicle,” he said. “This is only a once-in-a-while kind of use case. Otherwise, they would say that this is a use case for consecutive cycling, but they never mentioned this at all.”
Berdichevsky, the Sila Nano CEO, thinks the splash the Byd announcement made, however, shows that ultrafast charging is the future. “Ten years from now, I think this is the standard,” he said. “Maybe it’s eight minutes, maybe it’s five, maybe it’s nine, but it’s single digits because that’s good marketing.”