What if batteries could last forever? A research team led by a core Tesla consultant found that ordinary lithium-ion batteries can still retain more than 80% of their capacity after being charged and discharged more than 20,000 times. This equates to approximately 7 million miles of driving, or approximately 500 years of service life in typical vehicle usage scenarios. In fact, these batteries almost never run out.
Jeff Dahn's lab at Dalhousie University.
Are there any hidden dangers? Jeff Dahn, an emeritus professor at Dalhousie University in Nova Scotia, Canada, said that there are basically no obvious shortcomings. He led a team of doctoral and postdoctoral researchers to complete the long-life battery research, and the related paper was published in the Journal of the Electrochemical Society last week. Dahn is also a core battery advisor to Tesla, the main funder of the Dalhousie University lab.
Such batteries require only "mild use," Dahn said: kept below 80 degrees Fahrenheit via a cooling system; charged only to about 70 percent capacity before long trips; and typically on a slow-charging mode -- the study's battery took about three hours to fully charge.
Once you do this, you may have a nearly permanent battery. “It’s incredible, it’s crazy,” Dahn said. “The data shows these batteries are incredibly durable. We’re now doing 12 charge-discharge cycles a day for eight years, which is unbelievable.”
Electric car manufacturers still have reservations about this. The industry typically offers an 8-year or 150,000-mile warranty on vehicle batteries. If Dahn's findings are confirmed, it means that existing warranty conditions are far from reflecting the true lifespan of batteries. Batteries already play an important role in power grid expansion planning, and this role will increase significantly in the future.
Power companies can use the batteries in electric vehicles to meet grid demand during peak power consumption periods. When the electric vehicle reaches the end of its service life, the battery can be removed and loaded into a large container to provide long-term backup power for the data center, ushering in a second long service life.
The battery developed by Dahn uses a nickel manganese cobalt (NMC) ternary material system. This paper provides a subversive refutation of the currently popular lithium iron phosphate (LFP) battery. LFP batteries are favored by Chinese car companies, accounting for more than half of the world's installed electric vehicles, and are almost the only choice for AI data centers, power grids and home energy storage. Although Western car companies mostly use NMC batteries with stronger performance, they are increasingly turning to the LFP route.
LFP is highly regarded because its cost is generally lower than NMC, its low-temperature performance is better, it does not contain nickel and cobalt, and it has fewer supply chain bottlenecks. Industry veterans also generally believe that the charge-discharge cycle life of LFP is much higher than that of NMC.
But Dahn points out that this claim about cycle life is not true: NMC batteries actually have a longer cycle life.
Dahn arguably has a personal stake in the controversy - he is a co-inventor of NMC technology. However, he also said that Dalhousie University has a battery laboratory with 40 people. In view of the wide range of applications of LFP, the team is also synchronously optimizing its performance.
Dahn’s research into long-life NMC batteries dates back to at least 2019, when he caused a stir in the industry by publishing a paper announcing the development of a battery that could last up to 1 million miles. Headlines from major media outlets, including mine, are reporting “The era of million-mile electric cars is coming.”
The new breakthrough this time is that some batteries have been running continuously for 6, 7 or even 8 years, and their performance is still being verified.
The idea of connecting electric vehicle batteries to the grid originated from a 1997 paper by University of Delaware professor Willett Kempton. He noted that the 200 million vehicles in the United States sit idle 95 percent of the time, with much of their value being wasted. Kempton wrote that once electric vehicles become commonplace, power companies should take advantage of onboard energy storage.
This idea later evolved into the virtual power plant. Power companies can tap into car and home batteries during grid peaks or extreme weather. Renewable energy research organization Bloomberg New Energy Finance said that relevant pilot projects have been carried out in California, the United Kingdom and China.
But the core sticking point in all plans has always been: whether a large number of electric vehicle owners are willing to participate. After all, no one wants to wear out the most expensive component of their vehicle – the battery. Once a battery is damaged, replacement costs can run into thousands of dollars.
Dahn said research from Dalhousie University shows that even if electric vehicle owners connect their vehicles to the grid every day, battery capacity will hardly degrade.
In a pilot conducted in the Dutch city of Utrecht, Renault's Ampere unit found that even users who interacted most frequently with the car network consumed minimal battery capacity. Anpei calculated the total amount of electricity users sent to the grid every day in six months, which was only equivalent to the battery being fully charged and discharged 20 times.
If the Utrecht experiment reflects the real usage habits of car owners, then the life of these batteries may even be longer than the life cycle of the power grid system itself.
Some maintenance issues remain: Battery electrolytes — the liquid that shuttles lithium ions between electrodes when charging and discharging — can dry out or leak over time. The authors of the paper recommend using metal cylindrical or prismatic batteries, which are less likely to leak than pouch batteries.
Max Reed, a battery analyst at energy research institute CRU Group, said the research team also injected much higher amounts of electrolyte into the battery than conventionally used.
The lab is still testing three separate NMC cells. Dahn's team has been charging and discharging it about eight times a day for 7.5 years. During this time, the battery still retains up to 87% of its original capacity. The paper predicts another 2.5 years of use before capacity drops to 80%, the industry's common end-of-life standard.
By then, its number of charges and discharges will be equivalent to driving 9.6 million miles, enough for 685 years of ordinary use.
"In the final analysis, this type of battery has such a long life. If it is not used for vehicle-network interaction and secondary use, it will be a waste of value." Dahn said.