Elon Musk is no stranger to attention-grabbing headlines, and the Tesla CEO said last April the company would in the future have a battery that lasts for a million miles.
According to a report on Wired.com, Musk’s statement may not be so far-fetched. The article said that earlier this month, a group of battery researchers at Dalhousie University, which has an exclusive agreement with Tesla, published a paper in The Journal of the Electrochemical Society describing a lithium-ion battery that “should be able to power an electric vehicle for over 1 million miles” while losing less than 10 percent of its energy capacity during its lifetime.
In the paper, the Dalhousie researchers, led by lithium-ion expert Jeff Dahn, showed that its battery significantly outperforms any similar lithium-ion battery previously reported. They foresee the battery powering self-driving robotaxis and long-haul electric trucks—two products Tesla is developing.
“Full details of these cells including electrode compositions, electrode loadings, electrolyte compositions, additives used, etc. have been provided,” Dahn and his colleagues wrote in the paper. “This has been done so that others can recreate these cells and use them as benchmarks for their own R+D efforts.”
Based on the average American commute, Dahn estimates that most electric vehicle owners use only about a quarter of a charge per day. But to make a fleet of robotaxis or long-haul electric trucks, the batteries would have to exhibit significantly higher energy because of the discharge and recharge cycles these vehicles have, which is the impetus for the research.
According to the article, the lithium-ion batteries described in the paper use lithium nickel manganese cobalt oxide, or NMC, for the battery’s positive electrode (cathode) and artificial graphite for its negative electrode (anode). The electrolyte comprises lithium salt blended with other compounds.
Dahn’s team achieved the battery’s high performance by optimizing the battery’s chemistry and tweaking the nanostructure of the battery’s cathode. Instead of using many smaller NMC crystals as the cathode, this battery relies on larger crystals.
Lin Ma, a former PhD student in Dahn’s lab who was instrumental in developing the cathode design, says this “single-crystal” nanostructure is less likely to develop cracks when a battery is charging. Cracks in the cathode material cause a decrease in the lifetime and performance of the battery.
The article noted that days after the benchmark paper was published, Tesla and Dahn were awarded a patent describing a single-crystal lithium-ion battery almost identical to the batteries described in the paper. The patented battery includes an electrolyte additive called ODTO that the patent claims can “enhance performance and lifetime of Li-ion batteries, while reducing costs.”
According to the article, it is not clear whether the battery described in the patent is the million-mile battery that Musk said would enter production next year.