While strongly making the case that lithium-ion batteries must have a good safety record and a minimum life of 10 years to be a mass-market solution, a prominent battery expert at a recent conference expressed deep skepticism about the viability of the Nissan Leaf and Chevrolet Volt.
Dr. Menahem Anderman made those points at a mid-May conference administered in Orlando by his consulting company, Advanced Automotive Batteries.
In his presentation, “Can Li-ion Batteries Support the Proliferation of Plug-in and Electric Vehicles?” Anderman said many in the automotive industry believe cost and energy density are the most important keys to a Li-ion future. “Those are, of course, very important matters, but I would suggest they are, in priority, the 4th and 5th most important," he said. "The top one is safety,” followed by reliability and durability.
The major automakers must ensure that their vehicles with Li-ion batteries experience no fire of such significance it generates headlines in the New York Times or ABC News, Anderman said. Such publicity would have “very significant negative impact” on the technology’s prospects.
An Li-ion fire in a vehicle produced by one of the many smaller EV makers would not be good, but the PR damage could be contained, Anderman said. “Probably the industry can say: Of course, this start-up or this little company did not do the type of engineering verification we do, and what happened to them does not translate to what we are doing,” he said.
In the next four to five years, he said, most automakers will put a PHEV or an EV on the road in small volume “to establish safety, reliability, and durability from a technology point of view,” and consumer acceptance and behavior from another point of view.
“If we have all those three [safety, reliability, durability]—and I’m not saying we will not; I think we will have all three, but it may take 5 to 10 years—then we can start talking about cost,” Anderman continued. “Cost will become high priority once safety, reliability, and durability are proven.” After cost comes performance in terms of priority, he said.
Although related, durability and reliability are distinct, Anderman explained. Reliability addresses early failure. A battery can have an impressive average life of 10 years but if 10% of the failures occur in the first three months, that’s poor reliability. The most important component of reliability is manufacturing quality, he pointed out.
Durability is average life, so a four-year battery can be considered reliable if 99% of them experience no failures in that time frame. But it couldn’t be considered durable if the industry's goal is a 10-year life and most of them give out at 5 years. The most important components of durability are cell design and chemistry, said Anderman.
“Don’t have any illusion that we can have a high-volume PHEV or EV business without a 10-year life from the battery,” he emphasized. Ten years of life is a lot to expect in this early stage of Li-ion development, Anderman allowed, and a shorter life can support the initial low-volume stages of PHEV and EV development. But in a mass-market environment, asking buyers to pay many thousands of dollars for a replacement battery is unrealistic.
It is reasonable to expect continued government subsidies for the purchase of EV and PHEV vehicles but not subsidies for replacement batteries, said Anderman.
The Leaf EV and Volt PHEV (General Motors refers to the car as an extended-range EV) both use pouch-type Li-ion cells that, he said, do not measure up in terms of safety and reliability to so-called metal-can types that have hard casings. The Leaf especially does not look promising, he said, noting that the Volt has a gentle duty cycle and uses active liquid cooling of the battery pack.
Without proper cooling technology, "a pouch cell design with a manganese chemistry will perform very poorly” in hot climates, said Anderman of the Leaf battery. “Can you expect 10 years from the battery? Definitely not in Phoenix, I’m pretty sure not in L.A., and I’m not sure about San Francisco and Atlanta.”
Regarding the Leaf battery's life-cycle performance in Phoenix, he told AEI later: “If it lasts three years, I’d be surprised.”
Ironically, individual pouch cells are good at dissipating heat. However, when such cells are packaged tightly together, as in the Leaf, that advantage is lost, Anderman said. “There is a very poor thermal characteristic in this type of integration” of the battery into the vehicle.
Contacted by AEI for comment, Nissan North America Manager of Technology Communications Colin Price stated: “We are confident [the cells] will dissipate heat well and anticipate the battery pack will have 70 to 80% of capacity left after 10 years of automotive use.” He noted that the Leaf battery pack can be serviced to the cell level, so a single cell failure does not equate to battery pack failure.)
Anderman acknowledged that Nissan CEO Carlos Ghosn is a “very smart man” and might know of a way to make the Leaf work, and maybe General Motors has data that shows the Li-ion pouch design is viable. “But other car companies have shown that it is not ready,” he said.
Some of the slides from Anderman's presentation are included in a new AAB study (The EV-PHEV Opportunity Report) that Anderman pitched during his conference. He expressed great confidence in the data and insights he collected during many direct interviews with important global EV and PHEV players at all tier levels.Other opinions and projections from Anderman’s AAB presentation:
Written by Patrick Ponticel