Though three months still remain in 2020, Tesla has yet to sell a fully autonomous car, let alone one capable of robotaxi operation.
Musk’s talk of a major battery breakthrough, however, suggests a shift to solid-state technology, the “holy grail of batteries,” according to Richard M. Laine, a University of Michigan professor who researches batteries.
“We all know Elon Musk is a rather optimistic guy. So maybe three to four years, maybe five to six. Maybe higher than that,” Laine said. “It’s a very very big set of ifs.”
In a solid-state battery, the part of the battery that’s traditionally liquid is replaced with solid materials. If developed, solid-state batteries are expected to bring several advantages, experts say. Lithium-ion batteries, which are used in everything today from phones to laptops to electric cars, are highly flammable under the right conditions. The design and materials in solid state batteries promise to reduce the risk of fires.
Solid-state batteries should have a higher energy density, which could help reduce the costs of electric vehicles as battery packs won’t need to be as large. Vehicles’ range could improve too, as more batteries could be included in a small car.
M. Stanley Whittingham, who won a 2019 Nobel Prize for his development of lithium-ion batteries, cautions that solid-state batteries may be much more expensive to manufacture than traditional batteries. He also said solid-state batteries may not have the needed power capabilities.
He expects solid-state batteries will first come to small devices such as cell phones and smartwatches, before going into larger things. Those markets can tolerate higher costs, he said, because consumers are less likely to notice a price increase on a device with a small battery, rather than a large one where the battery makes a big contribution to the overall price.
Another challenge for solid-state batteries is longevity, according to Yang Shao-Horn, an MIT professor who studies batteries.
For example, an electric car with 500 miles of range isn’t that great if the battery loses most of its capacity in a matter of months. Shao-Horn said she’s not aware of any solid-state batteries that are three or four years away.
Others are more optimistic about solid-state battery timelines. Solid Power, a Colorado-based startup, says it’s testing 300 Watt-hours per kilogram batteries with auto suppliers already. CEO Doug Campbell told CNN Business he expects to see the 400-mile benchmark achieved in the next several years.
Yi Cui, a Stanford professor who still sits on the board of Amprius, a battery startup he founded, thinks Musk’s prediction is accurate. Cui said that Amprius is already testing a battery with 400 Watt-hours per kilogram. He thinks that innovations, such as using silicon in batteries, can lead to major breakthroughs.
“It’s the gift that God sent to us,” Cui said. “This material is so powerful.”