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Solid-state battery form factor once being researched by Bosch, which subsequently decided not to continue battery-cell development or manufacturing. (Bosch)

Battery experts: Solid-state EV tech could be five years out

Solid-state batteries remain the bogey to solve almost all EV drawbacks, but despite expanding R&D, few expect solid-state to be viable for at least half a decade.

Solid-state batteries are the “reach” energy-storage technology slated to take electric vehicles (EVs) –and to a lesser extent, other consumer-electronic products – to the next level. And at September’s 2019 Battery Show of North America, speaker panels and presentations about solid state certainly were in abundance. Just one problem: experts at the show’s Solid State Battery Feasibility roundtable discussion where brutally realistic in agreeing the technology won’t meet criteria for mass-production EVs for at least five years.

The reasons for the five-year wait are manifest, but the two primary factors are familiar to the automotive sector: cost and manufacturability. Nonetheless, most experts are in agreement that solid-state batteries for EVs certainly are not an “if,” but a “when.” One analyst estimate indicates $500 million was invested in solid-state battery ventures in 2018 alone.

Solid-state ‘glide path’
None on the five-person panel that included representatives from Ford and Toyota, two cell developers and a university researcher, questioned the potential or the science for solid-state technology, often referred to as lithium-metal because of the lithium-foil anode widely used to help the design overcome the reduced-conductivity typical of non-liquid electrolytes. Solid-state batteries already are in use for heart pacemakers and other applications, but determining how to manufacture the batteries for automobiles in volume at a reasonable cost currently isn’t possible.

“We’re doing this [developing solid-state batteries] for cost,” said Brian Sisk, vice-president of battery development at A123 Systems. He said the technology’s oft-touted potential to double the energy density of current conventional lithium-ion batteries means a concurrent potential to halve battery cost for a given capacity (not to mention reduce size and weight).

But Sisk said he is certain that unless and until solid-state technology can be installed in EVs at less cost than today’s lithium-ion batteries, solid-state batteries will not be able to compete. There may be “premium” or high-performance applications for which a higher-cost battery might be an acceptable trade for longer range or reduced weight, but for mass-production vehicles, he believes today’s cost per kilowatt-hour ratio must be improved for solid-state technology to be adopted.

Venkat Anandan, Ford’s Group Leader, solid state batteries, said the company is “actively looking at many types of solid-state batteries,” saying Ford is anxious to reap the energy-density, safety and cost benefits. Ford announced in April that it is investing Colorado’s Solid Power, a developer of solid-state technology that also counts BMW, Hyundai and Samsung as investors. Anandan said he believes it will be at least five years before solid-state batteries will be viable for mass-produced EVs.

Meanwhile, panelist Qichao Hu, CEO of battery developer SolidEnergy Systems, was slightly more optimistic in his timeline for solid-state technology – but with some caveats. His company already is manufacturing solid-state batteries with semi-solid electrolyte for high-altitude, long-endurance (HALE) vehicles, consumer drones and other aerospace applications. Hu said he believes the semi-solid design may be vehicle-applicable in 3-5 years and sees lithium-metal designs available in 7-10 years.

Panelist Timothy Arthur, principal scientist – Materials Research Dept. at Toyota Research Institute of North America, said, “It’s no secret that Toyota’s been high on solid-state batteries for a long time,” and reminded that the company has promised to have vehicles with solid-state batteries in operation during the 2020 Summer Olympic Games in Tokyo, Japan. But he did not directly speculate about when solid-state batteries will be fitted to production EVs.

Cell-cost mitigation
A123’s Sisk said the company intends to have a pilot production line in operation next year using a graphite anode while the company continues to work on the cost and other manufacturability challenges of lithium-metal.

He added that cost at the battery-cell level may not necessarily have to achieve parity with today’s lithium-ion cells; although solid-state battery cells might cost more, they could deliver cost-reductions at the systems level. Because solid-state batteries have no risk of fire or thermal runaway, he said battery-protection structure potentially could be reduced, as could battery-management and thermal-management costs.

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