Toyota has developed a working prototype of its long-promised solid-state batteries that are operating in running concept vehicles, and the company remains on track for limited production of them by 2025. That’s the gist of an interview Automotive News did with Keiji Kaita, executive vice president of Toyota Motor Corp.’s powertrain company and field general manager of its battery division.
Solid-state batteries, which replace liquid electrolyte with a solid, are seen by some as the “holy grail” of electric vehicle technology. They have the potential for higher energy density and range, greater safety, faster recharging and longer lifespan, in addition to being less prone to problems with extreme temperatures. But the technology presents many challenges, some of which Kaita discussed. Toyota has been talking about solid-state batteries for at least a decade, but appears to have backed off some of its earlier, ambitious goals. Its current goal is reportedly to develop a battery that hangs on to more than 90% of its original performance over as long as 30 years.
According to AN, Toyota has developed prototype cells shaped like plates that are about the size and thickness of a thin spiral notebook, sealed in pouches and arranged in modules. It’s using a sulfur-based electrolyte that appears to more efficiently transfer lithium ions between negative and positive electrodes, and charging from zero to full takes less than 15 minutes. But one of the challenges is reportedly developing an electrolyte that can be densely compacted while remaining flexible, all without negatively affecting battery performance over time. One other challenge: how to manufacture the cells in an ultra-dry environment in high volumes.
Companies including Hyundai, Honda and Fisker are pursuing solid-state battery technology as a way to speed mass adoption of EVs. Samsung recently announced a breakthrough via the development of a silver-carbon composite anode, though it stressed the technology isn’t ready for production yet. Toyota has a number of new BEVs in the pipeline.
Toyota had planned to show off the technology, which it’s developing through a joint venture with Panasonic, at the Summer Olympics this month in Tokyo before the coronavirus pandemic prompted organizers to postpone the Games to 2021. Kaita said it’s nevertheless too soon to say when the prototype batteries will make their public debut.