Toyota and Panasonic are collaborating to bring solid-state batteries into production by 2025. Toyota even built a working solid-state battery-powered prototype vehicle, which it was going to debut at the Tokyo Olympic Games if the event hadn’t been canceled because of the coronavirus pandemic. And while COVID-19 may have halted the 2020 Games, it hasn’t slowed down Toyota’s engineers!
The batteries are set to be a total game-changer for EVs since they charge quicker (zero to full in 15 minutes) and offer more range in the same size package. However, they will be manufactured in limited supply at first and likely won’t be in Toyota vehicles for sale right away because the automaker still has to solve the technology’s short life-span issue. This problem plagues solid-state batteries to this day.
The executive VP of Toyota Motor Corp.’s powertrain company, Keiji Kaita, told Automotive News all about the company’s commitment to delivering the breakthrough solid-state battery technology as soon as possible and the current obstacles that hinder commercialization from happening now.
Kaita said:
Solid-state batteries replace a liquid electrolyte with a solid and are expected to be lighter, longer-lasting, safer and eventually cheaper than today’s batteries. The solid-state prototypes recharge much faster than today’s lithium-ion batteries, but Toyota’s prototypes still face challenges. For one, because of safety and durability issues, our engineers have yet to harness the batteries’ true potential for higher energy densities. To counter limitations, we’re looking at how we might adjust the anode or other materials. We are trying to reduce the disadvantages that are found.
The team is tackling the issue by focusing on a sulfur-based electrolyte since it facilitates a more efficient lithium-ion-transfer between the electrodes. The engineers are still figuring out how to make an electrolyte that can remain flexible even when it’s densely compacted, and that won’t deform during charging and discharging.
Kaita explained:
The solid electrolyte needs to be compacted under high pressure to reduce the gaps between particles so ions and electrons can easily pass through. But it also needs to be flexible, because the anode expands and contracts during discharge, and the electrolyte must give a little leeway.
The hitch is, the more expansion and contraction there is, the more the electrolyte particles become deformed. And this deformation inhibits the flow of ions and electrons and degrades battery performance over time. The key is developing a material that won’t deform easily. A breakthrough might come from new materials or new designs.
Toyota aims to develop solid-state batteries that keep over 90% of its original performance for a long time. Kaita said:
That can be accomplished by adjusting the performance of the battery, but also through the control system or the cooling system. Alternatively, it could be based on how we use the battery or how we charge the battery. A holistic perspective is very important.
Another challenge is large-scale manufacturing because the cells have to be made in an ultra-dry, nonaqueous environment. Workers have to build them via compact transparent booths called gloveboxes – they reach inside the boxes through rubber gloves sealed around access openings. The process is awkward, slow, and next to impossible for mass production. Of course, this means the first batteries will be expensive, costing a lot more than lithium-ion batteries.
Regardless, the company is still on track to limited manufacturing for 2025. And if the team can figure out how to mass-produce them, then the price will drop, and solid-state batteries will change the world of future EVs and battery-powered electronics for the better.
Another company working on bringing solid-state batteries to the market is Samsung. Meanwhile, Brown University researchers have been researching ways to make solid-state batteries even stronger with graphene, and MIT researchers have been developing new kinds of battery architectures that improve their efficiency.
