TOKYO -- Toyota Motor Corp. says it has made major advances in developing smaller, more powerful solid-state batteries as the next-generation power pack to succeed lithium ion battery technology.
The new batteries, which have more than twice the energy density of lithium ion units, could power electric vehicles more than 300 miles on a single charge and enter production in the early 2020s, top engineers at the company said.
Since 2012, Toyota has managed a fivefold increase in the power output of its experimental solid-state batteries, Senior Managing Officer Soichiro Okudaira told a conference here.
The current coin-sized cell is still in the laboratory stage. But Toyota expects the technology to be ready for cars in the early 2020s, Hideki Iba, general manager for the Japanese carmaker's battery research division, said separately.
Toyota detailed its developments at Automotive World, an annual engineering and technical conference in Tokyo.
Solid-state batteries could herald a breakthrough in electrified driving because they are more compact and offer higher power output and energy density than today's batteries.
They are called solid-state because they replace the liquid electrolyte used in nickel-metal hydride and lithium ion batteries with a solid ceramic or polymer electrolyte.
That makes the battery more compact and stable, allowing higher voltage in a smaller bundle. They can also be molded into more flexible shapes for better packaging inside a vehicle.
Toyota's current solid-state battery has a power output of around 2,000 watts per liter, on par with a lithium ion battery but higher than that of a nickel-metal hydride unit.
The current solid-state battery's energy density is around 400 watt-hours per liter, compared with a maximum of around 300 watt-hours per liter for lithium ion batteries, Okudaira said.
And the energy density is still far below its potential.
Toyota aims to increase the density to between 600 and 700 watt-hours per liter by 2025, the engineers said.
Iba said the first wave of production batteries should deliver an electric vehicle driving range of at least 500 kilometers, or 300 miles, on one charge.
The problem, he said, is that still falls short of being an alternative to gasoline vehicles, which typically can travel twice as far on a single tank of fuel.
"One charge would ideally do 1,000 kilometers," Iba said. "We have to creatively break through many challenges."
Solid-state batteries, however, also can be used in hybrid vehicles to increase their performance and EV-mode driving.
Looking further ahead, Toyota is working on so-called lithium air batteries, which have energy densities around 1,000 watt-hours per liter. Their power output is on par with solid-state units.
In lithium air batteries, the lithium cathode used in lithium ion batteries is replaced with one that interacts with oxygen. This requires less material and allows for lighter packaging.
Toyota projected those would be ready after 2030.
The company's current lithium air batteries can deliver energy densities around 1,000 watt-hours per liter. But their power output is still below that even of nickel-metal hydride units.
