A Toyota logo on a car

Toyota to enter electric car market with new safer battery

Image credit: Reuters

Toyota engineers have developed a new lithium-ion battery that packs more power and offers extra safety features to avoid short-circuits. The technology will allow the Japanese car maker to enter the all-electric car market it has so far avoided.

The new lithium-ion battery has a capacity of 8.8 kilowatt hours, double the amount of previous devices used in Toyota’s hybrid vehicles. At the same time, the engineers only had to increase the size of the battery pack by around two-thirds and its weight by a half.

This was possible by reducing the distance between the anode and the cathode, where active ions travel when charging and discharging.

The battery is equipped with advanced control technology precisely monitoring the temperature and condition of each of the 95 cells in its new battery pack.

The new battery will power Toyota’s anticipated Prius Prime hybrid, which will be able to drive 60km on the battery before needing the help of its gasoline engine.

“It’s a tall order to develop a lithium-ion car battery which can perform reliably and safely for 10 years, or over hundreds of thousands of kilometers,” Koji Toyoshima, the chief engineer for the Prius told Reuters.

“We have double braced and triple braced our battery pack to make sure they’re fail-safe ... It’s all about safety, safety, safety.”

Toyota, which sees the ultimate future in fuel cell technology, has so far stayed away from the plug-in electrical vehicle market dominated by firms such as Tesla and Nissan.

The company says battery concerns were one of the most important reason for it to opt for hybrid technology instead. The Prius, commercially introduced in 1997, was the first mass-produced hybrid vehicle.

“Developing lithium-ion batteries for both hybrids and plug-ins will enable us to also produce all-electric cars in the future,” said Toyoshima. “It makes sense to have a range of batteries to suit different powertrains.”

Lithium-ion batteries used in electric vehicles as well as electronic devices have long been a cause of safety concerns. The latest high-profile affair involves exploding batteries of Samsung’s flagship Galaxy Note 7 smartphones. Previously, overheating lithium-ion batteries grounded fleets of Boeing’s Dreamliner passenger jets.

Many lithium-ion car batteries use a chemical combination of nickel, cobalt and manganese. These store more energy, take a shorter time to charge, and are considered safer than other Li-ion technologies.

However, they can still overheat and catch fire if not properly designed, manufactured and controlled.

“Our control system can identify even slight signs of a potential short-circuit in individual cells, and will either prevent it from spreading or shut down the entire battery,” said Hiroaki Takeuchi, a senior Toyota engineer involved in the development.

Toyota developed the new battery in cooperation with Panasonic, which also produces batteries for Tesla.

One of the prerequisites to ensure safety is a closely controlled manufacturing and assembly environment that prevents contamination. Even the smallest metal particles and impurities in the battery mix can trigger short-circuit, overheating and potential explosion.

“The environment where our lithium-ion batteries are produced is not quite like the clean rooms where semiconductors are made, but very close,” Takeuchi said.

Over the past five years, prices of lithium-ion batteries have fallen by about 60 per cent thanks to large-scale production. This price drop has enabled manufacturers to invest into smart control systems while keeping the technology affordable.

Battery experts say increasingly sophisticated systems that can track individual cell conditions are becoming closely-held trade secrets.

“State of charge management, safety management and algorithm development is becoming one of the higher tiers of proprietary internal development,” said Eric Rask, principal research engineer at Argonne National Laboratory, a US Department of Energy facility outside Chicago.

“It’s very internal, very strategic, and companies are seeing management algorithms as a competitive advantage.”

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