Toyota Develops Way of Observing Electric Vehicle Battery Degradation, Says It Will Lead to Longer Battery Life

When it comes to building mass-market electric vehicles, Japanese automaker Toyota has been more than a little hesitant to join the likes of Nissan and BMW in the plug-in marketplace. Instead, it has chosen to focus on bringing hydrogen fuel cell vehicles to market, claiming that hydrogen fuel cell vehicles represent a far more practical and sustainable solution in the long term to battery electric cars.

So much so that its most recent electric car. — the 2012-2014 Toyota RAV4 EV — featured a drivetrain that Toyota paid California company Tesla to engineer. Produced in order to meet California ZEV mandates Toyota showed no interest in bringing RAV4 EV drivetrain development in-house, despite doing exactly that with its first-generation RAV4 EV — which it produced in various forms and for various markets between 1997 and 2003.

Despite cars like the 2002 Toyota RAV4 EV, Toyota has never liked electric cars.

Despite cars like the 2002 Toyota RAV4 EV, Toyota has never liked electric cars.

But in recent weeks we’ve seen a definite shift in Toyota’s public attitude towards electric cars. A few weeks ago, the Japanese company said that it was forming a special four-person task force charged specifically with bringing together the people and skills needed to accelerate development of an electric car that it could bring to market within the next few years. Then, it hinted that electric vehicles would likely be offered alongside hydrogen fuel cell cars to give customers a choice over which fuel source suited their needs better.

Traditionally, understanding the flow (and clumping) of lithium-ions in a battery has been difficult.

Traditionally, understanding the flow (and clumping) of lithium-ions in a battery has been difficult.

Now, Toyota has said that it has made a battery breakthrough that will allow it to produce electric cars some time by the end of the decade with battery packs that offer fifteen percent more range and dramatically improved longevity over today’s electric car batteries.

According to Toyota’s official press release, the improvements — jointly developed by Toyota Central R&D Labs, Nippon Soken, Inc., and four leading Japanese universities — focus on the migration of ions within the battery itself.

It’s a problem that many battery chemistries suffer and can be influenced by a number of different factors, including rate of charge or discharge, ambient temperature, and to what extremes the battery is charged or discharged.

In the case of Lithium-ion batteries, it’s essentially the chemistry’s Achilles Heel: during charging and discharging, lithium ions can get bunched up as they pass through the electrolyte from one electrode to the other, restricting the flow of power through the battery and ultimately degrading performance and battery life. At the same time, other lithium ions become trapped within the electrodes themselves through warping of the pores on the electrodes or breakdown of the electrodes themselves which can trap ions and affect the amount of useable energy the battery can store when fully charged.

Using an electrolyte rich in heavy metals, Toyota is able to see what's going on as a battery discharges and charges.

Using an electrolyte rich in heavy metals, Toyota is able to see what’s going on as a battery discharges and charges.

To date, it’s been possible to study the degradation of the electrodes over time, but it hasn’t been possible to study the migration of the ions as they pass through the electrolyte, leaving electrochemists completely in the dark about ion bunching. But Toyota’s breakthrough involves replacing the traditional porous phosphorus-based electrolyte in a traditional lithium-ion battery with one made of heavier elements for laboratory use.

Sadly, Toyota doesn’t detail which of these heavier elements its battery electrolyte uses, but we can at least explain why it has chosen to use heavier elements. While we’re not chemists, it’s a general rule that heavier elements (elements with an atomic mass larger than 92) cast a darker shadow when bombarded with high-energy X-rays, making it easier to spot any changes taking place.

With laminate cells constructed with an electrolyte rich in heavy metals, Toyota has been making use of the SPring-8 synchrotron radiation facility in japan to carefully monitor exactly what happens to ions as they pass through the electrolyte during charging and discharging which, in turn, should allow it to experiment with new battery construction methods that discourages lithium-ion deviation.

Toyota says it believes its new laboratory observation technique should allow it to focus on increasing battery performance as well as extending battery life, leading to electric cars that can not only travel up to 15 percent further but also endure far more charge and discharge cycles before they degrade to the point of needing replacement.

Toyota's breakthrough could mean electric cars with battery packs that don't degrade as quickly.

Toyota’s breakthrough could mean electric cars with battery packs that don’t degrade as quickly.

That’s great news for the future of battery vehicle technology, but we can’t help wonder why Toyota isn’t putting more effort into building electric cars using existing battery technology. Current-generation technology lithium-ion batteries from Tesla, Nissan, and LG Chem are already capable of reliable, long-range use and long life. And given companies like Tesla and LG Chem are producing battery technologies that improve energy density — and thus range — by five percent or so every few years, Toyota’s breakthrough technology is less groundbreaking to the end consumer in the short term.

However, for longer-term battery development — and producing smaller, more lightweight batteries where more of the energy capacity can safely be used without degrading battery life or performance — Toyota’s breakthrough could have a big impact on the electric car world.



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