Toshiba’s new rapid-charge battery holds promise for electric cars

Less than 18 months ago, Toshiba unveiled a new lithium-ion battery called SCiB, capable of charging in minutes and lasting far longer than regular lithium batteries. There was only one problem: the batteries had a limited energy capacity compared to traditional lithium units. But a new version of SCiB promises twice the capacity, charing in as little as 90 seconds, and a 10,000-cycle lifespan — potentially making them ideal for electric cars.

The SCiB series is based on the lithium-titanate chemistry, which is also used by California startup AltairNano in its NanoSafe cells. Altair’s cells have a specific energy density (capacity per weight) of about 75wh/kg. Comparatively, the original SCiB cells promised just 50wh/kg. Altair’s batteries are considered to be on the threshold of what’s acceptable for EVs, making the first-generation SCiB inadequate for anything but limited-range city cars.

But the new SCiB cells have double the density of their predecessors. That means 100wh/kg, which puts the batteries much closer in capacity to the lithium-cobalt chemistry used in most cell phones, laptops, and cars like the Tesla Roadster. Although some lithium-cobalt cells have fairly high claimed energy density, they often require thermal management technology, which adds to the overall weight and therefore reduces the effective capacity. Moreover, consumers might be willing to accept slightly reduced range as a tradeoff for rapid charge capability and, critically, a much longer lifespan.

Another important benefit of the SCiB’s excellent deep cycle lifespan is that a greater portion of the battery’s capacity can be charged and discharged on a regular basis. Take the Chevrolet Volt’s LG Chem battery as an example. Although it has a 16 kWh capacity, only half of that, 8 kWh, is actually accessible to the consumer. This is because allowing the battery to be fully drained and recharged can drastically reduce its life.

The new SCiB cells are said have a deep cycle life between 5,000 and 10,000 cycles. Compare that to the batteries used by the Tesla Roadster or Chevy Volt, which are said to be good for 1,000 deep cycles. Deep cycle lifespan is considered to end when a battery has 80 percent of its original advertised capacity left. By this metric, it means an electric car with a 200 mile range using SCiB batteries would be able to travel 1 to 2 million miles before possibly needing a new battery.

Also critically important is SCiB’s rapid-charge capacity, which Toshiba says allows its electric car battery pack to charge fully in 90 seconds from a high-output charging station. Altair’s batteries, in comparison, can be charged in as little as 10 minutes. A competing technology from A123 Systems can charge in 15 minutes. Tesla’s battery pack takes a minimum of 45 minutes to charge via an industrial hookup.

Safety is another major benefit of the SCiB design. Thermal runaway, which can lead to fire or explosion, is not a concern with the batteries. As a result, cooling systems are not required. Another benefit of Toshiba’s new SCiB is improved power output. Toshiba says it has quadrupled the output density to 3,900 watts, making it one of the most powerful batteries in the world.

Toshiba’s says it intends to mass produce the new batteries with a new factory in Niigata Prefecture set to open this fall. That will increase production from the current 150,000 SCiBs per month to over 2 million. Toshiba’s mass production ability already gives it a significant price advantage over companies like Altair and A123. Ramping up production will serve to drive costs down even more. Toshiba says it expects monthly output to reach 10 million units per month by 2015, for everything from cell phones to electric cars.