Batteries For Electric Cars Have Barely Begun To Get Better

By Patrick Connor

Patrick Connor

LATEST ARTICLE
Batteries For Electric Cars Have Barely Begun To Get Better
Do you remember the shoe sized cell phones of the early 90s? Much of that size was due to the... Read More

• N/ALEADERBOARD RANK
• 1ARTICLES CONTRIBUTED
• 39COMMENTS POSTED

2,126 views Mar 23, 2011

Follow Patrick

Advanced Battery Pack

Enlarge Photo

Do you remember the shoe sized cell phones of the early 90s? Much of that size was due to the battery. Even with that large battery, you were lucky to get 30 minutes of talk time.

Battery tech has made slow and steady progress since then and has been doing so for the last 40 years. There were advancements before then too, but this modern era of advancement kicked off when NASA needed batteries for the Lunar Rovers of the Apollo Project.

More recently batteries have become the powerhouse for all of our high tech gadgets. This has spurred innovation investment to a level that battery tech has never seen before.

2011 Chevrolet Volt drive test, March 2011

Enlarge Photo

Battery technology didn't allow jumping directly from short-life giant phones to the iPhone. The advances have been slow and steady, some years only advancing a couple percent and other years smart engineering, new chemistries, membranes, or processes have yielded double digit percentage improvements.

This has resulted in an average growth of 8 percent improvement in the battery's energy density (measured in Watt-hours per kilogram) per year.

For comparison lead-acid batteries are 41 Wh/kg, nickel-metal hydride batteries are 95 Wh/kg, and some chemistries of today's battery of choice, Lithium-Ion, is 128 Wh/kg (1).

Can we assume this growth rate in energy density will continue? There is no sign of battery advancement slowing.

In fact, the influx of investment capital, government grants, and world-wide competition will likely cause a short term increase in the improvement rate.

First Chevrolet Volt battery pack built at Brownstown Township plant, January 2010

Enlarge Photo

In the last few decades we have seen alkaline, nickel cadmium, and nickel-metal hydride. In the next decade we could see Lithium-Air, Zinc-Air, ultra-capacitors or some yet-unheard-of chemistry.

Hybrid systems that use both ultra-caps and batteries are also possible. These systems use a small ultra-cap to absorb most of the energy from regenerative braking and return it to the acceleration that likely follows. This allows higher density, less responsive batteries to be used and reduces the cycling wear and tear on the batteries.

Given all these vast areas for exploration, it is highly likely that at least the current rate of improvement will continue into the next two decades.

Assuming this rate continues, by 2020 we can expect that long range batteries for electric vehicles will be more affordable. With the compounding annual technology improvements and the economies of scale in manufacturing that are starting to come on-line now, here are my predictions for battery prices:

• In 2020, batteries will be less than half of their current cost.
• In 2030, batteries will only be about one fifth their current cost.

At the projected 2030 price, a 300-mile range battery pack would cost less than $5,000.

This "300 mile" number assumes that vehicles are similar to today's vehicles with steel frames and bodies. But assuming that materials are still going to be the same two decades from now is naive.

John Duncan takes delivery of one of the first 2011 Nissan LEAF EVs, near Portland OR, 12/15/2010

Enlarge Photo

Carbon fiber bodies are lighter and stronger. Currently these exotic high tech materials are expensive. These will be coming down in price as new materials are created and innovative manufacturing techniques are invented. This could add another 5-25 percent in range or allow fewer batteries to be used.

Batteries will be improving and reducing in price each year. They don't improve at a Moore's Law rate, but the growth will far outpace anything that gas mileage advancements have done in the past 100 years.

If you hear someone say that EVs don't work, have too short a range, don't do well in cold weather, take too long to charge, or have some other limitation, remember: They are looking at the current technology and seeing only limitations.

You can look at it and see that potential. Improvements in all of these areas will come. EVs will evolve from the "shoe-sized phone" to the "iPhone". You can come along for the ride, or you can stick with the "rotary phone" internal combustion engine.

If you had waited for computers to be perfect before you started using one, you would still be waiting. Even with their current quirks, you can embrace the new technology of electric vehicles--or you can stand on the sidelines. The choice is yours.

1) data from AllAboutBatteries.com March 2011