Electric Battery: It’s the Chemistry


Besides powering consumer gadgets of all sizes, the electric battery industry has a new frontier – heavy-duty rechargeable batteries for the car market. This enormous opportunity is opening up as the electric car is gaining popularity and when people worry more about climate change. The electric car is probably the biggest market in view of over one billion vehicles worldwide burning gasoline whose costs keep on rising. It is also a market that will last over 100 years since it takes time to gradually replace the gasoline engine, which has reigned for over a century despite all the damages to the environment.

The challenges facing the electric car hinge on two factors linked to battery technology — to increase the limited driving range of the battery between recharges, and to reduce the high cost (currently about half the cost of the whole car). The weight of the battery is not a major problem because new composite materials (carbon fiber for instance) and the compact electric propulsion system will drive down the total weight of the car to compensate for that of the battery . The time for recharge is neither a big problem since most consumers can recharge during nighttime while the car is not in use.

Various new battery technologies are being pursued right now. A breakthrough requires a chemistry of electricity storage different from existing ones. A new chemistry means new kinds of materials to be used that fulfill the requirements of longer driving range and lower cost.

The older battery technologies are: lead acid, nickel metal hydride, and sodium (hot salt) still being widely used. The newer lithium-ion batteries are mostly used in laptops, cell phones and other consumer electronics. At present, the lithium-ion technology is scaled up in a large battery to power electric cars. The advantages of lithium-ion are: high energy density (over 200 watt-hours per kilogram), and high charge/discharge efficiency (80-90%). The downsides include: significant degradation after several years, and a short cycle-life (less than 1000 charge cycles).

Recently, a company in Silicon Valley (Envia) announced achieving a doubling of energy density to 400 watt-hours per kilogram. They also achieve cost reduction by using more manganese to replace the very expensive cobalt in the cathode of the battery (San Jose Mercury News, 5 January 2013).

Is there a possibility for bypassing the chemistry of the battery? Yes, of course. How can you limit the human imagination? Currently, there is research going on regarding wireless charging. That means the electric car can be wirelessly recharged while running on the road. This technology is based on magnetic resonance coupling. Wireless recharging can boost the driving range of the electric car using existing battery technology. It is not a dream anymore because some cell phones already have this capability built in.

The race is on for a less-expensive car battery that increases the driving range between recharges. The competition will get more intense as time passes. In the meantime, hybrid technology is an efficient intermediate solution that greatly increases the mileage at a higher initial cost of the car, which will be compensated by less gasoline consumed during the life of the automobile.

January 2013

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