GM has purchased enough lithium-ion batteries from Hitachi for over 100,000 hybrid electric cars over the next several years. While this doesn’t relate to the Volt, it does give GM a leg up on other hybrid car manufacturers by moving to lithium-ion technology first.
I’ve covered the batteries in question before, I believe they are Hitachi cells specifically designed for hybrid vehicles. They have different characteristics than the LG Chem cells used in the Volt. For hybrid vehicles you carry a small amount of storage (2-3kWh) and pull energy out of the battery quickly to accelerate and to store it quickly when braking. The Volt needs a higher specific energy (storage) while these hybrid batteries need high specific power (horsepower).
The batteries that GM is likely to get have a specific power of around 2,250W/kg. The PDF I link in the above article shows a 3kWh Li-Ion pack, 47kg and 1.4 cubic ft. This would provide for a total power of 90kW (120HP) in an area 41″ x 12″ x 5″. Being able to accept and output that much power could allow the vehicle to drive up to speeds of 35MPH on electricity alone (depending on car weight and other factors). However it is unlikely that GM would use this configuration – their mild hybrid systems only provide 20HP. The minimum battery pack for this size would be about 500Wh (or 8 of the above cells), and a larger 1kWh pack would be able to provide twice that (28kW/40HP).
All other mainstream hybrid vehicles currently use NiMH batteries, which are not as capable of high power output as lithium-ion batteries are. The switch to Li-Ion batteries would not only increase power output (allowing higher all-electric mode speeds), but also a lighter, smaller package. The 3kWh module mentioned above could even power the vehicle at all electric speeds for a few miles (again, depending on vehicle weight, etc).
Cost could be an issue, as these batteries are more expensive than their NiMH counterparts. Lithium-ion batteries command a cost between $800-1000/kWh, while NiMH batteries cost around $200-300/kWh.
via GM-Volt
Possibly Related Posts:
- Lithium Math – Quick Update
- Lithium Supplies – Locked and Loaded
- Lithium-Carbon-Fluorine Battery Breakthrough?
- Mitsubishi Demonstrates Ultracapacitor – Hype or Holy Grail?
- Japanese group announces 10,000 cycle capacitors
- Predictions for 2010
- MIT Powerpoint on electric cars
- Nissan forging ahead on Batteries
0 Responses
Stay in touch with the conversation, subscribe to the RSS feed for comments on this post.