Tag Archives: Battery

Is this Last Mile for the Million-Mile Battery?

Announcements from Tesla and CATL show that a long-lived, cobalt-free and competitively price EV and grid/home batteries may finally have arrived.
By John Blyler – The much discussed 1 million-mile (1.6 million kilometers) battery may now be a reality. As the name suggests, these batteries would last for 1 million miles without breaking down. Tesla, along with China-based Contemporary Amperex Technology (CATL), have announced such a battery that not only lasts longer but also costs less than $100/kWh and uses cobalt-free materials. Why are these two features important?

It has long been a metric for the success of electronic vehicles (EV) that their battery energy density be on parity with traditional gasoline-powered engines. Such a condition would allow EVs to compete with gasoline vehicles on both weight and range – especially the latter. This means that, if gasoline is 100 times more energy-dense than a battery, that a vehicle would need 100 lbs of battery to go as far as 1-lb of gasoline.

But past studies by the Argonne National Labs have shown that system efficiency is another key consideration when comparing EV and gasoline energy densities. The research lab noted that electric powertrains are far more efficient than powertrains powered by gasoline. In many cases, less than 20% of the energy contained in a gallon of gas actually gets converted to forward motion. After that power has been transmitted through a transmission and differential to the wheels, it would have suffered significantly more mechanical losses.

By contrast, an electric powertrain can be more than 90% efficient. This would suggest that the energy density of an EV battery could be far less than equivalent to a gasoline-powered vehicle and still come out ahead. more>


Self-charging power cell converts, stores energy in single unit

R&D Mag – Researchers have developed a self-charging power cell that directly converts mechanical energy to chemical energy, storing the power until it is released as electrical current. By eliminating the need to convert mechanical energy to electrical energy for charging a battery, the new hybrid generator-storage cell uses mechanical energy more efficiently than systems using separate generators and batteries.

“People are accustomed to considering electrical generation and storage as two separate operations done in two separate units,” says Zhong Lin Wang, a Regents professor in the School of Materials Science and Engineering at the Georgia Institute of Technology. “We have put them together in a single hybrid unit to create a self-charging power cell, demonstrating a new technique for charge conversion and storage in one integrated unit.”

The research was reported in Nano Letters. more> http://tinyurl.com/8b7ys5d