Electrical and electrochemical performance characteristics of large capacity lithium-ion cells

We are currently evaluating large capacity (20–40 Ah) Bluestar (cylindrical) and Yardney (prismatic) lithium-ion cells for their electrical and electrochemical performance characteristics at different temperatures. The cell resistances were nearly constant from room temperature down to −20°C, but increased by over 10 times at −40°C. The specific energies and powers, as well as the energy densities and power densities are high and did not reach a plateau even at the highest discharge rates tested. For example, the prismatic lithium-ion cells gave close to 280 Wh dm−3 from a 4 A discharge and 249 Wh dm−3 at 20 A, both at room temperature. For the same current range the specific energy values were 102 Wh kg−1 and 91 Wh kg−1. Cycle life and other electrical and electrochemical properties of the cells will be presented.