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Low temperature electrical performance characteristics of A&T, Moli, and Panasonic 18650 Li-ion cells are described. Ragone plots of energy and power data of the cells for different temperatures from 25 °C to −40 °C are compared. Although the electrical performance of these cells at and around room temperature is respectable, at temperatures below 0 °C the performance is poor. For example, the delivered power and energy densities of the Panasonic cells at 25 °C are ∼800 W l−1 and ∼100 Wh l−1, respectively, and those at −40 °C are