Theory of Ragone plots

The general theory of Ragone plots for energy storage devices (ESD) is disc ussed. Ragone plots provide the available energy of an ESD for constant act ive power request. The qualitative form of Ragone plots strongly depends on the type of storage (battery, capacitor, SMES, flywheel, etc.). For exampl e, the energy decreases as a function of power for capacitive ESD, but incr eases for inductive ESD. Analytical results for a representative set of ide al ESD (battery, capacitor, and SMES) are compared. Furthermore, the effect of leakage and of the specific loss type (Coulomb, Stokes, and Newton fric tion) is discussed for inductive ESD. Finally, we address the problem of ho w composite ESD should be treated, and illustrate it for a battery with ind uctance. (C) 2000 Elsevier Science S.A. All rights reserved.