Ragone chart

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Ragone chart is a chart used for performance comparison of various energy storing devices. On such a chart the values of energy density (in Wh/kg) are plotted versus power density (in W/kg). Both axes are logarithmic, which allows comparing performance of very different devices (for example extremely high, and extremely low power).

The Ragone chart was first used to compare performance of batteries. However, it is suitable to compare any energy-storing devices, as it is shown on the right.

Conceptually, the vertical axis describes how much energy is available, while the horizontal axis shows how quickly that energy can be delivered. For example, powering a small light-bulb may require low amounts of energy, but the power should be delivered slowly enough to operate a flashlight for minutes or hours of use. Conversely, a highspeed electronic switch inside a computer may require very little energy to activate; yet it must be delivered rapidly enough to complete the transaction in mere microseconds. These two devices would find themselves at opposite corners of the Ragone chart.