A Ragone plot ( ) is a plot used for comparing the energy density of various energy-storing devices. On such a chart the values of

specific energy Specific energy or massic energy is energy per unit mass. It is also sometimes called gravimetric energy density, which is not to be confused with energy density, which is defined as energy per unit volume. It is used to quantify, for example, sto ...

(in W·h/ kg) are plotted versus

specific power Power-to-weight ratio (PWR, also called specific power, or power-to-mass ratio) is a calculation commonly applied to engines and mobile power sources to enable the comparison of one unit or design to another. Power-to-weight ratio is a measuremen ...

(in W/kg). Both axes are logarithmic, which allows comparing performance of very different devices. Ragone plots can reveal information about gravimetric energy density, but do not convey details about volumetric energy density. The Ragone plot was first used to compare performance of batteries. However, it is suitable for comparing any energy-storage devices, as well as energy devices such as engines, gas turbines, and fuel cells. The plot is named after David V. Ragone. Conceptually, the vertical axis describes how much

energy In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat a ...

is available per unit mass, while the horizontal axis shows how quickly that energy can be delivered, otherwise known as

power Power most often refers to: * Power (physics), meaning "rate of doing work" ** Engine power, the power put out by an engine ** Electric power * Power (social and political), the ability to influence people or events ** Abusive power Power may a ...

per unit mass. A point in a Ragone plot represents a particular energy device or technology. The amount of time (in hours) during which a device can be operated at its rated power is given as the ratio between the specific energy (Y-axis) and the specific power (X-axis). This is true regardless of the overall scale of the device, since a larger device would have proportional increases in both power and energy. Consequently, the iso curves (constant operating time) in a Ragone plot are straight lines. For electrical systems, the following equations are relevant: :

\text = \fracm,

\text = \fracm,

where ''V'' is

voltage Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to m ...

(V), ''I''

electric current An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving pa ...

(A), ''t''

time Time is the continued sequence of existence and events that occurs in an apparently irreversible succession from the past, through the present, into the future. It is a component quantity of various measurements used to sequence events, to ...

(s) and ''m''

mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different elementar ...

(kg).

References

{{DEFAULTSORT:Ragone Plot Capacitors Battery (electricity) Charts