Ragone diagram

Ragone diagram — Plot of -> power density vs. -> energy density (or vice versa) for electrochemical power sources. As shown below (actual data may vary depending on source and time of data acquisition) a broad vari-... 

Ragone diagram — Figure. Ragone plot for selected electrochemical energy conversion and storage systems... 

Based on the Ragone diagram, we can see that for power applications, first come supercapacitors, then batteries and then fuel cells, whereas in terms of autonomy, it is the opposite sequence that prevails. Another important piece of information on this diagram is that none of these systems can currently compete with internal combustion engines. This is why, in the beginning of the 20th Century, electric... 

Figure 1.2. The different electrochemical devices, super capacitors, batteries and fuel cells are compared with fuel motors within the same Ragone diagram...

Figure 27.4. Ragone diagrams for various electrochemical rechargeable devices.

According to Ragone diagrams for HSC PAni/CMK-3 and, for comparison, for EDLC CMK-3/CMK-3, HSC energy density is twice higher than that of the corresponding symmetric EDLC (Cai et al., 2010). About 90% of the initial capacitance remained after 1000 cycles. A decrease in capacitance only by 10% offers fair prospects for practical application of this HSC. 

It is most convenient to use Ragone diagrams for the comparison of the main characteristics of electrochemical devices. Figure 30.1 shows a Ragone diagram for diverse commercial electrochemical devices conventional electrolytic capacitors, electrochemical supercapacitors (ECSCs), batteries, and fuel cells (Pandolfo and Hollenkamp, 2006). One should point out that it is mainly electric double-layer capacitors (EDLCs) of all the available ECSC types that are produced at present. 

Figure 30.1. Ragone diagram for electrolytic capacitors, ECSCs, batteries, and fuel cells.

FIGURE 1.61 Ragone Diagram Efficiency of new supercapacitor type (Figure provided by Nissan Chemical Ind.) [135]. 

We are interested here in tracing the Ragone plot for an ideal battery (meaning no inductive effect is taken into account, no frequency-dependency of the values, no intrinsic nonlinearity of the component). The battery is assumed to preserrt a charge Q0 at the initial time and an internal resistance of value R. It is connected to a charge/discharge system with constant power P (see the diagram below). 

Trace the Ragone plot for this ideal battery, assuming there to be no leakage resistance Rf = > on the diagram above). 

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