Ragone plot

A Ragone plot (Figure 7) compares the power and energy density of electrical energy storage devices. Electrolytic capacitors, based on an oxide dielectric, for example, arc associated with high-power densities... 

In subsequent sections we provide brief information on batteries of various electrochemical systems. The major electrochemical features of each type will be pointed out. The relative discharge characteristics of batteries of the various systems are shown in Fig. 19.4 as a Ragone plot of w vs. p. For specific details of design and manufacturing technology, as well as for more details on performance and characterization, battery books and monographs should be consulted. 

From experimental measurements it was found that there was a fairly good linear relation between the SC capacitance and current, the slope being dependent on the electrode material and electrolyte. If the dependence is known, it can be used to make the Ragone plot calculations more accurate. Therefore, the following method was employed in our evaluations. 

Figure 4. Ragone plots calculatedfor 2.3 V (1) and 3.0 V (2) experimental dots were obtained in Dr. A. Burke s lab at 2.3 V.

Fig. 7.11 Electrochemical performance of different carbons using a three-electrode cell in 1 mol L 1 H2S04 (a) cyclic voltammograms at a scan rate of 1 mV s 1, (b) galvanostatic charge/discharge curves at a current density of 0.2 Ag 1, (c) relationship of the specific capacitance with respect to the charge/discharge specific currents, and (d) Ragone plots.

Ragone plots are presented in Fig. 7.11(d). The highest specific energy of - 50 Wh kg 1 in 1 mol I, 1 H2S04 has been found for the sample CA-GA-2 at the specific power of 0.1 kW kg 1 with only weak fading at higher rates. 

Figure 3. Simplified Ragone plot of the energy storage domains for the various electrochemical energy conversion systems compared to an internal combustion engine and turbines and conventional capacitors.

Figure 15. Ragone plot for LiNio.5Mno.5O2 showing the capacity of the cathode as a function of the discharge current density (data from ref 258).

Figure 23. Electrochemical behavior of LiFeP04 (a) cycling at 1 mA/cm at 21 and 60 °C (reprinted with permission from ref 198, copyright 2003 Elsevier) and (b) Ragone plot for LiEeP04 from four groups, Chen (8 mg/ cm loading and about 10 wt % carbon), Ngala (20—80 mg/cm and 10% carbon), Zane (10 mg/cm and 20% carbon), and Huang (5 mg/cm and 20% carbon).

FIGURE 13 Ragone plot. Acceptable automobile performance requires the specific power and specific energy shown in the upper right corner of the plot. Several secondary battery systems can meet these technical objectives. 

Fig. 4.25 Ragone plot comparing the internal combustion engine with the ZEBRA battery and fuel cells (very approximate). [The plot was introduced for comparing batteries (standardized to a weight of 300 kg) to include the performances of engines and fuel cells in a meaningful way their masses, together with the fuel carried, should be standardized to 300 kg.].

The performance of electrochemical systems is compared in a Ragone plot (Figure 8.4). Supercapacitors have a higher power density than any battery by contrast, their energy density is much lower. The main research effort is now oriented to improving the energy. 

FIGURE 8.4 Ragone plot of electrochemical storage systems. 

At matched impedance, half of the energy is lost inside the capacitor in its internal resistance. This occurrence is represented by the position of the last point on the right in the Ragone plot. From... 

Fig. 13.37. (A) The idealized Ragone plot. (B) Real Ragone plots for certain batteries. The specific energy declines with the increase of the specific power demanded.

Fig. 13.53. Ragone plot comparing electrochemical capacitors with lithium ion batteries and electrolytic capacitors. (Reprinted from Electrochemical Society Proc. 97-18, p. 610, Fig. 1, 1997. Reproduced by permission of The Electrochemical Society Inc.)...

Ragone plots reveal some characteristic differences of fuel cells and batteries. To put the matter succinctly, batteries are known for their power and fuel cells for their energy, both per unit of weight. Discuss these characteristics as the basis for hybrid designs in the powering of automobiles. (Bockris)... 

This interdependence is captured in a so-called Ragone plot (Figure 3.5.3), where specific energy is plotted (usually double logarithmically) as a function of specific power. 

Figure 3.5.3 Ragone plot for different energy storage solutions. The stars show specific energy and power goals for different vehicle technologies (EV electric vehicle PHEV plugin hybrid EV HEV hybrid EV) compared to internal combustion (IC) engine. (V. Srinivasan, Berkeley Electrochemical Research Council). Used with author s permission.

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

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