Discharge rate energy density curves

At room temperature, discharge curves are exceptionally flat (Fig. 4.35), even at rates of up to 3 A for D-sized cells. As noted above, SOCl2 utilization is much higher at low current drains. Low rate cells manufactured by Mallory with a spiral configuration (4.45 cm X 25-38 cm electrodes) produced practical energy densities of 661 Wh/kg (1240 Wh/dm3)... 

The rated capacity is 0.75 Ah. Typical discharge curves and charge-discharge cycle behaviour of these 3 V batteries are shown in Figs 7.27 and 7.28, respectively. Energy density of 130 Wh/kg and 280 Wh/dm3 and 300 complete cycles at 100% depth of discharge have been reported. The electrolyte solution is stable at low to medium temperatures, but polymerizes when the temperature exceeds 125°C to form polydioxolane with a consequent rapid rise in the internal resistance of the cell. This provides an internal shut-off safety mechanism which, combined with a built-in vent,... 

Although the energy density of a 18650 cell (1100 mAh) is rather small, about 95 Wh/dm, discharge rates as high as 27C are possible, and a flat discharge curve profile is maintained throughout discharge. 

Volumetric energy density is, at times, a more useful parameter than gravimetric specific energy, particularly for button and small batteries, where the weight is insignificant. The denser batteries, such as the zinc/mercuric oxide battery, improve their relative position when compared on a volumetric basis, as shown in Table 7.4 and Fig. 7.9. The chapters on the individual battery systems include a family of curves giving the hours of service each battery system will deliver at various discharge rates and temperatures. 

The discharge properties of these solid-state batteries are characterized by high practical energy densities, low-rate capability, and low rates of self-discharge. From the linear polarization curve (Fig. 15.3) it is apparent that the resistance is essentially ohmic. Bridge measurements of cell resistance at 1 kHz are in agreement with values determined from polarization curves. 

The Ragone plot shown in Fig. 7.13 obtained from the high-rate discharge curves is totally different from the ordinary one (Fig. 7.1), because it contains the nanosize effects in nanociystalline LiCo02. The Ragone plot clearly suggests that the energy density... 

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