Cycle number, discharge capacity

Fig. 6.13 Cycle number vs. capacity of Sn02 (a, ) Sn02-rG0 ( , o), and solid Sn02 nanoparticles (a, a) size 5-10 nm. Filled symbols represent discharge, empty symbols represent charge (from [148]).

Figure 2. Discharge capacity of the electrodes of different composition versus the number of cycles. The cycling is within 0-3 V(solidlines) and0-0.5 V(dashedlines).

Figure 6. Prismatic 7 Ah battery discharge capacity vs. cycle number plot.

Figure 7. Prismatic 7Ah battery. Typical charge-discharge capacities vs. cycle number. Battery was cycled at different temperatures at C/4.

Figure 2. Change of discharge capacity with cycle number of Li/Li(Ni04Co02Mn04)O2 cells in the voltage range of 2.8-4.3Vat 0.2mA/cm2. (a) at room temperature (b) at 55 °C.

Cycle life is another important factor because it determines the longevity of the battery in practical use. The number of lifetime cycles depends strongly on the so-called depth of discharge if only some 10-20% of the full discharge capacity is used (as in the Toyota Prius for instance) the batteries can handle millions of shallow cycles . However, for PHEVs or BEVs the number of deep cycles (typically 80% discharge) is a relevant characteristic. 

It has been known for some time that lithium can be intercalated between the carbon layers in graphite by chemical reaction at a high temperature. Mori et al. (1989) have reported that lithium can be electrochemically intercalated into carbon formed by thermal decomposition to form LiCg. Sony has used the carbon from the thermal decomposition of polymers such as furfuryl alcohol resin. In Fig. 11.23, the discharge curve for a cylindrical cell with the dimensions (f) 20 mm x 50 mm is shown, where the current is 0.2 A. The energy density for a cutoff voltage of 3.7 V is 219 W h 1 which is about two times higher than that of Ni-Cd cells. The capacity loss with cycle number is only 30% after 1200 cycles. This is not a lithium battery in the spirit of those described in Section 11.2. 

Fig. 6.17 Loss in capacity as a function of cycle number following full discharge for a RENEWAL AA RAM cell. (By permission of Rayovac.)...

Fig. 13.49. Discharge capacity vs. cycle number for representative cells (at 20 °C) that were charged to 130 and 85% of their theoretical capacity. (Reprinted from J. M. Pope, T. Sotomura, and N. Oyama, Characterization and Performance of Organosulfur Cathodes for Secondary Lithium Cells Composites of Organosulfur, Conducting Polymer, and Copper Ion, in Batteries for Portable Applications and Electric Vehicles, C. F. Holmes and A. R. Landgrebe, eds., Electrochemical Society Proc. 97-18, p. 122, 1997. Reproduced by permission of The Electrochemical Society.)...

Fig. 6. Variation of discharge capacity with cycle number for the ball-milled materials 1, 1 h 2, 12 h 3, 72 h 4, 240 h.

Figure 5 Dependence of coulombic efficiency ( ) and discharge capacity (O) of (a) Li/PMMA gel/PPy battery, (b) Li/PAN gel/PPy battery on number of cycles. Charging and discharging current densities are 0.1 mA cm-2.

Figure 2. Plots of discharge capacity vs. the number of charge-discharge cycles for the cathodes LiMnjOiand LiMna.yCoooiYyOd (y=0.005,0.01,0.015) prepared by rheological phase reaction method. Voltage window is 3.6-4.3 V (vs. Li-metal). Tests were done at 0.2C rate for l-4th cycle, 0.5C rate for 5-14th cycle and finally at 1C rate for 15-60th cycle.

Figure 2. The variation in the discharge and charge capacity with the cycle number of MnOj/Li test cell.

Figure 12. Specific capacity of the Sn0/Ti02 and Sn/Ti02 films as a function of cycle number. Hollow and solid symbols represent the charge and discharge, respectively. The current density for both charge and discharge was lOOpAcm Courtesy of Ortiz et al.230 Reproduced by permission of ECS - The Electrochemical Society.

Figure 16.49. Discharge capacity and coulombic efficiency of polyaniline-polystyrenesulphonate as a fiinction of cycle number for ehai gc and discharge cycling in LiC104/PC + DME. (a) discharge capacity and (b) coulombic efficiency. Adapted from J. Elecirochem. Soc. 141(6), 1409 (1994), with permission of the Electrochemical Society, Inc.

Cycle life calculated as possible integral charge throughput at 20% depth of discharge (DoC), unit capacity <50% of initial (unless other conditions are mentioned cycle numbers should not be compared in that case). 

C/5 capacity i/s. cycle number during the TC-69 cycling test at 100% depth of discharge for batteries with lead—calcium—tin—silver grids. The grid alloy compositions are presented in Table 4.5 [83]. 

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