Cutoff voltage

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. 

Figure 62. Cycle life performance of SAFT DD-size lithium ion cells containing 1.0 M LiPFe/EC/DEC/DMC/ EMC (1 1 1 3) at various temperatures. Cutoff voltages for low-temperature charge were indicated in the graph. (Reproduced with permission from ref 515 (Figure 11). Copyright 2003 Elsevier.)...

Carbon-zinc is the generic term for the Leclanche and zinc chloride system. Carbon-zinc cells provide an economical source of electrical energy for low drain applications. The service life depends strongly on the discharge rate, the operating schedule and the cutoff voltage, as well as temperature and storage conditions. 

PVC = polyvinyl chloride, PVDF = polyvinylidene fluoride, PPS = polyphenylene sulfide, ENR = epoxy novolac resin. d The lower the preparation temperatures, the higher the reversible and irreversible capacities (within the limits specified in the table). e The reversible capacity depends on the cycle number, cutoff voltage, and other experimental parameters. Maximal reversible capacity around 650 mAh/gr could be obtained. 

Charging cut-off voltage is defined to protect a cells overcharge and damage. Cut-off voltage is called also cutoff voltage or end-voltage. 

The reversible capacity depends on the cycle number, cutoff voltage, and other experimental parameters. Maximal reversible capacity around 650 mAh/gr could be obtained. 

The charge/discharge curves of LiCoO and LiNiO are shown in Fig. 2.4. When the cutoff voltage is selected to be 4.3 V, LiCoO has a comparatively smooth curve, while LiNiO has a complicated curve with some voltage plateaus. In the following. 

Fig. 10.10 Plots of (a) rate capabilities and (b) normalized capacity of bare and Al Og- and AlPO -coated LiCo02 cathodes in Li-ion cells (with carbon anode) with a charge-cutoff voltage of 4.2 V...

The Li MAS NMR spectra of lithiated FeFs samples, taken at cutoff voltages between 3.3 and 1.7 V, display two resonances at approximately 0 ppm and another between 104 and 172 ppm. The resonance at higher frequencies is relatively... 

The cutoff voltage influences the discharge capacity. A cell with a sloping discharge profile is disadvantageous. 

FIGURE 2.14 Charge-discharge curves of a rubeanic acid/Li cell (cutoff voltage 1.5-4.2 V). 

As the specific gravity was not disclosed, we assume a value of 2.0, which is rather large for an organic material. In this case, the volumetric energy density would be 1.2 Wh/cm, only about 45% compared to that of LCO whose energy density is 2.6 Wh/cm. Moreover, if the cutoff voltage is fixed to 3.0 V, the discharge capacity would be less than 50 mAh/g. So, this compound can hardly be considered practical and attractive as a cathode active material, even if it is free from rare metals. 

FIGURE 25.5 Discharge profiles of LIB cells as a function of charge cutoff voltages (COV). 

Table 25.1 Discharge Data of LIB Cells vs. End of Charge Cutoff Voltage (COV) q, qcu and Ed Refer to Discharge Capacity, Discharge Capacity Loss, Average Discharge Voltage and Discharge Energy, Respectively...

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