Voltage plateaus

Lithium insertion in microporous hard carbons (region 3 in Fig. 2) is described in section 6. High capacity hard carbons can be made from many precursors, such as coal, wood, sugar, and different types of resins. Hard carbons made from resole and novolac resins at temperatures near 1000°C have a reversible capacity of about 550 mAh/g, show little hyteresis and have a large low voltage plateau on both discharge and charge. The analysis of powder X-ray diffraction. 

The cell made from BrlOOO appears most promising. Its reversible capacity is about 540 mAh/g and it has a long low voltage plateau. Similar results were found for the second cycles of samples made from Ar and Cr resins, except that the capacities were smaller. 

Sometimes two discharge voltage plateaus are seen on nickel oxide electrodes. Early observations are documented in previous reviews [2, 9]. Normally, nickel oxide electrodes have a voltage plateau on discharge in the potential range of 0.25-0.35V vs. Hg/HgO. The second plateau, which in some cases can account for up to 50% of the capacity, occurs at -0.1 to - 0.6 V. At present there is a general consensus that this second plateau is not due to the presence of a new, less-active, compound [91-94]. Five interfaces have been identified for a discharging NiOOH electrode [93]. These are... 

However, there are still some drawbacks in the use of CNT that need to be solved for practical applications. Not only large reversible capacities but also large irreversible capacities have been reported on CNTs [179, 183]. Such irreversible capacity together with the lack of voltage plateau during lithium extraction (hysteresis) limits the use of nanotubes as electrode material in LI Bs. However, an active study (based on CNT treatments, surface modification, use of CNT nanocomposite matrices, etc.) is being carried out in order to overcome such difficulties [184]. 

The better performance of the FeS2 electrode cells vis a vis the FeS cells led to these becoming the focus of the lithium-aluminium/iron sulphide battery development programme at Argonne. In 1986 a life of 1000 cycles was achieved on prismatic cells with flooded electrolyte and dense electrodes operating on the upper voltage plateau. 

Graphites exhibit an optimal discharge curve with a low-voltage plateau and a good intercalation capacity (300 370 mAh/g orx = 0.8 1.0 in... 

Composition of Cathode Mixture Reversible Voltage Plateau (v) Coulombic Efficiency <%)... 

Main voltage plateau for other plateaus see Figure 2. c Determined at C/4 cycling rate. d Based on average discharge voltage of 1.8 V. 

B. Slow Influx. The slow influx of Ca gets triggered off to equalize (balance) the loss besides maintaining a proper relative voltage plateau as shown in Fig. 11.1 (d). In fact, as the Ca entry slows down, the membrane potential becomes low very swiftly to the predepolarization levels (i.e., phase 4). Thus, in the heart muscle the electrical activity is coupled to a mechanical activity by Ca as the potential trigger. 

Figure 19.6. The voltage plateau for a neutron proportional counter.

---