Battery life cycles

An example of an interphase is the well-known and explored electrical double layer. Another example is the passivating layer between electrode and electrolyte solutions. Such a layer on Li electrodes, which arises from the reductive decompositions of a small amount of the electrolyte solutions, was named SEI (solid electrolyte interphase). SEI is a crucial factor in the performance of Li-ion batteries since its nature and behavior affect Li-ion battery cycle-life, life time, power capability, and safety. Li electrodes (and Li-C electrodes as well) develop a classical interphase between them and all the relevant polar aprotic electrolyte solutions. All... 

There are numerous advantages of using continuum models. They are widely used for system design and optimization. Continuum models tell us important information about the system, e g., discharge curves, state-of-health of the battery, cycle life behavior and subsequently capacity fade rate, etc. Battery models are also useful in predicting non-measurable internal variables such as solution phase concentration, solid phase concentration etc. This can be used to observe or measure buildup or loss of a certain chemical species within the domain of the battery and can be used efficient-... 

Attempts to increase the specific energy usually compromise the battery cycle life as exemplified in Fig. 5 for Pb-A batteries. The cycle life is also affected by the depth of discharge. Voss and Huster suggested an empirical equation... 

The effect of the addition of calcium sulfate to positive pastes has also been investigated [67]. Pasted electrodes were cycled three times as well as to the end of the battery cycle-life. The positive active-material was washed with water, dried, pulverized, and used to pack tubular electrodes. Additions of 0, 0.1, 0.2,... 

Both Shiomi et al. [26] and Saez et al. [27] have suggested that high levels of carbon improve the rechargeabihty of negative plates by providing eonduetive networks around the peripheries of lead sulfate crystals and, thereby, extend battery cycle-life. 

Fig. 5.10. Effect of barium sulfate additions on battery cycle-life.

Another feature of AGM separators is their compressibility. With compression of the plate and separator stack, this AGM property guarantees good plate-separator contact, even if the plates are not perfectly smooth. Also, battery assembly is facilitated since the stack can be easily inserted into the cell after compression to a thickness lower than the cell dimension. An undesirable result of the compressibility is that the AGM separator does not exert sufficient resistance against expansion of the positive plate during battery cycle-life. This expansion is particularly prevalent in deep-cycle applications and can cause the battery to suffer premature capacity loss (PCL) via reduced inter-particle conductivity — a phenomenon known as PCL-2 [7]. In the literature, two additional characteristics, which are related to the PCL-2 failure mode, are discussed, namely, AGM separators shrink when first wetted with electrolyte and their fibres can be crushed at high pressure levels [8-10]. These features result in a loss of separator resilience, i.e., a lessening of the ability to display a reversible spring effect. 

As a result of such considerations, the surface area, particularly fine-fibre content of AGM separators has been the subject of two ALABC projects on EV batteries. In the first project [16], acid stratification was found to decrease as the surface area of the separator was increased, see Table 7.5. Nevertheless, any advantage in terms of battery cycle-life was less clear-cut, see Table 7.6. 

In terms of life-cycle costs, batteries are usually the most expensive component of a RAPS system and, therefore, it is advantageous to minimize the required capacity. The battery should, however, be sized to supply a significant portion of the anticipated daily load in the absence of diesel- or PV-generated power, e.g., from 20 to 50%. This would allow the diesel to remain idle for much of the day and to operate under relatively constant, high-load conditions for only a few hours each day. Further, the battery should be sized such that the daily depth-of-discharge (DoD) is limited in the interest of enhancing battery cycle-life. (The cycle-life of a battery is affected by several factors which include DoD, temperature, and charging procedure.)... 

It comprises prismatic crystals with a length from 10 to 100 pm and diameter from 3 to 15 pm. 4BS is formed when leady oxide is mixed with sulfuric acid solution, H2S04/Pb0 < 6 wt%, at temperature higher than 75 °C, as well as during curing of the paste at high temperatures (>85 °C) in the presence of water steam. The structure of the active mass formed from 4BS ensures long battery cycle life. 

Battery cycle life vs H2SO4 concentration on cycling of 32-Ah batteries with 8 A (C4) or 3.2 A (Qo)... 

Dependence of (a) H2SO4 utilization, (b) measured initial capacity C20/C0 and (c) battery cycle life... 

An example of polymer additive to electrolyte is FORAFAC 1033D (polyfluoroalkyl sulfonic acid). Addition of FORAFAC 1033D in a concentration of 0.1 wt% to the electrolyte immobilized in AGM VRLA batteries leads to a major improvement of battery cycle life [49]. Standby batteries containing FORAFAC have improved their service bfe by a factor of 1.5, suffering smaller water loss and reduced self-discharge. 

Fig. 4.42b) even at high temperatures (60 °C), high mechanical properties, uniform corrosion at a very low rate and much longer battery cycle life at high temperatures (Fig. 4.43) than any other battery type [81]. 

The changes in paste density have but a slight effect on phase composition of the ciured paste and of the formed active mass as well as on capacity performance, but they exert a strong influence on battery cycle life. The life span is extended with increase of paste density, especially for pastes prepared with low H2SO4/LO ratio. 

Ah kg PAM specific capacity. What is the relation between these power characteristics (markers) and the cycle life of the hatteries Figure 6.28 presents battery cycle life (in number of cycles until 10 V end-of-discharge voltage) vs. discharge current density at 110 Ah kg PAM specific capacity. 

Figure 7.8 presents the capacity curves for cells assembled with negative plates with different expanders. It is evident from the data in the figure that expanders Mimosa and Velex have but a weak effect on battery cycle life. SNK and especially EZE-Skitan and Quebraco, improve... 

When the battery is cycled at 60 °C and is of the VRLA type, expanders containing lignin and its derivatives disintegrate, as a result of which the battery cycle life is reduced almost twice. In order to improve the cycle life performance of the negative plates, the battery temperamre should be kept equal to about 40 °C. 

The above batteries were then subjected to cycling tests at 1 h discharge rate. The end-of-life criterion was 80% C20- Figure 8.31 compares the number of cycles (i.e. battery cycle life) and the current density at 80 Ah kg PAM for the different battery types. 

Influence of Soaking Processes on Battery Cycle Life Performance [4]... 

Changes in NAM Structure on Cycling Limiting Battery Cycle Life... 

---