Deep discharge

Li—Al/FeS cells have demonstrated good performance under EV driving profiles and have deUvered a specific energy of 115 Wh/kg for advanced cell designs. Cycle life expectancy for these cells is projected to be about 400 deep discharge cycles (63). This system shows considerable promise for use as a practical EV battery. 

Susceptible to damage from deep discharge and high temperature. 

Unlike the automobile-type battery that is quite portable, the stationaiy lead-acid batteries that provide uninterruptible power to hospitals and other important facilities are not. Some may weigh over several tons because of the much heavier grid structure and other features to extend life expectancy and improve deep discharge capabilities. 

For the separation of such batteries, gel construction and microfiber glass fleece separators again compete because of the deep discharge cycles, the gel construction with its lower tendency to acid stratification and to penetration shorts has advantages for the required power peaks, microfiber glass fleece construction would be the preferred solution. The work on reduction of premature capacity loss with lead-calcium alloys has shown that considerable pressure (e.g., 1 bar) on the positive electrode is able to achieve a significantly better cycle life [31-36], Pressure on the electrodes produces counter pressure on the separators, which is not unproblematic for both separation systems. New separator developments have been presented with... 

Among the separator varieties described, the phenol-formaldehyde-resorcinol separator (DARAK 2000) [60] as well as the microporous PVC separator [86] have proven effective for this construction. For applications without deep discharges, concessions may be made with the respect to porosity and pore sizes of the separator therefore polyethylene separators or a spe-... 

The mobility of lithium ions in cells based on cation intercalation reactions in clearly a crucial factor in terms of fast and/or deep discharge, energy density, and cycle number. This is especially true for polymer electrolytes. There are numerous techniques available to measure transport... 

Flaving had over 150 years of technical development behind them, lead-acid batteries can be custom-tailored to specific applications, such as those requiring deep discharge cycles (e.g., where the batteries are used as the sole power source for electrical equipment) and for battery backup uses such as in large uninterruptible power supply systems in data centers. Moreover, lead-acid cells not only have low internal resistance but also experience no memory effect as do some more exotic cell designs, such as NiCads. This enables these cells to produce enormous currents and have a moderately long, predictable life.1... 

In this paper we would like to propose also an additional concept of utilization of rechargeable metal-air battery with PANI/ TEG catalysts. It is necessary to note the ability of PANI based electrode to self-charge in the presence of oxygen. A deep discharge of PANI electrode leads to the transformation of emeraldine (EM) to lecoemeraldine (LEM). It is well known that LEM is chemically non-stable at the presence of oxygen due to occurance of the following reaction ... 

The nickel—zinc (NiZn) system is attractive as a secondary cell because of its high energy density and low material cost and the low level of potential pollutants contained. The widespread use of nickel-zinc batteries, particularly as electric vehicle power sources, would be strongly enhanced by significantly extending the deep-discharge cycle life beyond the current level of 100—300 cycles. Considerable work has been done in the past to develop a suitable separator for nickel— and silver—zinc batteries. 272 An excellent discussion of separator development is contained in a comprehensive review. 2 ... 

Discharge curves show either the open circuit voltage of a cell or halfcell as a function of the fraction of discharge completed, or, much more commonly, the cell voltage during a deep discharge, usually under a fixed load or at constant current. The abscissa may be calibrated in terms of the quantity of electricity passed (Ah) or as a percentage of the theoretical capacity,... 

Certain problems sometimes arise with rechargeable multicell batteries which are associated with non-uniform capacities of the individual cells. In charging such batteries there must be either overcharge in some cells or undercharge in the whole system. More importantly, on deep discharge,... 

It is probable that a range of soluble species such as Fe(OH)2 and Fe02 are involved, and it is known that Fe(OH)3 or Fe304 may be formed on deep discharge. The practical energy density of conventional tubular plate cells is 20-30 Wh/kg with the more recent cells which use press-sintered iron electrodes, values of 40-60 Wh/kg have been reported. 

In applications such as load levelling, motive power or in consumer electronics, the battery is required to undergo a sequence of deep discharges followed by a recharge to maximum capacity. A number of methods may be used. 

---