Separators deep-cycle batteries

Rubber separators have good voltage characteristics, the ability to retard antimony transfer, properties to retard dendrite growth, and good electrochemical compatibility. Due to the hydrophilic properties of the rubber composition, the separators are highly wettable and renewable for the dry-charging process. Paik et al. showed that AGE-SIL (sulfur cured, hard rubber) separators performed well in industrial stationary or traction batteries. FLEX-SIL (electron-beam-cured. flexible rubber separator) separators are suited for deep-cycling batteries, and MICROPOR-... 

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. 

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... 

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 ... 

The Army Research Laboratory/Army Communications Electronics Command (ARL/CECOM) in 2002 defined three separate power regimes for the Land Warrior application 20 W average with 50 W peak, 100 W average with 200 W peak, and 1-5 kW high power drain applications. The batteries illustrated in the Table 4.5 fall within the first range (PB-LW-06) and partially fulfill the requirements of the second regime (PB-LWH-01). The relatively short guaranteed cycle life of these batteries (300 cycles) is based on the expectation of frequent deep... 

Special applications are often governed by different priorities as already discussed in relation to golf carts, the low water loss and the delay in antimony poisoning in heavy-duty service of a forklift are of eminent importance, with the result that rubber separators remain the preferred product there. Submarine batteries offer a different picture the number of cycles to be reached is far lower ( 500) and, due to the slow ( 100h) but very deep discharge, the acid availability becomes the decisive criterion, which favors, for example, the phenolic resin-resorcinol separator. Such requirements are already similar to the application in open stationary cells. 

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