Cells spirally wound

Similar electrolytes to Li/Cl ) cell can be used. Numerous coin-cell, spiral-wound and bobbin configurations are available, as well as three-cell-in-series prismatic 9 V [27], As with most other Li metal anode primary systems, the very low self-discharge rate affords many years of shelf life in standby usage. Therefore, applications such as smoke detectors are very popular for this system. 

Highly corrosion-resistant, antimony-free, lead alloys have been used successfully in the positive electrode grids of both single-plate and spiral-wound cells. Spiral-wound cells almost exclusively feature binary lead-tin alloys [36,41] whereas flat-plate electrodes use either lead-calcium alloys, with or without silver additive [26], or lead-tin alloys [48]. Binary lead-tin is known to be highly corrosion-resistant, but rather soft, which is a handicap for plate stacking in prismatic cells. 

Figure 18.16 Discharge graphs of 1 Ah lithium/thionylchloride cells (spirally wound) (Saft).

Figure 3. Tabbing for electrodes used in small lithium ion cells. Spirally-wound electrodes (a) and stacked plate (b).

Mechanical strength becomes an important criterion, because wound cells (spiral-type construction), in which a layer of separator material is spirally wound between each two electrodes, are manufactured automatically at very high speed. Melt-blown polypropylene fleeces, with their excellent tensile properties, offer an interesting option. Frequently two layers of the same or different materials are used, to gain increased protection against shorts for button cells the use of three layers, even, is not unusual. Nevertheless the total thickness of the separation does not exceed 0.2 - 0.3 mm. For higher-temperature applications (up to about 60 °C) polypropylene fleeces are preferred since they offer a better chemical stability, though at lower electrolyte absorption [ 114"]. 

The alternative alloy anodes which exhibit good cycle life in coin cells (Table 1) are not applied to cylindrical cells. This is because they are brittle and these alloy anodes turn into fine particles after cycling when the anode is spirally wound in the... 

Wilkinson et al. [77] examined the effect of stack pressure on the lithium turnover (FOM for lithium cycling efficiency) in Li/MoS2 prismatic cells containing 1 mol L1 LiAsF6-PC. The cycle life for spirally wound AA-size Li/MoS2 cells showed that when the electrode assembly is housed tightly in the cell the cycle life is better than with loosely housed cells. 

V2O5-P205 (95 5, molar ratio) cathode and a lithium anode (Li/a-V205 cell) [1]. In this section, we describe safety test results for AA Li/a- V2Os cells. The AA cell we fabricated has a pressure vent, a Polyswitch (PS, Raychem Co., thermal and current fuse) and is composed of a spirally wound cathode sheet, a metallic Li-based anode sheet and a polyethylene (PE) separator [87]. 

This section reviews the state-of-the-art in battery separator technology for lithium-ion cells, with a focus on separators for spirally wound batteries in particular, button cells are not considered. 

The requirements for a battery separator can best be understood in the context of how the separator is used. The conventional process (Fig. 1) for making spirally wound cells involves threading the separator (a) through a winding pin (b). 

Currently, all commercially available, spirally wound lithium-ion cells use microporous polyolefin separators. In particular, separators are made from polyethylene, polypropylene, or some combination of the two. Polyolefins provide excellent mechanical properties and chemical stability at a reasonable cost. A number of manufacturers produce microporous polyolefin separators (Table 1.)... 

The simulated short-circuit test was developed to characterize the response of the separator to a short circuit without the complications of battery electrodes. The separator was spirally wound between lithium foils and placed in an AA-size can. To avoid lithium dendrite formation, an alternating voltage was applied to the cell. The cell current and can temperature were monitored. Figure 6 shows the behavior of Celgard membranes. 

Figure 1. Typical battery configurations (a) button cell (b) stack lead acid (c) spiral wound cylindrical lithium ion (d) spiral wound prismatic lithium-ion.

Fig. 4.12 Discharge characteristics of a spiral wound cylindrical cell (17 mm diameter X 33.5 mm height) based on the Li-(CFT)(I couple, at 20 pA over a wide range of temperatures. (By permission of National/Panasonic.)...

Bobbin-type and spirally wound cylindrical cells are now fabricated by a number of manufacturers. The former are used for low-drain long-term applications such as computer memory retention and have a useful life of at... 

Li-FeS2 cells were manufactured as button cells, and are now produced as spiral wound cylindrical cells (Fig. 4.28). The latter are currently being heavily marketed worldwide by the Eveready Battery Co, Inc. (especially... 

Fig. 4.28 Schematic cross-section of the upper part of the Energiser L 91 spiral wound Li-FeSn cylindrical cell, showing the positive temperature coefficient (FTC) resettable safety switch, and the pressure relief vent, (By permission of Eveready.)...

Fig. 5.1 Original Planl spiral wound lead-acid cell...

Some versions of the cell are manufactured in which the active materials are supported in tubular elements made from spirally wound perforated steel ribbon. Such a design is more common for alkaline nickel-iron cells, and will therefore be described for the latter system. 

Fig. 6.8 Schematic cross-seciion of spiral wound cylindrical sealed nickel-cadmium cell...

The cells can be entrapped by inclusion within membrane filter devices, such as hollow-fiber, flat plate, and spiral wound units. 

Figure 9.14 Pervaporation separation factor, /9pervap> as a function of the VOC evaporation separation factor, /3evaP- Data obtained with laboratory-scale spiral-wound modules containing a composite silicone rubber membrane and in laboratory cells with thick membranes...

SVO material utilized was prepared via a combination reaction. A spirally wound lithium/SVO cell was also described in 1998 by Takeuchi et al. [63], This cell achieved a volumetric energy density of 540 Wh/1, delivered greater than 50% of theoretical capacity under loads greater than 3 j, and was successfully pulse discharged at 2.0 A. Several safety tests were conducted, including short-circuit, forced overdischarge, crush, and charging tests, and the cells did not rupture, vent, or leak under these abusive conditions. 

Sterilin Ltd. (Appendix 3) produce a series of roller bottles containing a spirally wound insert on which the cells grow. These Spira-Cel bottles have a growth area of 3000-6000 cm2 but cost... 

Both the lithium sulfur dioxide (Li-SO and lithium thionyl chloride (Li-SOCy cells may be classified as liquid cathode systems. In these systems, S02 and SOCl2 function as solvents for the electrolyte, and as the active materials at the cathode to provide voltage and ampere capacity. As liquids, these solvents permeate the porous carbon cathode material. Lithium metal serves as the anode, and a polymer-bonded porous carbon is the cathode current collector in both systems. Both cells use a Teflon-bonded acetylene black cathode structure with metallic lithium as the anode. The Li-S02 is used in a spirally wound, jelly-roll construction to increase the surface area and improve... 

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