Prismatic batteries

Prismatic batteries, such as those used in smoke alarms and alkaline flat-pack cycle lamp batteries are also removed at this stage. 

The Trienekens operation uses two unique and patented steps during the size separation phase. This includes a rotating, angled disc to separate prismatic batteries... 

Small size Li-ion batteries have a typical capacity of 2Ah. Cylindrical and prismatic battery shapes are valued for applications in cell phones and personal... 

Low-rate cylindrical cells are employed for CMOS memories, radio-frequency ID tags, utility meters, toll collection systems, and wireless security systems, among others. High-rate cylindrical cells, disk-type cells and very large prismatic batteries have been used for military applications. Use in consumer products has been limited by safety and cost considerations. 

One of the most popular prismatic batteries is the so-called 9-V transistor battery with the lEC designation 6 F 22, available as Leclanche type and alkaline type as well as a rechargeable nickel/cadmium battery. Figure 15.10 shows a drawing and the dimensions. 

Sealable valves are normally closed to prevent the entrance of oxygen from air. The valve allows excess generated hydrogen to be vented under a set pressure. Venting pressures range from a high of 25 to 40 psi for a metal-sheathed, spirally wound cell to 1 to 2 psi for a prismatic battery. 

Low-rate batteries have been used commercially for a number of years for memory backup and other applications requiring a long operating life. The large prismatic batteries have been used in military applications as an emergency back-up power source. Medium- and high-rate batteries have also been developed as power sources for a variety of electric and electronic devices. Some of these batteries contain additives to the thionyl chloride and other oxyhalide electrolytes to enhance certain performance characteristics. These are covered in Sec. 14.7. 

The performance characteristics of the thin prismatic batteries are similar to those of the other sealed units. Their advantage becomes more apparent in the fabrication of battery packs as the minimum of void space required in the pack enhances the energy density. 

The loss of capacity with storage at different temperatures is also shown in Fig. 24.30. As with all lead-acid batteries, they should be recharged when the charge retention is below 50%. The cycle life of the thin prismatic batteries is similar to the one shown for the VRLA cells in Fig. 24.27. 

The thin prismatic batteries are designed to meet the needs of compact equipment. The rectangular shape permits more efficient battery assembly, eliminating the voids that occur with the assembly of cylindrical cells. The volumetric energy density of the battery can be increased by a factor of about 20%. The prismatic ceUs also offer more flexibility in the design of batteries, as the battery footprint is not controlled by the diameter of the cylindrical cell. 

Prismatic Batteries. Typical discharge curves for the prismatic sealed nickel-metal hydride batteries at room and other temperatures are shown in Figs. 29.5a and 29.5b. 

FIGURE 29.5 Discharge characteristics of nickel-metal hydride prismatic batteries ([Pg.850]

FIGURE 30.15 Temperature performance of 100 Ah NiMH EV prismatic batteries using commercial nickel hydroxide. 

Various types of cell and battery design and construction can be used in the nickel-zinc battery system. Cells have been built in both prismatic and cylindrical designs and both vented and sealed designs. However, most current commercial applications require the use of a sealed, maintenance-free design. A typical sealed prismatic battery is shown in Fig. 31.7. This type of construction can be used for a wide range of cell sizes and is particularly suited to larger capacity batteries (e.g. greater than 10 Ampere-hours). 

FIGURE 35.57 High and low temperature discharge of a 1.4 Ah CGP345010 C/LiCoOj wound prismatic battery at 1350 mA. Charged at 945 mA to 4.2 V followed by taper charge for 2 hours total at 20°C. Courtesy of Panasonic.)... 

Larger flat-plate prismatic cells of similar design offer comparable relative performance. See Fig. 35.76, which describes the capacity of a 35 Ah flat-plate prismatic battery at O.IC to C rates at 40°C, 20°C and —20°C. At the C rate at 20°C, the capacity was 12% less than that at the C/5 rate. 

Storage Stability of 20 Ah Flat-Plate Prismatic Batteries. The ability of flat-plate prismatic batteries to retain capacity on storage is indicated by the data presented in Table 35.22 which lists capacity retention after storage at 0°C, 40°C, and 50°C at either 50% or 100% state of charge for 8 or 16 weeks. These cells were on the C/LiCoJ Jij. tOj chemistry and used a ternary carbonate electrolyte. At or below 40°C, the batteries retained over 97% of their capacity. At 50°C, storage at 100% DOD resulted in 81% capacity retention, while storage at a 50% state of charge resulted in 91% capacity retention. 

A prismatic battery of larger capacity can be assembled from one or more stacked bicells, whose current collector tabs are welded inside the packaging and thus present only a single metal foil feed-through tab connected to each of the two multi-plate electrodes. To facilitate multi-plate battery assembly and alignment, individual bicells may be Z-folded to prevent electrodes and current collectors from breaking at the fold line they may also be eonneeted by common current collector(s), separator(s), electrode layer(s), ete. 

Lithium alloy/metal sulfide batteries employ a molten-salt electrolyte and solid porous electrodes. Depending on electrolyte composition, they operate over a temperature range of 375 to 500°C. Operation at these temperatures with molten-salt electrolytes achieves high power densities, due to the high electrolyte conductivities and fast electrode kinetics. A shift from prismatic battery designs to bipolar designs enhances the power characteristics further by reducing the battery impedance. 

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