Prismatic batteries sealed

Ni-Cd batteries are produced in prismatic, cylindrical, and button designs in different sizes. There are different kinds of Ni-Cd batteries available but all of them fall into any of the two categories vented Ni-Cd batteries and sealed Ni-Cd batteries. Sealed Ni-Cd batteries are not designed for a pressure build up. More details about sealed Ni-Cd batteries are given in Table 3. 

Figure 24.22 shows the effect of discharge rate and temperature on the delivered capacity of the battery. A fully charged battery can operate over a very wide temperature range. These data are summarized in Fig. 24.23 which plots the service life of the sealed prismatic lead-acid battery at various temperatures and discharge rates (C-rates). Manufacturers data should he obtained for specific performance characteristics as the characteristics may vary depending on the size and design of the battery. 

FIGURE 24.23 Service life of sealed prismatic lead-acid batteries. 

FIGURE 29.2c Construction of a sealed prismatic nickel-metal hydride battery. 

TABLE 29.4fi Specifications of Sealed Prismatic Nickel-Mebil Hydride Single-ceU Batteries... 

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). 

Almost all lead-acid battery cases are rectangular (prismatic) in shape. The interior may be manufactured with projections to locate the plates and support them above the case floor, in order to leave mud or sludge space where shed materials can accumulate (Fig. 5.9). In other batteries the plates are suspended from the case lid or from a ledge in the case wall. The lid is welded or sealed to the case and is provided with apertures for terminal pillars, venting valves and simple screw caps or complex automatic systems for adding distilled water to the elctrolyte. 

Button, cylindrical and prismatic sealed cells are similar in design to the starved-electrolyte configuration of nickel-cadmium cells. A schematic diagram of a six-cell battery is shown in Fig. 6.11. Because of the slightly... 

The prismatic sealed cells are not self-supporting and are normally used in battery operation where the battery case is used to constrain cell cases because internal cell pressures in the range of 690 kPa (100 psi) are common. 

Sealed lead-acid batteries are in both cylindrical and prismatic shapes. The cyclindrical ones (usually designed as SLA batteries) have excellent high-rate characteristics. Other than in portable devices, sealed batteries can be used in standby applications, e.g. telephone exchange stations, were they are kept in float charge. In this case too, oxygen recombination is possible. 

Lithium ion cells serve the smaU-sealed rechargeable battery market and compete mainly with the Ni-Cd and Ni-MH cells for the various applications. The Li-Ion cells are available in cylindrical and prismatic format as well as flat plate constructions. The cylindrical and prismatic constructions use a spiral-wrap cell core where the ceU case maintains pressure to hold and maintain compression on the anode, separator, and cathode. The lighter-weight polymer constructions utilize the adhesive nature of a polymer/laminate-based electrolyte to bond the anode to the cathode. 

Alternatively, a roll can be wound to fit a prismatic case as commonly found in lithium ion batteries. The roll is placed in a fitted conductive metal casing that has a Teflon or rubber gasket seal separating the outer can and top button contact. The cylindrical metal rod around which the film is wound becomes the internal contact. Contacts are ensured by soldering and then electrolyte is injected into the cell followed by a curable polymer sealant. The top of the casing is fitted with a vent, gasket layer, and top contact plate. To seal the device, the top of the can is mechanically crimped and the outer metal casing acts as the other contact and provides mechanical stability and rupture resistance. 

Market surveys indicate that thin prismatic-sealed Ni-MH batteries are widely used in several applications, where portability, low-power consumption, compact packaging, and minimum room-temperature storage loss are the principal procurement specifications. The cathode of the Ni-MH battery produces a cobalt oxide (CoO), which has much higher conductivity than nickel oxide hydro oxide (NiOOH). The addition of yttrium oxide (YjOj) increases the utilization of the positive ions. Oj that evolves at the positive electrode on overcharge could oxidize the separator element. Therefore, a chemically stable separator material is needed to avoid the oxidation of the separator. The suffocated polypropylene is the most suitable separator material to avoid oxidation. 

The cell itself can be built in many shapes and configurations—cylindrical, button, fiat, and prismatic—and the cell components are designed to accommodate the particular cell shape. The cells are sealed in a variety of ways to prevent leakage and dry-out. Some cells are provided with venting devices or other means to allow accumulated gases to escape. Suitable cases or containers, means for terminal connection and labeling are added to complete the fabrication of the cell and battery. 

Muhicell 9-V Battery. The Li/Mn02 system has also been designed in a 9-V battery with 1200 mAh capacity in the ANSI 1604 configuration as a replacement for the conventional zinc battery. The battery contains three prismatic cells, using an electrode design that utilizes the entire interior volume, as shown in Fig. 14.41. An ultrasonically sealed plastic housing is used for the battery case. 

Major battery Prismatic cells Based on Based on Sealed cylindrical Prismatic cells Prismatic cells Button cells to Prismatic designs... 

Thin flat prismatic sealed lead-acid cells have been designed for portable applications as they offer more flexibility in the design of the battery. They use space more efficiently than cylindrical cells, resulting in a higher volumetric energy density, and the slim design is adaptable to small-footprint equipment. " An exploded view of a typical flat cell is shown in Fig. 24.5. 

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. 

FIGURE 24.28 Characteristic discharge curves for thin prismatic single-cell sealed lead-acid batteries at 20°C. Courtesy of Portable Energy Products, Inc.)... 

Sealed nickel-metal hydride cells and batteries are constructed in cylindrical, button, and prismatic configurations, similar to those used for the sealed nickel-cadmium battery. 

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. 

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