Manufacturing processes battery assembly

Batteries intended to be used within 2 or 3 months after manufacture are produced with lead—ealeium—tin alloys, filled with electrolyte and ready for use. In this case, the technological scheme in Fig. 2.52 is modified. The tank formation and plate drying steps are eliminated and plate curing is followed by battery assembly, the formation process being completed in the battery itself. 

Wet-charged batteries. These batteries are manufactured by the simplest produetion technology, but have the shortest shelf-life (of between 3 and 8 months). Formation of the plates is performed in assembled batteries fiUed with sulfurie aeid solution (eontainer formation). Two main technological processes are employed for this type of formation as follows ... 

This chapter is intended to provide an overview of the varions aspects of manufacturing lithium-ion (Li-Ion) cells. While the basic principles of cell design and manufacture are well known, each manufacturer maintains proprietary, specific details of their cell designs and assembly and the equipment used in cell fabrication. Nonetheless, the overall principles and processes involved are detailed below. Figure 8.1 shows a schematic of the components of a cell (battery). 

For an average-sized electric vehicle, the mass of lithimn needed to create a battery pack is around 3 kg. At 6/kg, the cost of the lithium works out at less than 20 once again, a very small part of the final cost of the battery pack. Amongst other things, this is attributable to the quality of manufacture, which has to ensure a lifetime which is compatible with the usage of the vehicle, but also to the brace of processes needed to assemble cells into a battery pack (connections, mechanics, offsetting of R D costs, etc). 

Battery manufacturers have found that older style cellulosic separators are reasonably resistant to attack by chromium or manganese, but they eliminate the ability to automate the assembly process or pocket the plates to prevent side and bottom shorts. In these cases, battery manufacturers are left with a compromise in battery design. Recent advances have been made in improving the oxidation resistance of the PE separator by a factor of 5 when in the presence of strong oxidizers. This newly formulated PE separator is referred to as Daramic Multi-Sep [40],... 

Metal contact strips are used to attach the ends of the assembled battery to the battery terminals (e.g., 9-V transistor battery). The orientation of the stack subassembly (cathode up or anode up) is only important for each manufacturer s method of assembly. The use of contact strips allows either design mode. The entire assembly is usually encapsulated in wax or plastic. Some manufacturers also sleeve the assembly in shrink film after waxing. This aids the assembly process cleanliness and provides additional insurance against leakage. Cost, ease of assembly, and process efficiencies usually dictate the orientation during the assembly process. 

Another potential advantage of the solid polymer battery is that the design lends itself to manufacture by automatic processes and the capability to be easily fabricated in a variety of shapes and forms. Very thin batteries for cell phones, PDAs and similar applications can be manufactured. At the other extreme, large thin plates can be manufactured and assembled in multiplate prismatic or bipolar batteries. 

Polymer lithium-ion batteries, or strictly called gel lithium-ion batteries, were first disclosed by the former Bellcore Company. However, the initial process had a low qualification rate, and the large-scale production cost was too high. In 1999, mass production started. The detail assembly process depends on the manufacturer. 

The crimping process applied pressure to the top part of the battery containing the current break assembly, the positive temperature coefficient (PTC) and cap-up. After sealing the current break, the PTC, and the cap-up either soldered shut by a laser beam or into a heat-sealed soft pouch, the crimped ceU is pressed to maintain a constant height. The cell is ready for inspection by X-rays to check for any defect and verify the internal assembly of all these elements. After washing with water to remove electrolyte and any impurity at the surface, the ceU is dried to eliminate moisture. FinaUy, the battery in imprinted with the manufacturing factory, line number and date. 

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