Alkaline nonwoven materials

Separators for Alkaline Storage Batteries JJ5 Table 11.15 Nonwoven materials for alkaline batteries. 

In most batteries, the separators are either made of nonwoven fabrics or microporous polymeric films. Batteries that operate near ambient temperatures usually use separators fabricated from organic materials such as cellulosic papers, polymers, and other fabrics, as well as inorganic materials such as asbestos, glass wool, and Si02. In alkaline batteries, the separators used are either regenerated cellulose or microporous polymer films. The lithium batteries with organic electrolytes mostly use microporous films. 

Most commonly used separator materials for alkaline Zn/Mn02 batteries are nonwoven polymers, such as cellulose, vinyl polymers, polyolefin, and others. The separator materials must be chemically stable in concentrated KOH solutions and electrochemically stable under both oxidizing and reducing conditions in the cell. In addition to its good electronic insulation, physical strength, and porous structure, good wettability to concentrated KOH solutions is especially crucial to provide a good ionic pathway for the battery operation. 

Typically, carbon zinc and alkaline cells use nonwoven separators. In these cases, cost is an important design consideration, and the high conductivity of the electrolyte enables thicker separator materials. However, the thickness of the separator also defines the gap or distance between electrodes, which can impact the cell s ability to support high current densities. Pores are not well defined and are typically on the order of... 

Nonwovens have been well established as traditional materials for alkaline batteries, NiCd and NiMH cells, and for absorbed glass matt (AGM) lead—acid batteries. Alkaline batteries use a variety of materials, mostly composed of wet-laid cellulose and polyvinyl alcohol (PVA). NiCd and NiMH use a variety of materials, from spunbond and melt blown to dry-laid materials. Lead—acid AGM batteries use a wet-laid glass matt as the separator, often in conjunction with another membrane. These materials range in thickness from 100 to 300 pm. One review article in 2007 even states that for lithium ion cells, nonwoven not possible. However, these traditional nonwovens are a significant industrial market for several manufacturers, with total sales into these types of cells of 450 million globally. 

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