Separator material and method of producing the same, and alkali secondary battery separator

Abstract

The separator material of the present invention is a sulfonated non-woven fabric comprising polyolefin ultrafine short fibers with a denier of less than 0.5 dtex and one or more other polyolefin short fibers. The other polyolefin staple fibers include polyolefin thermally bonded staple fibers. At least a portion of the polyolefin thermally bonded staple fibers are flattened to bond the component fibers together. The nonwoven fabric has a specific surface area in the range of 0.6 m2 / g to 1.5 m2 / g and satisfies the following range. (1) The ratio (S / C)E of the number of sulfur atoms (S) to the number of carbon atoms (C) in the non-woven fabric measured by electron spectroscopy (ESCA) for chemical analysis is in the range of 5×10-3-60×10- 3 range. (2) The ratio (S / C)B of the number of sulfur atoms (S) to the number of carbon atoms (C) in the nonwoven fabric measured by the flask combustion technique is in the range of 2.5×10-3-7×10-3. (3) The ratio (S / C)E / (S / C)B (depth of sulfonation) of (S / C)E to (S / C)B is in the range of 1.5-12. Thus, there are provided a separator material having high self-discharge performance when charge and discharge are repeatedly performed, high processability when assembling a storage battery, and high resistance to short-circuit capability; a method of producing the separator; and a An alkaline secondary battery separator.

Description

technical field

[0001] The present invention relates to a separator material which is a sulfonated nonwoven fabric comprising polyolefin short fibers and is applied to alkaline secondary batteries, lithium ion secondary batteries, electrochemical devices (e.g., electrical double layer capacitors, capacitors) etc.), ion exchange separators (for example, ion traps, etc.), and the like. Specifically, the present invention relates to a separator material having high self-discharging performance and suitable for alkaline secondary battery applications such as nickel-cadmium batteries, nickel-zinc batteries, nickel-hydrogen batteries, and alkaline secondary battery separators. Background technique

[0002] In recent years, nonwoven fabrics made of polyolefin fibers such as polypropylene and the like and subjected to hydrophilic treatment are preferably used as separator materials applied to alkaline secondary batteries and the like. Specifically, a separator material subjected to...

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