Separator for organic electrolyte battery, process for producing the same and organic electrolyte battery including the separator

Abstract

The separator for an organic electrolyte battery of the present invention is composed of a non-woven fabric containing a wet heat gelling resin capable of being gelled by heating in the presence of moisture and other fibers that are moist-heated from the wet heat gelling resin The gelled product is fixed, and the average pore diameter of the nonwoven fabric measured in accordance with ASTM F316 86 is in the range of 0.3 μm to 5 μm, and the maximum pore diameter is in the range of 3 μm to 20 μm. In this way, the other fibers constituting the nonwoven fabric can be fixed with the hydrothermal gelling resin, and the desired average pore size and maximum pore size can be obtained, thus providing an organic electrolyte battery with good safety, less short circuit, and excellent battery characteristics. .

Description

technical field [0001] The present invention relates to an organic electrolyte battery, and particularly relates to a battery separator made of a nonwoven fabric that can be applied to a lithium ion secondary battery, and an organic electrolyte battery including the separator. Background technique [0002] In recent years, the development of IT (Information Technology) and resource and environmental issues have promoted the development of secondary batteries represented by alkaline secondary batteries and organic electrolyte secondary batteries. In particular, lithium-ion secondary batteries using organic electrolytes are building a huge market due to their high voltage, high capacity, high power, and light weight, along with the need for smaller and lighter products. Furthermore, the battery is also being developed as a power source for hybrid electric vehicles (HEV) and electric vehicles (PEV). Lithium-ion secondary batteries include: a positive electrode composed of a co...

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Problems solved by technology

However, polyphenylene sulfide is expensive, so it does not contribute to cost reduction

The diaphragm of JP-A-2002-151037 (page 6, Examples 1 and 2) has a maximum pore size of 9 μm and has a certain degree of anti-micropowder short-circuit performance, but the average pore size has not been studied, so it is not sufficient

In addition, when the constituent fibers are thermally bonded together to form a nonwoven fabric, it needs to be carried out at a temperature near or above the melting point of the binder resin, but at this temperature, thermal shrinkage occurs as the binder fibers are thermally melted. , which causes the thermal shrinkage of the non-woven fabric itself, the yield rate of the non-woven fabric (hereinafter referred to as the yield rate) is poor, and the weight and thickness of the non-woven fabric per unit area are prone to deviation, or the non-uniformity of the pore diameter increases. Large, etc., therefore, the existing problem is that the electrolyte cannot be kept uniform, or it is easy to produce micropowder short circuit and dendrite short circuit at the same time, and the failure rate of the battery (hereinafter sometimes only referred to as "battery failure rate") is high.

Therefore, it is difficult to make the average pore diameter and the maximum pore diameter of the nonwoven fabric uniform, and the nonwoven fabric has a large pore diameter deviation, so that a stable puncture strength cannot be obtained.

In addition, JP-A-3-257755, JP-A-63-235558, JP-5-109397 and JP-8-138645 disclose separators using moisture-heat bonding fibers, but all separators tend to be Used as a separator for alkaline batteries, it is difficult to obtain a separator with a small pore size required for organic electrolyte batteries

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