The oxidation resistance of the PE separator
By studying and discussing the oxidation resistance of PE separator and its testing methods, the following conclusions can be drawn:
1. The selection of raw materials for PE separator takes into account the antioxidant properties of the product. The molecular weight of ultra-high molecular weight polyethylene(UHMWPE) is increasing, with some reaching 6.8 million, which undoubtedly provides reliable assurance for the antioxidant properties of PE separators. The silica specially used for separators, as an inorganic material with extremely high purity, has very stable properties and will not undergo any chemical reactions under normal usage conditions. The specially selected antioxidants are beneficial in ensuring the antioxidant properties of the product, both during production and during product use. The specific composition of the specially used raw material oil is also beneficial for improving the antioxidant properties of the product. The colorant carbon black also contributes to the improvement of antioxidant properties. From the perspective of raw material selection, it can be seen that PE separator undoubtedly have good antioxidant performance.
2. In general, the higher the content of PE powder in the product, the larger the molecular weight, the better the antioxidant resistance of the separator. However, the performance of PE separator must be considered comprehensively, and the amount of PE powder in the formula cannot be increased simply to improve the antioxidant resistance of PE separator . In addition, the molecular weight of utra-high molecular weight polyethylene(UHMWPE) in the product is not only related to the molecular weight of the raw material PE powder, but also related to the process control. Under the condition of ensuring normal production, the high temperature degradation of utrahigh molecular weight polyethylene(UHMWPE) should be reduced as far as possible. If the production of higher molecular weight polyethylene, it must fully consider the production equipment and adjust the appropriate process.
3. The thicker backweb of the separator and the higher oil content in the product are beneficial for improving the antioxidant properties of the PE separator. A thicker backweb of the separator will also improve the strength and puncture resistance of the PE separator, but the resistance of the PE separator will also increase correspondingly. The increase in oil content in the PE separator can also affect resistance, porosity, and even oil precipitation during battery use. So any performance change will cause a series of changes, which must be comprehensively considered.
4. Pay attention to the storage and usage environment of the separator. Through our experimental research, it was found that high temperature and the presence of oxygen are necessary conditions for the oxidation of PE partitions. Therefore, when storing separator, they should be kept away from heat sources and avoid direct sunlight. During use, it is necessary to prevent overcharging to prevent the temperature of the separator and electrolyte from being too high, resulting in the production of oxygen through water electrolysis reaction, and the reduction of electrolyte, which can cause the separator to be exposed and come into contact with air, causing rapid oxidation of the separator.
