Currently, the adhesives used in the production and manufacturing of domestic polymer lithium-ion batteries are classified into white adhesive, black adhesive, yellow adhesive and single-layer adhesive. But which type of adhesive is more suitable for sealing battery tab? Below is a brief comparative analysis of various adhesives: ### Comparison Between Yellow Adhesive Tab and Black Adhesive The functional layer and PP layer of black adhesive are composites of different substances, resulting in multiple interfaces. After immersion in electrolyte, the adhesive itself will delaminate and peel off. In addition, the PP layer of black adhesive contains three substances with different melting points: melanin at 66℃, PE at 105℃, and PP at 137℃, making the interface even more unstable. The functional layer of yellow adhesive tab has a melting point close to 300℃, which makes it easier to operate during heat sealing. The middle functional layer uses a non-woven fiber layer instead of the original polyethylene terephthalate, achieving better interface fusion than black adhesive. However, it still cannot solve the problem of complete fusion between different substances. Due to the technical limitations of its PP layer, yellow adhesive becomes extremely hard and loses flexibility after heat sealing. During battery packaging and subsequent processing (such as nickel plating and plate attaching), this easily causes the tab adhesive and tab metal to break, leading to battery leakage, swelling and other issues. ### Comparison Between Yellow Adhesive Tab and White Adhesive Tab White adhesive is made of three layers of PP materials with different functions through co-extrusion. Its functional layer has a wide heat-sealing temperature range of 150–180℃, which is slightly lower than the battery packaging temperature (180–220℃). This can effectively prevent the problem of cross-section short circuit, expand the operable temperature range during battery packaging, and improve the yield rate of battery production. As mentioned earlier, yellow adhesive tab becomes extremely hard and loses flexibility after heat sealing due to the technical limitations of its PP layer, which easily causes the tab adhesive and tab metal to break during battery packaging and subsequent processing (nickel plating and plate attaching), resulting in battery leakage and swelling. In contrast, since the three functional layers of white adhesive tab are made of the same type of material (PP series), it can maintain high flexibility even after heat sealing. ### Comparison Between White Adhesive Tab and Single-layer White Adhesive Single-layer white adhesive is similar to the inner layer of the initial aluminum-plastic film. As it has only one melting point, if the heat-sealing temperature exceeds the melting point, it is prone to complete melting and short circuit; if the heat-sealing temperature is insufficient, it will soften, which leads to failure of complete melting and polymerization with the CPP layer of the aluminum-plastic film, causing the battery to leak and swell easily. The white adhesive tab is a three-layer adhesive. Its outer layer is made of materials similar to the inner layer of the aluminum-plastic film, featuring a wider heat-sealing temperature range to ensure fusion with the aluminum-plastic film. Meanwhile, the obvious temperature difference among the three PP layers enhances the operability of packaging. Our single-sided three-layer white adhesive series are slitted from Showa master rolls, while the double-sided three-layer white adhesive is produced with original raw materials from Showa Denko K.K. of Japan. Based on the basic principle of imported white adhesive and manufactured by high-precision equipment, this product has been trialed by manufacturers in the past two years and demonstrated excellent performance in various aspects. It can resist electrolyte at 85℃ for 24 hours. The combination of materials of each layer is more reasonable; targeting the inner layer of aluminum-plastic film, it has better fusion performance and compatibility with the inner layers of various aluminum-plastic films, and is thus widely applicable to the packaging of various soft-packaged lithium-ion batteries. In fact, the current concerns of battery manufacturers—such as the adhesion between tab adhesive and aluminum-plastic film, electrolyte resistance, sealing degree with metal strips, and tightness of melted edges and corners—are not only closely related to the performance of the tab adhesive, but also inseparable from the anti-corrosion and wettability treatment of metal strips, the tab manufacturing process, and the battery sealing process. Therefore, simply comparing tab adhesives without considering the manufacturing process is a superficial understanding.