Aluminum foil for plastic-aluminum film used for flexible package of lithium ion battery, and preparation method thereof

Abstract

The invention discloses an aluminum foil for a plastic-aluminum film used for flexible package of a lithium ion battery, and a preparation method thereof. The aluminum foil is composed of a core layerand a protective layer which are compounded together. The core layer comprises, by weight, no less than 0.1% and no more than 1.0% of Si, no less than 0.1% and no more than 1.8% of Fe and no less than 0.1% and no more than 1.8% of Mn, with the balance being Al. The protective layer comprises, by weight, no less than 0.1% and no more than 1.0% of Mn, no less than 0.1% and no more than 1.0% of Si,no less than 0.1% and no more than 1.8% of Fe and no less than 0.1% and no more than 1.8% of Zn, with the balance being Al. According to the invention, the production process flow of the plastic-aluminum film is simplified, and the protective layer is allowed to directly contact with an antifreezing solution and performs protection effect as a sacrificial anode; and a special annealing process iscooperatively used to guarantee uniform corrosion of a material in the process of corrosion, so the high corrosion resistance of the plastic-aluminum film in the antifreezing solution is effectively ensured, local corrosion is prevented, and the requirement of a power battery for long-lasting corrosion resistance of the plastic-aluminum film is met.

Description

technical field [0001] The invention relates to an aluminum-plastic film used for lithium-ion battery packaging. Background technique [0002] With the increasing demand for lithium-ion batteries in the market, the packaging materials of lithium-ion batteries have increasingly become the focus of attention. Among them, the flexible packaging materials of lithium-ion batteries are relatively resistant to liquid chemicals such as corrosive acids, alkalis, salts or organic solvents. High stability, its design, manufacture and application technology have become one of the technical problems to be solved in the lithium battery industry. Because the flexible packaging material is in direct contact with the internal materials of the battery, there are strict requirements for the use of flexible packaging materials, two of which are very important: [0003] (1) It needs to have extremely high barrier properties. Poor barrier properties will reduce the specific capacity of the polym...

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Problems solved by technology

[0003] ⑴ It needs to have extremely high barrier properties. Poor barrier properties will reduce the specific capacity of polymer lithium-ion batteries, make the batteries bulge, lead to a decrease in cycle life and electrochemical performance, and seriously cause the battery to fail

[0008] The antifreeze system is generally weakly alkaline, and the general pH is around 8.5. Under weakly alkaline conditions, the dense oxide film formed on the surface of the aluminum alloy is easily destroyed, and the aluminum alloy is prone to uneven corrosion, and the overall reliability of the material decreases. , causing the actual working life of the material to decrease or even short-term corrosion and perforation, resulting in battery failure

[0009] At present, the traditional aluminum-plastic film has a double-sided film structure, and its surface film is made of polymer materials, which are prone to aging after long-term immersion in the antifreeze system. Once the film material is damaged, the internal aluminum foil is easily damaged in the antifreeze system. Corrosion or even perforation will cause the battery to fail. At the same time, the use environment of large-capacity automotive power batteries is different from that of ordinary electronic product batteries, and there is a greater risk of impact. Therefore, in order to ensure the reliability of the battery, the overall structure and reliability of the battery are required. needs to be improved

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