| The nickel-plated battery steel case is the main carrier of new energy batteries,but it is prone to corrosion,which will affect the subsequent battery assembly and the performance of the battery pack.Currently,water-based chromium-free protective agents are used to seal holes and prevent rust.In recent years,water-based chromium-free protective agent technology has been widely used in production due to its simple equipment and convenient operation and management.However,at present,its protective agent has problems such as insufficient corrosion resistance or affecting the electrical performance of the battery case.In order to solve the problems existing in the water-based chromium-free protective agent of nickel-plated battery steel shell,this study carried out the design,performance testing and characterization of new water-based chromium-free protective agent based on the theory of metal corrosion and protection,colloidal chemistry and electrochemistry.The main work is as follows:The neutral salt spray test,electrochemical test and porosity test were used to test the basic performance of the existing protective agent products.Combined with the factory’s on-site inspection method,a set of reliable,efficient and fast performance evaluation methods were determined and formulated.Based on the evaluation method determined by the above experiments,the main film-forming agent,auxiliary film-forming agent,etc.were screened to determine the basic components of the water-based protective agent.The study found that the main film-forming agent plays a major film-forming role and can isolate corrosive media such as air.Mercaptan substances can form a hydrophobic protective film on the surface of the coating layer through adsorption to further improve the corrosion resistance of the film layer.MF type corrosion inhibitors have both slow-release rust prevention and pH adjustment,and form a synergistic corrosion resistance effect with the polar groups of other components.Triethanolamine sebacate can improve the appearance and water washability of the film of the protective agent system,and improve the continuity and uniformity of the film.By single factor experiment and orthogonal experiment,the best combination of each component in the new type of water-based protective agent was determined-with oleic acid alcohol amine salt as the main component,the amount of thiol added was 1.0%(mass fraction,compared with oil The amount of acid alcohol amine salt,the same below),the amount of MF corrosion inhibitor added is 1.0%,the amount of triethanolamine sebacate added is 8.0%.On this basis,according to the nickel-plated shell standard YS-T 877-2013 for rechargeable batteries and customer site evaluation requirements,the performance of the new water-based protective agent developed was tested.The film has good appearance,good hydrophobicity,and contact resistance has little effect on the coating.The neutral salt spray rating is 7 and the porosity is only 1.2/cm2.The performance meets industry standards and customer requirements.The morphology of the film layer was observed by SEM.EDS and XPS were used to analyze the composition of the film.The film layer is mainly composed of C element,O element,S element and N element.The mechanism of the film formation and corrosion resistance of the protective agent film was discussed preliminarily.The protective agent system is green and environmentally friendly,has both rust prevention and electrical performance,and is easy to operate.With the development of the new energy industry in recent years,its application prospects are promising. |
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