| Since the excessive resource utilization, energy crisis, shortage of resource and environmental pollution have become increasingly hot issues, and then national security and social development have been threaten. A clear energy saving plan and limited object set up in our nation's 12th five year plan aimed to these problems. Meanwhile, in the future seven strategic new industries that the State Council projected, as a representative of new materials and energy saving technology, Lithium-ion battery industry will receive a rapid development in the five year.Lithium-ion battery have a higher energy density, which is environmentally friendly. They hold a high working voltage, high specific energy, low self-discharge, no memory effect , long cycle life, fast charge and discharge, and no environmental pollution which compared with other rechargeable batteries (such as hydrogen– nickel battery, nickel– cadmium battery, and lead-acid battery). As lithium-ion battery technology is the basis of the information industry and new energy industry, therefore, lithium-ion battery are widely used. So the research and development of lithium-ion battery have become the hot point in electrochemical and materials area at home and abroad in recent yearsEspecially, as a key component of lithium-ion battery, shell materials have great effect on the storage performance and safety of lithium-ion battery. In order to meet shell requirements of lithium-ion battery, especially power-lithium-ion battery, pulsed electrodeposition and heat treatment are adopted together in this paper, and the samples that nickel - cobalt alloy coating elctrodeposited on strap of punching cold rolled carbon steel (SPCEN) are prepared.The main steps are as follows:(1) Firstly, the proper technology and parameters of pulse-elctrodeposition are chosen, and then samples were heated with different temperatures. According to the element diffusion of sample cross section, the best treatment condition, 700℃and 3h, are picked out.(2) Three samples that electodeposited Ni-Co alloy of 4μm on metal basis (sample 1) , 3h heat treatment under a temperature of 700℃after plating (sample 2), two layer alloy of 2μm were elctrodeposited respectively before and after heat treatment(sample 3) were prepared. (3) The surface morphology, cross section morphology and texture of samples were characterized by SEM, EDS and XRD, meanwhile, the corrosion resistance was investigated by tafel curve and EIS. The results indicated that the corrosion resistance of sample 3 is the best when the test system is 0.1mol/LH2SO4 , 1% NaCl, and 10% alkaline NaOH.(4) The hardness and tensile strength of samples were tested by micro hardness tester, universal draw machine and other equipments. The results indicated that sample 2 have the minimum hardness, maximum elongation, and appropriate yield ratio, which are suitable for stamping;(5) Three samples are stamped into battery shell, the corrosion resistance are tested by Neutral Salt Spray Test, Copper Sulfate Drip Experiments and Immersion Corrosion Test, and other methods. By compared with general nickel-plated shell and ordinary pre-roll shell, the results indicated that the shell of sample 2 have the best corrosion resistance, apparently better than general nickel-plated shell and ordinary pre-roll shell.After heat treatment, sample 2 possessed a nickel-cobalt-iron alloy layer. Moreover, the coating and the substrate bond tightly. Elongation and yield ratio is moderate, and beneficial to stamping. After stamping, shell hold a excellent corrosion resistance and significantly better than general nickel-plated shell and ordinary pre-roll shell. |
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