| The new energy has been attracting attention as one of the most important industries for21 st century. People are paying their attention on the energy’s sustainability and cleanness,because petroleum and coal are being depleted with a lot of pollution brought to the environment. The electric energy is the only clean energy to ensure the human being to survive. It can be expected that the human being’s travel will be more frequently, and transportations for the civilization will be turned out to be more advanced, which will lead to more dependence to the vehicles. The vehicles must employ the electric energy as a power source, so the support for the electric energy should be a limelight. Lithium ion vehicle batteries as one of the main parts of the electric vehicles should have the same market potential as electric vehicles. According to the analysis from experts, in 21 st century China will become a batteries and batteries’ materials kingdom, and no matter in resources or environmental maintenance, electric vehicles will receive a tremendous boost with a high market occupation, especially because the lithium iron phosphate industry has become a hot focus of the world’s economic development. Lithium iron phosphate based batteries have the merits such as clean, safety, long life, low volume, light, low cost, high open circuit potential for single cells, and convenience for building models. Furthermore, such batteries are suitable for industry which make them as an alternate for mine oil used in vehicles.The potential of electric vehicles and whether they can be accepted by people are dependent on the cycling life, safety, battery consistency, and high power density. Developing lithium ion batteries with long life, safety, and high power density is one of the important targets for batteries researcher. My work focuses on enhancing batteries’ cycle performance by optimizing the current collector, and building facile and high efficiency battery assembly line. The aluminum current collector which has been oxidized with an oxide layer has been characterized by AFM, XRD, SEM, and CR2016 coin cell testing as well as 20 Ah soft pack full cell evaluation, which showed improved battery performance. We coated a carbon layer on Cu collector which were characterized by SEM, XRD, and EIS, CV, charge/discharge, and1 Ah cell at different temperatures, cycles, and rates, which brought an enhanced performance for the batteries. Based on the theory of simple, high efficiency, and integrating human being,machine, materials, environment, and test, we finished building up a sixty million assembly line for Sinopoly Company. The main contents are as the follows.The internal structure of a lithium ion battery requires the current collector to be highly conductive, soft(facile the coating of active materials and subsequent handles), low cost, and good mechanical stability; meanwhile reduce the electrochemical reaction at high potential.Redox reactions easily occur at high potential which lead to an insulating oxide film on Cu foil, and thus increase the external resistance and inhibit the charge/discharge of batteries. Al foil is relatively stable at high potential with a thin oxide film on its surface, and electron passes based on channel effect. However, the conductivity will become poor if the thicknessis very high. Therefore, the quality of the Al foil surface directly influences the internal resistance and charge/discharge performance.A high conductivity of positive electrode was obtained by oxidized treatment. The rough surface of current collector has an improved adhesion for current collector and active materials, and thus increase the conductivity and low the polarization resistance at high rate charge/discharge. The anti-corrosion property was also improved which can enhance the cycle life, low the ohmic resistance as well as polarization resistance, and no side reactions occur at the batteries reactions.A concave was formed on Cu foil by a high potential distance between carbon rod and the current collector when they approach together by a home-made machine. The carbon rod electrode lowed its position by the machine and copy its morphology on the Cu foil surface,which can increase its conductivity and adhesion, and improves the conductivity and reduce the polarization resistance during charge/discharge. The current collector was characterized by RAMAN,XRD, EIS, and CV to evaluate the effect of presence of carbon layer. And with the charge/discharge, rate performance, and cycle curves at different, it can be seen that the carbon layer greatly improved the battery performance. The basic technologies for battery assembly include coating and film making(roll and cut, etc.), and the specific performance are capacity, potential, internal resistance, cycle life, storage performance, and temperature effect. The following mainly analyze the effect of the property and quality on the battery electrode making and battery performance(capacity, internal resistance, and cycle performance, etc.)The performance improvement of lithium ion batteries is not only dependent on the improvement of the quality of raw materials, but manufacturing techniques also plays a key role on the whole industry. The lithium ion battery belongs to high techniques, and with many complicated manufacturing control conditions. The cost of manufacturing occupies 80 % of the whole industry. Intelligentization of manufacturing and improvement of key techniques play an extremely key role on the batteries’ performance, which lead to much effort has been devoted to the manufacturing techniques by many companies. The author finished the design,confirmation of equipment specifications, invite public bidding, installation, testing, modeling manufacturing, and standard for process of a 1 sixty million Ah lithium ion battery assembly line which was based on experimental attempts.Investigation on test techniques for failure batteries of electric vehicles and balance methods for secondary used batteries. The results indicated that 80% capacity maintenance was observed for most of the batteries in electric vehicles. The batteries can be used at the temperature range between 10℃ and 40℃ in the facilities which require lower than 0.2 C discharge rate. The investigation on the balance techniques indicated that the batteries can realize their secondary use. By secondary use, the life of batteries can be extended which can low the cost and promote the health development of electric vehicle industry. |
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