Surface Modification and Fabrication of Li-ion Battery offers some unique advantages over other welding Components for Plug-in Hybrid Electric Vehicle processes with the high energy concentration of the beam for reduced heat input to the joint. Several important Ben Luan, Glen Campbell, Xing Yang Liu, John Nagata, processing parameters were investigated for laser welding ♣ Maxime Gauthier, *Isobel Davidson of battery tabs, such as power level, travel speed, and depth of penetration (Figures 2, 3 & 4). 800 Collip Circle, London, Ontario, Canada, N6G 4X8, Industrial Materials Institute 3. Fabrication and Surface Modification of Current National Research Council Canada Collectors ♣ 75 boulevard de Mortagne, Boucherville, QC, Canada, The performance of current collectors is an important J4B 6Y4 issue related to not only the electrical conductivity but Industrial Materials Institute also the cycling kinetics of the battery. This research National Research Council Canada focuses on the fabrication of anodic and cathodic current collectors with increased specific surface area and *M-12, 1200 Montreal Road, Ottawa, Ontario, Canada, improved retention of active materials. Various K1A 0R6 fabrication technologies are investigated including Institute for Chemical Processes and Environmental powder metallurgy and electrochemical methodologies. Technologies National Research Council Canada Introduction This research addresses an important issue for the practical application of lithium ion batteries in PHEV. Since its revolutionary introduction into the portable electronics market by Sony in 1991, lithium ion cells have enjoyed a constantly increasing market share. This raised the expectations for its implementation in PHEV, particularly with the heightened needs for alternative energy and environment protection. However, even though the basic chemistry and design of Li-ion PHEV cells are quite similar to those of small consumer cells, the major challenge for PHEV cells is the demand for Figure 1 SEM Images and Elemental Mapping for much higher power performance. Furthermore, this Uncoated and Coated Separator demand is also linked to the safety/abuse resistance, operating life (including calendar life and cycle life), and cost of manufacturing. Li-ion battery components such as separators, current collectors and battery tabs are important components related to the power performance, cyclic kinetics, and cycle life. This paper presents results on the surface modification and fabrication of separators, current collectors and laser welding of battery tabs. Figure 2 SEM Image showing the Laser Fusion Zone Results and Discussion 1. Surface Modification of Separators An important issue for battery performance and safety is related to the separator. Unexpected short- circuits across the separator induces hot spots where thermal runaway may breakout. Internal short-circuits are believed to occur either by protrusions on the electrode Figure 3 SEM Image of the Interfacing of substrate and surface or by shrinkage of the separator upon heating. the fusion zone One way to prevent this from happening is to coat the polymeric separator with ceramic coating. Several simple immersion methodologies using various precursors and/or solvents were experimented with some results shown in Figure 1. All these methodologies demonstrated promising results. 2. Laser Welding of Battery Tabs Figure 4 EDX Mapping of fusion zone (Fe-left; Ni-right) Joining of battery leads and tabs is the basis of the electrical connection between cells, current-collectors Conclusions and cell-cans. The main drivers in joining of the battery leads and tabs are energy transfer capabilities, joint This research addresses important issues related to the reliability and manufacturing costs. fabrication and modification of key battery components (separator, tab welding, and current collectors). Promising The laser process is a non-contact process that results are shown to improve the performance of Li-ion produces high quality joints, excellent repeatability and batteries.
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