Effect of Lamination Parameters and Mechanical Folding on SOH Degradation of Li-ion Battery Subjected to Accelerated Life Testing

The growing interest in the flexible field of electronics has provided impetus to incorporation of electronic components such as resistors, capacitors, LEDs, sensors, etc. into flexible circuits. Power sources are another significant component of a majority of electronic circuits which need to be integrated in flexible circuits so as to push the bounds of the wearable technology. One way to do this is by using a laminated film to laminate ultra-thin pouch batteries and then bind them to a flexible substrate. During the lamination process, these batteries are exposed to higher temperatures (above 100 °C), albeit for a short period of time, which can result in damage to the battery’s internals. In this study, a Li-ion pouch cell has been laminated using a hot roller lamination process with different conditions of lamination speed and temperature. The laminated batteries have then been subjected to accelerated life testing in presence and absence of static and dynamic mechanical folding so as to investigate the effect of folding on the laminated batteries. Further, the SOH degradation of the tested batteries is computed and has been incorporated in a regression model so as to study the effect of lamination parameters.

Design of Circular Composite Cylinders for Optimal Natural Frequencies

This study concerns optimizing the eigenfrequencies of circular cylindrical laminates. The stiffness properties are described by lamination parameters to avoid potential solution dependency on the initial assumptions of the laminate configurations. In the lamination parameter plane, novel response contours are obtained for the first and second natural frequencies as well as their difference. The influence of cylinder length, radius, thickness, and boundary conditions on the responses is investigated. The lamination parameters yielding the maximum response values are determined, and the first two mode shapes are shown for the optimum points. The results demonstrate that the maximum fundamental frequency points of the laminated cylinders mostly lie at the inner lamination parameter domain, unlike the singly curved composite panels. In addition, the second eigenfrequency shows a nonconvex response surface containing multiple local maxima for several cases. Moreover, the frequency difference contours appear as highly irregular, which is unconventional for free vibration responses.