Life Prediction of Thin Flexible Batteries under U-Flex-to-Install, Dynamic Folding, Dynamic Twisting and Battery Lamination

Abstract

Flexible hybrid electronics in wearable applications requires power sources capable of sustaining static and dynamic stresses of daily motion without significant degradation in the battery capacity while subjected to various depths of charge for several charge-discharge cycles. In this research study, the combined effects of deep and shallow depths of charge, static-folding, dynamic-folding and twisting load(s), under varying fold orientations and varying C-rates have been characterized for thin-flexible Li-Ion batteries. Output parameters such as battery capacity and its degradation have been analyzed for battery state assessment. The use of lamination for thin-flexible battery integration has also been studied. Effect of lamination process conditions on the peel strength has been quantified. Laminated batteries have been subjected to static and dynamic fold tests as well so as to investigate the combined effect on capacity degradation. Finally, a life-prediction model has been developed for used in estimation of the battery capacity deterioration as a function of number of cycles, operating temperature, and depth-of-discharge. The model can be used to compute acceleration factors between accelerated test conditions and use-conditions.