Folding Reliability of Flexible Batteries in Wearable Applications

There is an increased focus on development of technologies for flexible hybrid electronics because of its benefits such as flexibility, lightweight and compactness. A wearable assembly needs power sources such as flexible batteries. Power sources in wearable applications need to sustain stresses of flexing, folding, twisting and bending. Little is known about the reliability of power sources under the stresses of daily motion or acceleration factors to assure reliability. There is need for studies focused on experimental analysis of reliability and characterization of the flexible batteries. In this study, state-of-health evolution of lithium-ion batteries have been studied under 150 charging/discharging cycles in conjunction with 60 folding loads per a discharging cycle. A folding test-stand capable of replicating the stresses of daily motion in a lab-environment has been developed for the test. The stresses in the battery have been studied using finite element models. Both LCO and NMC lithium-ion batteries have been studied.