Effect of Flex-to-Install and Dynamic Folding on Li-Ion Battery Performance Degradation Subjected to Varying Orientations, Folding Speeds, Depths of Charge and C-Rates

Abstract

The growing need for wearable devices, fitness accessories and biomedical equipment has led to the upsurge in research and development of thin flexible battery research and development. Wearable equipment and other asset monitoring applications require versatile installation of power sources on non-planar surfaces. For power sources in wearable electronics, perseverance towards repetitive mechanical stresses induced by human body motion is necessary along with the usual desirable characteristics such as high capacity, high C-rate capability and good life cycle stability. Prior studies which document the reliability of power sources subject to static and dynamic folding are scarce and at times fail to follow definitive test protocols which limit their application to real-life battery use scenarios. Particularly, the use of manual mechanical stressing of the power sources instead of a mechanical test setup is a key shortcoming in existing literature. Data is lacking on battery life cycling and in-situ mechanical stressing of the power sources including their impact of performance and reliability. Present study aims to overcome these deficiencies by testing a commercial Li-ion power source under static as well as dynamic folding. Furthermore, the fold-orientation and its fold-speed are varied to evaluate the effect of different mechanical stress topologies on the power source. Finally, a regression model was developed to capture the effect of these use parameters on battery capacity degradation.