| dc.description.abstract | Over the past three decades, consumer electronics demand has surged, with products like smartphones, laptops, smartwatches, and VR headsets becoming widespread. These devices have evolved to become sleeker and more powerful. Concurrently, rising carbon emissions have prompted a shift towards sustainable manufacturing processes. This dual drive led to the adoption of li-ion battery technology in the early 2000s, now widely used across various sectors including automotive and healthcare. Additionally, the push for sustainability and miniaturization has spurred growth in printed electronics, particularly in the automotive and aerospace industries, due to their lighter, more eco-friendly designs.
Li-ion batteries became the popular choice among power sources for applications in consumer electronics devices owing to their combination of high specific capacity and specific energy density along with several other benefits such as long cycle life and ability to be charged rapidly. However, owing to their inability to tolerate overcharge as well as deep discharge, li-ion batteries require stringent control during operation via a battery management system which also needs to inform the user of the battery’s available capacity to prompt recharge as well as battery health to prompt battery replacement. Moreover, li-ion batteries are sensitive to operation at higher charge currents as well as higher temperatures owing to their susceptibility to thermal runaway, they must be qualified for operation under these conditions and the battery life under such conditions must be examined. In this work, two li-ion coin cells and one li-ion pouch cell have been subjected accelerated life cycle testing along with different electrical and environmental parameters to quantify their lifetimes as a response to the selected use parameters. Apart from this, the cells have also been subjected to calendar aging tests and knee-point tests to evaluate the effect of various degradation modes that the battery encounters not only when use in a device, but throughout its lifetime. The gathered data from the accelerated life test has then been used to model the battery state of health considering battery use parameters for individual cells. Post model generation, the models were then evaluated on quasi-real-world randomized use battery datasets to investigate model robustness and a combined model for all the three cells was proposed.
Li-ion batteries of the ultra-thin flexible pouch cell configuration are also finding applications in wearable electronic devices such as e-textiles, fitness trackers, and biomedical sensors, as well as in rollable displays. In such applications, the ultra-thin pouch cells are expected to undergo and endure mechanical flexing during operation, which can have critical effects on battery capacity degradation as well as safety. In this work, an ultra-thin flexible pouch cell has been subjected to static as well as dynamic flexing to investigate the effects of parameters such flex radius, orientation, and speed along with accelerated life cycling so as to investigate the effect on battery life. Furthermore, an investigation of battery lamination for integration with printed electronics has also been conducted while investigating the effect of laminating conditions on battery cycle life performance.
In modern consumer electronics, a major component of the power supply system apart from the battery, is the battery management system which has traditionally been employed on a rigid PCB format which contributed to the overall weight and bulk of the device. Transitioning the BMS from a rigid PCB format to a flexible format can allow for further device miniaturization, weight reduction of the device and such an effort has been made in this work by fabricating linear and buck topology charging circuits on flexible substrates using printed electronics techniques. The printed circuits have been fabricated with various inks and interconnect materials as an effort to compare the performance of sustainable materials for printed electronics with traditional non-sustainable materials. The fabricated circuits have also been tested for their reliability by subjecting them to repeated cycling. Finally, sustainable materials for printed electronics have been further explored for different printing techniques via different circuit designs. The application of printed electronics for developing in-mold-electronics which are thermoformed circuits for applications in the automotive industry has also been explored. | en_US |
