Characterizing the Recovery behavior of Hybrid Capacitors for IoT

Sammanfattning

Internet of Things (IoT) devices frequently rely on extended sleep states interrupted by high-intensity transmission bursts, which induce voltage drops. Unlike standard capacitors, which exhibit a purely linear discharge profile, the unique chemical component of Lithium-Ion Capacitors (LiCs) enables a partial voltage recovery during the rest periods. This thesis characterizes this chemical recovery behavior to optimize IoT duty cycles. Using an automated UUCoRe testbed, LiCs were subjected to a matrix of varying current intensities, pulse durations, and recovery intervals to map failure thresholds. The results demonstrate that allocating adequate sleep time allows this chemical rebound to significantly increase the total successfully extracted charge. The recovery exhibits diminishing returns, typically plateauing within the first 10 to 30 seconds depending on the load intensity. Extending the sleep state beyond this yields virtually no additional capacity. This research suggests that by optimizing IoT firmware to execute short pulses separated by targeted 10-second recovery windows, engineers can exploit the LiC's chemical recovery to extend device lifespan within the tested configurations.