Effects of the Hybrid Composition of Commercial Lithium-Ion Capacitors on Their Floating Aging

• Published in: IEEE transactions on power electronics Vol. 34; no. 3; pp. 2292 - 2299
• Main Authors: El Ghossein, Nagham, Sari, Ali, Venet, Pascal
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-03-2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE); Institute of Electrical and Electronics Engineers
• Subjects: Accelerated aging; Accelerated aging tests; Accelerated tests; Aging mechanisms; Capacitance; Capacitors; Charging; Composition; Degradation; Electric potential; Electric power; Electrodes; Energy storage; Engineering Sciences; floating aging; Floating structures; Hybrid structures; lifetime analysis; Lithium; Lithium-ion batteries; lithium-ion capacitor (LiC); performance degradation; Rechargeable batteries; Resistance; Storage systems; Supercapacitors; Temperature measurement; Lithium-ion capacitor; floating aging; performance degradation; lifetime analysis; aging mechanisms
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2018.2838678

Lifetime of energy storage systems is a key factor that is extremely influenced by the operating conditions. For this reason, lithium-ion batteries (LiBs) and supercapacitors (SCs) were subjected to accelerated aging tests in several previous research in order analyze their lifespan. Lithium-ion capacitors (LiCs), which fall in between LiBs and SCs, are still considered as a novel technology. Their behavior during accelerated aging tests is not yet well studied in the literature. This paper focuses on studying the degradation of their properties during floating aging. Eighteen samples were tested under three different voltage values and two different temperatures over 12 months. Cells that were discharged to the minimum voltage showed a severe capacitance decrease that was much higher than the one of fully charged cells. The best storage voltage of LiCs was found to be 3 V, which is equivalent to a half charging state. The hybrid structure of LiCs was found to be the major cause of this change in behavior during aging at different voltages. Mechanisms that affect the electrodes and the internal composition of the cells in the diverse conditions were analyzed and predicted.