Lithium Ion Capacitor Safety Testing

Abstract

Lithium – Ion Capacitor (LIC) is a recent innovation in the area of electrochemical energy storage that hybridized lithium ion battery anode material and electric double layer capacitor cathode material as its electrode. The high-power density offered by LIC has made it a promising energy storage devices for powering hand-held and portable electronic systems/consumer electronics, Hybrid Electric Vehicles, and Electric Vehicles. The swelling and gassing of the LIC, when subjected to abuse conditions, is still a critical issue concerning the safe application. LIC is relatively safer than Li-ion batteries due to the absence of little or no oxygen and oxides in the cell, limited lithium deposition, and quick energy release. This features has made LICs less prone to thermal runaway when abused. There have been very few studies on the LICs safety but they have been very brief and do not investigate the entire range of safety issues. However, it is imperative to carry out thorough investigation that characterizes the safe operation of LICs. To further investigate the safety of LIC for commercial applications, comprehensive abuse tests were conducted on LIC 200F pouch cell type with voltage ranging from 3.8V to 2.2V developed by General Capacitors LLC and their responses were studied. The investigated cell has a specific energy and specific power to be 14Wh/kg and 6kW/kg respectively. In this study, different types of abuse testing were performed on LIC 200F specification and their result showed differences in response due to different types of abuse conditions. The overcharge, over discharge, external short circuit, crush (flat plate and blunt), and nail penetration test were performed on the cell. The thermal characterization of the cell heat generation, thermal stability and ability to withstand high temperature (150ºC) limit without resulting to thermal runaway was also studied. Figure 1