Used Lithium-Ion Batteries in Second-Life Applications: Feasibility Study

Lithium-ion (Li-ion) batteries have become key factors in powering various consumer products and industrial loads. However, the increase in battery production has raised environmental issues as approximately 95 percent of Li-ion batteries are landfilled upon reaching end of life. Studies suggest, however, that almost 95 percent of Li-ion batteries could be recycled, for example, in second-life applications. A conventional method to characterize a battery is to use the battery state-of-charge (SOC) and state-of-health (SOH). These quantities can be used for predicting the remaining battery life cycle and for selecting reusable batteries. However, measuring the SOC and SOH is difficult using existing technology. Recent studies have shown that the SOC and SOH can be evaluated using the battery internal impedance. This paper demonstrates the applicability of the internal impedance in evaluating the suitability of used Li-ion batteries in second-life applications. Experimental measurements are shown from several commercial Li-ion batteries.