A Fast Diagnostic to Inform Screening of Discarded or Retired Batteries

Abstract

With the increased pervasiveness of Lithium-ion batteries, there is growing concern for the amount of retired batteries that will be entering the waste stream. Although these batteries no longer meet the demands of their first application, many still have a significant portion of their initial capacity remaining for use in secondary applications. Yet, direct repurposing is generally not possible and each cell in a battery must be evaluated, increasing the cost of the repurposed packs due to the time intensive screening process. In this paper, a rapid assessment of the internal resistance of a cell is proposed. First, this method of measuring the resistance is completed on cells from twelve retired battery packs and one fresh pack using a hybrid pulse power characterization (HPPC) test as a benchmark for the analysis. Results from these tests show relatively constant resistance measurements across mid to high terminal voltages, allowing this metric to be independent of state of charge (SOC). Then, the relation between internal resistance and capacity across the various packs is discussed. Initial experimental results from this study show a correlation between internal resistance and capacity which can be approximated with a linear fit, suggesting internal resistance measurements taken above a threshold cell terminal voltage may be a suitable initial screening metric for the capacity of retired cells without knowledge of the SOC.

A Review of the Technical Challenges and Solutions in Maximising the Potential Use of Second Life Batteries from Electric Vehicles

“…To rapidly test the battery capacity and measure the highest and lowest voltages of retired batteries, various tools such as the Deutronic DBL1200HV-60 diagnostic and conditioning system workshop tool (Deutronic Electronic Technology Co., Ltd., Shenzhen, China) are available on the market [54]. While these tools offer a rapid overview of the battery status, they do not reveal the true electrochemical state of the battery or estimate its remaining useful life [92].…”