  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.
