Method for grouping unit cells using pattern matching technology of impedance spectrum

Abstract

A method for grouping unit cells of a similar impedance spectrum uses pattern matching technology to optimize the performance of a battery pack made of primary or secondary batteries as the unit cells connected in series, in parallel or in combination of them. To make an optimal battery pack with unit cells of a different internal characteristic, the method includes measuring the impedance spectrum of the individual unit cell in a wide frequency region at the same temperature and in the same state of charge (SOC), digitizing the difference in impedance spectrum among the unit cells into a relative value using the pattern matching technology, and selecting unit cells of a most similar impedance spectrum (i.e., a smallest relative difference in impedance spectrum) to make a battery pack.

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