광대역 합성 섭동을 이용한 리튬이온 전지의 그레이딩용 고속 임피던스 분광 시스템의 개발

Abstract

Retired lithium-ion batteries are reused in second life energy storage applications. However, the overall performance of repurposed energy storage system(ESS) is limited by the unevenness of individual batteries used in it. Therefore, battery grading is required for optimal performance of ESS. Electrochemical impedance spectroscopy(EIS)-based evaluation of battery aging is a promising method to grade lithium-ion batteries. However, measuring the impedance of mass retired batteries is not practical due to high complexity and slowness. In this paper, a broadband multi-sine binary signal(MSBS) perturbation was presented to measure the impedance spectra for high-speed aging evaluation of lithium-ion batteries or modules. The measurement speed of the proposed system is multiple times faster than those of conventional EIS systems. The broadband MSBS was validated by measuring the impedance spectra of Samsung INR18650-29E batteries and comparing them with those measured with commercial EIS instrument. The measured impedance results were validated through Kramers-Kronig transform.