ESS용 VRFB의 내부저항 특성 평가에 관한 연구 = A Study on Characteristics Evaluation of Inernal Resistance of VRFB for ESS

다국어 초록 (Multilingual Abstract)

In general, VRFB (vanadium redox-flow battery) is considered as one of the next generation ESS, since it can be used for more than 20 years semi-permanently, and its safety is much greater than lithium-ion battery due to the low risk of harmfulness, flammability and chemical reaction. However, in case of operating VRFB interconnected with the distribution system, the lifespan and output performance of VRFB may be degraded due to the hazardous factors, which may deteriorate the VRFB stacks and increase the internal impedance. Therefore, in order to evaluate the characteristics of internal impedance, which is one of the significant index of the degradation rate of VRFB, this paper proposes a modeling of VRFB section, which simulates the operation characteristics of VRFB, and EIS (electrochemical impedance spectroscopy) test device section that calculates the Nyquist plot according to the resistance and reactance components depending on the frequency. And also, in order to evaluate the characteristics of output and internal impedance of VRFB, this paper implements a 6 [kWh] scaled internal impedance test device, which is composed of VRFB, EIS test device and BMS section etc. From the simulation and test reuslts based on the proposed modeling and test device, it is confirmed that the proposed modeling is a useful tool to effectively evaluate the electrolyte resistance, charge transfer resistance and Warburg impedance at both initial and 160 cycles deteriorated conditions.