전압 특성이 다른 리튬 이온 배터리에 대한 증분용량 분석법 기반 용량 추정 연구

Abstract

Capacity Estimation of Lithium-Ion Batteries with Different Voltage Characteristics Based on Incremental Capacity Analysis Song, Hee wook Advisor : Prof. Lee, Seong jun, Ph.D. Department of Mechanical Engineering Graduate School of Chosun University As environmental pollution and resource depletion become more serious problems around the world, research on energy storage system in the field of clean energy is also being actively conducted to address these issues. Recently, energy storage systems using lithium-ion batteries are widely used in various applications, such as electric vehicles (EVs), ESS (Energy Storage System), E-mobility, and electric-powered ships, because they have a higher energy density than energy storage devices using other types of batteries. To predict the lifespan and operate efficiently in various applications, it is necessary to accurately estimate the capacity of the battery system. Among the various battery capacity estimation methods, the incremental capacity analysis method is a method of estimating capacity based on the characteristics of the three changes in internal materials, LAM (Loss of Active Material), LLI (Loss of Lithium Inventory), and CL (Conductivity Loss) during battery aging. In this paper, we apply the incremental capacity analysis method, which is a capacity estimation method that quantifies the capacity change trend according to changes in internal materials, to estimate the capacity of various lithium-ion batteries with different voltage characteristics. To do this, we design the factors necessary for incremental capacity analysis and estimate the capacity by applying the designed factors. In this case, the factors necessary for incremental capacity analysis can be divided into three categories: characteristic points that are closely related to capacity, the range of voltage increases (△ V), and current conditions. Through correlation analysis of each factor, we propose the most efficient factor for each battery type. The proposed factors were applied to batteries with different voltage characteristics, and the capacity estimation results using the incremental capacity analysis method were compared with the capacity errors in the actual batteries. The estimation accuracy was verified at the capacity error level of RMSE 0.3%. The design formula for estimating the capacity by expanding the battery cell to a battery pack was verified. However, the design formula can only be used in conditions where the imbalance between the modules inside the battery pack is insufficient when it is expanded to a battery pack. Therefore, a battery pack simulation model was designed and the accuracy of the model was verified. The verified battery pack model was simulated in an unbalanced condition and the characteristics according to the unbalanced condition were analyzed to suggest the possibility of expansion to a battery pack