G-K curve-based knee point prediction method for Li-ion batteries

Abstract

Lithium-ion batteries (LIBs) are very promising energy storage devices because of their eco-friendly characteristics and economic efficiency. Because the capacity of LIBs decreases with use, predicting the pattern of capacity fade is very important for both manufacturers and users. In particular, with the recent surge in interest in battery reuse, a method that can predict the 'knee point' phenomenon, which is a rapid decrease in capacity occurring in the later stage of battery life, is becoming more critical. This paper proposes a Gradient 1-Knee point (G-K) curve that can predict the knee point simply using long-term experimental data of Samsung SDI commercial cell (2170 NMC). This method can easily predict the knee point without using a battery model consisting of complex differential equations. Therefore, the proposed G-K curve allows us to estimate the approximate knee point even on practical devices with limited computational power. © 2021 ICROS.