Influence of temperature on the aging behavior of 18650-type lithium ion cells: A comprehensive approach combining electrochemical characterization and post-mortem analysis

The understanding of the aging behavior of lithium ion batteries in automotive and energy storage applications is essential for the acceptance of the technology. Therefore, aging experiments were conducted on commercial 18650-type state-of-the-art cells to determine the influence of the temperature during electrochemical cycling on the aging behavior of the different cell components. The cells, based on Li(Ni0.5Co0.2Mn0.3)O-2 (NCM532)/graphite, were aged at 20 degrees C and 45 degrees C to different states of health. The electrochemical performance of the investigated cells shows remarkable differences depending on the cycling temperature. At contrast to the expected behavior, the cells cycled at 45 degrees C show a better electrochemical performance over lifetime than the cells cycled at 20 degrees C. Comprehensive post-mortem analyses revealed the main aging mechanisms, showing a complex interaction between electrodes and electrolyte. The main aging mechanisms of the cells cycled at 45 degrees C differ strongly at contrast to cells cycled at 20 degrees C. A strong correlation between the formed SEI, the electrolyte composition and the electrochemical performance over lifetime was observed. (C) 2016 Elsevier B.V. All rights reserved.