Understanding Low Temperature Limitations of LiNi0.5Co0.2Mn0.3O2 Cathodes for Li-Ion Batteries

A major drawback of today's Li-ion batteries is inadequate performance at low temperatures, which slows down the user-friendliness and thus market expansion of electromobility. Due to the complexity of the system, many possible low-temperature limitations and various dependencies on the operating conditions exist. As a result, the origin of the performance limitations at low temperatures is still controversial and not completely clarified to date. We herein demonstrate a comprehensive analysis of the performance limitations at low temperatures using a LiNi0.5Co0.2Mn0.3O2-based cathode as an example. To separate the overpotential phenomena, the complex system is decomposed as much as possible and individual aspects are investigated separately. Complementary electrochemical methods are employed to quantify the C-rate and SOC dependence of the individual overpotential phenomena. Based on the comprehensive analysis of the intercalation kinetics, mass and charge transport, we obtain a coherent picture of the performance limitations as a function of operating conditions. This can serve for targeted optimization or parameterizing models to simulate battery behavior. However, the present work is not only concerned with identifying the low-temperature limits of the system studied but also shows how the rate-determining step of the electrode reaction can be efficiently identified as a function of temperature, SOC, and C-rate, which can serve as a guide for future work.