Survey and sensitivity analysis of critical parameters in lithium-ion battery thermo-electrochemical modeling

To achieve fast charging and high discharge capacity with thick electrodes, the impact of degradation phenomena and internal heat generation on Li-ion cells must be considered. Pseudo-2-Dimensional (P2D) thermo-electrochemical models can be used to investigate heat generation at electrode and cell level. However, even for common materials, in the literature there is a significant dispersion of thermal properties which, in some cases, go beyond physical limits. This study provides a sensitivity analysis of the critical thermal parameters, evaluating the impact of their fluctuation on cell electrochemical response. First, we establish a comprehensive database of materials properties for conventional graphite/Nickel- Cobalt-Manganese oxide (NMC) cells, so that literature values are critically compared. Then, we carry out a sensitivity analysis of the latter for benchmark charging and discharging scenarios focusing on the prediction of accessible capacity and maximum temperature. The results show that an inaccurate estimation of electrode density and heat capacity may lead to a remarkable error in maximum temperature evaluation in high C -rate scenarios while producing negligible changes at low C -rate; conversely, the effective thermal conductivity is never critical. During charge a proper optimization of the external cooling coefficient may impact positively on the total charging time.