Electrical lithium battery performance model for second life applications

The aging behavior of lithium cell has a profound impact on its performance in terms of energy and power efficiency, especially when it is considered in End Of Life (EOL) in automotive field. Lithium battery is considered in EOL if at 85-80% of nominal capacity. Today, the reusing of Electric and Hybrid Vehicles EOL batteries on stationary applications, giving a second life to these batteries, is a solution to reduce high potential cost of lithium batteries. Currently, there is a lack of investigation of the performances of these second life batteries. This paper depicts the performance results of five NMC cells at different SOH, where four of these cells are considered in EOL, so ready to be investigated for possible second use. By results, there are many way to correlate battery SOH and battery performance, e.g. an increase of the internal resistance and the constant-voltage (CV) phase charging duration, the change of the open circuit voltage shape curve. Finally, a battery model based on electrical equivalent circuit is build and implemented in Matlab/Simulink, which is validated by comparison between voltage experimental and simulated data.