As the size of lithium-ion batteries (LIBs) becomes larger, it is also time consuming and expensive to get lots of electrochemical properties experimentally. In particular, it needs more resources to optimize all cases for designing and developing the right large format cell for a given application. Hence, we adopt a previously designed pseudo two dimensional (P2D) model to simulate the electrochemical performance of a 20 Ah pouch cell consisting of LiFePO₄cathode and a graphite anode. The model was used to analyse the adequacy of two pulse based power measurement methods; hybrid pulse power characteristics (HPPC) and J-pulse (JEVS D 713, Japan Electric Vehicle Association Standards), in predicting the direct resistance (DC-IR) and power as a function of state of charge by comparing the simulation results to those of experiments.

There was a good agreement between the simulation results and those of the experiment. DC-IR as a function of SOC was obtained from P2D model, and converted to power. Both two methods showed that DC-IR of charge and discharge increase from about 10% to about 20% at the SOC below 20%. DC-IR of the cell during charge in HPPC was predicted to be higher than discharge and vice versa for J-Pulse. Hence, a different current density should be used for the two methods for effective power predictions.

References

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2. M. Doyle and J. Newman et al., Journal of the Electrochemical Society, 143, 1890-1903 (1996).

3. H. Lee and Y. M. Lee,  Journal of The Korean Electrochemical Society, 10(3), 115-123 (2012).

Acknowledgements

This work was supported by the Human Resource Training Program for Regional Innovation and Creativity through the Ministry of Education and National Research Foundation of Korea (NRF-2014H1C1A1066977) and by the Sebang Global Battery.