Numerical thermal control design for applicability to a large-scale high-capacity lithium-ion energy storage system subjected to forced cooling

Abstract

Overheating and non-uniform temperature distributions within the energy storage system (ESS) often reduce the electric capacity and cycle lifespan of lithium-ion batteries. In this numerical work, the thermal design inside the battery cabinet is explored. The battery cabinet has seven-level configurations with the suction fans located on the top of the ESS to efficiently realize heat dissipation. First, the numerical modeling is validated by the available experimental data, and the discrepancy in the maximum temperature increase between the experimental and computational results is found to be 3.2% or 0.64 K. Then, the optimum airflow rates of the fans are determined, where the single-cell model is also compared with the model of seven-level modules (i.e., 1/3ESS cabinet). Finally, the airflow channel widths, air gaps between the battery modules, as well as the air gaps between the 7th level module and the fans are examined. It is indicated for the precise model of 1/3ESS cabinet that: i) The maximum temperature rise of 4.63 K, and the maximum temperature variation of 2.14 K from cell to cell & the temperature uniformity of 2.82 K from module to module are all controlled with the requirements of operating temperature < 313.15 K, and temperature differences < 5.0 K, respectively; ii) The airflow channel width of 3.0 mm and the air gap of 10 mm between two adjacent modules & air gap of 20 mm between 7th level module and six parallel-fans are designed, and the ESS cabinet can increase the batteries of one level caused by the saved inside space.