Thermal Management of Small-Scale Li-ion Battery Module Using Graphite Matrix Composite with Phase Change: Effect of Discharge Rate

Abstract

An experimental study is performed to investigate the performance (thermally and electrically) of a small-scale li-ion module (3s2p) using passive thermal management strategy of phase change material (PCM)/graphite matrix. The PCM/graphite matrix was obtained by impregnating the graphite matrix (bulk density: 75 g L-1) with phase change material (paraffin/organic, RT-35). The performance tests of a li-ion module are conducted at 1C and 1.6C discharge rates for graphite matrix composite with phase change (phase change composite or PCM/graphite matrix) and also air cooling, comparatively. To illustrate the performance of the PCM/graphite matrix, transient temperature variations, thermal imaging, discharge capacity, and energy capacity are achieved comprehensively. The results illustrate that graphite matrix composite with phase change has a significant contribution to melting heat transfer, operating temperature, utilized capacity, and energy capacity compared to air cooling. Effective thermal conductivity of PCM/graphite matrix is increased 35 times by comparison with pure paraffin. Operating temperature and temperature gradient throughout the li-ion surface decrease by 22 % and 43 % compared to the air cooling, respectively, for high discharge rate. Operating time and energy capacity is increased 33 % and 28% compared to natural air cooling, respectively, for high discharge rate. It is also disclosed that dominant heat transfer mechanism is conduction depending on micro/nano-size porous structure of graphite matrix.