Thermal performance enhancement of composite phase change materials (PCM) using graphene and carbon nanotubes as additives for the potential application in lithium-ion power battery

To improve the performance of lithium-ion power battery thermal management system, multi-walled carbon nanotubes (MWCNT)-based, graphene-based and MWCNT/graphene-based composite phase change materials (PCM) were prepared and experimentally studied. MWCNT-based and graphene-based composite PCM were studied to obtain the optimal addition amounts which could not only improve thermal conductivity but also restrain a rapid temperature rise in liquid PCM. Based on that, composite PCM with various proportion of graphene and MWCNT have been prepared and characterized under the optimal addition amount. In comparison, results showed that composite PCM at the MWCNT/graphene mass ratio of 3/7 could exhibit the best synergistic enhancement heat transfer effect, which the thermal conductivity was increased by 31.8%, 55.4% and 124% compared to graphene-based composite PCM, MWCNT-based composite PCM and pure PCM respectively. In addition, this composite PCM has the highest increase/decrement rate of temperature which can be shortened by 63.3% and 50.0% compared to pure PCM. Finally, the phase change properties and thermal properties of the MWCNT/graphene-based PCM were compared with those of pure PCM. The composite PCM showed great potential in lithium-ion power battery thermal management.