基于复合相变散热的锂离子电池热管理实验研究

Experimental study on Li-ion battery thermal management based on composite phase change heat dissipation

以纳米氮化硼(BN)为填料,制备不同质量分数的石蜡基纳米复合材料,对其进行热物性表征,并将该材料用于锂离子电池的热管理。实验结果发现,BN与石蜡之间为物理复合作用;复合材料的熔点和相变潜热随着BN含量增加均有所降低,复合材料导热系数发生转折的点对应于熔点;由于BN在石蜡中发生沉降,导致其含量为1%时复合材料热导率最大,为0.3386W/m·K。将1%的复合材料应用于锂离子电池的热管理,发现在3C和5C倍率放电条件下,电池表面最高温度较纯石蜡分别降低1.43℃和3.39℃,具有3.5%和7.6%的降温效果;最大温差分别降低0.24℃和0.35℃,比纯石蜡降低20%以上,电池表面温度更趋于均匀。因此复合相变材料在电池热管理上具有较好的应用前景。

The paraffin-based composites with different mass fractions were prepared by adding nano-boron nitride(BN).The thermophysical properties and application of paraffin/BN in the Li-ion battery thermal management were analyzed.The results showed that it was a physical interaction between BN and paraffin.The melting point and latent heat of paraffin/BN had a certain decrease with the increasing of BN contents.The turning place of the thermal conductivity values was the melting point.Due to the settlement of BN,the thermal conductivity of paraffin/BN with 1 wt%BN was the highest,which was 0.3386 W/m·K.Paraffin/BN with 1 wt%BN was used to study the heat dissipation of Li-ion battery.It was obtained that when the discharge rate was 3C and 5C,the highest temperature of the battery surface using paraffin/BN was reduced by 1.43℃and 3.39℃,respectively.Acooling effect with 3.5%~7.6%was realized comparing to those of pure paraffin.The maximum temperature difference was respectively reduced by 0.24℃and 0.35℃,which decreased over 20%.The battery surface temperature using paraffin/BN distributed more evenly than paraffin.Therefore,composite phase change material had good application prospects in battery thermal management.