Experimental study on phase change material based thermal management design with adjustable fins for lithium-ion battery

The performance and safety of lithium-ion (Li-ion) battery rely heavily on its working temperature and temperature differences in its cells. In this article, to facilitate Li-ion battery in a favourable thermal state, a battery thermal management (BTM) design integrating phase change material (PCM), metal fins and air cooling is proposed. Different from previous studies, the fin structure in this design can move in the PCM pool, and thus generates forced convection of the PCM when it has fully melted as liquid. A series of experiments were conducted to examine cooling effectiveness of this proposed BTM design at different room temperatures, together with its comparison to some representative conventional PCM cooling schemes. The results show that the BTM design in this article can offer economical and efficient passive PCM cooling for Li-ion battery working in mild thermal conditions. When the room temperature elevates over the PCM melting point, it will drive fins or/and fans to generate forced convection of the melted liquid PCM and air. Through flexible use of these multiple cooling means, the maximum temperature on the battery surfaces has been well controlled at 40°C, 45.1°C and 50.7°C during the battery discharge at the room temperatures T₀=25°C, 32°C and 40°C. They have dropped by 19.8%, 18.9% and 18.6% in comparsion to their counterparts on a bare Li-ion battery without any BTM protections. Moreover, the corresponding maximum temperature differences were only 2.3°C, 2.2°C, and 1.9°C, respectively, far lower than the general requirement of the battery temperature difference (i.e., ≤5°C). All these experimental results clearly demonstrate that the proposed BTM design can effectively cool down Li-ion battery and improve its temperature uniformity in a wide range of thermal conditions. Importantly, its dual (passive and active) cooling mode underlies its good cooling effectiveness with balanced power consumption.