Experimental study on heat transfer performance of mesh-type ultra-thin vapor chamber for large-area pouch battery

Ultra-thin vapor chambers (UTVCs) with high heat transfer characteristics in tight spaces are ideal for the heat dissipation needs of compact, high-energy-density battery systems for electric vehicles (EVs). This has also led to the expansion of the UTVC area to accommodate the battery size. In this study, a large-area (197 mm x 215 mm) UTVC with cost-effective flat meshes as the internal structure was designed for LiNi1-x-yCoxMnyO2 (NCM) pouch battery. Different from traditional mesh-type UTVCs, the vapor core is designed with multiple partially-through vapor channels to reduce vapor flow resistance. Experimental methods were used to investigate the impact of the UTVC placement and the position of the vapor channel in the vapor core on the heat transfer performance, as well as to examine the actual heat dissipation effect on the battery. The results show that gravity affects the performance of UTVC through placement. The UTVC under gravity-assisted placement has an advantage in both heat transfer performance and maximum heat dissipation power, reaching 0.142 degrees C/W and 144 W, respectively. And it is beneficial to reduce the thermal resistance of the UTVC by locating the vapor channel deeper into the evaporation section. The heat dissipation of the large-area battery by UTVC reduces the maximum temperature of the battery at the rate of 2.4C charging and 3C discharging by 22.3 and 23.8 degrees C, and the temperature difference is reduced by 62.31 % and 67 %, respectively.