A novel cylindrical lithium-ion battery thermal management system based on PCM and liquid cooling coupling

To address the risks of thermal runaway and temperature non-uniformity in cylindrical lithium-ion batteries under high-rate discharge conditions, a novel thermal management system integrating a net-type liquid cooling channel with a square-cavity-encapsulated phase change material (PCM) was proposed. The effects of coolant flow rate and inlet temperature, channel width, the melting temperature and thickness of PCM were evaluated using the maximum battery temperature, intra-cell temperature difference, pack-level temperature difference and PCM liquid fraction. Under a 2.5C discharge condition, the proposed system limits the maximum pack temperature to 37.86 °C, while maintaining the maximum intra-cell and pack-level temperature differences within 4.05 °C and 0.31 °C, respectively. Channel width mainly affects coolant-side convection, and channel widening does not necessarily enhance effective heat removal. Owing to the strong cooling capacity of the net-type channel, reducing PCM thickness lowers conductive heat resistance and improves the peak-temperature control, while a lower PCM melting temperature promotes earlier latent-heat absorption without premature depletion of its latent-heat buffering capacity of the PCM. The parametric sensitivity analysis provides useful insight into the relative importance of the investigated parameters within the considered ranges and offers a theoretical reference for further optimization of the proposed hybrid BTMS.