Design and Thermal Performance Analysis of a Liquid Cooling Plate Based on Gradually Varied Circular Notched Fins for Lithium-Ion Batteries

Thermal management of lithium-ion batteries is crucial for enhancing the performance and safety of electric vehicles. This study proposes a novel liquid cooling plate featuring gradually varied circular notched fins (GV-CNF) to improve the thermal management of a commercial LiFePO4 battery. The results indicate that GV-CNF provides a more uniform temperature distribution, a lower Ta, and a reduced ∆P compared to circular fins under identical conditions, leading to a 41.1% improvement in the comprehensive performance evaluation indicator (TP). Notably, the value of TP increases with the height of the coolant channel; however, when the channel height exceeds 4 mm, the change in TP value becomes minimal. Afterward, further studies were conducted to investigate the effects of different inlet–outlet configurations on the cooling performance. The single-inlet, dual-outlet configuration (Type III) for the liquid cooling plate not only reduces the Ta value but also exhibits the lowest ∆P and a smaller high-temperature region. Additionally, when the outlet spacing (L) is 81 mm, the lowest Ta recorded is 27.87 °C, and the ∆P is 3.13 Pa, indicating that this is the best outlet spacing. Additionally, comparative analysis of GV-CNF with serpentine-channel and circular-fin cooling structures reveals that the GV-CNF design effectively reduces the maximum temperature of the battery module, minimizes localized heat accumulation, and maintains low energy consumption, demonstrating superior overall thermal performance.