Sandwiched thermal management system combining topology-optimized liquid channels and phase-change materials for cylindrical Li-ion batteries

To address lithium-ion battery thermal management challenges under extreme high-rate discharging (5C constant-current, initial ambient temperature of 298.15 K), this study proposes a sandwiched 3D composite system. It integrates a topology-optimized cold plate with phase change materials (PCM) for a synergistic “base-load and peak-shaving” cooling strategy. Fluid-thermal coupled simulations systematically investigated the topology evolution and cyclic stability. Results reveal an “over-optimization trap” where excessive channel branching merges boundary layers, causing localized flow stagnation. The optimal dendritic network ( ω = 0.3) circumvents this, reducing system pressure drop by 34.3% while minimizing peak temperatures. Furthermore, the shape-stabilized paraffin/expanded graphite (PA/EG) composite exhibits superior temperature regulation over microencapsulated PCMs through the synergistic effect of a matched phase transition threshold and high thermal conductivity. Under a 3-cycle continuous 5C operation, the optimal system securely stabilizes maximum temperatures around 308.3 K and fully recovers its latent heat capacity within merely 216 s during resting, demonstrating exceptional resilience against thermal fatigue. Finally, parametric evaluations identified the optimal configuration (inlet velocity v in = 0.020 m/s, fluid volume fraction V f = 0.4), achieving a superior balance between thermal safety and pumping power for high-power energy storage applications.