All‐Climate Thermal Management Performance of Power Batteries Based on Double‐Layer Flexible Phase Change Materials

Abstract Thermal management systems for power batteries based on phase change materials (PCM) are limited by low heat transfer efficiency, leakage issues, and high rigidity, and most of them cannot meet the needs of all‐climate thermal management. A double‐layer flexible phase change material (FPCM) sleeve structure for all‐climate thermal management is proposed in this study for the first time. Innovations in both material and design have enhanced the adaptability of the thermal management system. The outer layer FPCM achieves high thermal conductivity (4.23 W m⁻¹ K⁻¹) and electrical conductivity (0.95 S m⁻¹), the inner layer FPCM achieves insulation (22.76 MΩ) and flexibility, the thermal contact resistance (TCR) between the double‐layer sleeve structure and the battery are measured to be only 0.15 °C W⁻¹, significantly improved thermal management performance. Experimental results show that at 30 °C ambient temperature, 5 C discharge, the system reduces the maximum temperature by 14.5 °C, from 61.4 to 46.9 °C, compared to natural convection. Additionally, during heating, the system achieves heating rates of 7.0, 8.3, and 8.7 °C min⁻¹ at −20, −10, and 0 °C, respectively, extending battery discharge duration by 32.5%, 65.9%, and 33.6%.