GenSheng fei

The increased overheating hazards of degraded batteries have become the predominant cause of thermal safety issues in energy storage devices. To address this issue, dynamic thermal management strategies are urgently needed for all-lifespan safe operations, especially under the growing demands for ultra-fast charging. This study proposes a multi-objective optimization framework of immersion cooling strategy for all-lifespan ultra-fast charging, considering the thermal control and energy cost. First, all-lifespan fast charging evolution mechanisms are revealed. Results indicate that degraded batteries generate more heat due to more significant side reactions. Module maximum temperature (Tmax) and temperature standard deviation (TSD) rise to 164.35℃ and 5.5 K under 4C charging (60% SOH), inducing nonuniform temperature distribution, and degradation. Moreover, module temperature can also be controlled within a desirable level (Tmax: 43.7℃, TSD: 2.3 K) under the most challenging operation (4C charging, 60% SOH), through immersion cooling. Furthermore, the coolant flow rate thresholds are optimized for all-lifespan cooling control under the harshest conditions, evaluated from temperature control and energy cost perspectives. Tmax, TSD, and energy cost (W) are decreased below 33℃, 6 K, and 180 kJ, respectively, with the threshold q1. This study guides all-lifespan thermal safety management for future energy storage devices.