Machine learning optimized integration of a transcritical CO2 heat pump for sustainable and simultaneous heating-cooling in lithium-ion battery electrode drying

Lithium-ion battery electrode drying, a pivotal yet highly energy-consuming step in manufacturing, predominantly relies on inefficient electric heating, resulting in significant carbon emissions and energy waste. The concurrent need for high-grade heating for drying and deep cooling for solvent recovery in industrial ovens presents a critical thermodynamic challenge that conventional systems fail to address efficiently. Here, we integrate a transcritical CO2 heat pump into an industrial battery electrode drying oven, exploiting the temperature glide of supercritical CO2 to simultaneously provide high-temperature drying air, recover N-methyl-2-pyrrolidone (NMP) solvent, and generate byproduct hot water. Using machine-learning-assisted multi-objective optimization with a back-propagation neural network and the Non-dominated Sorting Genetic Algorithm II, the optimal system achieves a coefficient of performance of 3.85, a solvent recovery rate of 90.9%, and produces byproduct hot water at 65.4°C. A comprehensive 4E (Energy, Exergy, Economic, Environmental) evaluation demonstrates compelling practical viability: the system attains a ‌dynamic payback period of only 2.28 years‌ and reduces ‌carbon emissions by 74.0%‌ compared to the traditional electric heating baseline. Exergy diagnosis identifies the evaporator and compressor as primary sources of irreversibility, offering clear guidance for future technological refinement. This work presents a novel industrially viable integration of a transcritical CO2 heat pump into infrared-hot air combined battery electrode drying process, resolving the fundamental heating-cooling conflict through intelligent design and advanced optimization. It establishes a scalable, economically attractive blueprint for deep decarbonization in advanced manufacturing, applicable not only to battery production but also to a wide range of industrial drying and thermal processes.