Infrared Drying-Induced PVDF Crystallinity Control for Enhanced Lithium Cobalt Oxide Cathodes

The electrode fabrication process remains a critical stage in lithium-ion battery (LIB) manufacturing, where further advancements are needed to improve the energy efficiency and scalability. The conventional route relies on drying slurry-cast electrodes through circulating warm air, followed by vacuum postdrying, a practice that incurs high energy costs and involves multiple processing stages. Here, we investigate infrared (IR) drying to simplify electrode processing while tuning the binder structure at the molecular level. Lithium cobalt oxide (LCO) cathode slurry was cast onto a current collector and subjected to three drying conditions: (i) dried until visibly solvent-free, (ii) further IR-treated after reaching the solvent-free state, and (iii) vacuum-dried following the visibly solvent-free stage. Comprehensive characterization revealed that electrodes subjected to extended IR treatment exhibited superior mechanical adhesion, more effective solvent removal (negligible weight loss between 100 and 300 °C in thermogravimetric analysis), and lower internal resistance with a minimal increase after prolonged cycling, outperforming both counterparts despite the absence of observable morphological differences. Electrochemical testing further demonstrates that extended IR exposure achieves high-rate performance of 112 mAh g–1 at 2 C and stable capacity retention for 500 cycles at C/3. Analysis of PVDF films prepared under comparable drying conditions confirmed that exposure near the melting temperature of the PVDF with extended IR treatment enhances crystallinity of α-phase, strengthening mechanical stability and improving electrochemical behavior of LCO cathodes. These results highlight IR drying as a practical route to control the binder structure, offering both energy savings and improved performance in LIB electrode manufacturing.