Hybrid Graphene‐Carbon Nanotube (CNT) Conductive Additives System for Regulating Polytetrafluoroethylene (PTFE) Fibrillization Toward High‐Energy‐Density LiFePO 4 Dry Cathodes

Abstract

The polytetrafluoroethylene (PTFE)‐based roll‐to‐roll (R2R) dry coating process is attracting significant attention as an environmentally benign and scalable manufacturing strategy for lithium iron phosphate (LiFePO 4 , LFP) electrodes toward sustainable, high‐energy‐density, and cost‐effective lithium‐ion batteries (LIBs). However, the use of nano‐sized LFP particles induces excessive shear stress transmission to PTFE, leading to the brittle electrodes with low ductility and toughness. To address these issues, regulating the PTFE fibrillization is crucial. In this study, two‐dimensional graphene sheets were introduced to regulate PTFE fibrillization by exploiting their intrinsically low‐friction characteristics. The graphene sheets positioned between LFP particles effectively mitigated shear stress transmission to PTFE, suppressed excessive fibrillization, and promoted the formation of thick, long, and continuous PTFE fiber networks throughout the electrode. Moreover, the hybrid conductive additive system comprising carbon nanotube (CNT) and graphene simultaneously improved mechanical robustness and electronic percolation pathways. The developed thick dry‐processed LFP electrodes (8 mAh cm −2 , 2.65 g cc −1 ) exhibited not only superior mechanical strength but also long electron percolation pathways, achieving improved rate capability and cycling stability. This work highlights the critical role of PTFE fibrillization behavior in nano‐sized LFP dry electrodes and presents a tribology‐inspired material design strategy for overcoming the intrinsic mechanical fragility of dry‐processed thick electrodes.