Nitrogen-Doped Carbon/Cellulose Nanofibers Synergistically Enhanced LiFePO4 Cathode Materials for Li-Ion Batteries

Lithium iron phosphate (LiFePO4) is recognized as one of the potential cathode materials for lithium-ion batteries owing to its environmental sustainability, affordable cost, and excellent thermal stability. Nevertheless, the sluggish diffusion of lithium ions and the relatively limited electronic conductivity emerge as critical factors that impede the advancement of LiFePO4 cathode materials. In this study, we present a simple, effective, and environmentally friendly method for incorporating cellulose nanofibers (CNF) as an additional carbon source into metal–organic coordinated structure-derived carbonized LiFePO4 cathode material (LFP@C). The hierarchical porous electrode material (LFP@C/CNF), consisting of a three-dimensional carbon nanofiber conductive network integrated with nitrogen-doped carbon-coated LiFePO4 nanoparticles, is successfully prepared via freeze-drying followed by pyrolysis. CNF forms a stable interaction with LFP@C particles through electrostatic self-assembly, thereby constructing a “core (LFP)-shell (C)-network (CNF)” multi-level hierarchical structure. The unique structure significantly shortens the transport distance for lithium ions and electrons, thereby enhancing their mobility. Additionally, the porous nature of this structure provides ample space for electrolyte storage. Owing to these distinctive structural features, LFP@C/CNF composites demonstrate exceptional specific capacity (158.5 mAh g–1 at 0.1 C), impressive rate performance (116.5 mAh g–1 at 5 C), and remarkable cycling stability (87.08% capacity retention after 200 cycles at 1 C). These outstanding characteristics position LFP@C/CNF composites as highly promising candidates for use in next-generation lithium-ion batteries.