In-situ interface engineering of NVOPF nanosheets with cross-linked conductive networks for superior sodium storage

Na 3 V 2 O 2 (PO 4 ) 2 F (NVPOF) as a prospective candidate for sodium-ion battery cathodes, faces practical challenges for its inherently low electronic conductivity, which impedes fast reaction kinetics and diminishes its sodium storage efficiency. To address these limitations, we introduce an in-situ interface engineering strategy for NVOPF by integrating 1D hydroxylated carbon nanotubes (CNTs) onto the surface of NVOPF nanosheets. The CNTs are arranged in-situ in multiple directions and significantly enhance adhesion to the NVOPF nanosheets via [PO 4 ] 3‒ ‒CNTs linkages, establishing a robust and conductive interface. This strategy effectively mitigates the aggregation of NVOPF nanosheets, ensuring optimized electronic contact and a persistent, efficient charge-transfer network within the composite. The resultant NVOPF-15%CNTs composite exhibits enhanced rate performance (88.01 mAh g ‒1 at 50 C) and excellent cyclability (retaining 82.4% capacity after 10000 cycles at 50 C). Comprehensive experimental and theoretical analyses confirm that the designed conductive interface accelerates charge-transfer kinetics and preserves structural integrity. This study provides valuable insights into optimizing NVOPF cathode and suggests a versatile approach applicable to improving other cathode materials.