Robust artificial interface combining AlF3 coating with carbon layer stimulates stable long lifespan for Na2TiV(PO4)3 in sodium storage

Dual-layer artificial interface of carbon/AlF 3 enhances conductivity and Na + transport, suppressing structural degradation. • NTVP@C/AF-1%: 184.58mAh g −1 at 0.1C, 93.66% capacity retention after 2500 cycles at 20C. • NTVP@C/AF-1% full cell: 81.88% capacity retention of after 300 cycles at 1C. The vanadium-based NASICON-type cathodes face challenges of excessive cost and capacity decay induced by structural degradation during cycling. Surface modification has been confirmed as a favorable strategy to purchase a reasonable balance between sodium storage performance and long lifespan for cathodes. A carbon/AlF 3 dual-layer artificial interface was ingeniously engineered to encapsulate the Na 2 TiV(PO 4 ) 3 cathode (NTVP). Through modulating AlF 3 coating content, the NTVP@C/AF-x% series (x = 0.5, 1, 2, 3, 5) were harvested to accelerate Na-ion diffusion and alleviate structural collapse, thereby strengthening the rate capability under high-rate conditions. Furthermore, the dual-layer artificial interface effectively reduces the polarization voltage and boosts the Na-ion diffusion coefficient. The strategy-modified NTVP@C/AF-1% cathode delivers a high specific capacity of 184.58 mAh g −1 at 0.1C, and maintains a capacity retention of 93.66% after 2500 cycles at 20C. Furthermore, the NTVP@C/AF-1% also serves as an anode, demonstrating favorable cycling durability with 91.67% capacity retention after 400 cycles at 1C. The NTVP@C/AF-1% cathode demonstrated excellent compatibility with the hard carbon anode. The assembled NTVP@C/AF-1% full cell exhibits enhanced electrochemical performance with a capacity retention of 81.88% after 300 cycles. This work demonstrates the modified interfacial structures can unlock more possibilities for the further development of NASICON-type cathodes. Download: Download high-res image (101KB) Download: Download full-size image