Boron doping in a carbon layer: a facile strategy to boost the electrochemical performance of Na₂FeTi(PO₄)₃@C

The scarcity of lithium resources has fueled research into sodium-ion batteries (SIBs), yet the performance of cathode materials remains a critical factor that severely limits their overall electrochemical performance. In this work, boron-doped carbon-coated NASICON-type Na₂FeTi(PO₄)₃ (NFTP@BC) has been successfully synthesized via a sol-gel method. The sample with optimized boron doping content (NFTP@BC-2) exhibits exceptional electrochemical performance: it achieves specific capacities of 122.88 and 102.49 mAh g^-1 at current densities of 20 and 1000 mA g^-1, respectively. Moreover, it demonstrates remarkable cycling stability: after 500 charge-discharge cycles at 500 mA g^-1, the capacity retention rate reaches 95.52%; even after prolonged cycling (1000 cycles) at a higher current density of 1000 mA g^-1, the capacity retention rate remains as high as 92.59%. Notably, this sample also exhibits superior performance in low-temperature and full-cell tests. The enhanced electrochemical performance is attributed to the boron-doped carbon layer, which improves electronic conductivity by introducing hole carriers and facilitating electron transfer; meanwhile, it boosts ionic conductivity by creating lattice defects for Na⁺ transport channels, regulating surface charge distribution to enhance Na⁺ adsorption. This study provides new insights for developing high-performance polyanionic cathodes for SIBs.