Zr doping and carbon coating endow NaTi2(PO4)3 electrode with enhanced performances

Highlights: • Zr doping and carbon coating were employed to promote NaTi₂(PO₄)₃ performance for aqueous lithium ion battery. • Zr doping accelerates Li ion intercalation/deintercalation by widening pathway. • Carbon coating effectively promote the electronic conductivity of electrode. • NaTi_1.9Zr_0.1(PO₄)₃/C electrode shows superior electrochemical property. -- Abstract: NaTi₂(PO₄)₃ displays promising foreground in aqueous lithium ion battery as anode owing to good stability and open frame. However, the property for anode demands to be further ameliorated to satisfy higher requirement. Herein, Zr doping and carbon coating strategies were employed to promote performance of NaTi₂(PO₄)₃ electrode conjointly in aqueous lithium ion battery. NaTi_2-xZr_x(PO₄)₃/C (x = 0.00, 0.05, 0.10, and 0.15) samples were prepared by sol-gel way. Zr doping and carbon coating together improve electrochemical performance of the materials. Zr doping at Ti position demonstrates no significant impact on morphology of composites. And it can significantly enhance electrochemical performance of NaTi₂(PO₄)₃/C. NaTi_1.9Zr_0.1(PO₄)₃/C (NC–Zr-10) presents the most attractive electrochemical property. NC-Zr-10 presents discharge capacity of 112.5, 102.7, and 94.1 mAh g⁻¹ at 0.2, 3.0, and 15 C, respectively, 41.0, 56.8, and 62.4 mAh g⁻¹ higher than those of the pristine sample. The improvement in electrochemical performance is probably due to that Zr doping accelerates Li ion intercalation/deintercalation by widening pathway, and carbon coating effectively promote the charge transfer of electrode. The study shows that Zr doping on Ti position and carbon coating are valid strategies to promote the electrochemical performance of NaTi₂(PO₄)₃.