Effect of Sn doping on the electrochemical performance of NaTi2(PO4)3/C composite

In this paper, NaTi2-xSnx(PO4)3/C (x = 0.0, 0.2, 0.3, and 0.4) composites were fabricated via facile sol-gel method, and employed as anodes for aqueous lithium ion batteries. Effect of Sn doping with various content on electrochemical properties of NaTi2(PO4)3/C was investigated systematically. Sn doping on Ti site has no obvious effect on the lattice structure and morphology of NaTi2(PO4)3/C. Among all samples, NaTi1.7Sn0.3(PO4)3/C (NC-Sn-3) demonstrates the best electrochemical properties. NC-Sn-3 exhibits the outstanding rate performance, delivering a discharge capacity of 103.3, 95.2, and 87.4 mAh g−1 at 0.5, 7, and 20 °C, respectively, 1.7, 30.5, and 56.2 mAh g−1 larger than those of pristine NaTi2(PO4)3/C. In addition, NC-Sn-3 shows excellent cycling performance with the capacity retention of 80.6% after 1000 cycles at 5 °C. This work reveals that Sn doped NaTi2(PO4)3/C with outstanding electrochemical properties are potential anode for aqueous lithium ion batteries.