The investigation of NaTi2(PO4)3@C/Ag as a high-performance anode material for aqueous rechargeable sodium-ion batteries

Silver and carbon coated NaTi2(PO4)(3) is synthesized via a facile sol-gel method, with polyvinyl alcohol as carbon source and silver nitrate as Ag source. NaTi2(PO4)(3)@C/Ag is characterized by XRD, SEM, TEM, EDS and XPS. It can be found that C/Ag composite layer is uniformly coated on the surface of NaTi2(PO4)(3). Compared with the pure NaTi2(PO4)(3), NaTi2(PO4)(3)@C/Ag material demonstrates significantly higher rate capability and cycling stability. It can deliver an initial discharge capacity of 126.5mA h g(-1) at a current rate of 2C with the capacity retention of 94.5% after 100 cycles. It can still deliver an initial discharge capacity of 97.5 mAhg(-1) at a current rate of 5C with a substantial capacity retention of 83.8% after 400 cycles. It is worth mentioning that NaTi2(PO4)(3)@C/Ag also exhibits pretty good rate capacity. When the current density ranges from 1 C, 2 C, 5 C, 10C and finally back to 1 C, NaTi2(PO4)(3)@C/Ag electrode still retains a discharge capacity of 84.6mAh g(-1) after 200 cycles at 5 C corresponding to a capacity retention ratio of 83.5%.