Chlorine doping enables NaTi2(PO4)3/C excellent lithium ion storage performance in aqueous lithium ion batteries

NaTi2(PO4)3-xCl3x/C (x = 0.00, 0.05, 0.10, and 0.20) samples were prepared by sol-gel modus, and were used as anode for aqueous lithium ion battery. Cl doping on PO43− site demonstrates no significant effect on morphology and crystallographic phase for NaTi2(PO4)3. And it can obviously improve electrochemical properties of NaTi2(PO4)3 electrode. Among all composites, NaTi2(PO4)2.9Cl0.3/C (NC-Cl-30) shows the best electrochemical performance. NC-Cl-30 presents discharge capacity of 131, 100, and 79 mAh g−1 at 0.2, 3.0, and 15C, separately, 55, 36, and 34 mAh g−1 higher than those of original sample. In addition, discharge capacity of 76.1 mAh g−1 for NC-Cl-30 is reserved, which is increased by 17.6 mAh g−1 than that of original sample after 1000 cycles (6C). This work shows that Cl doping on PO43− site is an effective way to promote the electrochemical performance of NaTi2(PO4)3.