LAUSR

Abstract NASICON-type NaTi2(PO4)3 with open framework shows great prospect in anode for aqueous lithium ion battery (ALIB). Nevertheless, low electrical conductivity and limited structure stability of NaTi2(PO4)3 in aqueous electrolyte result in poor rate and cycling performance. In this work, two strategies of carbon coating and related nitrogen doping were utilized to enhance performance of NaTi2(PO4)3 by sol-gel way, and employed as anode in ALIB. Carbon-coated NaTi2(PO4)3 with various carbon content were controlled by dosage of phenolic resin, and the best sample with carbon content of 4.9% was found. Based on this, loose nanostructured NaTi2(PO4)3 coated by nitrogen-doped carbon (NTP-2-N) was synthesized using urea as pore former and nitrogen source. NTP-2-N demonstrates excellent rate and cycling performance. It delivers the discharge capacity of 115.6, 103.4, and 74.6 mAh g−1 at 0.2, 5, and 20 C, respectively. And 80.7% of discharge capacity is retained after 1000 cycles at 5 C. The outstanding electrochemical performance of NTP-2-N mainly comes from the loose structure, carbon coating, and nitrogen doping, which protect NaTi2(PO4)3 crystal from H2O attack and accelerate the electron/Li ion transfer.