A High Rate and Long Cycling Performance NaTi2(PO4)3 Core–Shell Porous Nanosphere Anode for Aqueous Sodium‐Ion Batteries

Abstract

NASICON‐type material NaTi2(PO4)3 has a suitable working potential (−0.87 V vs saturated calomel electrode) in aqueous sodium‐ion cells. Nevertheless, the inherent electronic conductivity in the internal core and external shell limits its rate and cycling performance. Herein, a carbon‐coated porous nanosphere NaTi2(PO4)3 material is synthesized by the solvothermal method. This structure effectively improves the electrical conductivity, enlarges the contact area with the electrolyte, and facilitates the rapid intercalation/deintercalation of Na+. It delivers an excellent rate behavior of 123.59, 113.55, 102.81, 90.85, and 60.95 mAh g−1 at 0.2, 0.5, 1, 2, and 5 A g−1, respectively. Improved long cyclability under a 5 A g−1 high current density is also demonstrated by a capacity retention of 70.2% over 500 cycles and an average Coulombic efficiency of 98%. As‐prepared core–shell porous nanosphere NaTi2(PO4)3 exhibits potentially practical applications in a new type of aqueous sodium‐ion battery system.