3D porous Fluorine-Doped NaTi2(PO4)3@C as High-Performance Sodium-Ion battery anode with broad temperature adaptability

Abstract Sodium-ion batteries (SIBs) are an appealing alternative to lithium-ion batteries in large-scale energy storage systems owing to their low cost and the abundance of sodium resources. As promising anode materials for SIBs, NASICON type NaTi2(PO4)3 material with robust structure possesses high ionic mobility, whereas its intrinsic low electronic conductivity degrades the performance of SIBs severely. Herein, we propose a strategy of fluorine-doped NaTi2(PO4)3@C (F-NTP@C) with three-dimensional (3D) porous structure to boost Na+ storage capability. When applied to SIBs half cells, it delivers a reversible capacity of 108.7 mA h g−1 at 50C and a capacity retention of 75.5% after 2000 cycles at 10C, as well as showing broad temperature adaptability from 0 to 50 °C. In-situ XRD is also conducted to gain an insight into Na+ storage mechanism. By coupling the experiment data with theoretical calculation, it is concluded that the enhanced electronic conductivity and fast Na+ kinetics are attributed to the incorporation of F- ions and the design of 3D porous structure. Additionally, sodium ion full cells composed of F-NTP@C anode and Na3V2(PO4)2F3@C cathode exhibit durable and practical sodium storage performance in wide temperature range (0 ∼ 50 °C), which provides a feasibility for the large-scale production of high performance SIBs.