An interconnected NaTi2(PO4)3/carbon composite from an all-integrated framework with chelating Ti in a cross-linked citric acid-organic phosphonic acid skeleton for high-performance sodium storage

Abstract

Finding suitable hosts for Na+ ion storage holds the key to achieving large-scale applications of sodium-ion batteries (SIBs). NaTi2(PO4)3 is widely considered to be an advanced anode material for SIBs, because of its 3D open framework, high theoretical capacity, and good thermodynamic stability. However, the instability of electrolyte/electrode interface and intrinsic low electronic conductivity of NaTi2(PO4)3 lead to the poor cycling and rate performance. In this work, an all-integrated framework with chelating Ti in a cross-linked citric acid-organic phosphonic acid skeleton is fabricated as a precursor for the synthesis of NaTi2(PO4)3/carbon composite. The generated interconnected carbon provides extensive support for NaTi2(PO4)3 crystal. These unique structure delivers a high reversible capacity (225.8 mAh g−1 at 0.2 A g−1), good rate performance (219.7 mAh g−1 at 0.4 A g−1, and 189.6 mAh g−1 at 1 A g−1), and superb long-term cycling stability (156.0 mAh g−1 at 2 A g−1 after 4000 cycles). It is believed that this facile and effective strategy can shed light on the development of advanced phosphate electrode materials for SIBs.