N-doped carbon confined Na3V2(PO4)3 derived from an organophosphonic acid as a high-performance cathode for sodium-ion batteries

Na super ionic conductor (NASICON)-type Na3V2(PO4)3 has been regarded as one of the most attractive cathode materials for sodium-ion batteries (SIBs). However, its intrinsically low electronic conductivity leads to poor cyclability and rate capability. Carbon coating is an effective way to solve this problem, especially N-doped carbon. In this work, an organophosphonic acid, amino tris(methylene phosphonic acid) (ATMP), is employed as a multifunctional raw material for constructing N-doped carbon coated Na3V2(PO4)3. Na3V2(PO4)3 particles are well embedded in an interconnected N-doped carbon, which facilitates fast sodium ion and electron transfer. When used as a cathode material for SIBs, the obtained Na3V2(PO4)3/N-doped carbon composite shows promising sodium storage properties. It delivers high reversible charge/discharge capacities of 101.4/101.6 mA h g−1 at 1 C after 100 cycles. Moreover, it exhibits excellent rate capability (charge/discharge capacities of 100.5/100.4 at 5 C), and good long-term cycling stability (capacity retention of 90.1% after 600 cycles at 5 C). This work may provide an effective way for the synthesis of carbon coated Na3V2(PO4)3 with good sodium storage performance.