Polydopamine-derived N-doped carbon-wrapped Na3V2(PO4)3 cathode with superior rate capability and cycling stability for sodium-ion batteries

Abstract

Na superionic conductor (NASICON)-type Na3V2(PO4)3 (NVP) has been regarded as a promising cathode material for sodium-ion batteries (SIBs). However, NVP suffers from poor cyclability and rate capability because of its intrinsically low electronic conductivity. Herein, we successfully synthesized N-doped carbon-wrapped Na3V2(PO4)3 (NC@NVP) through the carbonization of polydopamine, which is rich in nitrogen species. The strong adhesion properties of the polydopamine lead to effective and homogeneous wrapping of NVP particles, and it is further turned into a conductive N-doped carbon network itself, providing facile diffusion of electrons and Na+ ions during battery operation. NC@NVP displays remarkable electrochemical performance, even under harsh operating conditions, such as a high rate capability (discharge capacity of 70.88, 49.21 mA·h·g−1 at 50 and 100 C), long-term cycling stability (capacity retention of 94.77% over 1,000 cycles at 20 C), and high-temperature cycling (capacity retention of 92.0% after 500 cycles at 60 °C).