Polydopamine-derived nitrogen-doped carbon-coated Na3V2(PO4)3 as high performance cathode materials for sodium-ion batteries

Abstract

Sodium-ion batteries (SIBs) have recently attracted remarkable attention for electrochemical energy storage and conversion systems due to the natural abundance, environmental friendliness and low cost of sodium compared to lithium. Among all proposed cathode materials for SIBs, Na superionic conductor (NASICON)-type Na3V2(PO4)3 (NVP) has been considered as promising cathode materials for SIBs. However, intrinsically low electronic conductivity of NVP causes unsatisfactory cycling stability and rate capability. Herein, N-doped carbon-coated Na3V2(PO4)3 (NC@NVP) was successfully prepared via a carbonization of polydopamine which is rich in nitrogen species. The strong adhesion properties of polydodamine lead to an effective and homogeneous coating of NVP surface, and also change to the conductive N-doped carbon network itself, making it facile to diffuse electrons and sodium ions during battery operation. The NC@NVP demonstrates remarkable electrochemical performance, even under harsh operating conditions, such as a superior cycling stability (capacity retention of 94.77% over 1,000 cycles at 20 C), high rate capability (discharge capacity of 70.88, 49.21 mA·h·g？1 at 50 and 100 C) and high-temperature cycling (capacity retention of 92.0% after 500 cycles at 60 °C). We believe that the prepared NC@NVP has a potential for accelerating the development of high-performance cathode materials and the commercialization of sodium-ion batteries.