Enhanced performances of mesoporous Na3V2(PO4)3/C microparticles: insights from morphological and textural characteristics

Abstract

Carbon-coated sodium vanadium phosphate nanocomposites with various morphology and textural properties have been demonstrated to be promising cathode materials for sodium-ion batteries (SIBs). However, downsizing and larger specific surface area significantly hinder their practical applications. Herein, mesoporous sodium vanadium phosphate microparticles with continuous carbon-coated layers (meso-NVP/C-FD MPs) are successfully synthesized via microwave-assisted sol-gel reaction, freeze-drying procedure, and calcination under an argon atmosphere. Given the distinctive textural characteristics, the resulting meso-NVP/C-FD MPs not only deliver remarkable rate capability (specific capacity at 7.0 C: 81 % of the value at 0.35 C) but also achieve an impressive lifespan (capacity retention: 94 % after 5,000 cycles at 7.0 C). Moreover, the sodium-ion full batteries assembled by commercial hard carbon anode and meso-NVP/C-FD cathode also possess excellent reversible capacity (92 mAh/g at 0.1 C and 80 mAh/g at 2.0 C) and comparable cyclability (88 % of retention after 300 cycles at 2.0 C). This study affords guidance for constructing the secondary pores within the NVP MPs, which is of great importance in boosting the mobilities of sodium ions and electrochemical performances.