Ascorbic Acid-Assisted Synthesis of Mesoporous Sodium Vanadium Phosphate Nanoparticles with Highly sp2-Coordinated Carbon Coatings as Efficient Cathode Materials for Rechargeable Sodium-Ion Batteries

Herein, mesoporous sodium vanadium phosphate nanoparticles with highly sp(2)-coordinated carbon coatings (meso-Na3V2(PO4)(3)/C) were successfully synthesized as efficient cathode material for rechargeable sodium-ion batteries by using ascorbic acid as both the reductant and carbon source, followed by calcination at 750 degrees C in an argon atmosphere. Their crystalline structure, morphology, surface area, chemical composition, carbon nature and amount were systematically explored. Following electrochemical measurements, the resultant meso-Na3V2(PO4)(3)/C not only delivered good reversible capacity (98mAhg(-1) at 0.1Ag(-1)) and superior rate capability (63mAhg(-1) at 1Ag(-1)) but also exhibited comparable cycling performance (capacity retention: approximate to 74% at 450 cycles at 0.4Ag(-1)). Moreover, the symmetrical sodium-ion full cell with excellent reversibility and cycling stability was also achieved (capacity retention: 92.2% at 0.1Ag(-1) with 99.5% coulombic efficiency after 100 cycles). These attributes are ascribed to the distinctive mesostructure for facile sodium-ion insertion/extraction and their continuous sp(2)-coordinated carbon coatings, which facilitate electronic conduction.