Nitrate Combustion Synthesis of NVP-Type Cathode Material for Na-Ion Batteries

Abstract

The synthesis and characterization of a Na3V2(PO4)3 cathode material for room-temperature sodium-ion battery is reported. The NVP material was prepared using a two-step process which proceeded via sol-gel nitrate combustion method for precursor preparation and subsequent pyrolysis under Argon. The materials have been investigated using SEM, EDX, XRD and TOF-SIMS methods. Electrochemical characterization has been carried out using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge method (GCD). The electrode slurry was prepared by mixing the active material, conductive additive (Super P) and polyvinylidene difluoride (PVdF) binder in a 75:15:10 mass ratio. The mixed slurry was cast onto aluminium foil using doctor-blade technique. The cast electrodes were dried under vacuum for 24h. Electrochemical tests were carried out in coin cells, which were assembled in an Argon-filled glovebox (O2 < 0.1 ppm, H2O < 0.1 ppm). Sodium metal was used as the counter electrode and 1M NaPF6 in EC:PC (1:1 vol) as the electrolyte in half-cell measurements. Acknowledgements The present study was supported by European Regional Development Fund (Centres of Excellence TK141 (2014-2020.4.01.15-0011)6, Higher education specialization stipends in smart specialization growth areas 2014-2020.4.02.16-0026), “Institutional development program for research and development and higher education institutions” (ASTRA) (Graduate School of Functional Materials and Technologies, Materials Technology Projects SLOKT12180T and SLOKT12181T, Energy Technology Project SLOKT10209T), Estonian Research Council (Institutional Research Grant IUT20–13 and by NAMUR project 3.2.0304.12-0397. Mr. Väli thanks Estonian Students Fund in USA for financial support.