Exploring the Characteristics of Na1.35CrO4 as Active Electrode for Energy Storage Application in Sodium-Ion Batteries

Abstract

For the first time, Na1.35CrO4 is successfully synthesized using a citric acid-assisted sol–gel method, and its physicochemical and electrochemical properties are explored as an active electrode material for sodium-ion batteries (SIBs). Extensive physicochemical analyzes confirm the phase purity, high crystallinity, and orthorhombic crystal symmetry of Na1.35CrO4, having well-controlled elemental stoichiometry and a smooth surface with nanoparticle morphology. The nanoparticles have an average particle size of 42.87 nm, providing a high active contact surface. Na1.35CrO4 coexists with Cr6+ and Cr7+ oxidation states, with Cr6+ as the dominant one. The electrochemical studies for Na1.35CrO4 as an active electrode are carried out through sodium half-cells. The cyclic voltammetry reveals an open circuit voltage of about 1.842 V and consistent redox peaks within a working voltage window of 0.01 to 3.0 V, representing the structural and phase stability of Na1.35CrO4. The power-law analysis shows battery-type features and diffusion-controlled charge transfer for energy storage. The electrochemical impedance spectroscopy analysis indicates good electrolyte compatibility and excellent charge transfer kinetics of Na1.35CrO4. The material also exhibits a low double layer capacitance, representing its suitability for high-energy-density applications. These investigations reveal that Na1.35CrO4 could be a promising electrode for SIBs. © 2025 Wiley-VCH GmbH.