Influence of oxygen vacancies enhances structural, optical, and electrochemical properties of P2 type NaxMnO2-δ for high-performance Na-ion cathode materials

Abstract

Due to the accessibility of raw materials and good cost-effectiveness, Sodium-ion batteries (SIB) are a possible replacement for lithium-ion batteries. The subject of this paper is the layered P2-type NaxMnO2-δ nanostructure which was synthesized by a solid-state process and annealed in an Ar–H2 atmosphere at various calcination temperatures. X-ray diffraction, Raman spectroscopy, Scanning electron microscopy, Ultraviolet–visible spectroscopy, and X-ray photoelectron spectroscopy were used to describe the cathode material's crystalline structure, vibrational analysis, surface morphology, elemental composition, optical properties, and electrochemistry performance. The calcination temperature significantly affects the structural, optical, and electrochemical characteristics of layered P2-type NaxMnO2-δ material. After 20 cycles, the reduction annealing of 400 °C has the highest specific discharge capacity of 130 mAhg−1 at C/10 where capacity retention is 98.84 % and average coulombic efficiency of 98.37 % in between 2.0 and 4.2 V range (Na+/Na).