Development and fabrication of an advanced NVPF@C/rGO composite cathode for improved sodium-ion battery performance

Abstract

Sodium-ion batteries are gaining attention as a viable alternative to lithium-ion batteries, primarily due to the widespread availability and affordability of sodium. However, the challenge of developing efficient cathode materials remains significant. In this study, we present an economical synthesis method to stabilize Na₃V₂(PO₄)₂F₃@C (NVPF@C) nanoparticles, which are encapsulated within a conductive reduced graphene oxide network (NVPF@C/rGO), serving as an advanced cathode material for sodium-ion batteries. The resulting structure features 50 nm nanoparticles encased in a carbon layer and intertwined with reduced graphene sheets, leading to improved electronic conductivity and better accommodation of volume changes during cycling. When used as a cathode in sodium-ion half-cells, the NVPF@C/rGO nanocomposite demonstrated an impressive reversible capacity of 130 mAh.g⁻¹ at a 0.5 C rate, along with exceptional cycling stability, maintaining 99% of its capacity after 500 cycles, and retaining a capacity of 115 mAh.g⁻¹ even at a high rate of 10 C. Detailed characterizations indicated that the graphene encapsulation not only supports efficient electron transport but also ensures reversible sodium storage by maintaining structural integrity. Moreover, the outstanding energy storage performance of the Na₃V₂(PO₄)₂F₃@C/rGO cathode material in full sodium-ion cell tests underscores its potential for practical applications.