From biomolecule to Na3V2(PO4)3/nitrogen-decorated carbon hybrids: highly reversible cathodes for sodium-ion batteries

Abstract

Sodium ion batteries (SIBs) working at room temperature offer promising opportunities for renewable energy storage applications because of the abundant supply and low cost of sodium, low capacity, inferior rate capability and limited cycle life remain a significant challenge in their electrochemical operations. Herein, we report the preparation of hierarchically Na₃V₂(PO₄)₃/nitrogen-decorated carbon hybrids via solvothermal reaction using biomolecule of adenosine 5′-triphosphate disodium salt (ATP), as a novel precursor and environmentally friendly multifunctional source, simultaneously including sodium, phosphorus, carbon, nitrogen. The results demonstrate that Na₃V₂(PO₄)₃ nanocrystals are encapsulated in interconnected carbon nanosheets with moderate nitrogen doping (2.88%) to form a bundle-like structure, where the carbon nanosheets not only serve as a highly conducting pathway facilitating electron and ion transport, but as a shielding matrix to accommodate volume changes upon electrochemical cycling; thus, improving stability and reversibility of the Na₃V₂(PO₄)₃ cathode. Thus, the obtained materials deliver a high reversible capacity of 110.9 mA h g⁻¹ at a low current rate of 0.2 C, as well as outstanding rate performance, suggesting that the Na₃V₂(PO₄)₃/nitrogen-doped carbon hybrids are promising cathode materials to be used in high-performance sodium ion batteries.