An advanced blackberry-shaped Na3V2(PO4)3 cathode: Assists in high-rate performance and long-life stability

Highlights: • The blackberry-shaped Na₃V₂(PO₄)₃ is dedicated to promoting more efficient e⁻ and Na⁺ transport. • It is unique in that it addresses the problems of low electronic conductivity and large volume deformation. • It exhibits high reversible rate capacity (116 mA h g⁻¹ at 0.2 C and 83 mA h g⁻¹ at 20 C). • It exhibits ultra-long-life stability (94.4% capacity retention after 4500 cycles at 10 C). Na₃V₂(PO₄)₃ is suitable for the rapid migration of Na⁺ in the electrochemical reaction process due to its open-ended structure of 3D sodium super ionic conductor type, but the low electronic conductivity and large volume deformation during the repeated Na⁺ extraction/insertion severely limit its rate and cycle performance. Herein, a blackberry-shaped Na₃V₂(PO₄)₃ is synthesized for the first time to address both of the problems, and the structure is composed of aggregated carbon-coated nanoparticles attaching to highly conductive 3D porous carbon scaffolds, hence provides efficient pathways for both electrons and ions. For sodium-ion batteries, the blackberry-shaped Na₃V₂(PO₄)₃ exhibits high reversible capacity (116 mA h g⁻¹ at 0.2 C), high-rate performance (83 mA h g⁻¹ at 20 C) and long-life stability (94.4% capacity retention after 4500 cycles at 10 C). The excellent electrochemical performance indicates that blackberry-shaped Na₃V₂(PO₄)₃ has better application prospects as an advanced cathode material for sodium-ion batteries.