Hierarchical Na3V2(PO4)2F3 Microsphere Cathodes for High-Temperature Li-Ion Battery Application

Sodium superionic conductor (NASICON)-struc-tured Na3V2(PO4)2F3 cathode materials have received vast attention in the high-temperature storage performance due to their structural and thermal stability. Herein, hierarchical Na3V2(PO4)2F3 microspheres (NVPF-HMSs) consisting of nano -cubes were designed by a one-pot facial solvothermal method. The hierarchical Na3V2(PO4)2F3 microsphere size is 2???3 ??m, which is corroborated by FE-SEM and HR-TEM analyses. The NVPF-HMSs have been demonstrated as a cathode in Li-ion batteries at both low and elevated temperatures (25 and 55 ??C, respectively). The NVPF-HMS cathode in a Li-ion cell exhibits reversible capacities of 119 mA h g???1 at 0.1 C and 85 mA h g???1 at 1 C with an 82% retention after 250 cycles at 25 ??C. At elevated temperatures, the NVPF-HMS cathode exhibits a superior capacity of 110 mA h g???1 at 1 C along with a retention of 90% after 150 cycles at 55 ??C. Excellent capacity and cyclability were achieved at 55 ??C due to its hierarchical morphology with a robust crystal structure, low charge-transfer resistance, and improved ionic diffusivity. The Li-ion storage performance of the NVPF-HMS cathode material at elevated temperatures was analyzed for the first time to understand the high-temperature storage property of the material, and it was found to be a promising candidate for elevated-temperature energy storage applications. Superscript/Subscript Available

Automated summary

Hierarchical Na3V2(PO4)2F3 microspheres were synthesized and investigated as cathode materials for Li-ion batteries at both low and elevated temperatures. The microspheres exhibited excellent capacity and cyclability at 55℃, making them a promising candidate for elevated-temperature energy storage applications.