Preparation of new Nb(PO₄)O derived from supramolecular polymer and its application in sodium ion batteries

Due to the limited distribution of lithium resources, the high cost disadvantage of lithium-ion battery gradually affects its large-scale application. In contrast, sodium resources are abundant in the world, as a substitute for lithium gradually gained widespread attention. However, due to the large radius of sodium ions, the material will undergo a large volume change during electrode insertion/removal, resulting in structural collapse. Therefore, in order to realize the high performance application of sodium electricity, it is necessary to develop cathode materials with long cycle life and good magnification performance. A novel polyanionic compound, niobium phosphate oxide Nb(PO₄)O, was synthesized by one-step calcination with phytate-melamine supramolecular polymer assisted strategy. First of all, the material has a stable large frame structure to ensure the rapid transmission of sodium ions. Secondly, the loose sheet structure of the surface is conducive to the mass transfer between the electrolyte and the electrode, effectively shortening the diffusion path. When used as a sodium anode, the group of sodium ion batteries, in 1 000 mA·g^-1 current density, 3000 cycles after reversible discharge capacity can reach 133.7 mA·h·g^-1, in 4 000 mA·g^-1 high current density, reversible specific capacity is still 117.9 mA·h·g^-1. Compared with Nb₂O₅, it has obvious magnification performance and long cycle stability.