3D ordered macroporous amorphous Nb2O5 as anode material for high-performance sodium-ion batteries

Abstract

The development of society has an increasing demand for clean energy. Sodium ion batteries (SIB) have emerged because of their abundant sodium reserves and low cost. However, there is still a gap in performance between sodium-ion batteries and lithium-ion batteries. Orthogonal Nb2O5 (T-Nb2O5) is a promising sodium carrier due to its good intercalation/deintercalation characteristics and surface capacitance reaction. However, T-Nb2O5 as electrode material suffers from the low conductivity, and the crystalline phase will change to amorphous during the charge and discharge process, resulting in poor electrochemical performance of SIB. Therefore, this work has carefully designed a 3D ordered macroporous amorphous Nb2O5 (3DOM A-Nb2O5) with rich mesoporosity as anode material for superior sodium storage. Unsaturation defects in A-Nb2O5 alter the electronic structure, thereby improving electrical conductivity. Meanwhile, the hierarchical porous structure facilitates the insertion and extraction of sodium ions, with the structural integrity can be well maintained upon long cycles at high current density. As a result, the 3DOM A-Nb2O5 electrode exhibits excellent cycle performance with high capacity retention of 131 mAh g−1 after 500 cycles at 5 A g−1.