An interpenetrating 3D porous reticular Nb2O5@carbon thin film for superior sodium storage

Abstract

Orthorhombic phase of niobium pentoxide (T-Nb2O5) has been considered as a potential anode material for sodium ion batteries (NIBs), because it can intercalate a large amount of sodium ion reversibly and durably without structural disruption. However, the inherent deficiency of low electrical conductivity results in a low reversible capacity and poor cycling stability. Here, we achieved the superior sodium storage performance of Nb2O5 by rational design self-supported 3D porous reticular Nb2O5@Carbon (Nb2O5@3D PRS) thin film with interpenetrating network. The film was prepared by a facial electrostatic spray deposition (ESD) technique. The Nb2O5@3D PRS displays outstanding electrochemical performance, especially long cycle life: it can still deliver a specific capacity of 130 mAh g-1 after 7500 times chare/discharge at high rate of 10 C. Furthermore, Na3V2(PO4)3//Nb2O5 full cells were assembled, the full cell displays a remarkable capacity retention of 105 mAh g-1 after 500 cycles at 10 C. The excellent sodium storage performance of the Nb2O5@3D PRS is ascribed to the synergistic effect of the unique porous structure, the nanosized Nb2O5 particles encapsulated in the carbonaceous matrix, which facilitates the electrochemical kinetics between the Nb2O5 and electrolyte. In addition, the key problems of Na ion insertion in Nb2O5, such as the low degree of reversibility are mitigated. Notably, this method is a general process and can be extended to prepare other electrode materials with 3D porous interpenetrating structure for energy storage application.