Heterojunction interfacial promotion of fast and prolonged alkali-ion storage of urchin-like Nb2O5@C nanospheres†
Abstract
The heterojunction interface plays a significant role in enhancing the electrochemical properties of electrode materials. Three-dimensional urchin-like Nb2O5 nanospheres encapsulated in nitrogen-doped carbon sheaths with the merits of long cycle durability and a high specific capacity were proved to have potential as sodium-/potassium-ion batteries anode materials. Density functional theory calculations were performed and demonstrated that the heterojunction interface between the Nb2O5 and carbon layer could serve as an active site for the adsorption of sodium/potassium ions. In sodium-ion storage, Nb2O5@C presented impressive electrochemical performance, delivering stable capacities of 255 mA h g−1 at 1 A g−1 over 150 cycles, and 160 mA h g−1 at 10 A g−1 over 1000 cycles. In terms of potassium-ion storage, it delivered a high capacity of 141 mA h g−1 at 0.5 A g−1 over 500 cycles and an ultra-stable capacity of 116 mA h g−1 at 3.5 A g−1 over 1600 cycles. The kinetic analyses revealed that a larger proportion of pseudocapacitive contribution guarantees Nb2O5@C achieving excellent electrochemical properties. Notably, the Na-ion full-cell of Nb2O5@C//Na3V2(PO4)3 retained a remarkable specific capacity of 154 mA h g−1 at 5 A g−1, accompanied with a retention of 86% over 1300 cycles.
- This article is part of the themed collection: Journal of Materials Chemistry A HOT Papers