A superior Na3V2(PO4)3-based cathode enhanced by Nb-doping for high-performance sodium-ion battery

Abstract

Na3V2(PO4)3 has been considered as the most promising cathode material for sodium-ion batteries because of its suitable sodium insertion/extraction plateau and good cycling stability. However, the inferior rate-capability resulting from the lower electronic conductivity restricts its commercial application. To address this issue, niobium ions (Nb5+) are introduced to partially substitute V3+ for generating V-mixed valence, ensuring the material with improved intrinsic electronic conductivity. Herein, nano-sized Na3V2−xNbx(PO4)3/C (x = 0, 0.05, 0.1, 0.2) materials with a core–shell structure are prepared via a simple sol–gel method. The optimized Na3V1.9Nb0.1(PO4)3/C material shows a high specific capacity (∼114 mA h g−1 at 0.5C), a superior rate-capability (∼100 mA h g−1 at 20C), and an excellent long-term cycling stability (a specific capacity of 74.7 mA h g−1 over 1000 cycles at 50C, corresponding to a capacity decay rate of 0.0258%/cycle). The improved cycling performance is mainly attributed to the enhanced intrinsic electronic conductivity and Na+ mobility, and the reduced charge-transfer resistance, as confirmed by the first-principles calculations, cyclic voltammetry, and electrochemical impedance spectra analysis. The constructed fast electron network, from the surface to the bulk, combining with the nano-sized feature, contributes to the facilitated electrode reaction kinetics and, thus, ensures improved rate-capability.

Constructing p-type substitution induced by Ca2+ in defective Na3V2−xCax(PO4)3/C wrapped with conductive CNTs for high-performance sodium-ion batteries

“…Furthermore, a comparison of the electrochemical properties of Ca0.04-NVP@CNTs with those of other reported materials is shown in Table 3. Previous works on K/Ca co-doping, 40 Mg/Mn co-doping 41 and Nb, 42 Bi, 43 Al 44 and Ti 45 doping involve similar doping principles as this work. Among all these samples, the Ca0.04-NVP@CNTs sample shows the best electrochemical properties in terms of both rate capability and cycling performance.…”

Research Progress and Modification Measures of Anode and Cathode Materials for Sodium‐Ion Batteries

“…adopted the co‐precipitation method to add transition metal salt into the mixed solution of sodium hydroxide and ammonia water, and the resulting precipitation was calcined at 950 °C to obtain a layer metal oxide with P2‐type junction Na 2/3 Co 2/3 Mn 1/3 O 2 . In this structure, Co 3+ and Mn 4+ ions in low spin states are stable [107] …”

“…Some of the electrode materials have entered the stage of industrial application. [65][66][67][68] However, like lithium-ion batteries, the electrode materials of SIBs also have the problem of sodium loss in the electrochemical cycle, which leads to the deterioration of their cyclic performance. The causes of irreversible capacity loss in sodium-ion batteries are as follows: electrolyte decomposition forms a solid electrolyte interface film (SEI film).…”

“…), alloy materials, oxygen compounds, organic materials, etc. Some of the electrode materials have entered the stage of industrial application [65–68] . However, like lithium‐ion batteries, the electrode materials of SIBs also have the problem of sodium loss in the electrochemical cycle, which leads to the deterioration of their cyclic performance.…”

Unleashing the Potential of Sodium‐Ion Batteries: Current State and Future Directions for Sustainable Energy Storage

“…Due to this arrangement, electron transfer usually follows V-O-P-O-V, rather than the faster V-O-V pattern. [122] Though various research groups [359] have come up with the idea of doping, [360] reducing the particle size, [361] designing an optimum morphology, [362] and so on to improve the electronic conductivity, [363] this could be a potential research direction to follow. [353] Copyright 2020, American Chemical Society.…”