Zero‐Strain Na₃V₂(PO₄)₂F₃@Rgo/CNT Composite as a Wide‐Temperature‐Tolerance Cathode for Na‐Ion Batteries with Ultrahigh‐Rate Performance

Abstract

Sodium‐ion batteries (SIBs) are widely considered a hopeful alternative to lithium‐ion battery technology. However, they still face challenges, such as low rate capability, unsatisfactory cycling stability, and inferior variable‐temperature performance. In this study, a hierarchical Na3V2(PO4)2F3 (NVPF) @reduced graphene oxide (rGO)/carbon nanotube (CNT) composite (NVPF@rGO/CNT) is successfully constructed. This composite features 0D Na3V2(PO4)2F3 nanoparticles are coated by a cross‐linked 3D conductive network composed of 2D rGO and 1D CNT. Furthermore, the intrinsic Na+ storage mechanism of NVPF@rGO/CNT through comprehensive characterizations is unveiled. The synthesized NVPF@rGO/CNT exhibits fast ionic/electronic transport and excellent structural stability within wide working temperatures (−40–50 °C), owing to the zero‐strain NVPF and the coated rGO/CNT conductive network that reduces diffusion distance for ions and electrons. Moreover, the stable integration between NVPF and rGO/CNT enables outstanding structural stability to alleviate strain and stress induced during the cycle. Additionally, a practice full cell is assembled employing a hard carbon anode paired with an NVPF@rGO/CNT cathode, which provides a decent capacity of 105.2 mAh g−1 at 0.2 C, thereby attaining an ideal energy density of 242.7 Wh kg−1. This work provides valuable insights into developing high‐energy and power‐density cathode materials for SIBs.

Multielement-Doped FexSey/Carbon Nanotube Composites for High Performance Sodium-Ion Storage

“…Given the excellent performance of the Fe 3 Se 4 /CNT anode in the half-cell tests, we fabricated a full cell with Na 3 V 2 (PO 4 ) 2 F 3 /C as the cathode and Fe 3 Se 4 /CNT as the anode to explore its potential for practical applications. The preparation of Na 3 V 2 (PO 4 ) 2 F 3 /C was recently published by our group, and its morphological and structural characterization is shown in Figure S10 Figure A schematically demonstrates the structure of the Fe 3 Se 4 /CNT//Na 3 V 2 (PO 4 ) 2 F 3 /C full cell.…”

“…The preparation of Na 3 V 2 (PO 4 ) 2 F 3 /C was recently published by our group, and its morphological and structural characterization is shown in Figure S10. 8 Figure 6A schematically demonstrates the structure of the Fe 3 Se 4 /CNT// Na 3 V 2 (PO 4 ) 2 F 3 /C full cell. The first five GCD curves with the voltage window of 0.5−4.0 V at 0.1 A g −1 are shown in Figure 6B, and the first loop showed low Coulombic efficiency due to the formation of SEI film in the anodic electrode.…”

“…6 However, due to the large size effect, the insertion/extraction of Na + has a slow reaction kinetics inside the solid anode electrodes and often causes large volume changes in the SIB anode materials. 7,8 Thus, researchers have been pursuing suitable anode electrode materials with robust structures and fast Na + storage properties during the past decades. 9 Transition metal selenides have been deemed as potential anode materials for SIB because of their outstanding electronic/ionic conductivity and excellent reversibility.…”

“…Compared to Li + , the weaker Lewis acidity equips Na + with a smaller Stokes radius (4.6 Å for Na + and 4.8 Å for Li + in propylene carbonate) and lower desolvation energy and therefore benefits its kinetics behavior in liquid electrolytes . However, due to the large size effect, the insertion/extraction of Na + has a slow reaction kinetics inside the solid anode electrodes and often causes large volume changes in the SIB anode materials. , Thus, researchers have been pursuing suitable anode electrode materials with robust structures and fast Na + storage properties during the past decades …”

Emerging Chemistry for Wide-Temperature Sodium-Ion Batteries

“…In the same year, the layer-by-layer Na 3 V 2 (PO 4 ) 3 @rGO further improved the working temperature up to 60 °C, and this could also be realized by titanium (Ti) substitution . Besides, Na 3 V 2 (PO 4 ) 2 O 2–2 x F 1+2 x (0 ≤ x ≤ 1), another promising polyanionic cathode for WT-SIBs, exhibited impressive LT tolerance down to −40 °C. , For the Prussian-blue analogue cathode, although it has received disproportionately less attention than the other two cathode materials, its operating temperature shown by existing research is relatively considerable. In particular, the Na-rich Prussian-blue cathode exhibited superior HT tolerance up to 80 °C .…”