Ultra-High-Rate Na₃V(PO₃)₃N Cathode with Superior Stability for Fast-Charging Sodium-Ion Batteries

Abstract

There is an increasing demand for fast-charging Na-ion batteries (SIBs), which requires the battery to be fully charged within a short time and still possess a large capacity. Such properties are commonly determined by the transport of electrons and ions in the electrodes, and a stable structure is also needed. Na3V­(PO3)3N is found to have high sodium diffusion coefficients and a small volume change during sodium intercalation/extraction, making it a promising high-rate and fast-charging cathode. However, these intriguing features are unknown yet due to its inferior reaction kinetics. In this work, Na3V­(PO3)3N is synthesized by a sol–gel method for the first time, and a carbon nanotube (CNT)-wrapped carbon-coated Na3V­(PO3)3N (NVPN/C@CNT) composite structure is constructed. Impressively, the NVPN/C@CNT material shows 70.0% of the theoretical capacity at an ultra-high rate of 50C. The excellent fast-charging property of NVPN/C@CNT is also identified from 1C to 5C. Ex situ X-ray diffraction (XRD) demonstrates that the crystal phase and parameters of the NVPN unit cell remain stable even under a high charging rate, which is the key to the remarkable capability of fast charging. The galvanostatic intermittent titration technique (GITT) and pseudocapacitance calculation are also employed to understand the reaction and kinetics.

Rationally Designed Sodium Chromium Vanadium Phosphate Cathodes with Multi‐Electron Reaction for Fast‐Charging Sodium‐Ion Batteries

“…To illustrate, stable structure, high ionic, and electronic conductivity are decisive factors when operating SIBs under high current density conditions. [39][40][41] NASICONs are intrinsically endowed with 3D open framework structure to readily diffuse Na + (≈10 −13 to 10 −8 cm 2 s −1 ) with minimal phase transformation and low volume change (≈7%), which outperform that of layered oxides and Prussian blue analogs. [42,43] Therefore, NASICONs with high energy density would be an ideal choice for fast charging scenarios if the low electronic conductivity issue could be addressed.…”

Comprehensive Study of Sodium Copper Hexacyanoferrate, as a Sodium-Rich Low-Cost Positive Electrode for Sodium-Ion Batteries

“…Still, the larger Na ion (0.98 Å) needs large and open framework materials with large interstitial spacing, in which Na ions have acceptable mobility . For this reason, electrode materials with established open framework structures such as metal–organic frameworks, − phosphate-based cathodes, − and sodium superionic conductor structures − (NASICON) have been investigated as electrodes for SIBs. Prussian blue and its analogues have recently received much attention as electrodes for SIBs. − Prussian blue analogues (PBAs) have advantages of a large open framework with large interstitial sites for Na-ion diffusion and mobility, low-cost, easily scalable, and a facile synthetic procedure. , The PBA, KM­[Fe­(CN) 6 ], one class of metal–organic frameworks, has a cubic structure, where M and Fe are on the alternate corners of a cube of a corner-shared octahedral bridge by the CN – ligand.…”

Structural features of the oxidonitridophosphates K3 M III(PO3)3N (M III = Al, Ga)

“…In recent years, oxidonitridophosphates containing the (PO 3 ) 3 N 6anion have been intensively studied as promising cathode materials for Na-ion and Li-ion batteries. In particular, ionic conductivities and redox properties were investigated in detail for Na 3 Ti(PO 3 ) 3 N (Liu et al, 2014), Na 3 V(PO 3 ) 3 N (Reynaud et al, 2017;Kim et al, 2017;Zhang et al, 2017;Xiao et al, 2021;Wang et al, 2021), Li 3 V(PO 3 ) 3 N (Liu et al, 2018), Na 2 Fe 2 (PO 3 ) 3 N and Li 2 Fe 2 (PO 3 ) 3 N (Liu et al, 2013), Na 2 Mg 2 (PO 3 ) 3 N (Cosby et al, 2020), and Li 2 Mg 2 (PO 3 ) 3 N (Liu et al, 2017). In addition, rareearth-doped Na 3 Al(PO 3 ) 3 N has been studied as a promising phosphor (Bang et al, 2013).…”