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

Abstract

Lithium-ion batteries (LIBs) have changed modern life-enabling mobile communication and electric vehicles. They are the most widespread energy storage devices but they are not totally suitable for sustainable development due to the limited lithium resources in countries often with underlying political disputes. [3][4][5] As alternative candidates, sodium-ion batteries (SIBs) have drawn increasing attention by both academic and industrial communities on account of the high abundance of sodium resources. [6,7] Of great promise are inexpensive, high-energy, long-lifespan, and fast-charging SIBs in order to improve on LIBs. [8] However, a key bottleneck in commercializing SIBs is to identify competitive cathodes with long lifespan, negligible volume change, cost-effectiveness, as well as high capacity. [9][10][11] Until now, several families of cathode materials have been developed for use such as layered oxides, [12,13] Prussian blues analogs, [14] and polyanion oxides. [15][16][17] Among these, sodium superionic conductor (NASICON)-structured Na x MeMe′(PO 4 ) 3 (Me/Me′ refers to transition metals) are capable of satisfying the above requirements in terms of high ionic conductivity (3D open frameworks), limited volume change (strong Sodium super-ionic conductor (NASICON)-structured phosphates are emerging as rising stars as cathodes for sodium-ion batteries. However, they usually suffer from a relatively low capacity due to the limited activated redox couples and low intrinsic electronic conductivity. Herein, a reduced graphene oxide supported NASICON Na 3 Cr 0.5 V 1.5 (PO 4 ) 3 cathode (VC/C-G) is designed, which displays ultrafast (up to 50 C) and ultrastable (1 000 cycles at 20 C) Na + storage properties. The VC/C-G can reach a high energy density of ≈470 W h kg −1 at 0.2 C with a specific capacity of 176 mAh g −1 (equivalent to the theoretical value); this corresponds to a three-electron transfer reaction based on fully activated V 5+ /V 4+ , V 4+ /V 3+ , V 3+ /V 2+ couples. In situ X-ray diffraction (XRD) results disclose a combination of solid-solution reaction and biphasic reaction mechanisms upon cycling. Density functional theory calculations reveal a narrow forbiddenband gap of 1.41 eV and a low Na + diffusion energy barrier of 0.194 eV. Furthermore, VC/C-G shows excellent fast-charging performance by only taking ≈11 min to reach 80% state of charge. The work provides a widely applicable strategy for realizing multi-electron cathode design for high-performance SIBs.

Electropolymerization reaction-driven 2,6-naphthalenediamine monomers to a multilayered sheet structure for ultralong cycling aqueous zinc-ion batteries

“…The issues of resource shortage and safety have limited the development of lithium-ion batteries (LIBs). [1][2][3] Aqueous rechargeable zinc-ion batteries (ZIBs) are regarded as one of the most prospective alternatives for advanced energy storage systems due to abundant Zn in the crust, high theoretical specific capacity (820 mA h g À1 ), greener environment, aqueous electrolytes, high safety, and ionic conductivity. [4][5][6] Metal Zn is generally used as anodes, while cathode materials were intensively investigated to regulate the voltage, capacity, rate capability and cycling stability for ZIBs.…”

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.…”

Fluorine anion modification of high-voltage Mn-rich phosphate cathodes for high-power and long-lasting sodium-ion batteries

“…From the BV maps in Fig. 4a, it can be clearly found that both NMCPF and NMCP possess 3D well-interconnected pathways for Na + with the lowest energy regions except for some subtle differences, which is the feature of typical NASICONs 23,26 . Convex-hull phase diagrams of NMCPF (Fig.…”