Nitrogen-Doped Carbon Coated Na₃V₂(PO₄)₂F₃ Derived from Polyvinylpyrrolidone as a High-Performance Cathode for Sodium-Ion Batteries

Abstract

Na super ionic conductor (NASICON)-type Na 3 V 2 (PO 4 ) 2 F 3 (NVPF) has been regarded as a prospective candidate of cathode materials for sodium-ion batteries due to its excellent structural stability, relatively high capacity and working voltage. However, the poor cyclability and rate capability, resulting from its low intrinsic electronic conductivity, have become a serious obstacle to their practical large-scale application. In this work, N-doped carbon coated NVPF composites (NVPF@NC) were successfully synthesized via a simple sol−gel method, in which low-cost polyvinylpyrrolidone was introduced as a nitrogen source. After high-temperature pyrolysis, a highly conductive N-doped carbon layer was in-situ constructed on the particle surface to enhance the sodium storage performance of NVPF. The optimized NVPF@NC cathode delivered high reversible capacity, excellent rate capability and long-term cycle life compared to pristine NVPF@C. The remarkable electrochemical performance of NVPF@NC cathode benefits from the modification strategy of introducing a heteroatom-doped carbon layer, triggering the formation of extrinsic defects and active sites in the N-doped amorphous carbon layer, which greatly enhances the electrical conductivity and the diffusion rate of sodium ions. This work provides a facile and effective approach for the preparation of N-doped carbon coated NVPF with remarkable sodium storage properties, which could be extended to other electrode materials electrochemical for energy storage. KEYWORDS: sodium-ion batteries, Na 3 V 2 (PO 4 ) 2 F 3 , nitrogen-doped carbon, cathode material, electrochemical energy storage

Entropy modulation strategy of P2-type layered transition metal oxide cathodes for sodium-ion batteries with a high performance

“…Since the cathode material is a key component determining the properties of SIBs, various structures have been investigated as cathodes, including layered transition metal oxides, analogues of Prussian blue, and polyanionic compounds. 4–9 Among these materials, layered transition metal oxides of sodium have been extensively investigated for their high energy density as cathode materials for SIBs. 10–14 The general formula of sodium layered oxide cathode materials is Na x TMO 2 (TM refers to transition metals), which was first proposed in 1980.…”

Toward high stability of O3‐type NaNi1/3Fe1/3Mn1/3O2 cathode material with zirconium substitution for advanced sodium‐ion batteries

“…Therefore, scientists have been actively working to develop sodium‐ion batteries (SIBs) to partially replace the utilization of lithium‐ion batteries (LIBs) in various applications. [ 1–9 ] However, sodium has a larger atomic mass and ionic radius than lithium, which greatly affects its structural stability as a cathode. [ 10–12 ] Therefore, it is imperative to develop SIBs with high specific capacity, long cycle life, and low cost.…”

A high-entropy layered P2-type cathode with high stability for sodium-ion batteries

“…15–18 Researchers have reported various types of potential cathode materials, the most common of which are transition metal oxides, 19–21 Prussian blue analogs 22–24 and polyanion compounds. 16,25–28…”