Highly Reversible Na Storage in Na₃V₂(PO₄)₃ by Optimizing Nanostructure and Rational Surface Engineering

Abstract

Sodium‐ion batteries (NIBs) have attracted more and more attention as economic alternatives for lithium‐ion batteries (LIBs). Sodium super ionic conductor (NASICON) structure materials, known for high conductivity and chemical diffusion coefficient of Na+ (≈10−14 cm2 s−1), are promising electrode materials for NIBs. However, NASICON structure materials often suffer from low electrical conductivity (<10−4 S cm−1), which hinders their electrochemical performance. Here high performance sodium storage performance in Na3V2(PO4)3 (NVP) is realized by optimizing nanostructure and rational surface engineering. A N, B codoped carbon coated three‐dimensional (3D) flower‐like Na3V2(PO4)3 composite (NVP@C‐BN) is designed to enable fast ions/electrons transport, high‐surface controlled energy storage, long‐term structural integrity, and high‐rate cycling. The conductive 3D interconnected porous structure of NVP@C‐BN greatly releases mechanical stress from Na+ extraction/insertion. In addition, extrinsic defects and active sites introduced by the codoping heteroatoms (N, B) both enhance Na+ and e− diffusion. The NVP@C‐BN displays excellent electrochemical performance as the cathode, delivering reversible capacity of 70% theoretical capacity at 100 C after 2000 cycles. When used as anode, the NVP@C‐BN also shows super long cycle life (38 mA h g−1 at 20 C after 5000 cycles). The design provides a novel approach to open up possibilities for designing high‐power NIBs.

Na 3 V 2 (PO 4 ) 3 @NC composite derived from polyaniline as cathode material for high‐rate and ultralong‐life sodium‐ion batteries

“…Figure b displays the XRD spectrum of the NVP@NC composite. The characteristic diffraction peaks of NVP are placed at 14.14°, 19.14°, 23.66°, 28.62°, 31.90°, and 35.5°, corresponding to (012), (104), (113), (024), (114), and (300) surfaces, respectively . The characteristic peaks of the NVP@NC composite are sharp and correspond exactly to the standard card (JCPDS 53‐0018), indicating that the purity of crystal of the NVP material and N‐doped carbon coating is amorphous or content is very small.…”

“…However, the intrinsic properties of these materials, such as serious capacity decay and voltage platform receding because of structural variations during Na + ‐intercalation/removal process or occurring the side reaction, hinder their application in SIBs. Compared with them, Na 3 V 2 (PO 4 ) 3 (NVP) with NASICON structure and higher theoretical specific capacity is considered as an ideal cathode material for SIBs . In addition, its stable 3D host framework brings about thermal stability and ultralong cycle life, although the low electronic conductivity of NVP causes inferior rate character, which limits its utilization .…”

Carbon‐Coated Na3V2(PO4)3 Supported on Multiwalled Carbon Nanotubes for Half‐/Full‐Cell Sodium‐Ion Batteries

“…Na 3 V 2 (PO 4 ) 3 (NVP), with a super ionic conductor framework, is regarded as one of the most promising candidate cathodes due to its high reversible capacity, excellent thermal stability, and fast Na‐ion diffusion tunnel . Furthermore, Na‐ion superionic conductor (NASICON)‐type NVP exhibits a suitable voltage plateau located at 3.4 V versus Na/Na + , correlated with the V 3+ /V 4+ redox couple, and the high theoretical energy density (400 W h kg −1 ) .…”

Designed One‐Pot Strategy for Dual‐Carbon‐Protected Na3V2(PO4)3 Hybrid Structure as High‐Rate and Ultrastable Cathode for Sodium‐Ion Batteries

“…[11] Therefore, it is always imperative to exploit high performance electrode materials with excellentr ate performance and cycling stability forS IBs, in order to meet the requiremento fc ommercialization. [22,25,[31][32][33][34][35][36][37][38][39] For example,S ong et al [24] reported the synthesis of thin-layer graphene-encapsulated NVP nanoparticles with about 100 nm, whiche xhibited optimized rate performance with discharge capacityo f7 0.1 mAh À1 g À1 at 30 Ca nd enhanced cyclings tability with about 86.0 %c apacity retention at 5Cafter 300 cycles. [13,14] Among variousc athode candidates, such as sodium-based layered metalo xides, [15,16] phosphates, [17,18] andP russian blue analogs (PBAs), [19] NASICON-type Na 3 V 2 (PO 4 ) 3 (denoted as NVP) has been considered as ap romising candidate because of the high theoretical specific capacity,e xcellent thermala nd structural stability.…”

“…[13,14] Among variousc athode candidates, such as sodium-based layered metalo xides, [15,16] phosphates, [17,18] andP russian blue analogs (PBAs), [19] NASICON-type Na 3 V 2 (PO 4 ) 3 (denoted as NVP) has been considered as ap romising candidate because of the high theoretical specific capacity,e xcellent thermala nd structural stability. [22,25,[31][32][33][34][35][36][37][38][39] For example,S ong et al [24] reported the synthesis of thin-layer graphene-encapsulated NVP nanoparticles with about 100 nm, whiche xhibited optimized rate performance with discharge capacityo f7 0.1 mAh À1 g À1 at 30 Ca nd enhanced cyclings tability with about 86.0 %c apacity retention at 5Cafter 300 cycles. [28][29][30] However,t he intrinsicl ow electronic conductivity results in poor rate performance and unsatisfactory cycle life, whichs eriously impedes its practical application.…”