Open AccessRealizing a High‐Performance Na‐Storage Cathode by Tailoring Ultrasmall Na 2 FePO 4 F Nanoparticles with Facilitated Reaction Kinetics
Author(s) -
Wang Fanfan,
Zhang Ning,
Zhao Xudong,
Wang Lixuan,
Zhang Jian,
Wang Tianshi,
Liu Fanfan,
Liu Yongchang,
Fan LiZhen
Publication year - 2019
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.201900649
Subject(s) - materials science , electrochemistry , cathode , anode , chemical engineering , nanoparticle , nanofiber , energy storage , carbon nanofiber , nanotechnology , cyclic voltammetry , electrode , chemistry , carbon nanotube , power (physics) , physics , quantum mechanics , engineering
Abstract In this paper, the synthesis of ultrasmall Na 2 FePO 4 F nanoparticles (≈3.8 nm) delicately embedded in porous N‐doped carbon nanofibers (denoted as Na 2 FePO 4 F@C) by electrospinning is reported. The as‐prepared Na 2 FePO 4 F@C fiber film tightly adherent on aluminum foil features great flexibility and is directly used as binder‐free cathode for sodium‐ion batteries, exhibiting admirable electrochemical performance with high reversible capacity (117.8 mAh g −1 at 0.1 C), outstanding rate capability (46.4 mAh g −1 at 20 C), and unprecedentedly high cyclic stability (85% capacity retention after 2000 cycles). The reaction kinetics and mechanism are explored by a combination study of cyclic voltammetry, ex situ structure/valence analyses, and first‐principles computations, revealing the highly reversible phase transformation of Na 2 Fe II PO 4 F ↔ NaFe III PO 4 F, the facilitated Na + diffusion dynamics with low energy barriers, and the desirable pseudocapacitive behavior for fast charge storage. Pouch‐type Na‐ion full batteries are also assembled employing the Na 2 FePO 4 F@C nanofibers cathode and the carbon nanofibers anode, demonstrating a promising energy density of 135.8 Wh kg −1 and a high capacity retention of 84.5% over 200 cycles. The distinctive network architecture of ultrafine active materials encapsulated into interlinked carbon nanofibers offers an ideal platform for enhancing the electrochemical reactivity, electronic/ionic transmittability, and structural stability of Na‐storage electrodes.