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Revealing the Multi‐Electron Reaction Mechanism of Na 3 V 2 O 2 (PO 4 ) 2 F Towards Improved Lithium Storage
Author(s) -
Yin Yameng,
Pei Cunyuan,
Liao Xiaobin,
Xiong Fangyu,
Yang Wei,
Xiao Biaobiao,
Zhao Yan,
Ren Zijie,
Xu Longhua,
An Qinyou
Publication year - 2021
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.202100880
Subject(s) - vanadium , x ray photoelectron spectroscopy , redox , electrochemistry , anode , lithium (medication) , nanosheet , ion , materials science , reaction mechanism , analytical chemistry (journal) , chemistry , electrode , inorganic chemistry , nanotechnology , chemical engineering , catalysis , medicine , biochemistry , organic chemistry , chromatography , engineering , endocrinology
Abstract Na 3 V 2 O 2 (PO 4 ) 2 F (NVOPF) as an attractive electrode material has received much attention based on the one‐electron reaction of V 4+ /V 5+ . However, the electrochemical reactions involving lower vanadium valences were not investigated till now. Herein, a composite of graphene decorated nanosheet‐assembled NVOPF microflowers (NVOPF/G) was synthesized and the multi‐electron reaction of NVOPF/G was conducted by controlling the operation voltage windows. The reaction mechanism, structural changes, and vanadium valences during the insertion/extraction of Li ions (from 2 to 6) were elucidated clearly by in‐situ X‐ray diffraction and ex‐situ X‐ray photoelectron spectroscopy. Theoretical computations also revealed the Li‐ion locations in the structure of NaV 2 O 2 (PO 4 ) 2 F. Due to the additional redox couple of V 3+ /V 4+ , NVOPF/G displayed a much higher initial capacity of 183.3 mAh g −1 in the wider voltage window of 1.0–4.8 V than that of 2.5–4.8 V (129.3 mAh g −1 ). Moreover, excellent Li‐storage performance of NVOPF/G at a lower voltage (≤2.5 V) with the active reaction of V 2+ /V 3+ /V 4+ was obtained for the first time, demonstrating the high potential of NVOPF/G as an anode material for Li ion storage.