Premium
Electrochemical Properties and Sodium‐Storage Mechanism of Ag 2 Mo 2 O 7 as the Anode Material for Sodium‐Ion Batteries
Author(s) -
Chen Nan,
Gao Yu,
Zhang Meina,
Meng Xing,
Wang Chunzhong,
Wei Yingjin,
Du Fei,
Chen Gang
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201600224
Subject(s) - anode , materials science , high resolution transmission electron microscopy , electrochemistry , cyclic voltammetry , sodium ion battery , amorphous solid , electrode , intercalation (chemistry) , sodium molybdate , sodium , analytical chemistry (journal) , molybdate , inorganic chemistry , chemical engineering , transmission electron microscopy , chemistry , nanotechnology , faraday efficiency , metallurgy , crystallography , chromatography , engineering
Silver molybdate, Ag 2 Mo 2 O 7 , has been prepared by a conventional solid‐state reaction. Its electrochemical properties as an anode material for sodium‐ion batteries (SIBs) have been comprehensively examined by means of galvanostatic charge–discharge cycling, cyclic voltammetry, and rate performance measurements. At operating voltages between 3.0 and 0.01 V, the electrode delivered a reversible capacity of nearly 190 mA h g −1 at a current density of 20 mA g −1 after 70 cycles. Ag 2 Mo 2 O 7 also demonstrated a good rate capability and long‐term cycle stability, the capacity reaching almost 100 mA h g −1 at a current density of 500 mA g −1 , with a capacity retention of 55 % over 1000 cycles. Moreover, the sodium storage process of Ag 2 Mo 2 O 7 has been investigated by means of ex situ XRD, Raman spectroscopy, and HRTEM. Interestingly, the anode decomposes into Ag metal and Na 2 MoO 4 during the initial discharge process, and then Na + ions are considered to be inserted into/extracted from the Na 2 MoO 4 lattice in the subsequent cycles governed by an intercalation/deintercalation mechanism. Ex situ HRTEM images revealed that Ag metal not only remains unchanged during the sodiation/desodiation processes, but is well dispersed throughout the amorphous matrix, thereby greatly improving the electronic conductivity of the working electrode. The “in situ” decomposition behavior of Ag 2 Mo 2 O 7 is distinct from that of chemically synthesized, metal‐nanoparticle‐coated electrode materials, and provides strong supplementary insight into the mechanism of such new anode materials for SIBs and may set a precedent for the design of further materials.