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Role of N‐Propyl‐N‐Methyl Pyrrolidinium bis(trifluoromethanesulfonyl)imide as an Electrolyte Additive in Sodium Battery Electrochemistry
Author(s) -
Manohar C. V.,
Forsyth Maria,
MacFarlane Douglas R.,
Mitra Sagar
Publication year - 2018
Publication title -
energy technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.91
H-Index - 44
eISSN - 2194-4296
pISSN - 2194-4288
DOI - 10.1002/ente.201800123
Subject(s) - electrolyte , electrochemistry , cathode , inorganic chemistry , dielectric spectroscopy , ionic liquid , materials science , x ray photoelectron spectroscopy , chemistry , electrode , chemical engineering , organic chemistry , catalysis , engineering
Electrolyte compatibility with sodium metal and known sodium‐ion battery cathodes is of intense interest recently. In this work, electrolytes including an ionic liquid (IL) additive are formulated and shown to enhance the properties of the well‐known Na 3 V 2 (PO 4 ) 3 /C (NVP/C) cathode. NVP/C composite material was synthesized by a carbothermal reduction process and studied in cells containing either organic electrolyte (1 M NaClO 4 in PC) or organic electrolyte with added [C 3 mpyr][NTf 2 ] IL. In an electrolyte containing 5 wt % [C 3 mpyr][NTf 2 ] IL, the cathode material exhibited a stable capacity of 107.0±0.7 mAh g −1 after 50 cycles at a C/2 rate; in contrast, the capacity obtained with the organic electrolyte was only 85±1 mAh g −1 after 50 similar cycles. In situ impedance spectroscopy revealed that the electrode‐electrolyte charge‐transfer resistance is lower in the organic electrolyte with IL. Consistent with this finding, XPS, SEM, EDX and TEM results indicate that the interfacial layer formed on the surface of the NVP/C cathode material in the presence of the IL is more compact than that formed in the organic electrolyte, and that reaction between cathode and electrolyte is suppressed by the IL.