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Influence of Salt Concentration on the Properties of Sodium‐Based Electrolytes
Author(s) -
Geng Chenxi,
Buchholz Daniel,
Kim GukTae,
Carvalho Diogo Vieira,
Zhang Huang,
Chagas Luciana Gomes,
Passerini Stefano
Publication year - 2019
Publication title -
small methods
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.66
H-Index - 46
ISSN - 2366-9608
DOI - 10.1002/smtd.201800208
Subject(s) - electrolyte , electrochemical window , electrochemistry , ionic conductivity , propylene carbonate , inorganic chemistry , conductivity , chemistry , salt (chemistry) , sodium , ionic liquid , ionic bonding , raman spectroscopy , materials science , ion , electrode , organic chemistry , catalysis , physics , optics
Electrolytes based on organic carbonates are widely used for sodium‐ion batteries (SIBs) due to several advantages such as high ionic conductivity, wide liquidus range, and high electrochemical stability. In this work, this class of electrolyte is investigated focusing on two conductive salts, namely NaPF 6 (sodium hexafluorophosphate) and NaTFSI (sodium bis(trifluoromethanesulfonyl)imide), using PC (propylene carbonate) as solvent. The investigation of different salt concentrations, from rather diluted to highly concentrated (i.e., 0.1, 1, and 3 m ), extends from their glass transition temperature to viscosity, ionic conductivity, electrochemical stability window, and electrochemical stability toward Al. Raman spectroscopy discloses the salt–solvent coordination and its possible modification due to changes in temperature, proving that the viscosity played a major role in influencing ionic conductivity rather than ions and molecules' coordination. Finally, the electrochemical performance of half‐cells employing Na x Ni 0.22 Co 0.11 Mn 0.66 O 2 as the cathode material with the various electrolytes is also reported, and cells containing electrolyte with 1 m salt concentration outperform the other in terms of delivered capacity and rate performance.