Open AccessHighly conductive ionogel electrolytes based on N-ethyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide FSI and NaFSI mixtures and their applications in sodium batteries
Author(s) -
Sneha Malunavar,
Xiaoen Wang,
Faezeh Makhlooghiazad,
Michel Armand,
Montserrat Galcerán,
Patrick C. Howlett,
Maria Forsyth
Publication year - 2021
Publication title -
jphys materials
Language(s) - English
Resource type - Journals
ISSN - 2515-7639
DOI - 10.1088/2515-7639/ac0800
Subject(s) - electrolyte , materials science , faraday efficiency , chemical engineering , ionic liquid , ionic conductivity , battery (electricity) , cathode , eutectic system , inorganic chemistry , chemistry , organic chemistry , composite material , electrode , microstructure , thermodynamics , power (physics) , physics , catalysis , engineering
The development of highly conductive and safe electrolytes for sodium-ion batteries is an emerging field beyond lithium battery technologies. In this work we have developed new ionogel electrolytes consisting of a binary mixture of an organic ionic plastic crystal, N -ethyl- N -methylpyrrolidiniumbis(fluorosulfonyl)imide (C 2 mpyrFSI), mixed with NaFSI supported on a mat of electrospun poly (vinylidene fluoride) nanofibers. The salt mixture near the eutectic composition (35 mol% NaFSI) was selected for further study after a detailed phase diagram analysis and ionogel electrolytes based on this were prepared. The ionic conductivity of the prepared ionogel composite reaches 2.6 × 10 −3 S cm −1 at ambient temperature. This ionogel membrane possessed a relatively high Na-ion transference number of 0.44 at 50 °C and we demonstrate the performance of a Na metal full cell using a NaFePO 4 cathode (1.75–4.0 V). The assembled cells show a good capacity retention with coulombic efficiency close to 100% at various C rates between C/20, C/10 and C/5, achieving 120 mAh g −1 at C/20. The long term charge/discharge performance is also demonstrated. Our study provides a feasible method to prepare highly conductive ionogel electrolytes for future Na-battery applications