scholarly journals Poly(ionic liquid) Based Composite Electrolytes for Lithium Ion Batteries

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4469
Author(s):  
Robert Löwe ◽  
Thomas Hanemann ◽  
Tatiana Zinkevich ◽  
Andreas Hofmann
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Ionic Conductivity ◽  
Lithium Ion Batteries ◽  
Polymer Electrolyte ◽  
Diffusion Coefficients ◽  
Lithium Ion ◽  
Liquid Electrolyte ◽  
Resonance Spectroscopy ◽  
Electrolyte Membranes

Polymerized ionic liquids (PIL) are an interesting substance class, which is discussed to transfer the outstanding properties and tunability of ionic liquids into a solid material. In this study we extend our previous research on ammonium based PIL and discuss the influence of additives and their usability as polymer electrolyte membranes for lithium ion batteries. The polymer electrolyte is thereby used as replacement for the commercially widespread system of a separator that is soaked with liquid electrolyte. The influence of the material composition on the ionic conductivity (via electrochemical impedance spectroscopy) and the diffusion coefficients (via pulsed-field-gradient nuclear magnetic resonance spectroscopy) were studied and cell tests with adapted membrane materials were performed. High amounts of the additional ionic liquid (IL) MPPyrr-TFSI (1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide) increased the ionic conductivity of the materials up to 1.3·10−4 S·cm−1 but made the usage of a cross-linker necessary to obtain mechanically stable membranes. The application of liquid electrolyte mixtures with ethylene carbonate (EC) and MPPyrr-TFSI decreased ionic conductivity values down to the 10−9 S·cm−1 range, but increased 7Li diffusion coefficients with increasing amounts of EC up to 1.7·10−10 m2·s−1. Cell tests with two membrane mixtures proofed that it is possible to build electrolyte membranes on basis of the polymerized ionic liquids, but also showed that further research is necessary to ensure stable and efficient cell cycling.

scholarly journals The Use of Succinonitrile as an Electrolyte Additive for Composite-Fiber Membranes in Lithium-Ion Batteries

Membranes ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 45 ◽  
Author(s):  
Jahaziel Villarreal ◽  
Roberto Orrostieta Chavez ◽  
Sujay A. Chopade ◽  
Timothy P. Lodge ◽  
Mataz Alcoutlabi
Keyword(s):  
Ionic Liquid ◽  
Ionic Conductivity ◽  
Lithium Ion Batteries ◽  
Specific Capacity ◽  
Lithium Ion ◽  
Composite Fiber ◽  
Galvanostatic Charge ◽  
Lithium Anode ◽  
Charge Discharge ◽  
Licoo2 Cathode

In the present work, the effect of temperature and additives on the ionic conductivity of mixed organic/ionic liquid electrolytes (MOILEs) was investigated by conducting galvanostatic charge/discharge and ionic conductivity experiments. The mixed electrolyte is based on the ionic liquid (IL) (EMI/TFSI/LiTFSI) and organic solvents EC/DMC (1:1 v/v). The effect of electrolyte type on the electrochemical performance of a LiCoO2 cathode and a SnO2/C composite anode in lithium anode (or cathode) half-cells was also investigated. The results demonstrated that the addition of 5 wt.% succinonitrile (SN) resulted in enhanced ionic conductivity of a 60% EMI-TFSI 40% EC/DMC MOILE from ~14 mS·cm−1 to ~26 mS·cm−1 at room temperature. Additionally, at a temperature of 100 °C, an increase in ionic conductivity from ~38 to ~69 mS·cm−1 was observed for the MOILE with 5 wt% SN. The improvement in the ionic conductivity is attributed to the high polarity of SN and its ability to dissolve various types of salts such as LiTFSI. The galvanostatic charge/discharge results showed that the LiCoO2 cathode with the MOILE (without SN) exhibited a 39% specific capacity loss at the 50th cycle while the LiCoO2 cathode in the MOILE with 5 wt.% SN showed a decrease in specific capacity of only 14%. The addition of 5 wt.% SN to the MOILE with a SnO2/C composite-fiber anode resulted in improved cycling performance and rate capability of the SnO2/C composite-membrane anode in lithium anode half-cells. Based on the results reported in this work, a new avenue and promising outcome for the future use of MOILEs with SN in lithium-ion batteries (LIBs) can be opened.

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