Interaction between Zn2+ cations and n-methyl-2-pyrrolidone in ionic liquid-based Gel Polymer Electrolytes for Zn batteries

Significance Statement

Zinc-based batteries have been extensively used due to their numerous advantages. Currently, several research groups focus their investigation mainly on Zn/air batteries, because of their highly specific energy, and the named Zinc-ion batteries (ZIBs), as most viable candidates for replacing Li-ion batteries. However, these batteries usually include alkaline aqueous electrolytes, which present several inconveniences. Use of gel polymer electrolytes  instead of conventional alkaline aqueous ones is considered a possible way to solve these problems. In our laboratory we prepare ionic liquid-based gel polymer electrolytes, trapping zinc triflate salt together with an ionic liquid into a polymer host, PVdF-HFP. Besides, presence of n-methyl-2-pyrrolidone into the gel polymer electrolytes turns out to be a key factor due to the interaction between Zn2+ cations and carbonyl groups of the n-methyl-2-pyrrolidone, as it has been confirmed by ATR-FTIR. It should be noted that cation transport number measurements confirm that this interaction improves the Zn2+ transport inside the gel polymer electrolytes. Remarkable electrical and electrochemical properties obtained reveal these gel polymer electrolytes as excellent candidates to be used in zinc batteries. Thus, we have probed these ionic liquid-based gel polymer electrolytes in Zn/MnO2 batteries, resulting specific capacities of 125 mAh g-1. Therefore, these gel polymer electrolytes may break through to the development of new Zn/air batteries in the near future.  

About the author

Prof. Dr. Antonio J. Fernández Romero received his Ph.D. degree on the topic “modified electrodes with viologens” from the Córdoba University, Spain, in 2000. He is currently member of the Advance Materials for Energy Production and Storage group research (MAPA) and Professor at the School of Industrial Engineering, Technical University of Cartagena, Spain. His main research interests include spectroscopy and electrochemical characterization of gel polymer electrolytes to be applied in Zn-based batteries, in situ analysis of charge storage mechanisms in electrodes and development of new metal/air batteries.

Juan Pablo Tafur Guisao received his B.Sc. in Industrial Engineering and M.Sc. in Renewable Energies from Technical University of Cartagena, Spain. Currently, he is finishing his Ph.D. in gel polymer electrolytes applied at Zn batteries, which will be defended in January 2016.  

nteraction between Zn2+ cations and n-methyl-2-pyrrolidone in ionic liquid-based Gel Polymer Electrolytes for Zn batteries

 

 

 

 

 

 

 

 

 

 

Journal Reference

Electrochimica Acta, Volume 176, 2015, Pages 1447–1453.

Juan P. Tafur Guisao, Antonio J. Fernández Romero,

Grupo de Materiales Avanzados para la Producción y Almacenamiento de Energía (MAPA), Universidad Politécnica de Cartagena, Aulario II, Campus de Alfonso XIII, Cartagena, 30203, Spain

 

Abstract

Gel Polymer Electrolytes (GPEs) composed by 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (EMIM TFSI), ZnTf2 salt, and poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) are synthesized using n-methyl-2-pyrrolidone (NMP) as solvent. Structural and Thermal characterization of gel polymer electrolytes with different ZnTf2concentrations are analyzed by ATR-FTIR, XRD, DSC and TG. Ionic conductivity versus temperature plots obeys the Vogel-Tammen-Fulcher (VTF) behavior and activation energy values are deduced from the slopes. Use of NMP solvent turns out to be a key factor for improving the Zn2+ transport inside the GPE due to the interaction between Zn2+ cations and carbonyl groups of the NMP. High values of ionic conductivity and low activation energy values, together with the high reversibility and high current density obtained in the voltammograms reveal these gel polymer electrolytes as good candidates to be used in Zn batteries. Furthermore, ionic liquids-based gel polymer electrolytes are probed in Zn/MnO2 batteries, resulting specific capacities of 125 mAh g−1.

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