Influence of the ionic liquid type on the gel polymer electrolytes properties

Abstract:

Gel Polymer Electrolytes (GPEs) composed by ZnTf<inf>2</inf> salt, poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP), and different ionic liquids are synthesized using n-methyl-2-pyrrolidone (NMP) as solvent. Three different imidazolium-based ionic liquids containing diverse cations and anions have been explored. Structural and electrical properties of the GPEs varying the ZnTf<inf>2</inf> concentration are analyzed by ATR-FTIR, DSC, TG, and cyclic voltammetry. Free salt IL-GPEs present distinct behavior because they are influenced by the different IL cations and anions composition. However, inclusion of ZnTf<inf>2</inf> salt inside the polymers provide GPEs with very similar characteristics, pointing out that ionic transport properties are principally caused by Zn²⁺ and triflate movement. Whatever the IL used, the presence of NMP solvent inside the polymer’s matrix 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, low activation energy values, and good voltammetric reversibility obtained regardless of the ionic liquid used enable these GPEs to be applied in Zn batteries. Capacities of 110-120 mAh·g⁻¹ have been obtained for Zn/IL-GPE/MnO<inf>2</inf> batteries discharged at −1 mA·cm⁻².

Año de publicación:

2015

Keywords:

• Ionic Liquid-based Gel Polymer electrolytes
• Zinc batteries
• Cation transport number
• Ionic Conductivity

Fuente:

scopus

google