“New MOF- based Hybrid Solid Electrolytes with high Li+ and Na+ conductivity”

Gonzalez Solano, Daliana Patricia (author), Genorio, Boštjan (mentor)

In the last decade, extensive research efforts have been dedicated to enhancing the safety and efficiency of energy conversion and storage systems. Within this context, solid-state electrolytes (SSEs) have attracted significant attention due to their favorable thermal stability and the safety concerns associated with liquid electrolytes. The trend in battery manufacturing techniques is gradually shifting towards the adoption of solid electrolytes due to their distinct advantages over liquid counterparts. However, a common limitation of solid electrolytes is their comparatively lower conductivity. This limitation has spurred the development of hybrid solid electrolytes as a promising solution, exemplified by the incorporation of Na+ and Li+conducting SSEs within the Metal-Organic Framework (MOF) MIL-121. In the synthesis and activation process of MOF, the protons of the free carboxylic groups within the one-dimensional pores are exchanged with Li+ or Na+ions through ion exchange mechanisms. The mobility of these ions is analyzed using impedance spectroscopy. A diverse range of modifications were applied to MOF MIL-121, encompassing ion exchanges with Maleates (Li2Mal and Na2Mal) and Acetates (LiAc and NaAc). Additionally, combinations involving electrolytes such as Perchlorates (LiClO4 and NaClO4), Hexafluorophosphate (LiPF6 and NaPF6), bis(fluorosulfonyl)amide (LiFSI and NaFSI) were explored. The study also delved into various solvents such as Propylene carbonate (PC), Ethylene carbonate (EC), Tetraglyme (4G), Diglyme (2G), and 1-Ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM-FSI). The pinnacle of the findings is the accomplishment of a conductivity value of 1.4823x10-3 S/cm at 20°C, as demonstrated by the sample that underwent ion exchange with Li2Mal and incorporated EMIM-FSI. These outcomes pave the way for the development of highly efficient MOF-based hybrid solid-state electrolytes (SSEs) tailored for advanced solid-state batteries (ASSBs). These SSEs exhibit considerable potential for meticulous tuning and strategic enhancement, thus holding promise for elevated performance standards.

• Language: English
• Keywords: MOF, conductivity, solid electrolytes, hybrid solid electrolytes, batteries, sodium, lithium, Mobil Organic Framework
• Work type: Master's thesis/paper
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2023
• PID: 20.500.12556/RUL-153471
• Publication date in RUL: 09.01.2024

Secondary language

• Language: Slovenian
• Title: “New MOF- based Hybrid Solid Electrolytes with high Li+ and Na+ conductivity”

Abstract

In the last decade, extensive research efforts have been dedicated to enhancing the safety and efficiency of energy conversion and storage systems. Within this context, solid-state electrolytes (SSEs) have attracted significant attention due to their favorable thermal stability and the safety concerns associated with liquid electrolytes. The trend in battery manufacturing techniques is gradually shifting towards the adoption of solid electrolytes due to their distinct advantages over liquid counterparts. However, a common limitation of solid electrolytes is their comparatively lower conductivity. This limitation has spurred the development of hybrid solid electrolytes as a promising solution, exemplified by the incorporation of Na+ and Li+conducting SSEs within the Metal-Organic Framework (MOF) MIL-121. In the synthesis and activation process of MOF, the protons of the free carboxylic groups within the one-dimensional pores are exchanged with Li+ or Na+ions through ion exchange mechanisms. The mobility of these ions is analyzed using impedance spectroscopy. A diverse range of modifications were applied to MOF MIL-121, encompassing ion exchanges with Maleates (Li2Mal and Na2Mal) and Acetates (LiAc and NaAc). Additionally, combinations involving electrolytes such as Perchlorates (LiClO4 and NaClO4), Hexafluorophosphate (LiPF6 and NaPF6), bis(fluorosulfonyl)amide (LiFSI and NaFSI) were explored. The study also delved into various solvents such as Propylene carbonate (PC), Ethylene carbonate (EC), Tetraglyme (4G), Diglyme (2G), and 1-Ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM-FSI). The pinnacle of the findings is the accomplishment of a conductivity value of 1.4823x10-3 S/cm at 20°C, as demonstrated by the sample that underwent ion exchange with Li2Mal and incorporated EMIM-FSI. These outcomes pave the way for the development of highly efficient MOF-based hybrid solid-state electrolytes (SSEs) tailored for advanced solid-state batteries (ASSBs). These SSEs exhibit considerable potential for meticulous tuning and strategic enhancement, thus holding promise for elevated performance standards.

• Keywords: MOF, conductivity, solid electrolytes, hybrid solid electrolytes, batteries, sodium, lithium, Mobil Organic Framework