Magnesium Ion Battery Electrolyte Solubility via Halide Mediators
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnesium ion batteries face poor performance due to the reactivity of magnesium-based electrodes, leading to low solubility of magnesium trifluoromethanesulfonate (Mg(OTf)2) in ether solvents, resulting in poor Coulombic efficiency and reversibility, which hampers their development as a viable alternative to lithium-ion batteries.
Innovation Solution
A liquid electrolyte composition comprising magnesium trifluoromethanesulfonate with additives such as organic halide salts like 1-ethyl-3-methylimidazolium chloride or tetrabutylammonium chloride, and inorganic halide salts like magnesium chloride, dissolved in ethers, which enhances the solubility of Mg(OTf)2 and improves Coulombic efficiency and areal capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Mg(OTf)2 is used as the electrolyte salt in ether solvents, then the electrolyte system shows promise for Mg-ion batteries, but the solubility of Mg(OTf)2 in ether solvents is low, resulting in poor Coulombic efficiency and reversibility
Solution Approach 1:
The patent introduces halide salts (such as LiCl, NaCl, KCl, or their hydrates) as intermediary substances that facilitate the dissolution of Mg(OTf)2 in ether solvents. The halide salts form soluble complexes with Mg(OTf)2, acting as mediators that enable the otherwise insoluble Mg(OTf)2 to dissolve effectively in the ether-based electrolyte system, thereby improving both solubility and electrochemical performance
Solution Approach 2:
The patent creates a composite electrolyte system by combining Mg(OTf)2 with halide salts in ether solvents. This composite approach forms a synergistic mixture where the halide salt component enhances the solubility and electrochemical properties of the overall electrolyte system, transforming the poor-performance individual components into a high-performance composite electrolyte with Coulombic efficiency exceeding 99%
2Adaptability or versatility
If organic solvents are employed to accommodate magnesium-based electrodes, then the electrodes can function, but the Coulombic efficiency and reversibility of magnesium deposition remain poor
Solution Approach 1:
The patent modifies the chemical composition parameters of the electrolyte by incorporating halide salts into the ether solvent system. This parameter change fundamentally alters the electrolyte's interaction with magnesium electrodes, transforming the poor electrochemical performance into superior Coulombic efficiency and reversibility while maintaining electrode functionality
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed electrolyte system achieves superior Coulombic efficiency (greater than 99%) and extended cycle life, enabling efficient plating and stripping of magnesium, thereby enhancing the performance of magnesium-ion batteries.
Implementation Method 1
the cation comprises at least one protonated nitrogen capable of dissociating the trifluoromethane sulfonate anion from the magnesium salt
Implementation Method 2
enabling efficient plating and stripping of magnesium
Implementation Method 3
The improvement in solubility may advantageously lead to superior Coulombic efficiency (e.g. greater than 99%), and areal capacity (e.g. larger than 5 mAh/cm2)
Data Source
AI summary
There is a liquid electrolyte composition comprising: i) a magnesium salt comprising a trifluoromethane sulfonate anion; ii) an additive comprising an organic halide salt, an inorganic halide salt or a mixture thereof; and iii) a solvent comprising one or more ethers, wherein the organic halide salt comprises a halide anion and a cation selected from an optionally substituted quaternary ammonium or a three to nine membered N-heterocyclic cation, and the cation comprises at least one protonated nitrogen capable of dissociating the trifluoromethane sulfonate anion from the magnesium salt, and wherein the total concentration of cations of the inorganic halide salt and magnesium ions of the magnesium salt divided by the concentration of anions of the inorganic halide salt is greater than 1 in the electrolyte composition. There is further provided an electrochemical cell comprising a) a positive electrode; b) a magnesium negative electrode; and c) the electrolyte composition as described herein, wherein the positive electrode and the magnesium negative electrode are in fluid communication with the electrolyte.