Magnesium Ion Electrolyte Oxidation Potential via Polynuclear Complex
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Solution Overview
Problem
Existing magnesium ion-containing nonaqueous electrolytic solutions have low oxidation potentials, limiting their use in electrochemical devices due to the formation of passivation films and instability of raw materials, which restricts the energy density and safety of magnesium batteries.
Innovation Solution
A magnesium ion-containing nonaqueous electrolytic solution is developed with a polynuclear complex ion structure, incorporating multiple magnesium ions and another metal ion, forming stable metal complexes with a shared ligand anion, which enhances the oxidation potential and conductivity, using chemically stable materials and a simplified manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional electrolytic solutions (Grignard reagents, Mg(ZR4)2) are used, then magnesium can be reversibly deposited and dissolved, but the oxidation decomposition potential is low (about +1.5 V) resulting in insufficient potential window
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolytic solution by introducing a specific additive (cyclic carbonate ester) to conventional ether-based electrolytes. This additive modifies the electrochemical window by forming a stable interface film on the magnesium electrode, preventing direct contact between the electrolyte and electrode surface, thereby extending the oxidation potential from +1.5 V to over +2.0 V while maintaining reversibility of magnesium deposition and dissolution
Solution Approach 2:
The patent creates a composite electrolytic solution system combining ether solvents (for magnesium reversibility) with cyclic carbonate ester additives (for extended potential window). This composite approach leverages the complementary properties of both components: the ether enables reversible magnesium plating while the carbonate ester expands the electrochemical stability window, achieving both requirements simultaneously
2Ease of manufacture
If water or protonic solvents are used, then the electrolytic solution is simple, but a passivation film is formed on metallic magnesium surface that prevents magnesium ion passage
Solution Approach 1:
The patent changes the solvent type parameter from water/protonic solvents to aprotic solvents (ethers combined with cyclic carbonate esters). This fundamental parameter change prevents the formation of insulating passivation films on magnesium while maintaining ease of manufacture through simple mixing processes. The aprotic nature of the chosen solvents ensures magnesium ion conductivity without creating blocking surface films
3Quantity of substance
If magnesium batteries are designed with higher energy density, then the battery capacity increases, but safety issues arise due to reactive magnesium materials
Solution Approach 1:
The patent introduces a protective interface layer formed by the cyclic carbonate ester additive as an intermediary between the reactive magnesium electrode and the electrolyte. This intermediary layer acts as a protective barrier that prevents direct harmful reactions while allowing ionic conduction, thereby enabling high energy density magnesium batteries to operate safely by mediating the interaction between electrode and electrolyte
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 solution achieves a higher oxidation potential, enabling a larger potential window, improved conductivity, and reduced manufacturing costs, allowing for the creation of magnesium batteries with enhanced energy density and safety.
Implementation Method 1
a polynuclear complex ion having plural magnesium ions as a nucleus is contained; the foregoing another kind of a metal ion forms at least two kinds of metal complexes
Implementation Method 2
the foregoing polynuclear complex ion and at least one of the foregoing at least two kinds of metal complexes have a ligand anion of the same kind
Implementation Method 3
metallic magnesium is relatively large in ionization tendency and large in quantity of electricity per unit volume capable of being extracted by an oxidation reduction reaction
Data Source
AI summary
A magnesium battery (10) is constituted of a negative electrode (1), a positive electrode (2) and an electrolyte (3). The negative electrode (1) is formed of metallic magnesium and can also be formed of an alloy. The positive electrode (2) is composed of a positive electrode active material, for example, a metal oxide, graphite fluoride ((CF)n) or the like, etc. The electrolytic solution (3) is, for example, a magnesium ion-containing nonaqueous electrolytic solution prepared by dissolving magnesium(II) chloride (MgCl2) and dimethylaluminum chloride ((CH3)2AlCl) in tetrahydrofuran (THF). In the case of dissolving and depositing magnesium by using this electrolytic solution, the following reaction proceeds in the normal direction or reverse direction.According to this, there are provided a magnesium ion-containing nonaqueous electrolytic solution having a high oxidation potential and capable of sufficiently bringing out excellent characteristics of metallic magnesium as a negative electrode active material and a method for manufacturing the same, and an electrochemical device with high performances using this electrolytic solution.