Mono-nuclei Magnesium Salt Electrolyte for Rechargeable Battery Passivation
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Solution Overview
Problem
The development of rechargeable magnesium batteries is hindered by the formation of a dense passivation coating on metal magnesium in non-protonic electrolyte solutions, preventing magnesium ions from conducting and resulting in malfunction, and existing electrolyte salts have complex structures and high costs, limiting their use in magnesium batteries.
Innovation Solution
A mono-nuclei cationized magnesium salt is synthesized through a reaction between Lewis acids and bases in a non-aqueous solvent, using inorganic magnesium and aluminum or boron salts, which forms a simple structure with improved electrochemical stability and conductivity, facilitating reversible magnesium deposition and dissolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple mono-nuclei cationized magnesium salts are used in non-protonic electrolyte polar solvents, then the electrolyte structure is simple and cost is low, but a dense passivation coating forms that does not conduct magnesium ions, preventing reversible deposition and dissolution
Solution Approach 1:
The patent uses composite electrolyte salts containing both magnesium cations and aluminum or boron cations (e.g., Mg(AlCl4)2, Mg(BCl4)2) to create a composite material that prevents passivation coating formation while maintaining simple structure and low cost, resolving the contradiction between structural simplicity and ion conduction reliability
2Reliability
If dual-nuclei magnesium cations are used in electrolyte salts, then magnesium deposition and dissolution can occur reversibly, but the cations have large size that adversely affects ion conduction and the anions contain organic radicals with poor electrochemical stability
Solution Approach 1:
The patent extracts the essential function of dual-nuclei cations (preventing passivation) while removing the harmful aspects (large size, organic radicals). By using aluminum or boron cations instead of complex organic cations, the invention maintains the preventive function against passivation while achieving smaller ionic size and better electrochemical stability
3Reliability
If existing electrolyte salts with organic radicals are used, then magnesium can perform reversible deposition and dissolution, but the anions have poor electrochemical stability and the preparation is complicated and high in cost
Solution Approach 1:
The patent replaces expensive, complex organic electrolyte salts with simple inorganic electrolyte salts (Mg(AlCl4)2, Mg(BCl4)2) that are cheaper to manufacture, have better electrochemical stability, and can be prepared through simple mixing of magnesium halide with aluminum or boron halides, eliminating the need for complex organic synthesis
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 mono-nuclei cationized magnesium salt enables high ionic conductivity and efficient reversible magnesium deposition-dissolution, enhancing the performance and scalability of rechargeable magnesium batteries, with initial discharging capacity exceeding 700 mAh/g and cycle numbers greater than 20, while reducing synthesis complexity and cost.
Implementation Method 1
Lewis acid containing Mg2+ reacts with Lewis base to form a mono-nuclei cationized magnesium salt
Implementation Method 2
The passivation coating is a poor conductor of magnesium ions, preventing magnesium ions from passing through
Implementation Method 3
magnesium can perform deposition and dissolution in a reversible way
Data Source
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AI summary
The invention relates to a mono-nuclei cationized magnesium salt, a preparation method and applications thereof. The mono-nuclei cationized magnesium salt has a chemical formula of MgRnMX4-mYm, wherein R is a non-aqueous solvent molecule, M includes Al3+ and/or B3+, X and Y respectively include halide ion and halogenoid ion, n is any one integer selected in the range of 0∼6, and m is any one integer selected in the range of 0∼4. The mono-nuclei cationized magnesium salt provided by the invention has a simple structure and excellent electrochemical properties, and the preparation method thereof features low cost, integrated synthesis, accessible raw materials, simple preparation process, and simple scaled production. The provided mono-nuclei cationized magnesium salt is used as the electrolyte of the rechargeable batteries; the generated electrolyte solution has a high ionic conductivity, high reversible magnesium deposition-dissolution efficiency, excellent circulating performance and a high anode oxidation deposition potential. For example, when the electrolyte solution is applied to the magnesium batteries, the initial discharging capacity of the batteries can reach over 700 mAh/g, and the cycle number is greater than 20.