Non-chlorinated Magnesium Electrolyte via Grignard-Borane Reaction
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Solution Overview
Problem
Current magnesium battery electrolytes are limited by low oxidative stability, leading to safety concerns and restricted voltage range due to dendrite formation and corrosion issues with non-noble metals, particularly stainless steel, which hampers the development of high voltage rechargeable magnesium batteries.
Innovation Solution
A non-chlorinated magnesium electrolyte is synthesized by reacting a Grignard reagent with a fluorinated aryl borane, resulting in a magnesium salt that is non-corrosive and compatible with stainless steel, allowing for higher voltage operation and improved electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional magnesium electrolytes (Mg(PF6)2, Mg(ClO4)2, Mg(TFSI)2) are used, then magnesium deposition can occur, but a blocking film forms on the anode surface that prevents successful deposition
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by using Grignard reagents (RMgX) instead of conventional magnesium salts, and by controlling the ratio of Grignard reagent to alkyl halide (0.95:1 to 1.05:1). This parameter change transforms the electrolyte chemistry to prevent blocking film formation while enabling reliable magnesium deposition.
Solution Approach 2:
The patent creates a composite electrolyte system combining Grignard reagents (RMgX) with alkyl halides (R'X) in specific ratios. This composite approach leverages the reactive magnesium source from Grignard while the alkyl halide modulates the chemistry to prevent blocking film formation, achieving both deposition and stability.
2Reliability
If Grignard reagents (EtMgBr, BuMgCl) are used as electrolytes, then magnesium deposition is achieved, but oxidative stability is limited to 1.3V vs. Mg which restricts cathode selection
Solution Approach 1:
The patent changes the chemical composition by introducing alkyl halides (R'X) with specific carbon chain lengths and structures into the electrolyte system. This compositional parameter change enhances the oxidative stability of the Grignard-based electrolyte, enabling operation at higher voltages compatible with a broader range of cathode materials.
3Stability of the object's composition
If magnesium organohaloaluminate electrolytes are used, then oxidative stability above 3.0V vs. Mg is achieved, but corrosiveness towards aluminum, nickel and stainless steel increases
Solution Approach 1:
The patent extracts the aluminum component from the electrolyte composition by using only Grignard reagents and alkyl halides, eliminating magnesium organohaloaluminate formation. This extraction removes the source of corrosiveness towards aluminum and stainless steel while maintaining high oxidative stability through the Grignard-alkyl halide system.
Solution Approach 2:
The patent employs a disposable Grignard reagent-based electrolyte system that does not form stable, corrosive complexes with metal components. The electrolyte can be consumed or replaced without causing long-term corrosion damage to battery components, particularly aluminum and stainless steel parts.
4Use of energy by moving object
If magnesium batteries operate at high voltages, then energy density increases, but dendrite formation and safety concerns arise
Solution Approach 1:
The patent changes the electrolyte composition parameters to use Grignard reagents with specific alkyl groups (R = Me, Et, Pr, Bu) combined with alkyl halides in controlled ratios. This parameter optimization enables high voltage operation that increases energy density while the specific chemistry prevents dendrite formation, maintaining safety.
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 new electrolyte system enhances oxidative stability, enabling higher voltage operation and compatibility with stainless steel, thus expanding the potential for high voltage cathodes and improving the safety and efficiency of magnesium batteries.
Implementation Method 1
A non-chlorinated magnesium electrolyte is synthesized by reacting a Grignard reagent with a fluorinated aryl borane
Implementation Method 2
Reports of effective magnesium electrodeposition from Grignard reagents in ethereal solutions date as far back as 1927
Implementation Method 3
Magnesium has a negative reduction potential of −2.356V vs NHE
Data Source
AI summary
A one-step method to prepare a magnesium electrolyte salt is provided. According to the method, the magnesium electrolyte is obtained by reacting a Grignard reagent and a fluorinated aryl borane. In addition, formation of monomeric or dimeric magnesium ion is determined by the choice of the Grignard reagent. The magnesium electrolyte may be non-chlorinated and non-corrosive. A magnesium battery containing the magnesium electrolyte is also provided.