Ionic Liquid Hydrogen Storage Phase Separation
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Solution Overview
Problem
Ionic liquids used for hydrogen storage in borohydride/borate systems face challenges with increasing melting points and viscosities as cation molecular weight decreases, leading to stability issues at elevated temperatures and phase separation problems during hydrogen release and recycling.
Innovation Solution
A method involving a recycling process with a phase separation inducer to separate recycled hydrogen storing borohydride ionic liquids from byproducts, maintaining a stable, homogeneous aqueous solution, and using specific cations and anions to control viscosity and phase behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the molecular weight of the cation is decreased to increase hydrogen storage density, then the hydrogen storage capacity is improved, but the melting point and viscosity increase leading to stability problems and phase separation
Solution Approach 1:
The patent changes the molecular weight parameter of the cation to optimize hydrogen storage density while managing the associated increase in melting point and viscosity. By selecting specific cation sizes and structures, the system achieves high hydrogen storage capacity while maintaining adequate operational stability.
Solution Approach 2:
The patent employs composite ionic liquid systems combining specific cations with borohydride anions. This composite approach allows optimization of both storage density and stability by selecting compatible ion pairs that mitigate the adverse effects of low molecular weight cations.
2Quantity of substance
If the molecular weight of the cation is decreased to increase hydrogen storage density, then the hydrogen storage capacity is improved, but phase separation occurs during hydrogen release and recycling
Solution Approach 1:
The patent adjusts cation molecular weight and structure parameters to achieve optimal phase behavior. By carefully selecting cation size and hydrophobicity, the system maintains homogeneity during hydrogen release and recycling operations while preserving high storage density.
Solution Approach 2:
The patent introduces phase separation inducers as intermediary substances to control phase behavior during recycling. These intermediaries facilitate controlled phase separation when needed while maintaining system homogeneity during storage and release operations.
3Ease of operation
If diluents are added to decrease melting point and viscosity, then the fluidity is improved, but the hydrogen storage capacity decreases
Solution Approach 1:
The patent optimizes the composition parameters of the ionic liquid system to achieve adequate fluidity without excessive dilution. By adjusting the ratio of ionic liquid components and selecting appropriate cation structures, the system maintains pumpability while preserving high hydrogen storage capacity.
Solution Approach 2:
The patent applies local quality modifications by selecting specific cation structures with appropriate side chain lengths and branching. This allows optimization of local molecular interactions to reduce viscosity without requiring bulk dilution, thereby maintaining overall hydrogen storage capacity.
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
Enables efficient hydrogen storage and release with improved stability and phase separation, allowing for a secure and efficient hydrogen storage medium suitable for automotive applications.
Implementation Method 1
ionic liquids which are particularly useful for storing and releasing hydrogen, e.g. in a borohydride/borate system
Implementation Method 2
A method involving a recycling process with a phase separation inducer to separate recycled hydrogen storing borohydride ionic liquids from byproducts
Data Source
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AI summary
Method of storing hydrogen by forming a first ionic liquid by inducing a borohydride in a second ionic liquid comprising a cation and an anion comprising borate, and forming the second ionic liquid by releasing the hydrogen out of the first ionic liquid by using water and/or a catalyst, which method is characterized in that the first and the second ionic liquid are both water miscible and the second ionic liquid is separated, particularly is salted out, from solution in water by adding a separation inducer; certain ionic liquids for storing and releasing hydrogen comprising a borohydride or for preparing a ionic liquid for storing and releasing hydrogen comprising a borate; and a process for preparing ionic liquids for storing and releasing hydrogen comprising a borohydride.