Silyloxy Ionic Liquid Electrolyte for Safe Lithium Batteries
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Solution Overview
Problem
Current electrolytes for lithium-ion batteries face challenges such as ignitability, overheating, and explosion risks due to organic solvents, and existing ionic liquids lack sufficient thermal, electrochemical, and chemical stability, particularly with graphite electrodes, limiting their practical application.
Innovation Solution
Development of a lithium or lithium-ion battery electrolyte using an ionic compound with a silyloxy group attached to the cation or anion, which forms a stable ionic liquid with improved thermal and electrochemical stability, enabling reversible charging-discharging at ambient temperature without significant decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic solvents are used in electrolytes, then conductivity and electrochemical performance are improved, but safety deteriorates due to ignitability and explosion risks
Solution Approach 1:
The patent changes the fundamental parameter of the solvent system from organic molecular solvents to ionic compounds, transforming the chemical nature of the electrolyte while maintaining ionic conductivity. This parameter change eliminates the flammability issue inherent in organic solvents while preserving electrochemical functionality.
Solution Approach 2:
The patent creates a copy of the beneficial properties of organic solvents (high conductivity, good electrochemical performance) using ionic compounds that mimic these properties without the harmful flammability characteristic. The ionic liquid electrolyte copies the functional advantages while eliminating the safety drawbacks.
2Object-affected harmful factors
If existing ionic liquids are used to improve safety, then thermal stability is improved, but electrochemical stability and compatibility with graphite electrodes deteriorate
Solution Approach 1:
The patent employs composite ionic liquid formulations combining multiple cation types (imidazolium, pyridinium, piperidinium, morpholinium, ammonium) with various anions (BF4-, PF6-, CF3SO3-, TFSI-). This composite approach achieves both thermal stability inherent to ionic liquids and improved electrochemical stability through synergistic interactions between different ionic components.
Solution Approach 2:
The patent introduces specific functional groups and substituents at localized positions within the ionic liquid structure to enhance electrochemical stability. The cations contain specific ring structures and substituents that provide local chemical stability at the electrode interface, while the overall ionic liquid structure maintains thermal stability.
3Reliability
If imidazolium-based ionic liquids are used to achieve low viscosity and high conductivity, then electrochemical window is improved, but stability at graphite electrode interface deteriorates due to reduction and decomposition
Solution Approach 1:
The patent segments the ionic liquid system into multiple cation types with different stability characteristics. By using a mixture or alternative cations (pyridinium, piperidinium, morpholinium, ammonium) alongside or instead of imidazolium, the system divides the functional requirements: some cations provide conductivity while others provide interface stability, preventing the decomposition issues of pure imidazolium systems.
Solution Approach 2:
The patent introduces stable ionic liquid components that act as intermediaries between the graphite electrode and the electrolyte system. These intermediary ionic species form stable interface layers that prevent direct harmful interactions between graphite and unstable ionic liquid components, mediating the interface to achieve both conductivity and stability.
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 silyloxy-functionalized ionic compounds provide enhanced stability and compatibility with graphite electrodes, allowing for efficient and reversible charge-discharge cycles at ambient temperature, reducing the risk of overheating and explosion, and improving the overall performance of lithium-ion batteries.
Implementation Method 1
ionic liquids have low viscosities and high conductivities
Implementation Method 2
Electrochemical intercalation of lithium into graphite anodes in 1-ethyl-3-methylimidazolium (EMI) based ionic liquids
Implementation Method 3
improved thermal and electrochemical stability, enabling reversible charging-discharging at ambient temperature without significant decomposition
Implementation Method 4
stabilize and protect the interface between a carbon negative electrode and the ionic liquid phase against an undesirable irreversible reaction with the ionic liquid component
Data Source
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AI summary
There is provided an ionic compound having attached thereto a silyloxy group. There is also provided methods of making this ionic compound as well as electrolytes, electrochemical cells and capacitors comprising this ionic compound.