Mesoionic Electrolyte Ether Side Chains Lithium Metal Stability
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Solution Overview
Problem
Conventional lithium secondary batteries using ionic liquids are unstable with lithium metals, limiting their reliability due to the chemical structure of these liquids, which leads to decomposition and contact between the anion part and lithium metals.
Innovation Solution
A liquid electrolyte for lithium batteries comprising a mesoionic compound with an ether group in its side chain, which keeps the anion part away from lithium metals, enhancing stability by preventing direct contact and reaction, and including a lithium salt at a specific concentration for improved ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ionic liquids are used as liquid electrolyte, then reliability is improved due to non-combustible and non-volatile properties, but stability to lithium metals deteriorates due to chemical structure leading to decomposition and anion contact with lithium metals
Solution Approach 1:
The patent modifies the chemical structure of the ionic liquid by introducing ether groups into the side chains of the cation. This structural parameter change increases the distance between the anion and lithium metal surface, preventing direct contact and decomposition reactions, thereby improving stability to lithium metals while maintaining the inherent safety advantages of ionic liquids
Solution Approach 2:
The patent creates a composite ionic liquid system combining cations with ether-containing side chains and appropriate anions. This composite structure leverages the benefits of both the ionic liquid framework (non-combustible, non-volatile) and the ether group functionality (protective barrier, enhanced stability), achieving improved reliability and stability simultaneously
2Reliability
If ionic liquid is used as liquid electrolyte, then safety is improved due to non-combustible properties, but chemical stability deteriorates leading to decomposition
Solution Approach 1:
The patent changes the chemical parameters of the ionic liquid by incorporating ether groups at specific positions in the side chains. This modification creates a protective layer that reduces chemical reactivity and prevents decomposition reactions, thereby improving chemical stability while preserving the safety advantages of the ionic liquid base
3Reliability
If conventional ionic liquid structure is used, then ion conductivity is maintained at acceptable levels, but stability to lithium metals deteriorates due to direct contact between anion and lithium metals
Solution Approach 1:
The patent introduces ether groups as intermediary structures in the side chains of the ionic liquid cation. These ether groups act as a physical barrier or mediator between the anion and the lithium metal surface, preventing direct harmful contact while allowing ionic conduction to proceed through the electrolyte medium
Solution Approach 2:
The patent optimizes the position and number of ether groups in the side chains to balance two competing requirements: maintaining sufficient ion conductivity for battery operation and creating adequate distance/barrier to prevent anion-lithium metal contact. The specific structural parameters are tuned to achieve both objectives simultaneously
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 mesoionic compound-based electrolyte exhibits excellent stability to lithium metals, reducing decomposition and maintaining ion conductivity, thereby improving the reliability of lithium batteries.
Implementation Method 1
when comparing an oxygen atom (—O−) in the anion part of the mesoionic compound to an ether oxygen atom in the side chain thereof, the ether oxygen atom in the side chain is closer to lithium metals than the oxygen atom in the anion part; therefore, when the liquid electrolyte for lithium batteries is used in a lithium battery, contact between the anion part and lithium metals can be prevented
Implementation Method 2
Lithium ions (Li+) generated by the reaction of the formula (I) are transferred by electro-osmosis from the anode side to the cathode side through an electrolyte sandwiched between the anode and the cathode
Data Source
AI summary
The present invention is to provide: a liquid electrolyte for batteries, which has excellent stability to lithium metals; a method for producing the liquid electrolyte; and a lithium battery comprising the liquid electrolyte. Presented is a liquid electrolyte for lithium batteries, wherein the liquid electrolyte comprises a mesoionic compound represented by the following general formula (1):wherein R1 is an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and R2 is a group represented by any one of the following general formulae (2), (3) and (4): General Formula (2): —ClH2l—(OCH2)m—CnH2n+1; General Formula (3): —CxH2x—(CH2OCH2)y—CzH2z+1; and General Formula (4): —CpH2p—(C2H4OCH2)q—CrH2r+1.