Ternary Eutectic Electrolyte for Thermal Stability in Secondary Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electrolytes for lithium secondary batteries face issues with thermal and chemical stability, leading to decomposition and degradation due to electrochemical reactions beyond the electrochemical window, and are prone to high volatility and ignitability.
Innovation Solution
A ternary eutectic mixture is developed by adding a carbonate-based compound to a binary eutectic mixture containing an amide group-containing compound and an ionizable lithium salt, with a molar ratio of 2-6:1, which forms a passivation layer and consumes overcharged current, resulting in improved thermal stability and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional organic solvents are used as electrolytes, then high ion conductivity is achieved, but thermal stability and flame resistance deteriorate due to high volatility and ignitability
Solution Approach 1:
The patent uses a composite electrolyte system combining ionic liquid and carbonate-based compound, where the ionic liquid provides thermal stability and flame resistance while the carbonate-based compound maintains ion conductivity. This composite approach allows both contradictory requirements to be satisfied simultaneously.
2Object-affected harmful factors
If noninflammable ionic liquid is used as electrolyte, then flame resistance is improved, but ion conductivity deteriorates due to high viscosity
Solution Approach 1:
The patent changes the physical parameters of the ionic liquid by adding a carbonate-based compound, which reduces the viscosity and enhances the ion conductivity while maintaining the flame resistance properties of the ionic liquid component.
3Quantity of substance
If charge potential increases to improve capacity, then structural stability of cathode deteriorates, leading to oxygen generation and overheating
Solution Approach 1:
The electrolyte system provides a protective environment that cushions against the degradation effects of high charge potentials, preventing structural instability and oxygen generation at the cathode by maintaining stable electrochemical conditions.
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 ternary eutectic mixture enhances the battery's safety and quality by minimizing decomposition, extending the drive voltage range, and providing flame resistance, while maintaining high ion conductivity and stability across a broad temperature range.
Implementation Method 1
a first compound capable of forming a passivation layer by being reduced upon a first charge at a higher potential vs. lithium potential (vs. Li/Li+) than the lowest limit of the electrochemical window of the ternary eutectic mixture
Implementation Method 2
conductivity of lithium ions decreases due to high viscosity of the ionic liquid
Data Source
Figure 1~2
Figure 3~4
AI summary
Disclosed is a secondary battery including a cathode, an anode, a separator, and an electrolyte, wherein the electrolyte includes a ternary eutectic mixture prepared by adding (c) a carbonate-based compound to a eutectic mixture containing (a) an amide group-containing compound and (b) an ionizable lithium salt, and the carbonate-based compound is included in an amount of less than 50 parts by weight based on 100 parts by weight of the electrolyte. The use of the disclosed ternary eutectic mixture having flame resistance, chemical stability, high conductivity, and a broad electrochemical window, as the electrolyte material, improves both the thermal stability and quality of the battery.