Lithium Battery Electrolyte Additives for High-Temperature Stability
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Solution Overview
Problem
Lithium secondary batteries face challenges in maintaining high-temperature performance and lifespan due to electrolyte decomposition and viscosity issues, with existing additives failing to completely prevent decomposition and ion conductivity reduction.
Innovation Solution
Incorporating polyethyleneglycol diglycidylether into the electrolyte mixture, specifically with a composition of ethylene carbonate, ethylmethyl carbonate, diethyl carbonate, lithium salt, vinylene carbonate, and propylene sulfone, to reduce decomposition reactions and ion conductivity issues at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cyclic carbonates with high polarity are used to dissociate lithium ions, then ion conductivity is improved, but viscosity increases
Solution Approach 1:
The patent combines cyclic carbonates (EC, PC) with linear carbonates (DMC, DEC, EMC) in a specific ratio to create an electrolyte mixture that achieves both high ion conductivity and low viscosity. The cyclic carbonates provide high polarity for lithium ion dissociation, while the linear carbonates reduce the overall viscosity of the mixture, resolving the contradiction between these two properties.
Solution Approach 2:
The electrolyte is formulated as a composite system containing multiple carbonate components (cyclic and linear) along with specific additives (vinylene carbonate, ethylene sulfite, propylene sulfone). This composite approach allows the electrolyte to simultaneously achieve high ion conductivity from the cyclic carbonates and low viscosity from the linear carbonates and additives.
2Reliability
If vinylene carbonate is added to form protection film, then electrolyte decomposition is inhibited, but it cannot completely prevent decomposition at high temperatures
Solution Approach 1:
The patent uses a composite additive system containing vinylene carbonate (0.01-5 wt%), ethylene sulfite (0.01-5 wt%), and propylene sulfone (0.01-5 wt%) together in the electrolyte. This combination of additives works synergistically to form a more robust protection film on electrodes and provide superior thermal stability compared to using vinylene carbonate alone, effectively preventing decomposition even at high temperatures.
Solution Approach 2:
The additives (vinylene carbonate, ethylene sulfite, propylene sulfone) act as intermediaries that form protective films on the electrode surfaces. These films serve as barriers that prevent direct contact between the electrolyte and electrodes, thereby inhibiting decomposition reactions. The sulfone compounds particularly enhance the thermal stability of this protective layer.
3Reliability
If EC is used to form stable protection film, then anode stability is improved, but EC shows increased activity at high temperature causing decomposition
Solution Approach 1:
The electrolyte uses a composite formulation combining EC with linear carbonates (DMC, DEC, EMC) and additive compounds (vinylene carbonate, ethylene sulfite, propylene sulfone). This composite system maintains the beneficial film-forming properties of EC at the anode while the linear carbonates and sulfone additives suppress EC's high-temperature decomposition activity, allowing EC to function effectively across a wider temperature range.
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
This configuration significantly reduces gas generation, inhibits thickness swelling, and enhances safety by minimizing capacity reduction and performance deterioration, especially at elevated temperatures, while maintaining comparable performance to conventional batteries.
Implementation Method 1
The non-aqueous electrolyte is a medium through which the lithium ions move between the anode and the cathode
Implementation Method 2
such ester compound as an additive is decomposed at either an anode or a cathode and forms a film on a surface of the electrode so as to inhibit decomposition of the electrolyte
Data Source
Figure 1~2
Figure 3
AI summary
Provided is a secondary battery containing polyalkyleneglycol diglycidylether represented by formula I added in a predetermined amount to an electrolyte for the battery. The secondary battery containing the above additive exhibits remarkably improved high-temperature characteristics, prevents deterioration in rate characteristics and cycle characteristics, and considerably reduces thickness swelling of the battery so as to prevent battery leakage, ultimately enhancing safety of the battery.