Battery Electrolyte Additives for Uniform SEI at High Temperature
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Solution Overview
Problem
Existing lithium secondary batteries face issues with high-temperature safety, performance degradation, and reduced lifespan due to uneven SEI coating films and improper electrolyte additives, leading to gas generation, increased resistance, and decreased capacity.
Innovation Solution
An electrolyte composition comprising a non-aqueous organic solvent, lithium salt, a primary additive represented by Formula 1, and secondary additives such as vinylene carbonate (VC) and fluoroethylene carbonate (FEC) forms a uniform coating on the electrode surfaces, enhancing the SEI film and improving high-temperature stability and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte additives are used, then battery operation is possible, but uneven SEI coating film forms leading to poor output characteristics and reduced high-temperature safety
Solution Approach 1:
The patent employs a composite electrolyte additive system combining multiple compounds (cyclic carbonate, chain carbonate, and fluoroethylene carbonate) in specific ratios. This composite approach creates a synergistic effect where each component contributes to forming a uniform SEI coating film with balanced properties, resolving the contradiction between film uniformity and high-temperature safety.
Solution Approach 2:
The patent optimizes the concentration ratios of different electrolyte additives (specifically 10-30% cyclic carbonate, 70-85% chain carbonate, and 0.5-5% fluoroethylene carbonate) to achieve the desired SEI film characteristics. By precisely controlling these compositional parameters, the invention achieves both uniform coating formation and enhanced high-temperature stability.
2Manufacturing precision
If electrolyte additive amount is increased to improve SEI film formation, then coating quality improves, but high-temperature reactions occur causing electrolyte decomposition and reduced battery lifespan
Solution Approach 1:
The patent identifies and optimizes the critical parameter of additive concentration, establishing that 0.5-5% fluoroethylene carbonate combined with specific cyclic and chain carbonate ratios achieves optimal SEI film formation without triggering detrimental high-temperature decomposition reactions, thus extending battery lifespan.
Solution Approach 2:
The patent replicates the successful SEI film formation mechanism observed in lower-temperature operations by carefully selecting additive compositions that maintain film quality across temperature ranges, effectively copying the beneficial low-temperature film properties to high-temperature conditions without the harmful side effects.
3Productivity
If high-temperature cycle characteristics are improved through electrolyte additives, then battery performance increases, but gas generation and metal ion elution occur reducing overall safety
Solution Approach 1:
The patent converts the potential harm of electrolyte additives at high temperatures into a benefit by selecting specific compounds (particularly fluoroethylene carbonate in controlled amounts) that, when used optimally, suppress gas generation and metal ion elution while enhancing cycle characteristics, thus turning a potentially harmful situation into a protective mechanism.
Solution Approach 2:
The composite electrolyte additive system works synergistically to simultaneously improve high-temperature cycle characteristics while suppressing harmful effects. The combination of cyclic carbonate, chain carbonate, and fluoroethylene carbonate creates a multi-functional SEI film that enhances performance without generating gas or facilitating metal ion elution.
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 solution reduces gas generation, prevents metal ion elution, and enhances battery performance and safety by forming a robust SEI film, improving high-temperature storage characteristics and lifespan.
Implementation Method 1
lithium gets highly reactive, thus creating a coating film on the surface of a negative electrode by reacting with a carbon electrode and forming Li 2 CO 3 , LiO, LiOH, etc. Such membrane is called a Solid Electrolyte Interface (SEI)
Implementation Method 2
it only passes through lithium ions by acting as an Ion Tunnel
Data Source
AI summary
The present invention describes an electrolyte composition with improved high temperature safety and a lithium secondary battery including the same, and the electrolyte composition containing a primary additive comprising a compound represented by Formula 1, and specific amount of a secondary additive that contains one or more of the cyclic carbonates, can not only reduce the generation of gas during secondary battery charge-discharge, but also improve storage characteristics and the lifespan characteristics under a high temperature condition by strengthening the SEI coating film on the surface of an electrode.