Lithium Battery Electrolyte Additive for Overcharge Stability
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Solution Overview
Problem
Lithium secondary batteries face instability and safety issues due to excessive lithium flow during overcharge and overvoltage, leading to performance degradation and increased internal resistance.
Innovation Solution
An electrolyte composition including a lithium salt, organic solvent, and a specific additive represented by Formula 1, which forms a protective film on the positive electrode, suppressing voltage rise and electrolyte decomposition, thereby enhancing overcharge characteristics and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additives are added to the electrolyte to solve overcharge and overvoltage instability, then safety is improved, but performance of the lithium secondary battery degrades
Solution Approach 1:
The patent modifies the chemical structure of the additive by introducing specific functional groups (cyano groups at R3 and R5 positions, fluorinated alkyl groups) to change its electrochemical properties. This structural parameter change allows the additive to form protective films at lower potentials, improving safety without the severe performance degradation associated with conventional additives.
Solution Approach 2:
The electrolyte uses a composite additive system combining multiple components with specific functional groups working synergistically. The combination of cyano-containing groups and fluorinated alkyl groups creates a composite molecular structure that provides both safety improvement and performance maintenance through cooperative effects in film formation and electrode protection.
2Reliability
If conventional additives are used to improve overcharge characteristics, then safety is enhanced, but internal resistance increases and performance deteriorates
Solution Approach 1:
The specially structured additive performs preliminary protective action by forming stable surface films on electrodes during normal operation before overcharge conditions occur. These pre-formed protective layers prevent excessive lithium deposition and electrolyte decomposition during overcharge events, improving safety without significantly increasing internal resistance.
Solution Approach 2:
The additive acts as an intermediary substance between the electrode and electrolyte, forming interfacial protective films that mediate the interaction during overcharge conditions. This intermediary layer prevents direct harmful reactions while maintaining ionic conductivity, thus improving overcharge characteristics without excessive internal resistance increase.
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 electrolyte effectively reduces gas generation and maintains battery performance, especially at high temperatures, by protecting the positive electrode and minimizing degradation.
Implementation Method 1
an additive represented by Formula 1... which forms a protective film on the positive electrode, suppressing voltage rise and electrolyte decomposition
Implementation Method 2
Lithium secondary batteries have three or more times higher energy density per unit weight than existing lead-acid batteries
Data Source
AI summary
An electrolyte for a lithium secondary battery and a lithium secondary battery including the electrolyte are provided. The electrolyte for a lithium secondary battery may include a lithium salt, an organic solvent, and an additive represented by Formula 1, where at least one selected from among R1 to R6 may be a C1-C5 alkyl group including a cyano group, and one or two selected from among R1 to R6 may each be a fluorinated C1-C5 alkyl group.