Electrolyte for rechargeable lithium battery and rechargeable lithium battery including the same
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in maintaining high-temperature characteristics, cycle-life, and safety due to increased resistance and capacity degradation, which are not adequately addressed by existing electrolytes.
Innovation Solution
An electrolyte composition for rechargeable lithium batteries is introduced, comprising a non-aqueous organic solvent, a lithium salt, and an additive mixture of an imide cesium salt compound and a crown ether compound, which forms a stable solid electrolyte interface (SEI) film on the negative electrode, improving solubility and reducing internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytes are used in rechargeable lithium batteries, then basic battery operation is achieved, but high-temperature storage characteristics and cycle-life deteriorate due to increased resistance and capacity degradation
Solution Approach 1:
The patent introduces a novel additive composition with specific chemical structure parameters (imide cesium salt with fluoroalkyl groups combined with crown ether) to change the electrolyte's chemical composition parameters. This enables the formation of a stable SEI film that resists degradation at high temperatures, directly addressing the resistance increase problem while improving high-temperature storage characteristics
Solution Approach 2:
The patent uses a composite additive system combining two different compounds (imide cesium salt and crown ether) in specific weight ratios (1:4 to 1:16). This composite approach creates synergistic effects where the combination provides superior high-temperature stability and resistance suppression compared to individual additives, resolving the contradiction between reliability and compositional stability
2Duration of action of stationary object
If conventional electrolytes are used in rechargeable lithium batteries, then basic battery operation is achieved, but cycle-life characteristics deteriorate due to capacity degradation
Solution Approach 1:
The additive composition performs preliminary action by forming a stable solid electrolyte interface (SEI) film on the electrode surfaces before battery operation begins. This pre-formed protective film prevents subsequent capacity degradation during cycling, thereby extending cycle-life characteristics while minimizing substance loss
Solution Approach 2:
The patent modifies the electrolyte's chemical composition by introducing specific additives that change the SEI film formation parameters. This enables the SEI film to maintain stability over extended cycling periods, preventing capacity degradation and improving cycle-life characteristics
3Reliability
If conventional electrolytes are used in rechargeable lithium batteries, then basic battery operation is achieved, but safety deteriorates at high temperatures due to increased resistance
Solution Approach 1:
The patent introduces additives with specific chemical parameters (imide cesium salt containing fluoroalkyl groups and crown ether) that change the electrolyte's thermal stability parameters. This enables the formation of a heat-resistant SEI film that suppresses resistance increase at elevated temperatures, improving safety while maintaining operational characteristics
Solution Approach 2:
The patent converts the potentially harmful effect of high temperature into a beneficial outcome by using temperature-stable additive compounds that form exceptionally stable SEI films. These films utilize the thermal energy environment to maintain their structural integrity, transforming high-temperature conditions from a safety risk into a demonstration of enhanced battery performance
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 composition effectively suppresses resistance increase and enhances high-temperature storage characteristics, leading to improved cycle-life and safety of rechargeable lithium batteries by forming a more stable SEI film and reducing side reactions.
Implementation Method 1
an additive mixture of an imide cesium salt compound and a crown ether compound, which forms a stable solid electrolyte interface (SEI) film on the negative electrode
Implementation Method 2
The electrolyte composition effectively suppresses resistance increase and enhances high-temperature storage characteristics, leading to improved cycle-life and safety of rechargeable lithium batteries by forming a more stable SEI film and reducing side reactions
Data Source
AI summary
Provided are an electrolyte for a rechargeable lithium battery including a non-aqueous organic solvent, a lithium salt, and an additive, wherein the additive is a composition including a first compound and a second compound, the first compound is an imide cesium salt compound represented by Chemical Formula 1, and the second compound is a crown ether compound represented by Chemical Formula 2.Details of Chemical Formulas 1 and 2 are as described in the specification.