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 achieving high output characteristics, high-temperature storage stability, and safety, particularly in terms of resistance increase and cycle-life characteristics.
Innovation Solution
An electrolyte composition for rechargeable lithium batteries is developed, comprising a non-aqueous organic solvent, a lithium salt, and an additive mixture of a cesium salt compound and a bicyclic sulfate-based or sulfite-based compound, which forms a solid electrolyte interface film to control lithium ion elution and suppress resistance increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte compositions are used, then the battery can operate, but resistance increases during high-temperature storage leading to poor cycle-life characteristics
Solution Approach 1:
The patent applies preliminary action by introducing a cesium salt compound that pre-forms a stable solid electrolyte interface (SEI) film on the electrode surfaces before battery operation. This pre-formed film acts as a protective barrier that prevents subsequent resistance increase during high-temperature storage and cycling, thereby improving cycle-life characteristics without sacrificing initial performance
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by incorporating specific compounds (cesium salt compound with imide or phosphate anions, and bicyclic sulfate/sulfite compounds) at optimized concentrations (0.05-3.0 wt% for cesium salt, 0.1-10.0 wt% for bicyclic compound). These parameter changes result in a fundamentally different SEI film composition that exhibits superior thermal stability and lower resistance growth rates at elevated temperatures
2Power
If high output characteristics are pursued, then power density increases, but stability and safety deteriorate
Solution Approach 1:
The patent applies local quality by creating a heterogeneous electrolyte system where different components perform specialized functions: the cesium salt compound forms a stable protective SEI film on electrode surfaces (local protection function), while the bicyclic sulfate/sulfite compounds enhance bulk electrolyte conductivity and output characteristics. This spatial and functional differentiation allows simultaneous achievement of high power output and improved stability
Solution Approach 2:
The patent employs composite materials by combining multiple electrolyte components (cesium salt compound, bicyclic sulfate/sulfite compound, lithium salt, and organic solvents) into a synergistic electrolyte system. The composite nature of this electrolyte provides both the high conductivity needed for power output and the stable SEI film formation required for safety and stability
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 enhances cycle-life characteristics and safety by reducing resistance increase during high-temperature storage and improving output characteristics, leading to a rechargeable lithium battery with improved performance and stability.
Implementation Method 1
an additive mixture of a cesium salt compound and a bicyclic sulfate-based or sulfite-based compound, which forms a solid electrolyte interface film to control lithium ion elution and suppress resistance increase
Implementation Method 2
The electrolyte serves as a medium for moving lithium ions between the negative electrode and the positive electrode
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 a cesium salt compound, and the second compound represented by Chemical Formula 1, and a rechargeable lithium battery including the same.Details of Chemical Formula 1 are as described in the specification.