Lithium Battery Electrolyte Additives for Stable SEI at High Voltage
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Solution Overview
Problem
Rechargeable lithium batteries face challenges with reduced cycle-life and increased resistance at high voltage and/or high temperature.
Innovation Solution
An electrolyte for rechargeable lithium batteries is developed, comprising a lithium salt, a non-aqueous organic solvent, a first additive with both hydrophilic and hydrophobic groups, and a second additive that stabilizes the lithium salt, improving wettability and forming a stable SEI film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytes are used in rechargeable lithium batteries, then the batteries can operate, but the cycle-life is reduced and resistance increases at high voltage and/or high temperature
Solution Approach 1:
The patent modifies the chemical composition parameters of the electrolyte by introducing specific additives (lithium difluoro(oxalato)borate and lithium fluoroacetate) to change the electrochemical properties, forming stable SEI films that improve high-temperature stability and extend cycle-life
Solution Approach 2:
The patent creates a composite electrolyte system combining lithium salt, non-aqueous organic solvent, and multiple additives with complementary functions, where the additives work synergistically to form protective films that enhance reliability under high-temperature conditions
2Reliability
If conventional electrolytes are used in rechargeable lithium batteries, then the batteries can operate, but resistance increases at high voltage and/or high temperature
Solution Approach 1:
The additives in the electrolyte perform preliminary action by forming stable solid electrolyte interface (SEI) films on the electrode surfaces before high-voltage operation begins, preventing subsequent degradation and resistance increase under electrochemical stress
Solution Approach 2:
The lithium difluoro(oxalato)borate and lithium fluoroacetate act as intermediary substances that form protective interface layers between the electrolyte and electrodes, mediating the interaction and preventing direct harmful reactions that would increase resistance
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 enhances high-voltage and high-temperature characteristics by suppressing lithium dendrite precipitation, reducing transition metal elution, and maintaining a stable SEI film, thereby improving cycle-life and reducing resistance.
Implementation Method 1
a non-aqueous organic solvent; a lithium salt... electrical energy is produced through oxidation and reduction reactions if lithium ions are intercalated/deintercalated
Implementation Method 2
a first additive represented by Chemical Formula 1... improving wettability
Implementation Method 3
a second additive represented by Chemical Formula 2... forming a stable SEI film... suppressing lithium dendrite precipitation
Data Source
AI summary
Disclosed are an electrolyte for a rechargeable lithium battery and a rechargeable lithium battery including the same, the electrolyte for a rechargeable lithium battery including a lithium salt; a non-aqueous organic solvent; a first additive represented by Chemical Formula 1; and a second additive represented by Chemical Formula 2. The description of each of the chemical formulas is provided in the specification.