Battery Electrolyte Additives for High-Voltage Cycle-Life Stability
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Solution Overview
Problem
Rechargeable lithium batteries face challenges with reduced cycle-life and increased resistance at high voltage and high temperature conditions.
Innovation Solution
An electrolyte composition for rechargeable lithium batteries, including a lithium salt, a non-aqueous organic solvent, a first additive with both hydrophilic and hydrophobic groups, and a second additive such as an oxalate borate compound substituted with a fluoro group, which improves the battery's high-voltage and high-temperature characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional electrolytes are used in rechargeable lithium batteries, then the battery can operate at high voltage and high temperature, but the cycle-life is reduced and resistance increases
Solution Approach 1:
The patent introduces a mediator substance (lithium difluoro(oxalato)borate additive) that acts as an intermediary between the electrolyte and electrode materials. This additive forms a protective interface layer that mediates the interaction between high-temperature conditions and the battery components, preventing direct harmful reactions while maintaining ionic conductivity, thus preserving cycle-life during high-temperature operation
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by incorporating specific fluorinated additives with controlled concentrations. This parameter change modifies the electrochemical window and stability characteristics of the electrolyte, enabling it to withstand high-temperature and high-voltage conditions without degrading battery reliability and cycle-life
2Power
If conventional electrolytes are used in rechargeable lithium batteries, then the battery can operate at high voltage, but resistance increases and performance degrades
Solution Approach 1:
The fluorinated lithium salt additive serves as an intermediary that forms a stable protective film on the electrode surface at high voltage conditions. This intermediary layer prevents direct contact between the electrolyte and electrode, eliminating harmful side reactions that would increase resistance, while still allowing efficient lithium ion transport to maintain high-voltage power output
3Use of energy by moving object
If high voltage and high temperature conditions are applied to rechargeable lithium batteries, then energy density is improved, but cycle-life is reduced
Solution Approach 1:
The patent applies beforehand cushioning by pre-forming a stable protective interface film on the electrode surfaces using fluorinated additives before the battery undergoes high voltage and high temperature cycling. This pre-formed protective layer cushions the electrodes against degradation from harsh operating conditions, allowing the battery to achieve high energy density while maintaining long cycle-life
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 the stability of the solid electrolyte interface (SEI) film, reduces lithium dendrite precipitation, and suppresses transition metal elution, thereby improving the battery's cycle-life and resistance at high voltage and high temperature conditions.
Implementation Method 1
a first additive represented by Chemical Formula 1... The first additive functions as a surfactant having both (e.g., simultaneously) hydrophilic and hydrophobic groups in one molecule
Implementation Method 2
a second additive represented by Chemical Formula 2... The second additive is an oxalate borate compound substituted with a fluoro group
Implementation Method 3
The electrolyte composition enhances the stability of the solid electrolyte interface (SEI) film, reduces lithium dendrite precipitation
Data Source
AI summary
An electrolyte for a rechargeable lithium battery includes 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:A rechargeable lithium battery includes a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and the electrolyte.