Fluorinated Electrolyte Additives for High-Temperature Li Battery Cycle Life
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in maintaining high-temperature stability and cycle-life characteristics due to electrolyte decomposition and resistance increase.
Innovation Solution
Incorporation of an electrolyte additive represented by Chemical Formula 1 or Chemical Formula 2, which forms a solid electrolyte interface (SEI) film on the negative electrode, preventing electrolyte decomposition and reducing internal resistance, along with additional additives to enhance high-temperature cycle-life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte is used, then battery can operate normally, but resistance increases and cycle-life deteriorates at high temperatures
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonate additive as an intermediary substance that mediates between the electrolyte and electrode surfaces. This additive preferentially decomposes to form stable fluorinated SEI films on the negative electrode and protective films on the positive electrode, preventing direct harmful interactions between the conventional electrolyte and electrodes at high temperatures, thereby improving cycle-life characteristics while maintaining high-temperature stability.
Solution Approach 2:
The patent modifies the electrolyte composition by incorporating fluorinated cyclic carbonate compounds with specific molecular structures (Formula 1 and Formula 2). This changes the chemical parameters of the electrolyte system, enabling formation of more thermally stable solid electrolyte interface films that resist decomposition at high temperatures, thus resolving the contradiction between temperature stability and cycle-life.
2Reliability
If electrolyte additive is added to improve high-temperature characteristics, then resistance increase is suppressed, but electrolyte composition becomes more complex
Solution Approach 1:
The fluorinated cyclic carbonate additive serves multiple functions simultaneously: it forms protective SEI films on the negative electrode, forms protective films on the positive electrode, suppresses electrolyte decomposition, and stabilizes resistance at high temperatures. This multi-functionality allows a single additive component to address multiple performance issues without significantly complicating the electrolyte formulation.
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 additive improves battery performance by suppressing resistance increase and enhancing cycle-life characteristics at high temperatures.
Implementation Method 1
Incorporation of an electrolyte additive represented by Chemical Formula 1 or Chemical Formula 2, which forms a solid electrolyte interface (SEI) film on the negative electrode, preventing electrolyte decomposition
Implementation Method 2
The electrolyte is for example, prepared by adding a lithium salt such as LiPF6, LiBF4, LiFSI, and the like in a mixed solvent of high dielectric cyclic carbonate such as propylenecarbonate, ethylenecarbonate, and the like and chain carbonate
Implementation Method 3
The electrolyte serves as a medium for moving lithium ions between negative and positive electrodes
Data Source
AI summary
Provided are an electrolyte additive represented by Chemical Formula 1 or Chemical Formula 2, and an electrolyte for a rechargeable lithium battery including the same.Details regarding Chemical Formula 1 and Chemical Formula 2 are as described in the specification.