Lithium Battery Electrolyte Additive for SEI Film Formation
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in achieving improved safety and cycle-life characteristics due to limitations in electrolyte stability and decomposition issues.
Innovation Solution
An electrolyte composition for rechargeable lithium batteries is developed, including a lithium salt, a non-aqueous organic solvent, and an additive represented by Chemical Formula 1, which forms a solid electrolyte interface (SEI) protection film on electrodes, enhancing stability and safety through the inclusion of functional groups like —CN, —NC, —NCS, and —SCN, and optionally other additives such as vinylene carbonate or metal fluorides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytes are used in rechargeable lithium batteries, then the battery can operate, but the cycle-life and safety characteristics are insufficient due to electrolyte decomposition
Solution Approach 1:
The patent introduces a specific additive compound as an intermediary substance that mediates between the electrolyte and electrode. This additive forms a protective interface layer that prevents direct harmful interactions, thereby improving cycle-life characteristics while maintaining electrolyte stability. The additive acts as a buffer that suppresses decomposition reactions.
Solution Approach 2:
The patent modifies the electrolyte composition by changing the chemical parameters - specifically adding compounds with particular functional groups (—CN, —NC, —NCS, —SCN) at optimized concentrations (0.1-10 parts by weight per 100 parts solvent). This parameter change transforms the electrolyte's properties to enhance both stability and cycle-life performance.
2Reliability
If conventional electrolytes are used in rechargeable lithium batteries, then the battery can operate, but safety characteristics are insufficient due to decomposition issues
Solution Approach 1:
The patent applies preliminary anti-action by pre-forming a protective solid electrolyte interface (SEI) film on the electrode surfaces using the additive compound before harmful decomposition can occur. This pre-formed protective layer prevents subsequent decomposition reactions and safety issues during battery operation.
Solution Approach 2:
The patent converts the potentially harmful decomposition reactions into beneficial effects. The additive compound undergoes controlled decomposition first to form a stable protective layer, and any further decomposition is prevented. Thus, the decomposition process is transformed from a harmful event into a beneficial film-forming mechanism that enhances safety.
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 improves the cycle-life characteristics and safety of rechargeable lithium batteries by suppressing electrolyte decomposition and forming protective films on electrodes, leading to better performance and penetration safety.
Implementation Method 1
which forms a solid electrolyte interface (SEI) protection film on electrodes, enhancing stability and safety
Implementation Method 2
a positive electrode including a positive active material capable of intercalating/deintercalating lithium and a negative electrode including a negative active material capable of intercalating/deintercalating lithium
Implementation Method 3
Batteries transform chemical energy generated from an electrochemical redox reaction (a reduction-oxidation reaction) of a chemical material in the battery into electrical energy
Data Source
AI summary
An electrolyte for a rechargeable lithium battery includes a lithium salt, a non-aqueous organic solvent, and an additive, where the additive includes a compound represented by Chemical Formula 1. A rechargeable lithium battery including the electrolyte includes a positive electrode including a positive active material, a negative electrode including a negative active material, and the electrolyte.