Lithium Battery Electrolyte Flame Retardancy via Composite Additives
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in maintaining performance while ensuring safety, as existing electrolytes often compromise between flame retardancy and battery performance, and are prone to deterioration when exposed to high temperatures.
Innovation Solution
An electrolyte composition comprising a lithium salt, an organic solvent, a sulfur-containing compound, a phosphazene compound, and a nitrile-based compound, which work together to enhance oxidation stability, flame retardancy, and ion conductivity, forming a solid electrolyte interphase film and capturing oxygen to prevent combustion, thus maintaining battery performance and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a self-extinguishing material is added to the electrolyte to improve flame retardancy, then flame retardancy is improved, but battery performance deteriorates
Solution Approach 1:
The patent uses a composite electrolyte system combining four specific components: a sulfur-containing compound ( Formula 1), a phosphazene compound (Formula 2), a nitrile-based compound (Formula 6), and a sultone-based compound (Formula 9 or 10). This composite approach allows each component to contribute different functions - the sulfur-containing compound provides flame retardancy while the phosphazene and nitrile compounds maintain ion conductivity and battery performance, resolving the contradiction between safety and performance
Solution Approach 2:
The patent optimizes the concentration parameters of each additive component within specific ranges (0.1-20 parts by weight relative to 100 parts by weight of organic solvent). By carefully controlling these parameters, the electrolyte achieves both flame retardancy and acceptable battery performance, transforming the trade-off into a balanced solution through parameter optimization
2Reliability
If existing electrolyte compositions are used to maintain battery performance, then ion conductivity is maintained, but flame retardancy is insufficient
Solution Approach 1:
The patent employs a multi-component additive system where each compound serves a specific function. The phosphazene compound and nitrile-based compound work together to maintain ion conductivity and battery performance, while the sulfur-containing compound provides flame retardancy. This composite strategy eliminates the need to choose between performance and safety
Solution Approach 2:
The sultone-based compound acts as an intermediary that forms protective films on electrode surfaces, which improves high-temperature stability and prevents decomposition reactions. This mediator allows the electrolyte to maintain performance characteristics while enabling the use of flame-retardant additives
3Temperature
If the electrolyte is exposed to high temperatures, then battery operation continues, but the electrolyte deteriorates and stability decreases
Solution Approach 1:
The sultone-based compound and phosphazene compound react preferentially at high temperatures to form stable protective films on electrode surfaces before electrolyte decomposition can occur. This preliminary protective action prevents the electrolyte from deteriorating under thermal stress, maintaining both stability and operability at elevated temperatures
Solution Approach 2:
The patent optimizes the concentration of heat-stable compounds (sultone-based and phosphazene compounds) within specific ranges to enhance high-temperature stability. By adjusting these parameters, the electrolyte maintains its compositional stability and prevents degradation even when exposed to high operating temperatures
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 significantly improves flame retardancy, ion conductivity, and high-temperature stability, ensuring excellent performance and safety of rechargeable lithium batteries by reducing the likelihood of fires and maintaining cycle-life characteristics.
Implementation Method 1
forming a solid electrolyte interphase film
Implementation Method 2
the self-extinguishing material reacts with active radicals, for example, H and OH, produced by the combustion reaction and suppresses the radical chain reaction
Implementation Method 3
capturing oxygen to prevent combustion
Implementation Method 4
The electrolyte may include an organic solvent in which a lithium salt is dissolved
Data Source
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Figure 2B
AI summary
An electrolyte for a rechargeable lithium battery comprising a lithium salt, an organic solvent and an additive, where the additive includes a sulfur-containing compound represented by Chemical Formula 1, a phosphazene compound represented by Chemical Formula 2, and a nitrile-based compound. A rechargeable lithium battery comprising the electrolyte. In Chemical Formulae 1 and 2, each substituent is the same as defined in the detailed description.