Battery Electrolyte Composition for Fast Charging and Heat Stability
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Solution Overview
Problem
Existing electrolytes struggle to achieve both high wettability and high-temperature stability under high winding pressure, and fail to meet fast-charging requirements due to poor chemical stability and increased viscosity.
Innovation Solution
The electrolyte is formulated with specific ratios of cyclic and linear carbonates, carboxylic esters, and additives to maintain a low overall viscosity while ensuring chemical stability, comprising lithium salts, cyclic carbonates like fluoroethylene carbonate, and additives like 1,3-propane sultone to form a stable solid electrolyte interphase film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the content of low-viscosity solvent is increased to improve electrolyte wettability, then the wettability is improved, but the chemical stability deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a carboxylic ester component and optimizing the ratios of cyclic carbonate, linear carbonate, and carboxylic ester. This parameter optimization achieves the dual goal of maintaining low viscosity for good wettability while ensuring chemical stability for fast charging performance.
Solution Approach 2:
The patent creates a composite electrolyte system combining four types of solvents (cyclic carbonate, linear carbonate, carboxylic ester, and low-viscosity solvent) with specific mass percentage ranges. This composite approach allows the electrolyte to simultaneously achieve low viscosity for wettability and chemical stability, resolving the contradiction between these two properties.
2Speed
If the viscosity of electrolyte is reduced to improve fast-charging capability, then the fast-charging capability is improved, but the high-temperature storage performance deteriorates
Solution Approach 1:
The patent optimizes the viscosity parameter by carefully controlling the content of low-viscosity solvents within specific ranges (5%-20% for linear carbonate, 10%-30% for carboxylic ester) while maintaining chemical stability through the synergistic composition of multiple solvent types. This balanced parameter optimization enables both fast charging and high-temperature storage performance.
Solution Approach 2:
The patent employs a composite solvent system with four components in optimized ratios, where each component contributes different properties. The carboxylic ester (20%-40%) and cyclic carbonate (60%-70%) provide chemical stability, while the controlled addition of low-viscosity linear carbonate and carboxylic ester maintains low overall viscosity, achieving both fast charging and thermal stability.
3Force
If the content of carboxylic ester is increased to reduce viscosity, then the viscosity is reduced, but the chemical stability deteriorates
Solution Approach 1:
The patent optimizes the carboxylic ester content parameter within the range of 10%-30% (or 20%-40% in broader embodiments) and balances it with cyclic carbonate content (60%-70%) to achieve the optimal balance between low viscosity and chemical stability, enabling fast charging capability.
Solution Approach 2:
The patent creates a composite electrolyte where carboxylic ester (providing low viscosity) is combined with cyclic carbonate (providing chemical stability) and linear carbonate in specific ratios. This composite structure allows the electrolyte to simultaneously achieve low viscosity for fast charging and sufficient chemical stability, resolving the contradiction between these two properties.
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 optimized electrolyte achieves excellent fast-charging capability and high-temperature stability in batteries with high energy density winding structures by maintaining low viscosity and chemical stability, enhancing cycling performance and conductivity.
Implementation Method 1
A viscosity of the first component at 25±2℃ is 0.4 mPa·s to 0.5 mPa·s. A viscosity of the second component at 25±2℃ is 0.3 mPa·s to 0.4 mPa·s.
Implementation Method 2
The electrolyte further comprises an additive, and the additive comprises a 1,3-propane sultone, an ethylene sulfate, and a tetravinylsilane
Implementation Method 3
The electrolyte includes a lithium salt and a solvent
Data Source
AI summary
An electrolyte and a secondary battery, belonging to the technical field of secondary batteries. The electrolyte includes a lithium salt and a solvent. The solvent includes a cyclic carbonate, a linear carbonate, and a carboxylic ester. A mass percentage of the cyclic carbonate is 8% to 24%. The linear carbonate includes a dimethyl carbonate and at least one of a methyl ethyl carbonate and a diethyl carbonate. A mass percentage of a mass sum of the methyl ethyl carbonate and the diethyl carbonate is 2% to 10%. A mass percentage of the carboxylic ester is 20% to 40%. The carboxylic ester includes a first component and a second component. Viscosities of the first and second components at 25±2°C are respectively 0.4 mPa·s to 0.5 mPa·s and 0.3 mPa·s to 0.4 mPa·s. Mass percentages of the first and second components are respectively 15% to 40% and 0% to 15%.