Lithium Battery Electrolyte Additives for High-Temperature Wetting
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Solution Overview
Problem
Lithium secondary batteries face challenges in maintaining high-temperature and low-temperature characteristics due to increased lithium salt concentration in non-aqueous electrolyte solutions, leading to reduced durability and electrolyte wetting issues, especially at high driving voltages.
Innovation Solution
A non-aqueous electrolyte solution for lithium secondary batteries is developed, comprising two types of lithium salts, an oligomer additive, and a mixed additive of lithium difluorophosphate, fluorobenzene, and tetravinylsilane, which improves wetting and reduces interfacial resistance by forming a stable film on the electrode surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the concentration of lithium salt in the non-aqueous electrolyte solution is increased, then the capacity and output of the battery are improved, but the viscosity of the electrolyte solution increases significantly, reducing electrolyte wetting and durability at high and low temperatures
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a specific mixed additive system (lithium difluorophosphate, fluorobenzene, and tetravinyl silane) to modify the electrolyte's physical properties. This allows maintaining high lithium salt concentration while improving wetting characteristics and temperature durability through altered molecular interactions in the electrolyte solution
Solution Approach 2:
The patent uses a composite additive system combining three different substances (lithium difluorophosphate, fluorobenzene, and tetravinyl silane) that work synergistically. Each component contributes different functions: lithium difluorophosphate forms protective films, fluorobenzene improves wetting, and tetravinyl silane enhances stability, together resolving the contradiction between high concentration and temperature durability
2Quantity of substance
If the concentration of lithium salt in the non-aqueous electrolyte solution is increased, then the capacity and output of the battery are improved, but side reactions between electrode active material and electrolyte increase, degrading life characteristics
Solution Approach 1:
The patent applies preliminary anti-action by having the additive components (particularly lithium difluorophosphate and tetravinyl silane) form protective films on the electrode surfaces before significant side reactions can occur. This preemptive film formation prevents harmful interactions between the high-concentration electrolyte and electrode materials during battery operation
Solution Approach 2:
The mixed additive system acts as an intermediary between the high-concentration lithium salt electrolyte and the electrode active materials. These additives mediate the interaction by forming interfacial layers that allow beneficial lithium ion transport while blocking harmful side reactions, thus preserving electrode integrity and extending battery life
3Power
If the driving voltage of the battery is increased to 4.45 V or more, then the output and capacity of the battery are improved, but electrolyte wetting is significantly reduced and durability at high and low temperatures deteriorates
Solution Approach 1:
The patent modifies the electrolyte's physical and chemical parameters by adding the mixed additive system, which changes the surface tension, viscosity, and interfacial properties of the electrolyte. These parameter changes enable the electrolyte to maintain effective wetting and ionic conductivity even at high driving voltages of 4.45 V or more, while preserving temperature durability
Solution Approach 2:
The patent employs a composite additive formulation where fluorobenzene specifically addresses wetting issues at high voltage, while tetravinyl silane and lithium difluorophosphate provide thermal stability. This composite approach allows the electrolyte to withstand high driving voltages without sacrificing temperature durability
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 solution enhances lithium ion mobility, improves wetting, and stabilizes the electrolyte, resulting in improved high-temperature and low-temperature characteristics, cycle life, and capacity retention of the lithium secondary battery.
Implementation Method 1
a mixed additive of lithium difluorophosphate (LiDFP), fluorobenzene (FB), and tetravinylsilane (TVS), as a second additive... which improves wetting and reduces interfacial resistance by forming a stable film on the electrode surface
Implementation Method 2
an electrolyte solution as a medium for transferring lithium ions
Data Source
AI summary
A non-aqueous electrolyte solution for a lithium secondary battery and a lithium secondary battery including the same are disclosed herein. In some embodiments, a non-aqueous electrolyte solution for a lithium secondary battery includes an organic solvent, LiPF6 as a first lithium salt, a second lithium salt excluding the LiPF6, an oligomer represented by Formula 1, as a first additive, and a mixed additive of lithium difluorophosphate (LiDFP), fluorobenzene (FB), and tetravinylsilane (TVS), as a second additive.