Lithium Battery Electrolyte Additives for Thermal Stability
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Solution Overview
Problem
Lithium-ion batteries face challenges in achieving higher capacity, longer life, higher energy density, safety, and performance to meet the increasing demands of portable devices, particularly in maintaining performance and safety under varying conditions.
Innovation Solution
The development of an electrolyte composition for lithium secondary batteries that includes a lithium salt, specific solvents, and additives such as vinylene carbonate, fluorinated ethylene carbonate, and propenyl sulfite, which are formulated to enhance the battery's performance and safety by optimizing the chemical structure and concentration of these components within the electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte compositions are used, then basic battery function is maintained, but capacity restoration rate and thermal performance are insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing specific additives (vinylene carbonate at 0.1-10%, fluorinated ethylene carbonate at 0.5-25%, and propenyl sulfite at 1-15%). These parameter changes optimize the electrolyte's ability to form protective SEI films on electrodes, thereby improving capacity restoration rate while maintaining battery capacity.
Solution Approach 2:
The patent creates a composite electrolyte system by combining multiple carbonate solvents (EC, PC, DEC, GBL) with specific additive compounds. This composite approach synergistically improves both capacity restoration and thermal performance, resolving the contradiction between reliability and productivity.
2Quantity of substance
If electrolyte composition is optimized for higher capacity, then energy density improves, but thermal stability and safety deteriorate
Solution Approach 1:
The patent uses propenyl sulfite and vinylene carbonate as intermediary substances that form protective interface layers between the electrolyte and electrodes. These intermediaries prevent direct harmful thermal reactions while allowing ionic conduction, thus maintaining energy density while improving thermal stability.
Solution Approach 2:
By adjusting the concentration parameters of fluorinated ethylene carbonate (0.5-25%) and other additives, the patent optimizes the electrolyte's thermal decomposition temperature and stability, achieving high energy density without sacrificing thermal safety.
3Object-affected harmful factors
If electrolyte formulation is modified to improve safety, then thermal resistance increases, but capacity restoration rate may be compromised
Solution Approach 1:
The patent applies local quality by forming different functional layers at electrode interfaces through specific additives. Vinylene carbonate and propenyl sulfite create localized protective films on electrode surfaces that enhance safety without blocking ionic transport, thus maintaining capacity restoration rate while improving thermal resistance.
Solution Approach 2:
The patent employs fluorinated ethylene carbonate as a multi-functional additive that simultaneously provides thermal stability, safety protection, and maintains good ionic conductivity for capacity restoration. This universal approach resolves the contradiction between safety and reliability.
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 proposed electrolyte composition improves the capacity restoration rate, thermal performance, and safety of lithium-ion batteries, with batteries exhibiting better overcharge and thermal resistance, indicating enhanced ruggedness and safety compared to reference samples.
Implementation Method 1
an electrolyte having a lithium salt, a solvent, and an additive
Implementation Method 2
the additive includes substances A, B and C... substance A has the following chemical structure... substance B has the chemical structure of at least one of... substance C includes at least one of ethylene sulfite, 1,3-propane sultone and propenyl sulfite
Data Source
AI summary
Electrolyte and lithium secondary batteries containing the same are disclosed. In one instance, the electrolyte includes a lithium salt, a solvent and an additive. In some examples, the additive includes substances A, B and C, wherein substance A is vinylene carbonate, substance B includes at least one of fluorinated or chlorinated ethylene carbonate or diethylene carbonate, and substance C includes at least one of ethylene sulfite, 1,3-propanesultone and propenyl sulfite.