Lithium Battery Electrolyte Additive for Interfacial Film Stability
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Solution Overview
Problem
Lithium secondary batteries face rapid deterioration and performance issues due to interfacial reactivity between electrodes and electrolyte solutions, leading to reduced energy density and lifespan, especially in high-capacity applications like electric vehicles, where current materials and electrolytes fail to form stable protective films effectively.
Innovation Solution
An electrolyte solution comprising a lithium salt, solvent, and a functional additive, specifically 2-(dodec-1-en-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, and vinylene carbonate, which forms protective ion transport films on electrode surfaces, enhancing ionic conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional electrolyte solutions are used with high-capacity electrode materials, then energy density is improved, but interfacial reactivity increases causing rapid deterioration of charge and discharge performance
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonate compound as an intermediary substance that mediates between the electrode and conventional electrolyte. This compound forms a stable protective film (intermediary layer) on the electrode surface, preventing direct harmful interactions while allowing ionic transport, thus resolving the contradiction between maintaining high energy density and ensuring performance stability.
Solution Approach 2:
The patent modifies the electrolyte composition by adding fluorinated cyclic carbonate compounds with specific molecular structures and ratios. By changing the chemical parameters (adding F-containing groups, adjusting concentration ratios between different carbonates), the electrolyte's interfacial properties are altered to reduce reactivity while maintaining ionic conductivity for high-capacity electrodes.
2Quantity of substance
If existing electrolyte formulations are used to achieve high capacity electrodes, then energy storage capability is improved, but lifespan deteriorates due to electrolyte decomposition
Solution Approach 1:
The fluorinated cyclic carbonate compound performs preliminary protective action by forming a stable surface film on the electrode before the main electrolyte can decompose. This pre-formed protective layer prevents subsequent electrolyte degradation and electrode deterioration during cycling, thereby extending battery lifespan while maintaining high capacity.
Solution Approach 2:
The patent converts the potential harm of electrolyte decomposition into a benefit by using fluorinated cyclic carbonate compounds that preferentially react to form protective films. These films, which would normally be considered decomposition products, actually protect the electrode and extend battery life, turning a harmful process into a protective mechanism.
3Reliability
If standard electrolyte additives are used to form protective films, then electrode stability is improved, but ionic conductivity and output performance are reduced
Solution Approach 1:
The patent applies local quality by creating a protective film with specific fluorinated cyclic carbonate compounds that has differentiated properties: highly stable at the electrode interface (providing protection) while maintaining high ionic conductivity in the bulk electrolyte (enabling power). The local composition and structure of the protective film are optimized to balance stability and conductivity requirements.
Solution Approach 2:
The electrolyte system becomes a composite material system combining conventional carbonates (EMC, DEC, DMC) with fluorinated cyclic carbonate additives. This composite electrolyte formulation creates a multi-functional system where the base electrolyte provides ionic conductivity and the fluorinated additive provides protective film formation, achieving both stability and high power output.
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 significantly improves the lifespan and output characteristics of lithium secondary batteries by forming stable protective films on electrodes, maintaining capacity retention and output performance even at high temperatures and after multiple charge-discharge cycles.
Implementation Method 1
the electrochemical decomposition characteristics of a fluorinated cyclic carbonate compound to prepare a protective film on a surface of an electrode
Implementation Method 2
an electrolyte serving as a lithium ion transfer medium
Data Source
AI summary
An embodiment electrolyte solution includes a lithium salt, a solvent, and a functional additive, wherein the functional additive includes an electrode film additive of 2-(dodec-1-en-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane represented byAn embodiment lithium secondary battery includes this electrolyte solution, a positive electrode including a positive-electrode active material including Ni, Co, and Mn, a negative electrode including a negative-electrode active material including a carbon (C)-based material or a silicon (Si)-based material, and a separator interposed between the positive electrode and the negative electrode.