Pyridine-Silyl Electrolyte Additive for High-Temperature Li Battery Stability
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Solution Overview
Problem
Lithium secondary batteries face performance degradation and safety issues at high temperatures due to the destruction of the solid electrolyte interphase (SEI) film, leading to metal ion elution, increased resistance, and battery expansion, which are exacerbated by the thermal decomposition of lithium salts like LiPF6.
Innovation Solution
A non-aqueous electrolyte containing a compound with a pyridine group and a silyl group, along with a lithium salt and organic solvent, forms a stable film on the electrode surface, effectively suppressing metal ion elution and by-products, thereby enhancing high-temperature stability and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If compounds capable of forming SEI film are added to the non-aqueous electrolyte, then the negative electrode surface is protected, but the lifespan performance and high-temperature stability of the secondary battery deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte additive, specifically using a compound with both pyridine group and silyl group (Formula 1) instead of conventional SEI-forming compounds. This parameter change enables the additive to form a stable SEI film that does not decompose at high temperatures, thereby protecting the negative electrode while maintaining long lifespan performance.
Solution Approach 2:
The patent employs a composite functional additive containing both pyridine group (for SEI formation) and silyl group (for thermal stability) in a single molecular structure. This composite approach allows the additive to simultaneously provide surface protection and high-temperature stability without the side effects associated with conventional single-function additives.
2Temperature
If the secondary battery is stored at high temperatures in a fully charged state, then the solid electrolyte interphase (SEI) is gradually destructed, but this exposes the negative electrode surface causing continuous side reactions and gas generation
Solution Approach 1:
The patent applies preliminary action by having the pyridine-silyl compound (Formula 1) pre-form a stable SEI film on the negative electrode surface before high-temperature storage conditions cause decomposition of conventional SEI. This pre-formed stable film acts as a protective barrier that prevents exposure of the negative electrode surface and subsequent continuous side reactions during high-temperature storage.
Solution Approach 2:
The patent converts the potential harm of high-temperature storage (which normally causes SEI decomposition) into a benefit by using the pyridine-silyl compound that not only withstands high temperatures but actually forms an even more stable SEI film under these conditions. The high temperature that would normally be harmful becomes a condition that enhances the stability of the protective film formed by this special additive.
3Reliability
If conventional electrolyte additives are used to form SEI film, then negative electrode protection is achieved, but overall performance of the lithium secondary battery is reduced
Solution Approach 1:
The patent changes the chemical structure parameters of the electrolyte additive by incorporating both pyridine group (for SEI formation) and silyl group (for stability) in Formula (1). This structural parameter change enables the additive to form a protective SEI film while maintaining excellent overall battery performance, including high discharge capacity and long cycle life, unlike conventional additives that sacrifice performance for protection.
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 improves high-temperature lifespan and suppresses battery expansion, maintaining performance by forming a stable film that prevents SEI destruction and reduces internal resistance.
Implementation Method 1
a compound containing a pyridine group and a silyl group as an additive... capable of forming a stable film on an electrode surface
Implementation Method 2
a method of adding compounds capable of forming a film, that is, a solid electrolyte interphase (SEI) on the surface of the negative electrode
Implementation Method 3
The metal ions eluted from the positive electrode are electrodeposited on the negative electrode and deteriorate the negative electrode... The addition of these electrolyte additives may cause other side effects
Implementation Method 4
the lithium ions cross the non-aqueous electrolyte and the separator to move to the negative electrode part and are inserted into the carbon negative electrode
Implementation Method 5
a non-aqueous electrolyte in which lithium salt is dissolved in a mixed carbonate-based organic solvent
Implementation Method 6
improved high-temperature lifespan of the lithium secondary battery and suppression of an increase in the thickness of the secondary battery when stored at high temperatures
Data Source
AI summary
The present invention relates to a novel electrolyte additive, a non-aqueous electrolyte for a lithium secondary battery comprising the novel electrolyte additive, and a lithium secondary battery comprising the non-aqueous electrolyte. More specifically, the present invention relates to a non-aqueous electrolyte for a lithium secondary battery comprising an additive capable of forming a stable film on an electrode surface. The present invention also relates to a lithium secondary battery comprising such a non-aqueous electrolyte, thereby improving the high-temperature lifespan performance of the lithium secondary battery without deterioration, the resistance of the lithium secondary battery without increasing when the lithium secondary battery is stored at high temperatures, and the performance of suppressing expansion of the volume (thickness) of the secondary battery when the lithium secondary battery is stored at high temperatures.