Composite Electrolyte SEI Stabilization for Li-Ion High-Temperature Cycling
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Solution Overview
Problem
Lithium-ion batteries face challenges in energy density, high-temperature safety, and service life due to unstable solid electrolyte interface films (SEI) rich in Li2CO3 components, which decompose and produce gas, leading to negative electrode expansion and reduced coulombic efficiency.
Innovation Solution
Incorporation of a compound of Formula (I) with a rigid bridge ring structure in the SEI film, along with a fluorocarbonate compound, to stabilize the film and inhibit decomposition, promoting lithium ion transport and enhancing cycling and high-temperature storage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluorocarbonate compound is used to form SEI film, then negative electrode surface is stabilized, but Li2CO3 components decompose at high temperature causing gas production and electrode expansion
Solution Approach 1:
The patent uses a composite electrolyte system combining fluorocarbonate compound and compound of Formula (I) to form a composite SEI film that integrates the protective properties of fluorocarbonate with the thermal stability and rigid bridge ring structure of Formula (I), preventing decomposition and gas production at high temperatures
Solution Approach 2:
The patent optimizes the mass ratio of fluorocarbonate compound to compound of Formula (I) within specific ranges (0.001≤a/b≤1, with preferred ranges 0.03≤a/b≤0.8 and 10≤b≤20), changing the compositional parameters to achieve the optimal balance between film stability and high-temperature resistance
2Duration of action of stationary object
If SEI film is formed to stabilize negative electrode, then cycling performance improves, but film-forming impedance increases reducing lithium ion transport
Solution Approach 1:
The patent creates a SEI film with locally differentiated properties: the fluorocarbonate provides protective coverage while the compound of Formula (I) with its rigid bridge ring structure creates localized channels with lower impedance, allowing lithium ion transport through specific regions of the film without compromising overall film integrity
Solution Approach 2:
The compound of Formula (I) forms a SEI film structure with controlled porosity and rigid bridge ring channels that facilitate lithium ion diffusion, reducing film-forming impedance while maintaining film protective function for improved cycling performance
3Productivity
If conventional electrolyte is used, then basic battery function is achieved, but coulombic efficiency and high-temperature storage performance are insufficient
Solution Approach 1:
The compound of Formula (I) acts as an intermediary substance that mediates between the electrolyte and electrode surfaces, forming a protective interface layer that simultaneously improves coulombic efficiency by reducing side reactions and enhances high-temperature storage performance by preventing thermal decomposition
Solution Approach 2:
The patent creates a composite electrolyte system where fluorocarbonate compound and compound of Formula (I) work synergistically to form a dual-function SEI film that delivers both high coulombic efficiency and superior high-temperature storage stability
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 improves coulombic efficiency, cycling performance, and high-temperature storage performance by reducing Li2CO3 components and film-forming impedance, while promoting lithium ion transport.
Implementation Method 1
the contained fluorocarbonate compound can react with a lithium salt and undergo a strong film-forming reaction on a surface of a negative active material, to form a solid electrolyte interface film (SEI film)
Implementation Method 2
The compound of Formula (I) is introduced and can have a polymerization reaction at a film-forming stage to introduce a rigid bridge ring structure in the SEI film
Implementation Method 3
an anhydride/amide group in the compound of Formula (I) synchronously forms a film on a surface of an active material, and minor amounts of water and acid in the electrolyte can be captured
Implementation Method 4
transport of lithium ions between the active material and the electrolyte can be promoted
Data Source
Figure 1~2
AI summary
This application relates to an electrolyte, an electrochemical device, and an electronic device. The electrolyte includes a compound of Formula (I) and a fluorocarbonate compound. When the electrolyte in this application is applied to the electrochemical device, coulombic efficiency, cycling performance, and high-temperature storage performance of the electrochemical device can be improved.