Electrolyte Additive for SEI Thickening and Impedance Control
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Solution Overview
Problem
Lithium secondary batteries face issues with oxidative decomposition of the electrolyte due to oxygen free radicals generated during charging, leading to thickening of the SEI film, increased interface impedance, and deterioration of cycling performance.
Innovation Solution
Using a compound as an electrolyte additive that captures R+ substances generated from oxidative decomposition products, suppressing the reduction reaction in the negative electrode and thereby inhibiting SEI film thickening and interface impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a positive electrode lithium supplement is used to improve battery capacity, then the battery capacity can be increased, but oxygen free radicals are generated during charging which cause oxidative decomposition of the electrolyte and lead to thickening of the SEI film and increased interface impedance
Solution Approach 1:
The patent introduces a specific electrolyte additive compound as an intermediary substance that captures oxygen free radicals and R+ substances. This additive acts as a mediator between the positive electrode lithium supplement and the electrolyte, preventing the harmful oxidative decomposition while allowing the beneficial capacity enhancement to occur.
Solution Approach 2:
The patent converts the harmful oxygen free radicals generated during charging into a beneficial process by having them react with the electrolyte additive to form protective species. The additive transforms the harmful oxidative decomposition into a controlled reaction that produces beneficial effects on the SEI film and interface impedance.
2Reliability
If the SEI film thickens due to reduction of R+ substances in the negative electrode, then the interface impedance increases, but this deteriorates the cycling performance of the battery
Solution Approach 1:
The patent applies preliminary anti-action by having the electrolyte additive capture R+ substances before they can reach the negative electrode and cause SEI film thickening. The additive proactively prevents the harmful reduction reaction from occurring at the negative electrode interface.
Solution Approach 2:
The electrolyte additive serves as an intermediary that intercepts R+ substances in the electrolyte bulk, preventing them from directly interacting with the negative electrode. This mediator approach stops the harmful chain reaction before it can deteriorate the SEI film.
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
Improves cycling performance and capacity of the battery by reducing SEI film thickening and interface impedance, enhancing safety performance.
Implementation Method 1
The oxygen free radicals and the oxygen that may be generated can easily lead to oxidative decomposition of the electrolyte
Implementation Method 2
suppress the reduction reaction of the R+ substances in a negative electrode plate
Implementation Method 3
The positive electrode lithium supplement generates oxygen free radicals during the first cycle of charging, and the oxygen free radicals may further generate oxygen
Data Source
AI summary
Provided a method using of a compound as an electrolyte additive, an electrolyte, a battery and an electrical apparatus. The present application relates to the use of a compound shown in Formula I as an electrolyte additive. The compound in the present application can capture byproducts generated from oxidative decomposition products of electrolytes, thereby suppressing the increase in the interface impedance of negative electrode plates, and further improving the capacity and cycling performance of batteries.