Electrode Assembly Polymers for Battery Polarization and Cycle Life
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Solution Overview
Problem
The internal resistance of battery cells causes polarization, affecting the cycle performance of batteries, and the use of fluorinated polymers in the negative electrode film layer generates hydrogen ions that reduce the stability of the positive electrode, limiting the improvement in cycle performance.
Innovation Solution
An electrode assembly is designed with a fluorinated polymer in the negative electrode film layer to form a stable SEI film and a nitrile-based polymer material in the positive electrode film layer to capture hydrogen ions and enhance ion transport, reducing polarization and improving cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluorinated polymer is used in the negative electrode film layer to form stable SEI film, then ionic conductivity is enhanced and polarization is reduced, but hydrogen ions are generated that reduce the stability of the positive electrode
Solution Approach 1:
A protective film is formed on the positive electrode surface to act as an intermediary layer that captures hydrogen ions generated by the fluorinated polymer in the negative electrode. This protective film prevents hydrogen ions from attacking the positive electrode active material, thereby maintaining positive electrode stability while allowing the fluorinated polymer to continue enhancing ionic conductivity and reducing polarization.
2Reliability
If internal resistance is reduced to improve cycle performance, then polarization is reduced, but maintaining low internal resistance while using fluorinated polymers becomes difficult due to hydrogen ion generation
Solution Approach 1:
The hydrogen ions generated by the fluorinated polymer, which were previously harmful to the positive electrode stability, are converted into a beneficial effect by using them to form a protective film on the positive electrode surface. This protective film not only captures excess hydrogen ions but also enhances the overall stability of the positive electrode, thereby converting the harmful byproduct into a protective mechanism that supports long-term cycle performance.
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 synergistic effect of fluorinated and nitrile-based polymers enhances ion transport and stabilizes the positive electrode, resulting in improved cycle performance of the battery.
Implementation Method 1
the fluorinated polymer in the negative electrode film layer can form a fluoride-rich negative electrode solid electrolyte interphase film (SEI film)
Implementation Method 2
the nitrile-based polymer material in the positive electrode film layer can, on one hand, enhance the ion transport performance of the positive electrode plate and, on the other hand, capture hydrogen ions to prevent their adverse effects on the positive electrode interface
Implementation Method 3
enhance the ion transport performance of the positive electrode plate
Data Source
AI summary
This application provides an electrode assembly, a battery cell, a battery, and an electric device. The electrode assembly includes a negative electrode plate, a positive electrode plate, and a separator, where the negative electrode plate includes a negative electrode film layer, the negative electrode film layer including a fluorinated polymer, and the positive electrode plate includes a positive electrode film layer, the positive electrode film layer including a nitrile-based polymer material. Using this electrode assembly can significantly improve the cycle performance of batteries.