Ether-Polymer Separator Coating for Battery Cell Storage Stability
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Solution Overview
Problem
Existing battery cells exhibit poor storage performance due to issues with electrolyte solution diffusion and polymer dissolution, leading to reduced ion conductivity and concentration polarization.
Innovation Solution
A separator with a polymer layer made of ether polymer, characterized by a specific elastic modulus G′-loss modulus G″ curve slope (1<K<∞) and glass transition temperature (−100≤Tg≤50 °C), which forms a three-dimensional connected interface with electrode plates, enhancing ion diffusion and reducing polymer dissolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the polymer layer uses conventional polymer materials, then the storage performance is poor due to polymer dissolution, but using ether polymer with specific elastic modulus characteristics improves storage performance
Solution Approach 1:
The patent changes the physical and chemical parameters of the polymer by selecting ether polymer with specific glass transition temperature (−100≤Tg≤50°C) and controlling the elastic modulus G′-loss modulus G″ curve slope (1<K<∞). These parameter changes prevent polymer dissolution while maintaining storage performance, resolving the contradiction between reliability and compositional stability.
Solution Approach 2:
The patent creates a composite structure by forming a polymer layer on the separator body using ether polymer. This composite material system combines the separator substrate with the functional polymer layer, where the polymer layer provides ion conductivity while the specific ether polymer composition prevents dissolution, thus improving storage performance without compromising stability.
2Reliability
If the polymer layer has high molecular chain entanglement, then the polymer maintains structural stability, but ion diffusion between molecular chains is hindered
Solution Approach 1:
The patent optimizes the molecular weight and entanglement characteristics of the ether polymer to achieve a balance between structural stability and ion diffusion. By controlling the elastic modulus G′-loss modulus G″ curve slope parameter K (1<K<∞), the patent finds the optimal entanglement state that provides sufficient structural stability while maintaining adequate free volume for ion transport, thus resolving the contradiction between reliability and speed.
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 storage performance by increasing ion conductivity, reducing concentration polarization, and facilitating uniform ion deposition, thereby enhancing battery cell stability and cycling performance.
Implementation Method 1
the polymer and the electrolyte solution can form a three-dimensional connected interface between the separator and an electrode plate, and the interface has a mesh structure, which is conducive to increasing the rate of diffusion of active ions, such as lithium ions, from the electrolyte solution to the electrode plate
Implementation Method 2
the polymer still maintains a certain molecular chain entanglement state, which is capable of locking the electrolyte solution inside the polymer, and is capable of reducing the risk of the polymer dissolving in the electrolyte solution
Data Source
AI summary
The present application provides a separator, a battery cell, a battery and an electrical apparatus. The separator includes a separator body and a polymer layer arranged on at least one surface of the separator body. The polymer layer includes an ether polymer. The ether polymer is made into a sheet-like structural body; the sheet-like structural body is subjected to a dynamic frequency scanning test at (Tm+20)° C. to obtain an elastic modulus G′-loss modulus G″ curve, and the elastic modulus G′-loss modulus G″ curve has a slope of K, where 1<K<∞, and Tm° C. represents the melting temperature of the ether polymer.