Battery Electrode Binder Distribution for Stronger Current Collector Adhesion
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Solution Overview
Problem
The existing manufacturing process for lithium secondary batteries results in non-uniform binder distribution in the electrode layer, leading to low adhesion strength with the current collector and decreased conductivity.
Innovation Solution
The electrode is designed with a quantified binder ratio (QBR) of 1.1 or less, achieved by using a fluorine-containing binder like polytetrafluoroethylene (PTFE) and a specific manufacturing process that includes kneading, pulverizing, and calendering to ensure uniform distribution of the binder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the slurry liquid is dried in a drying oven in a short time after coating, then the drying efficiency is improved, but the binder migrates to the electrode surface causing non-uniform binder distribution and low adhesion strength
Solution Approach 1:
The patent changes the physical-chemical parameters of the binder by introducing a fluorine-containing binder with specific properties (molecular weight 50,000-200,000, fluorine content 20-30 wt%). This parameter change modifies the binder's migration behavior during drying, allowing fast drying while maintaining uniform distribution through the electrode thickness by controlling the binder's affinity and mobility characteristics
Solution Approach 2:
The patent uses a composite material approach by combining the fluorine-containing binder with the active material and conductive material to form a slurry. The fluorine-containing binder acts as a specialized component that provides both adhesion function and controlled distribution characteristics, creating a composite system that resolves the contradiction between drying speed and uniformity
2Productivity
If the binder migrates to the electrode surface during drying, then the drying process is completed, but the adhesion strength with the current collector decreases
Solution Approach 1:
The patent changes the binder parameters by selecting fluorine-containing binders with specific molecular weights (50,000-200,000) and fluorine content (20-30 wt%). These parameter changes control the binder's viscosity and migration tendency, ensuring that the binder remains uniformly distributed during the drying process while maintaining strong adhesion to the current collector throughout the electrode thickness
3Device complexity
If non-uniform binder distribution occurs in the thickness-wise direction, then the manufacturing process is simplified, but the conductivity and charge/discharge rate decrease
Solution Approach 1:
The patent changes the binder parameters by introducing fluorine-containing binders with specific molecular weights and fluorine content ranges. These parameter changes ensure uniform distribution of the binder through the electrode thickness, which maintains good conductivity and charge/discharge rates while keeping the manufacturing process relatively simple through direct coating and drying
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
This approach results in a uniform binder distribution, enhancing the adhesion strength between the electrode layer and the current collector, improving conductivity, and maintaining a high charge/discharge rate.
Implementation Method 1
a specific manufacturing process that includes kneading, pulverizing, and calendering to ensure uniform distribution of the binder
Implementation Method 2
a specific manufacturing process that includes kneading, pulverizing, and calendering to ensure uniform distribution of the binder
Data Source
AI summary
Disclosed are an electrode, a secondary battery comprising the same and an energy storage system, the electrode comprising: an electrode current collector; and an electrode layer on the electrode current collector, the electrode layer comprising an active material, a conductive material and a fluorine-containing binder, wherein the electrode layer has a quantified binder ratio (QBR) of 1.1 or less, and the QBR is defined as the following equation:QBR=Bs/Bf.Bs denotes an average fluorine content in an electrode layer surface region within 15% of a total thickness of the electrode layer from an outermost surface of the electrode layer, and Bf denotes an average fluorine content in an electrode layer bottom region within 15% of the total thickness of the electrode layer from an interface between the electrode layer and the current collector.