Two-Layer Electrode Sheet for Binder Migration Control
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Solution Overview
Problem
Lithium manganese iron phosphate (LMFP) cathode materials face challenges such as particle agglomeration, poor dispersibility, and increased binder content affecting energy and power density, while anode binders like SBR float up during baking, impacting conductivity and cycle lifetime.
Innovation Solution
The electrode sheet is designed with a two-layer structure where the binder mass percentage is higher in the first layer near the current collector, enhancing adhesion and peeling force, and redistributing the binder to improve uniformity and conductivity, reducing the overall binder usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the usage amount of cathode binder is increased to enhance interconnection between cathode particles, then the adhesion and interconnection are improved, but the energy density and power density are limited due to occupied space of active materials
Solution Approach 1:
The patent applies local quality by creating a two-layer binder distribution where the first layer near the current collector has higher binder content (1.5-3.0 mass%) to ensure strong adhesion, while the second layer has lower binder content (0.5-2.0 mass%) to maximize active material content and energy density. This spatial differentiation resolves the contradiction by concentrating binder where it is most needed for structural integrity.
Solution Approach 2:
The patent segments the electrode structure into two distinct layers with different binder concentrations. The first layer serves as an adhesive layer with higher binder content, while the second layer serves as an active material-rich layer with lower binder content. This segmentation allows the electrode to simultaneously achieve strong adhesion and high energy density.
2Power
If the particle size of LMFP material is small to improve reactivity, then the reactivity is enhanced, but the dispersibility deteriorates leading to particle agglomerating
Solution Approach 1:
The patent applies local quality by concentrating higher binder content in the first layer near the current collector, which provides a stable matrix that prevents particle agglomeration. This localized binder enrichment creates a supportive environment that maintains uniform dispersion of fine particles while preserving their high reactivity characteristics.
3Strength
If the anode binder SBR is used in the baking process, then the adhesion is provided, but the binder floats up weakening adhesion and driving conductive agent to float up affecting electrical conductivity
Solution Approach 1:
The patent applies local quality by concentrating binder in the first layer near the current collector where adhesion is most critical. This localized concentration creates a stable adhesive layer that prevents binder floating up during baking, thereby maintaining both adhesion strength and electrical conductivity in the second layer where conductive agents remain uniformly distributed.
Solution Approach 2:
The patent segments the electrode into two functional layers: the first layer serves as an adhesive layer with higher binder content that prevents floating up, while the second layer maintains electrical conductivity with lower binder content and uniform conductive agent distribution. This segmentation resolves the contradiction between adhesion and conductivity.
Data Source
AI summary
Provided in the present application are an electrode sheet and a lithium-ion battery including the same; the active layer of the electrode sheet includes a first layer and a second layer, wherein the first layer is disposed close to the current collector, the second layer is disposed on one side of the first layer which is facing away from the current collector, and the mass percentage of the binder in the first layer is greater than that of the second layer; by redistributing the binder, the peeling force and adhesion are ensured, and simultaneously the migration of the binder is improved; the influence of binder migration on uniformity and conductivity is reduced, thereby, the manufacturability and electrical properties such as energy density of the electrode sheet are improved.