Lithium-Ion Electrode Sheet With Gradient Binder Distribution
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Solution Overview
Problem
Lithium manganese iron phosphate (LMFP) materials face challenges such as particle agglomeration and poor dispersibility due to high binder content, which limits energy and power density, and anode binders like SBR floating during baking affect adhesion and conductivity.
Innovation Solution
The electrode sheet is structured with a first layer closer to the current collector having a higher binder content than a second layer, optimizing binder distribution to enhance adhesion and conductivity, and reducing 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 gradient distribution of binder content within the cathode slurry. The binder concentration is higher near the current collector to ensure strong adhesion, and gradually decreases toward the outer layers to maximize active material content. This spatial variation in binder quality resolves the contradiction by providing sufficient adhesion only where needed while preserving energy density in the bulk structure.
2Strength
If the content of cathode binder is increased to improve interconnection, then the adhesion is enhanced, but the dispersibility of LMFP particles deteriorates due to particle agglomerating
Solution Approach 1:
The patent implements local quality through controlled binder distribution in the slurry system. By concentrating binder near the current collector rather than uniformly distributing it throughout the slurry, the invention maintains good dispersibility of LMFP particles in the bulk slurry while still achieving sufficient adhesion at the critical electrode-current collector interface.
3Strength
If the anode binder SBR is used in the baking process, then the adhesion is provided, but the binder floats up and drives conductive agent to float up, weakening adhesion and affecting electrical conductivity
Solution Approach 1:
The patent applies parameter changes by modifying the binder distribution profile through controlled drying and baking parameters. The drying process is optimized to minimize binder migration to the surface, and the baking parameters are adjusted to prevent flotation of binder and conductive agent. This control of process parameters ensures both adhesion and electrical conductivity are maintained.
Solution Approach 2:
The patent employs preliminary anti-action by pre-distributing the binder in a gradient pattern before baking, with higher concentration at the bottom layer near the current collector. This preliminary arrangement counteracts the natural tendency of binder to float up during baking, preventing the harmful effect of binder and conductive agent migration before it can occur.
Data Source
Figure 1
AI summary
The present application belongs to the field of lithium-ion batteries. 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, and the electrode sheet is very suitable for the lithium manganese iron phosphate cathode with small particle size and large specific surface area and the batteries including the same.