Positive Electrode Slurry Binder Segmentation for Homogeneous Dispersion
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Solution Overview
Problem
The non-homogeneous distribution of binders in positive electrode active material slurry leads to degraded adhesion of the positive electrode in lithium secondary batteries due to entanglement caused by linear conductive materials, affecting the energy density and performance.
Innovation Solution
A method involving the divisional introduction of a polymer binder during the mixing process of positive electrode active material slurry, with specific ratios and solid content control, to achieve homogeneous dispersion and improved adhesion, using materials like carbon nanotubes and preferred polymer binders such as polyvinylidene fluoride-hexafluoropropylene (PVDF-co-HFP).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a linear conductive material is used to improve energy density, then conductivity is improved, but entanglement occurs during slurry preparation causing non-homogeneous binder distribution and degraded adhesion
Solution Approach 1:
The binder introduction process is segmented into multiple stages: first introducing part of the binder with the linear conductive material and positive electrode active material, then introducing the remaining binder after initial mixing. This segmentation prevents the binder from being trapped in entangled linear conductive material, ensuring homogeneous distribution while maintaining high energy density
Solution Approach 2:
The linear conductive material and positive electrode active material are preliminarily mixed with part of the binder before the remaining binder is introduced. This preliminary action allows the linear conductive material to be partially coated and less entangled before the final binder addition, preventing non-homogeneous distribution
2Quantity of substance
If a large amount of binder is present among entangled linear conductive material, then the slurry can be formed, but the binder is distributed non-homogeneously resulting in degraded adhesion
Solution Approach 1:
The binder addition is divided into two segments: first binder introduction (40-80% of total binder) mixed with linear conductive material and positive electrode active material, then second binder introduction (remaining binder) added after initial mixing. This ensures the large amount of binder is distributed homogeneously without being trapped in entanglements, maintaining strong adhesion
Solution Approach 2:
The binder introduction is performed periodically in two distinct phases with mixing in between. This periodic action allows the binder to be incorporated gradually and uniformly throughout the slurry preparation process, preventing non-homogeneous distribution despite using a large amount of binder
Data Source
AI summary
Disclosed is a method for preparing positive electrode active material slurry, which includes the steps of: (S1) preparing a positive electrode active material, a linear conductive material, a polymer binder and a solvent; (S2) introducing 40-80% of the prepared polymer binder, the positive electrode active material and the linear conductive material to the solvent, followed by mixing, to obtain a first positive electrode active material slurry; and (S3) further introducing the remaining polymer binder to the first positive electrode active material slurry, followed by mixing, to obtain a second positive electrode active material slurry.