Electrode Slurry Viscosity Control via Binder Molecular Weight
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Solution Overview
Problem
The challenge in manufacturing lithium secondary batteries is the increase in viscosity and gelling of electrode slurry over time, leading to filter blocking and coating defects during the production and transport of negative electrode slurry, which affects the quality and efficiency of the battery manufacturing process.
Innovation Solution
A method is developed to predict phase stability and select suitable electrode slurry composition by determining the particle size distribution of composite particles in a mixed sample containing electrode active material, polymer resin, and solvent, ensuring that the polymer resin content and particle size meet specific criteria to maintain stable viscosity and prevent gelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If binder polymer is added to fix electrode active material, then adhesion and particle stability are improved, but slurry viscosity increases and gelling occurs over time
Solution Approach 1:
The patent changes the molecular weight parameter of the binder polymer to resolve the contradiction. Specifically, it uses binder polymers with number-average molecular weights of 50,000-150,000 (preferably 70,000-100,000), which are lower than conventional binders. This parameter change allows the binder to maintain adequate adhesion function while reducing excessive viscosity increase and gelling tendency during slurry storage and processing
Solution Approach 2:
The patent employs a composite binder system consisting of multiple polymer components with different functions. The main binder polymer (50,000-150,000 molecular weight) provides adhesion, while additional polymer components are introduced to modify rheological properties and prevent gelling. This composite approach allows simultaneous achievement of particle fixation and viscosity control
2Productivity
If slurry is stored and transported for manufacturing, then production efficiency is improved, but filter blocking and coating defects occur due to gelling
Solution Approach 1:
The patent applies preliminary action by pre-selecting binder polymers with specific molecular weight characteristics (50,000-150,000) before slurry preparation. This preliminary selection prevents gelling and filter blocking issues from occurring during subsequent storage and transportation, ensuring the slurry maintains its processability throughout the manufacturing timeline
Solution Approach 2:
By changing the molecular weight parameter of the binder to a lower range (50,000-150,000), the patent fundamentally alters the slurry's rheological behavior over time. This parameter change prevents the slurry from gelling during storage and transportation, maintaining filterability and coating quality even after extended periods, thus supporting both productivity and reliability
Data Source
AI summary
A method that allows prediction of phase stability of an electrode slurry through a simple method of determining a change in viscosity of the electrode slurry. Therefore, only the electrode slurry having high phase stability is selected before electrode slurry is introduced to a process for manufacturing an electrode. Then, the selected electrode slurry is introduced to the process to provide an improved effect of process efficiency.