Lithium-Ion Electrode Slurry Viscosity Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing lithium-ion secondary battery electrodes result in chemical damage to active materials, leading to decreased electric capacity retention rates and cycle stability.
Innovation Solution
A method involving a two-process slurry production for both positive and negative electrodes, where the first process mixes active materials, conductive additives, and nonaqueous solvents to achieve specific viscosity and low water content, followed by a second process that maintains these conditions to minimize chemical damage and enhance dispersibility and binding forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the positive electrode slurry is produced using conventional mixing methods with specified water content, then the battery capacity retention rate is improved, but the active material is chemically damaged and activity is decreased
Solution Approach 1:
The invention changes the water content parameter to 1000 ppm or less and controls viscosity to 500-8000 cP, which resolves the contradiction by optimizing these parameters to prevent chemical damage while maintaining capacity retention. The specific parameter range creates conditions where the active material remains stable and active throughout the slurry production process.
Solution Approach 2:
The invention introduces a nonaqueous solvent as an intermediary substance to replace water in the slurry system. This mediator prevents chemical damage to the active material while still achieving proper slurry formation and adhesion, thus resolving the harm caused by water content specification in conventional methods.
2Stability of the object's composition
If the slurry viscosity is increased to improve mixing and dispersibility, then the active material dispersibility is improved, but the gas generation in the battery increases
Solution Approach 1:
The invention optimizes the viscosity parameter to a specific range of 500-8000 cP, which resolves the contradiction by finding the optimal balance point. Within this range, the slurry achieves sufficient dispersibility for uniform active material distribution while avoiding excessive viscosity that would trap gases and cause generation during battery operation.
3Stability of the object's composition
If the water content in the electrode slurry is reduced to prevent chemical damage, then the active material stability is improved, but the binding force between materials decreases
Solution Approach 1:
The invention uses a nonaqueous solvent as an intermediary binding agent that replaces water's binding function without causing chemical damage. This mediator maintains adequate binding force between active material particles and between the electrode mixture and current collector while keeping water content at 1000 ppm or less to prevent degradation.
Solution Approach 2:
The invention creates a composite slurry system combining active material, conductive additive, binder, and nonaqueous solvent in specific proportions. This composite formulation ensures that even with reduced water content, the binding force is maintained through the synergistic interaction of multiple components, particularly the binder and nonaqueous solvent working together.
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 lithium-ion secondary batteries with improved cycle stability and battery performance, characterized by high capacity retention rates and reduced gas generation.
Implementation Method 1
a first process in which, at least, the positive electrode active material or the negative electrode active material, a conductive additive, and a nonaqueous solvent are mixed
Implementation Method 2
a second process in which the electrode slurry is produced by diluting or concentrating a slurry obtained in the first process and mixing the diluted or concentrated slurry
Data Source
AI summary
A method for producing a positive electrode containing a positive electrode active material and/or a negative electrode containing a negative electrode active material. The method includes a process for producing an electrode slurry including: a first process in which a positive or negative electrode active material, a conductive additive, and a nonaqueous solvent are mixed to obtain a slurry; and a second process in which the slurry is diluted or concentrated and then mixed to obtain the electrode slurry. In the first process, the mixing is performed such that the obtained slurry has a water content of 1000 ppm or less and a viscosity of 500 cP or more and 8000 cP or less, and, in the second process, the mixing is performed such that a water content of the obtained electrode slurry is maintained at the water content of the slurry after the first process is completed.