Negative Electrode Paste Hard Kneading for CMC Dissolution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The use of high-viscosity carboxymethyl cellulose (CMC) in non-aqueous electrolyte secondary battery negative electrode pastes can lead to defects due to incomplete dissolution and inadequate peeling strength, affecting both output and cycle characteristics.
Innovation Solution
A method involving hard kneading of a mixture of adsorbed oil, CMC, and negative-electrode active material, followed by dilution and addition of a binder, with specific viscosity and oil adsorption ranges to ensure complete dissolution and optimal peeling strength, including an oil adsorption amount of 50-62 ml/100 g and CMC viscosity of 6000-8000 mPa·s, and a CMC percentage of 0.6-0.8% by weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If CMC with high viscosity is used to reduce additive amount, then output characteristics are improved, but CMC dissolution becomes incomplete causing defects during coating
Solution Approach 1:
The patent changes the viscosity parameter of CMC from conventional low viscosity to high viscosity range (6000-8000 mPa·s at 1% aqueous solution), and simultaneously adjusts the oil adsorption amount parameter (50-62 ml/100g) to achieve complete dissolution while maintaining high output characteristics and reducing defects
Solution Approach 2:
The patent performs preliminary oil adsorption on the negative-electrode active material before CMC addition, ensuring the surface is pre-conditioned with optimal oil coverage. This preliminary action prevents incomplete dissolution during subsequent kneading and eliminates coating defects
2Stability of the object's composition
If oil adsorption amount is increased to improve CMC dissolution, then peeling strength deteriorates, but if oil adsorption is reduced, CMC dissolution becomes incomplete
Solution Approach 1:
The patent optimizes the oil adsorption amount parameter to a specific range (50-62 ml/100g) and CMC viscosity parameter (6000-8000 mPa·s), achieving a balance where complete CMC dissolution occurs without compromising peeling strength of the composite material layer
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 reduces defects and maintains high peeling strength, enhancing both output and cycle characteristics of non-aqueous electrolyte secondary batteries, such as lithium-ion batteries.
Implementation Method 1
the solubility of CMC also depends on the amount of oil that has been adsorbed on the negative-electrode active material
Implementation Method 2
subjecting a mixture of a negative-electrode active material on which oil has been adsorbed, carboxymethyl cellulose and water to hard kneading
Data Source
AI summary
A method for producing a non-aqueous electrolyte secondary battery includes: subjecting a mixture of a negative-electrode active material on which oil has been adsorbed, CMC and water to hard kneading to prepare a primary kneaded mixture; diluting the primary kneaded mixture with water to prepare a slurry; and adding a binder to the slurry. The method further includes defining an amount of the oil to a value equal to or more than 50 ml/100 g and equal to or less than 62 ml/100 g, wherein the amount of the oil is an amount at the time when the viscosity characteristics of the negative-electrode active material exhibits 70% of the maximum torque that is generated when the oil is titrated onto the negative-electrode active material. The 1% aqueous solution viscosity of the CMC is defined to a value equal to or more than 6000 mPa·s and equal to or less than 8000 mPa·s.