Carbon conductive material dispersion Development Department of Company Q, a Chemical manufacturer
Uniform dispersion of carbon materials in slurry
PVP reduces slurry viscosity, improving productivity
Company Q develops dispersions and pastes of conductive fillers such as carbon black (CB) and carbon nanotubes (CNT). The development department was busy responding to a request from a battery manufacturer to reduce the viscosity of slurry for electrodes.
Challenges
It is desirable to reduce the viscosity of the electrode slurry used in lithium-ion batteries, but it is difficult to achieve this while also improving the dispersibility of carbon-based materials.
When the development department leader, Mr. S, interviewed a battery manufacturer, he learned that the manufacturer wanted to reduce the viscosity of electrode slurry in order to increase the productivity of electrode components for lithium-ion batteries.
Mr. S immediately began to investigate the issue and discovered that there was an issue with the dispersibility of carbon-based conductive materials such as CB and CNT, which are the conductive additives used in the electrodes.
"Carbon-based materials have excellent electrical conductivity, but because their specific surface area is large, they have strong cohesive forces, making them difficult to mix and disperse uniformly in the dispersion liquid. In addition, the viscosity of the uniformly dispersed electrode slurry increases, which reduces its coatability. If the solvent content is increased to lower the viscosity, it will take longer to dry the solvent and it will also be difficult to make thicker electrode films, which are necessary to increase the capacity of batteries, so we were concerned that this could cause various problems." (Mr. S)
Mr. S tried to improve the dispersion by preparing various dispersants and changing the compounding and dispersion method. However, the results were not satisfactory and the slurry viscosity could not be improved. Some prototypes had insufficient adhesion of the coating film to the electrodes, and there were concerns about an increase in the rate of defects.
The battery manufacturer kept urging Mr. S to check on the progress every day, and with no sign of the prototype he wanted being completed, Mr. S was in a dire situation.
Key Challenges
Carbon-based conductive materials such as CB and CNT, which are conductive assistants used in electrodes, have strong cohesive forces, making them difficult to mix and disperse uniformly in the dispersion liquid, and the viscosity of the dispersion liquid also becomes high, making it difficult to handle.
We tried to improve the dispersibility by using various dispersants and changing the formulation and dispersion method, but we could not achieve the desired performance.