PVDF Binder Powder for Low-Viscosity Electrode Mixing
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Solution Overview
Problem
The use of vinylidene fluoride polymer powders dispersed in NMP as binders for electrodes leads to increased viscosity during kneading, necessitating higher amounts of organic solvent to maintain viscosity, which is inefficient and costly.
Innovation Solution
A vinylidene fluoride polymer powder with a median diameter of 50 µm or less, a maximum melting peak temperature of 130°C or higher, and a shear viscosity that increases to 5 times its initial value at 30°C between 44°C and 80°C, inhibiting dissolution and viscosity increase in the electrode mixture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If vinylidene fluoride polymer powder is dispersed in NMP as a binder, then the amount of organic solvent used for adjusting viscosity can be reduced, but the viscosity of the electrode mixture increases during kneading due to temperature rise
Solution Approach 1:
The patent changes the physical and chemical parameters of the vinylidene fluoride polymer powder, specifically controlling the melting peak temperature (Tm1 ≥ 130°C) and the viscosity-temperature relationship (temperature at which viscosity becomes 5 times at 30°C value is 44°C or higher but lower than 80°C). These parameter changes enable the polymer to maintain stable dispersion viscosity during the temperature rise in kneading process, solving the contradiction between reducing solvent amount and controlling viscosity increase.
2Temperature
If the amount of dispersion medium is increased to compensate for viscosity increase, then the viscosity can be kept constant, but the amount of dilution solvent used increases
Solution Approach 1:
The patent modifies the polymer's inherent viscosity-temperature characteristics by controlling its melting behavior and molecular structure. The specific parameter range (viscosity becomes 5 times at 30°C value when temperature is 44°C or higher but lower than 80°C) creates a buffer zone that prevents rapid viscosity increase during kneading, eliminating the need to add more dispersion medium and thus reducing dilution solvent usage.
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 solution reduces the amount of dilution solvent needed and maintains low viscosity in the electrode mixture, even at high temperatures, enhancing the production efficiency and adhesiveness of the electrode.
Implementation Method 1
a maximum melting peak temperature Tm1 of 130°C or higher at a first heating in differential scanning calorimetry
Implementation Method 2
a shear viscosity of a dispersion obtained by dispersing the vinylidene fluoride polymer powder in N-methylpyrrolidone
Data Source
Figure 1
AI summary
The vinylidene fluoride polymer powder according to the present invention is a vinylidene fluoride polymer powder having a median diameter of 50 µm or less as determined by a laser diffraction scattering method, in which the vinylidene fluoride polymer powder has a maximum melting peak temperature Tm1 of 130°C or higher at a first heating in differential scanning calorimetry, and the temperature at which a shear viscosity of a dispersion obtained by dispersing the vinylidene fluoride polymer powder in N-methylpyrrolidone at a concentration of 6 wt.% becomes equal to 5 times as great as the shear viscosity thereof at 30°C, is 44°C or higher and less than 80°C, where the shear viscosity is defined as a value measured at a shear rate of 100 s-1 using a parallel plate rheometer while heating is performed from 25°C to 80°C at a temperature increasing rate of 5°C/min.