Surface-Controlled Carbon Black for Low-Viscosity Battery Slurry
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Solution Overview
Problem
The challenge in lithium ion secondary batteries is to maintain conductivity while reducing the viscosity of the slurry, as decreasing the particle size of carbon black increases slurry viscosity, making uniform dispersion difficult, and adding more dispersing agents can deteriorate battery characteristics.
Innovation Solution
Carbon black with a specific surface area of 150 m2/g to 400 m2/g and a thermal desorption spectroscopy ratio (S2/S1) of less than 2.00, along with controlled DBP absorption, ash, and iron content, is used to create a low-viscosity slurry, enhancing conductivity and battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the particle size of carbon black is decreased to increase the number of particles per unit mass, then conductivity is improved, but slurry viscosity increases significantly making uniform dispersion difficult
Solution Approach 1:
The invention changes the surface chemical composition parameter of carbon black by controlling the ratio of polycyclic aromatic hydrocarbons (naphthalene derivatives) to aliphatic hydrocarbons. This parameter change reduces surface hydrophobicity and improves wettability with the slurry medium, thereby reducing viscosity while maintaining the high particle count needed for conductivity.
2Quantity of substance
If the proportion of conductive agent is decreased to increase active material proportion, then battery capacity is improved, but conductivity path formation becomes difficult
Solution Approach 1:
By changing the surface chemical parameters of carbon black to reduce hydrophobicity, the invention improves dispersion and distribution of conductive particles throughout the electrode. This allows for more efficient conductive path formation even at lower conductive agent concentrations, as the particles are more uniformly distributed and accessible.
3Stability of the object's composition
If dispersing agent amount is increased to improve dispersion of fine carbon black particles, then dispersion is improved, but battery characteristics deteriorate
Solution Approach 1:
The invention makes the carbon black particles self-dispersing by modifying their surface chemical properties. The reduced hydrophobicity and improved wettability allow particles to disperse uniformly in the slurry without requiring excessive dispersing agents, as the particles themselves facilitate their own dispersion through improved interfacial compatibility.
4Stability of the object's composition
If strong collision energy is applied with high pressure jet mill to achieve high dispersion, then dispersion is improved, but contamination with impurities occurs due to device wear
Solution Approach 1:
The invention changes the surface chemical parameters of carbon black to reduce hydrophobicity, which improves wettability and spontaneous dispersion in the slurry medium. This chemical parameter modification enables effective dispersion without requiring aggressive mechanical treatment that would cause device wear and contamination.
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 allows for a high specific surface area carbon black that forms a low-viscosity slurry, improving conductivity and battery capacity while minimizing local conductivity decreases and discharging capacity issues.
Implementation Method 1
surface properties analyzed through thermal desorption spectroscopy greatly affect the slurry viscosity
Data Source
AI summary
Carbon black having a specific surface area of 150 m2/g or more and 400 m2/g or less, and a ratio (S2/S1) of a peak area (S2) of a peak at m/z 128 to a peak area (S1) of a peak at m/z 57 detected through thermal desorption spectroscopy of less than 2.00.