Binder Particle Distribution for Uniform Solid-State Battery Separators
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Solution Overview
Problem
The formation of aggregates in slurry compositions containing sulfide-based solid electrolytes for all-solid-state batteries leads to variations in separator thickness, increasing discharging resistance due to non-uniform discharging reactions.
Innovation Solution
A binder composition with a specific particle size distribution and a dispersion medium like butyl butyrate is used, along with controlled stirring and ultrasonic dispersion to prevent aggregate formation, and the sulfide-based solid electrolyte is processed to reduce its specific surface area and aggregating force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a binder composition with polymer material is used to bind sulfide-based solid electrolyte, then the separator can be formed, but granular aggregates are generated causing thickness variation
Solution Approach 1:
The patent applies parameter changes by controlling the particle size distribution of binder particles within specific ranges (D10: 5-15 μm, D50: 20-30 μm, D90: 40-60 μm) and adjusting the mass ratio of binder particles to solid electrolyte particles (0.5-5 mass%). These parameter optimizations prevent aggregate formation while maintaining separator thickness uniformity.
Solution Approach 2:
The patent employs ultrasonic treatment (mechanical vibration) at a power density of 0.1-10 W/mL for 1-60 minutes to disperse binder particles and prevent aggregate formation in the slurry composition, thereby improving separator thickness uniformity.
2Reliability
If aggregates are formed in the slurry composition, then the separator thickness varies, but this leads to increased discharging resistance
Solution Approach 1:
The patent optimizes the particle size distribution parameters (D10, D50, D90 values) and the mass ratio of binder to solid electrolyte particles to prevent aggregate formation. This ensures uniform separator thickness and maintains low discharging resistance by enabling uniform discharging reactions throughout the battery.
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 the likelihood of aggregate formation, resulting in a more uniform separator thickness and lower discharging resistance in all-solid-state batteries.
Implementation Method 1
the binder composition is stirred by ultrasonic wave
Implementation Method 2
The slurry composition can be applied to a surface of a substrate and dried to form the separator
Data Source
AI summary
A binder composition includes a dispersion medium and a group of binder particles. The group of binder particles is dispersed in the dispersion medium. The group of binder particles include a polymer material. The polymer material includes a constitutional unit originated from vinylidene difluoride. The group of binder particles has a number-based particle size distribution. The particle size distribution satisfies the following conditions: “0.19≤X≤0.26”, “0.69≤Y≤0.76”, and “0≤Z≤0.05”. Here, “X” represents a frequency of particles each having a particle size of less than or equal to 40 μm. “Y” indicates a frequency of particles each having a particle size of more than 40 μm and less than or equal to 110 μm. “Z” indicates a frequency of particles each having a particle size of more than 110 μm and less than or equal to 250 μm.