Sulfide Solid Electrolyte Particles with Controlled Crystal Structure
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Solution Overview
Problem
Sulfide solid electrolytes with stable crystal structures face challenges in achieving both small particle size and high ionic conductivity, as high-temperature firing promotes particle growth, and grinding lowers ionic conductivity.
Innovation Solution
Sulfide solid electrolyte particles with a stable crystal structure and small particle size are produced by pulverizing and then heat-treating the material, maintaining a specific intensity ratio (Ib/Ip) of less than 0.09 in powder X-ray diffraction, resulting in particles with an average size of 0.1 μm to 10 μm and ionic conductivity of 4.0 mS/cm or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If sulfide solid electrolyte is fired at high temperature to achieve stable crystal structure, then crystal structure stability is improved, but particle size increases
Solution Approach 1:
The patent applies preliminary action by conducting high-temperature firing first to establish the stable crystal structure, then subsequently pulverizing the material to reduce particle size. This sequence ensures the crystal structure is formed before size reduction, resolving the contradiction between achieving structural stability and maintaining small particle size.
2Volume of moving object
If sulfide solid electrolyte is ground to reduce particle size, then particle size is improved, but ionic conductivity deteriorates
Solution Approach 1:
The patent performs high-temperature firing before pulverization to pre-establish the stable crystal structure. This preliminary action ensures that even after grinding reduces particle size, the ionic conductivity is preserved because the crystal structure was already optimized before size reduction.
Solution Approach 2:
The patent controls the intensity ratio (Ib/Ip) of specific diffraction peaks as a parameter indicator to ensure the crystal structure maintains high ionic conductivity after pulverization. By monitoring and controlling this parameter, the patent achieves small particle size while preserving ionic conductivity.
3Productivity
If sulfide solid electrolyte is pulverized to achieve small particle size, then productivity is improved, but manufacturing precision deteriorates
Solution Approach 1:
The patent establishes the stable crystal structure through high-temperature firing before pulverization. This preliminary structuring allows subsequent grinding to achieve small particle sizes without degrading crystal quality, as the structure was already optimized beforehand.
Solution Approach 2:
The patent uses the intensity ratio (Ib/Ip) of diffraction peaks as a control parameter to monitor and ensure crystal structure quality after pulverization. This parameter-based control enables the patent to achieve both high productivity through size reduction and manufacturing precision through structure quality maintenance.
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
The method enables the production of sulfide solid electrolyte particles with high ionic conductivity and small particle size, suitable for use in lithium-ion batteries, enhancing their performance and production efficiency.
Implementation Method 1
a high ionic conductivity. As such a sulfide solid electrolyte, for example, a sulfide solid electrolyte having an argyrodite type crystal structure
Implementation Method 2
the powder X-ray diffraction pattern of the sulfide solid electrolyte changes before and after the pulverization. Then, when the intensity ratio (Ib/Ip) of an peak intensity Ib at a high angle-side low part of the diffraction peak to a peak intensity Ip of the diffraction peak
Data Source
AI summary
A sulfide solid electrolyte particles comprising lithium, phosphorus and sulfur, having a volume-based average particle size measured by laser diffraction particle size distribution measurement of 0.1 μm to 10 μm, having a diffraction peak having 2θ of 29.0 to 31.0 deg in powder X-ray diffraction measurement using CuKα ray, and an intensity ratio (Ib/Ip) of a peak intensity Ib at a high angle-side low part of the diffraction peak to a peak intensity Ip of the diffraction peak is less than 0.09.