Sulfide Solid Electrolyte Agglomerates for Stable Battery Slurries
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Solution Overview
Problem
Sulfide-based solid electrolytes face challenges with limited grain growth due to high-temperature heat treatment issues, resulting in weakly cohesive primary particles that are prone to breakdown during cell manufacturing, leading to slurry instability and safety concerns in lithium secondary batteries.
Innovation Solution
A sulfide-based solid electrolyte with secondary particles formed by agglomeration of primary particles, featuring a high primary interparticle binding force, achieved through controlled temperature reaction and heat treatment between 400°C to 550°C, and a stable slurry with low viscosity and minimal secular change, ensuring uniform dispersion and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If high-temperature heat treatment is performed for crystallization, then grain growth is promoted, but elemental volatilization occurs and safety issues arise
Solution Approach 1:
The patent changes the temperature parameter from conventional high-temperature treatment (>550°C) to a lower temperature range (400-550°C), which prevents elemental volatilization while still achieving sufficient crystallization and grain growth through optimized heat treatment time and atmosphere control
Solution Approach 2:
The patent performs preliminary sintering at a first temperature (300-400°C) before the main heat treatment, which pre-forms the crystal structure and reduces the required temperature for final crystallization, thereby avoiding elemental volatilization while achieving complete grain growth
2Object-affected harmful factors
If limited grain growth occurs due to restricted heat treatment temperature, then elemental volatilization is prevented, but primary particles remain fine and weakly cohesive
Solution Approach 1:
The patent performs preliminary sintering at 300-400°C before the main heat treatment to pre-form crystal nuclei and strengthen particle cores, which enables subsequent grain growth at lower temperatures (400-550°C) without elemental volatilization, while achieving sufficient interparticle binding force through the two-stage process
Solution Approach 2:
The patent creates a composite structure with a crystalline core formed during preliminary sintering and an outer layer that develops during the second heat treatment, where the core provides strength and the outer layer provides cohesion, achieving both volatilization prevention and strong interparticle binding
3Quantity of substance
If fine primary particles are produced, then high surface area is achieved, but particles are easily broken down during cell manufacturing causing slurry instability
Solution Approach 1:
The patent performs preliminary sintering to pre-strengthen particle cores before the main heat treatment, creating a robust internal structure that prevents fine particles from breaking down during subsequent handling and cell manufacturing, while maintaining high surface area through controlled grain growth
Solution Approach 2:
The patent creates local quality differences within particles by forming a strengthened crystalline core through preliminary sintering, where the core provides mechanical strength to prevent breakdown while the outer surface maintains high surface area for reactivity, resolving the contradiction between fine particle size and particle strength
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 approach results in a sulfide-based solid electrolyte with enhanced particle cohesion and stability, preventing disintegration during slurry preparation and improving the safety and performance of lithium secondary batteries by maintaining a stable and uniform slurry viscosity.
Implementation Method 1
the primary particles having a strong interparticle binding force
Implementation Method 2
heat treatment for crystallization cannot be performed at high temperatures because of elemental volatilization
Implementation Method 3
heat treatment for crystallization
Implementation Method 4
the particle size ibefore may represent a median diameter D50... before ultrasonic treatment
Data Source
AI summary
A sulfide-based solid electrolyte includes secondary particles in which primary particles are agglomerated. With the use of the sulfide-based solid electrolyte, a uniform, stable, and high-quality slurry in which the primary particles have a strong interparticle binding force can be prepared.