High-Purity Lithium Sulfide Preparation for Whiteness and Cost Control
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Solution Overview
Problem
Current methods for producing lithium sulfide for all-solid-state batteries face challenges due to low purity and whiteness, which restrict industrial production and the development of sulfide solid-state batteries, as they are susceptible to water and air, leading to high production costs and limited commercial viability.
Innovation Solution
A method involving mixing and grinding a lithium source with a sulfur source, reacting with hydrazine hydrate in an inert atmosphere, followed by secondary reactions, drying, calcination, and ball milling to achieve high-purity lithium sulfide with enhanced whiteness and particle size, utilizing microwave calcination for efficient impurity removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional drying method is used to prepare lithium sulfide, then production cost is reduced, but purity and whiteness are low (maximum 97.88% purity)
Solution Approach 1:
The invention divides the reaction process into two distinct stages: primary reaction to form intermediate product, and secondary reaction to convert intermediate to final lithium sulfide product. This segmentation allows each stage to be optimized independently, with the secondary reaction specifically designed to achieve >99.9% purity and whiteness >80, resolving the contradiction between manufacturing precision and ease of manufacture.
Solution Approach 2:
The invention performs preliminary drying of the intermediate product before the secondary reaction. This preliminary action removes excess moisture and facilitates the subsequent secondary reaction, enabling high-purity product formation while maintaining process simplicity and cost-effectiveness.
2Manufacturing precision
If lithium sulfide is produced with high purity, then it is suitable for EV-grade applications, but production complexity increases due to susceptibility to water and air
Solution Approach 1:
The invention conducts both primary and secondary reactions in an inert atmosphere (nitrogen or argon) to prevent lithium sulfide from reacting with water and air. This inert environment protection enables the production of EV-grade high-purity lithium sulfide without requiring complex production systems, as the inert atmosphere can be easily maintained throughout the process.
3Shape
If conventional preparation method is used, then process is simple, but whiteness and particle size are insufficient for downstream applications
Solution Approach 1:
The invention optimizes multiple reaction parameters including temperature (60-80°C for primary reaction, 80-100°C for secondary reaction), pH value (controlled between 6.5-7.5), and reaction time to achieve optimal whiteness and particle size. These parameter changes enable the production of lithium sulfide with whiteness >80 and controlled particle size suitable for downstream sulfide solid electrolyte applications, while maintaining relatively simple process conditions.
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 results in EV-grade high-purity lithium sulfide with a mass purity above 99.9% and whiteness above 80, suitable for industrial production, offering simple operation, high safety, low energy consumption, and reduced production costs.
Implementation Method 1
mixing the mixture with hydrazine hydrate in an inert atmosphere and reacting to obtain an intermediate slurry
Implementation Method 2
performing secondary reaction on the intermediate slurry in the inert atmosphere and drying to obtain a crude lithium sulfide product
Implementation Method 3
calcining and ball milling the crude lithium sulfide product to obtain the EV-grade high-purity lithium sulfide
Data Source
AI summary
The invention relates to EV-grade high-purity lithium sulfide and a preparation method therefor, and pertains to the technical field of lithium battery materials. The preparation method for EV-grade high-purity lithium sulfide includes: A. mixing and well grinding a lithium source and a sulfur source to obtain a mixture; B. primary reaction: mixing the mixture with hydrazine hydrate in an inert atmosphere and reacting to obtain an intermediate slurry; C. secondary reaction: performing secondary reaction on the intermediate slurry in the inert atmosphere and drying to obtain a crude lithium sulfide product; and D. calcining and ball milling the crude lithium sulfide product to obtain the EV-grade high-purity lithium sulfide. The purity of the EV-grade high-purity lithium sulfide prepared by the method of the invention is above 99.9%, the whiteness thereof is above 80, and D50≤15µm; the method is characterized by simple process operation, high safety, low energy consumption, low equipment requirements and low production cost; therefore, the method is suitable for industrial production.