Garnet Oxide Solid Electrolyte Flux Method
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Solution Overview
Problem
The production of garnet type oxide solid electrolytes using Li-containing compounds as fluxes leads to reactions with crucible components, resulting in impurities and reduced Li ion conductivity, and poses environmental concerns due to alkaline waste solutions.
Innovation Solution
A method involving the use of NaCl and KCl as fluxes, with a specific composition formula (Lia1, Aa2)La3-bEbZr2-cMcO12, where a1, a2, and c are within defined ranges, to inhibit reactions with crucibles and promote high-crystallinity synthesis at temperatures below 1100°C, avoiding Li evaporation and environmental hazards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Li-containing compounds (e.g., LiOH) are used as flux, then the synthesis of garnet type oxide solid electrolyte is facilitated, but the flux reacts with crucible components producing impurities and reducing Li ion conductivity
Solution Approach 1:
The patent introduces an auxiliary flux (NaCl or KCl) as an intermediary substance that mediates between the Li-containing flux and the crucible. This auxiliary flux forms a protective layer that prevents direct contact and reaction between the Li-containing flux and crucible components, thereby eliminating impurity formation while maintaining the synthesis facilitation benefits of the Li-containing flux
2Productivity
If Li-containing compounds are used as flux, then synthesis proceeds effectively, but environmental harm increases due to alkaline waste solutions
Solution Approach 1:
The patent separates the flux system into two functional components: the Li-containing flux that performs the synthesis function and is discarded after use, and the auxiliary flux (NaCl or KCl) that protects the crucible and can be recovered and reused. This allows the harmful Li-containing waste to be minimized while maintaining synthesis efficiency, and the benign auxiliary flux to be recovered reducing overall environmental impact
3Reliability
If NaCl is used as flux, then crucible reaction is inhibited, but crystal plane growth is poor and impurity phases are present
Solution Approach 1:
The patent merges the advantages of two different fluxes by combining Li-containing compounds (which facilitate synthesis and promote good crystal growth) with NaCl or KCl (which inhibit crucible reaction). This combined flux system achieves both crucible protection and high-quality crystal formation, resolving the contradiction between reliability and manufacturing precision
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 yields high-quality, high-crystallinity garnet type oxide solid electrolytes with reduced impurities and enhanced Li ion conductivity, while minimizing environmental impact through neutral effluent solutions.
Implementation Method 1
a flux method is known, in which materials for the solid electrolyte and a flux are mixed and heated
Implementation Method 2
heating them in combination with solid electrolyte raw materials
Implementation Method 3
high Li ion conductivity
Data Source
AI summary
A method for producing a garnet type oxide solid electrolyte that is inhibited from a reaction of a flux and a crucible in heating and from a contamination with a crucible component produced by the reaction. The method for producing a garnet type oxide solid electrolyte represented by a general formula (Lia1, Aa2)La3-bEbZr2-cMcO12 may comprise the steps of: preparing raw materials for the garnet type oxide solid electrolyte at a stoichiometric ratio of the above general formula; preparing flux raw materials by using NaCl and KCl at a molar ratio of NaCl:KCl=x:(1−x) where x satisfies 0≤x≤1; mixing the solid electrolyte raw materials prepared in the above step and the flux raw materials prepared in the above step; and heating a mixture of the solid electrolyte raw materials and the flux raw materials at a temperature of less than 1100° C.