Halide Solid Electrolyte Synthesis by Matched Powder Particle Size
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Solution Overview
Problem
Existing methods for synthesizing halide solid electrolytes, such as heat treatment in a vacuum-sealed tube and mechanochemical milling, are unsuitable for mass production due to low ionic conductivity and high impurity content, and using oxides outside stoichiometric composition leads to incomplete reaction and residual raw materials.
Innovation Solution
A halide producing method involving heat-treating a mixture of rare-earth oxide and ammonium halide powders with closely matched average particle diameters in an inert gas atmosphere or vacuum, allowing for enhanced reactivity and reduced impurities, and potentially combining with mechanical milling for improved mass production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat treatment is performed using a vacuum-sealed tube, then halide solid electrolytes can be synthesized, but the ionic conductivity is low and the method is unsuitable for mass production
Solution Approach 1:
The patent changes the particle size parameters of raw materials (MOx and NH4X) to have closely matched average particle diameters within a specific ratio range, which fundamentally alters the reaction characteristics and enables both high ionic conductivity and mass production suitability
Solution Approach 2:
The patent replaces the traditional vacuum-sealed tube heat treatment method with a simplified heat treatment process using a crucible in an inert gas atmosphere, eliminating the need for complex vacuum equipment while achieving superior results
2Reliability
If mechanochemical milling is used to synthesize halide solid electrolytes, then synthesis can be achieved, but the method is unsuitable for mass production and yields are low
Solution Approach 1:
The patent replaces the complex mechanochemical milling process with a simple heat treatment process, eliminating mechanical grinding equipment requirements while achieving complete reactions and high yields suitable for mass production
Solution Approach 2:
The patent changes from mechanical energy input (milling) to thermal energy input (heat treatment), fundamentally altering the reaction mechanism to enable scalable production
3Reliability
If oxide raw materials are used outside stoichiometric composition to ensure complete reaction, then reaction completeness improves, but residual raw materials remain and impurity content increases
Solution Approach 1:
The patent changes the particle size parameters of reactants to have closely matched average particle diameters, which fundamentally alters the reaction kinetics and enables complete reactions at stoichiometric compositions, eliminating the need for excess raw materials
Solution Approach 2:
The patent performs preliminary particle size control of raw materials before mixing, ensuring optimal particle size matching that enables complete reactions without requiring excess reactants, thus preventing impurity formation from unreacted materials
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 method enables the production of halide solid electrolytes with higher ionic conductivity and reduced impurities, suitable for mass production and application in batteries like all-solid-state secondary batteries.
Implementation Method 1
heat-treating a material mixture that is a material containing an MOx powder and an NH4X powder
Implementation Method 2
a material mixture that is a material containing an MOx powder and an NH4X powder is heat-treated
Implementation Method 3
heat-treating a material mixture that is a material containing an MOx powder and an NH4X powder in an inert gas atmosphere or in a vacuum
Data Source
AI summary
A halide producing method according to the present disclosure includes heat-treating a material mixture that is a material containing an MOx powder and an NH4X powder in an inert gas atmosphere or in a vacuum. M represents at least one element selected from the group consisting of rare-earth elements, X represents at least one element selected from the group consisting of F, Cl, Br, and I, x is greater than or equal to 1 and less than or equal to 2, and Requirement (a) or Requirement (b) below is satisfied,D1≤D2 and D2−D1≤0.5×D2 (a)D2<D1 and D1−D2≤0.5×D1 (b)where an average particle diameter of the MOx powder is denoted by D1, and an average particle diameter of the NH4X powder is denoted by D2.