Garnet Composite Oxide Powder for Dense Solid Electrolytes
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Solution Overview
Problem
Conventional solid electrolytes for lithium-ion secondary batteries have limitations in achieving high ionic conductivity and density, which are essential for improving battery performance and safety.
Innovation Solution
A composite oxide powder with a cubic garnet-type crystal structure, composed of lithium, lanthanum, zirconium, and oxygen, and optionally doped with gallium, is produced using a specific method involving raw material blending, firing, pulverization, and heat-treatment to achieve a fine particle size and low pyrochlore phase content, resulting in a dense solid electrolyte with enhanced ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solid electrolyte production methods are used, then production process is simple, but ionic conductivity and density are insufficient
Solution Approach 1:
The production process is divided into multiple discrete steps: raw material preparation, blending, firing at specific temperatures, pulverization to control particle size, and heat treatment to reduce pyrochlore phase. This segmentation allows each step to be optimized independently, achieving high ionic conductivity through precise control of particle size (1000 nm or less) and phase composition (10 mass% or less pyrochlore phase).
Solution Approach 2:
The invention employs specific parameter ranges to achieve optimal performance: firing temperatures of 900-1100°C, particle size D50 of 1000 nm or less, and pyrochlore phase content of 10 mass% or less. These parameter changes transform the conventional simple process into a controlled multi-step process that achieves superior ionic conductivity and density.
2Reliability
If particle size is reduced to improve density, then manufacturing complexity increases, but ionic conductivity improves
Solution Approach 1:
The raw materials are carefully prepared and blended in predetermined ratios before firing, and the firing conditions are pre-optimized to achieve the desired crystal structure. This preliminary action ensures that subsequent pulverization can efficiently achieve the target particle size (D50 ≤ 1000 nm) without excessive complexity, while the resulting fine particles directly improve density and ionic conductivity.
Solution Approach 2:
The invention uses composite oxide particles with specific composition (Li, La, Zr, O) and controlled particle size. The composite nature of these particles, with controlled morphology and size distribution, enables high density achievement through standard pulverization techniques, avoiding excessive manufacturing complexity while improving ionic conductivity.
3Reliability
If pyrochlore phase content is reduced to improve ionic conductivity, then production precision requirements increase
Solution Approach 1:
The invention specifies precise parameter ranges: firing temperature of 900-1100°C, particle size D50 of 1000 nm or less, and pyrochlore phase content of 10 mass% or less. By controlling these parameters within defined ranges, the manufacturing process achieves consistent phase composition with minimal pyrochlore phase, ensuring high ionic conductivity through reproducible precision rather than extreme precision requirements.
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 produces a dense solid electrolyte with high ionic conductivity, enabling the production of lithium-ion secondary batteries with improved energy density and safety by minimizing grain boundary resistance and hetero-phases.
Implementation Method 1
pulverizing the fired product to obtain a pulverized product, wherein the fired product is pulverized in an organic solvent using a bead mill
Implementation Method 2
heat-treating the pulverized product to obtain a heat-treated product
Implementation Method 3
it is possible to obtain a fine powder including fewer hetero-phases and that use of the powder makes it possible to produce a dense solid electrolyte having high ionic conductivity
Data Source
AI summary
Provided are a composite oxide powder from which dense solid electrolyte objects having a high ion conductivity can be produced and a method for producing the composite oxide powder. The composite oxide powder is composed of particles comprising lithium (Li), lanthanum (La), zirconium (Zr), and oxygen (O) and having a cubic garnet-type crystal structure, and has a volume particle size distribution in which the 50% diameter (D50) is 1,000 nm or smaller, the composite oxide powder having a pyrochlore phase content of 10 mass % or less.