Garnet Oxide Electrolyte with Dual Tetragonal Phases for High Li Conductivity
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Solution Overview
Problem
The production of garnet-type oxides with high lithium ion conductivity requires rigorous control of raw materials and firing methods to stabilize the cubic phase, making the process complex and difficult.
Innovation Solution
The development of an oxide with a garnet-type crystal structure containing Li, La, and Zr, featuring at least two tetragonal phases with different lattice constants and specific Li occupancy, allowing for a simpler production method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rigorous control of raw material preparation and firing method is applied to stabilize the cubic phase, then high ion conductivity is achieved, but manufacturing complexity increases
Solution Approach 1:
The invention changes the crystal structure parameter from cubic to tetragonal system with specific space group I41/amd, and controls Li occupancy at 8a sites to be 95% or less. This parameter change allows the material to achieve high ion conductivity (10^-4 S/cm or higher at room temperature) while being producible through simpler firing processes without requiring rigorous control to stabilize the cubic phase.
Solution Approach 2:
The invention utilizes the tetragonal phase of LLZ that can be stabilized through controlled Li occupancy rather than requiring the cubic phase transition. By maintaining Li occupancy at 8a sites at 95% or less, the tetragonal phase is stabilized and exhibits high ion conductivity, eliminating the need for complex cubic phase stabilization procedures.
2Reliability
If cubic phase stabilization is pursued through element substitution, then high ion conductivity is achieved, but production difficulty increases
Solution Approach 1:
Instead of substituting elements to stabilize the cubic phase, the invention changes the occupancy parameter of Li at 8a sites to be 95% or less. This simpler parameter control enables the tetragonal phase to exhibit high ion conductivity without requiring complex element substitution and rigorous compositional control.
Solution Approach 2:
The invention inverts the conventional approach by not trying to stabilize the cubic phase through element substitution, but rather by stabilizing the tetragonal phase through controlled Li occupancy. This inverted strategy simplifies the production process while achieving the same high ion conductivity goal.
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 enables the production of an oxide with ion conductivity up to 100 times higher than existing tetragonal LLZ, facilitating easier and more efficient manufacturing of power storage devices.
Implementation Method 1
an oxide which has a garnet-type crystal structure including Li, Zr, and La exhibits high chemical stability and a lithium ion-conductive property
Data Source
AI summary
An oxide which has a garnet-type crystal structure including Li, La, and Zr, in which the crystal structure includes a first tetragonal phase and a second tetragonal phase, a lattice constant of the first tetragonal phase and a lattice constant of the second tetragonal phase are different from each other, a ratio (a/c) of a and c of the lattice constant of the first tetragonal phase falls within a range of 1.003 to 1.03, and a ratio (a/c) of a and c of the lattice constant of the second tetragonal phase falls within a range of 1.001 to 1.01.