Cubic LLZO Nanopowder Synthesis at Lower Temperature
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Solution Overview
Problem
Current methods for synthesizing lithium lanthanum zirconate (LLZO) require high temperatures, lengthy processes, and often result in impurity phases due to the use of extrinsic dopants, which reduces the overall ionic conductivity.
Innovation Solution
A molten salt synthesis method is employed, where a reagent composition with a lithium:lanthanum:zirconium molar ratio of 7:3:2 is combined with a salt composition to form a molten salt reaction medium, which is then heated to produce phase-pure, cubic LLZO nanoparticles without the need for extrinsic dopants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid state reaction method is used to synthesize cubic LLZO, then high lithium-ion conductivity is achieved, but high temperatures (>600°C) and lengthy processes are required
Solution Approach 1:
The patent changes the synthesis method from solid state reaction to molten salt reaction, fundamentally altering the reaction parameters. This allows cubic LLZO to be synthesized at lower temperatures (500-700°C) while maintaining high lithium-ion conductivity, as the molten salt medium enables ion transport and reaction at reduced temperatures compared to traditional solid state methods
Solution Approach 2:
The patent utilizes the phase transition of the salt medium from solid to molten state to enable the reaction. By heating the salt composition to its melting point and maintaining it in the molten state during synthesis, the process achieves lower temperature requirements than solid state reactions while still producing the thermodynamically stable cubic phase at room temperature
2Stability of the object's composition
If extrinsic dopants are added to stabilize cubic phase, then cubic phase stability is improved, but impurity phases form at interfaces and grain boundaries
Solution Approach 1:
The patent extracts and eliminates the need for extrinsic dopants by using a molten salt synthesis approach that inherently stabilizes the cubic phase through controlled cooling and phase transformation. This removal of dopant requirements prevents the formation of impurity phases at interfaces and grain boundaries, achieving both cubic phase stability and high phase purity simultaneously
Solution Approach 2:
The molten salt medium acts as an intermediary that facilitates the formation of pure cubic LLZO without requiring extrinsic dopants. The salt composition mediates the reaction process, enabling controlled crystallization and phase stabilization during cooling, thereby achieving phase purity while maintaining cubic structure stability
3Stability of the object's composition
If repeated heat treatments and ball milling are used, then cubic phase formation is achieved, but process time and complexity increase
Solution Approach 1:
The patent performs preliminary mixing of reagents in the molten salt medium before the actual synthesis reaction. This preliminary action ensures homogeneous distribution of reactants and pre-establishes the conditions for cubic phase formation, eliminating the need for subsequent repeated heat treatments and ball milling steps, thereby significantly reducing total synthesis time
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 allows for the synthesis of cubic LLZO at lower temperatures and in shorter times, stabilizing the cubic phase at room temperature and achieving high lithium-ion conductivity, while minimizing impurity phases and reducing energy consumption.
Implementation Method 1
combining a reagent composition with a salt composition to yield a molten salt reaction medium
Implementation Method 2
The molten salt reaction medium is heated to yield a reaction product
Implementation Method 3
the reaction product is washed to yield a crystalline powder including lithium lanthanum zirconate
Data Source
AI summary
Synthesizing lithium lanthanum zirconate includes combining a reagent composition with a salt composition to yield a molten salt reaction medium, wherein the reagent composition comprises a lithium component, a lanthanum component, and zirconium component having a lithium:lanthanum:zirconium molar ratio of about 7:3:2; heating the molten salt reaction medium to yield a reaction product; and washing the reaction product to yield a crystalline powder comprising lithium lanthanum zirconate.