Nanosized LLZO Synthesis via Polymer-Chelate Combustion
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Solution Overview
Problem
Current methods for synthesizing lithium lanthanum zirconate (LLZO) require high temperatures and extrinsic dopants, leading to impurity phases and reduced conductivity due to the instability of the cubic phase at room temperature.
Innovation Solution
Reducing the crystallite size of LLZO to nanometric dimensions stabilizes the cubic phase at low temperatures without extrinsic dopants, using a polymer-mediated synthesis that forms a carbonaceous foam to distribute lithium, lanthanum, and zirconium, allowing for lower temperature processing and higher conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If solid state reactions with high temperatures and extrinsic dopants are used to synthesize LLZO, then the cubic phase can be stabilized at room temperature, but impurity phases form at interfaces and grain boundaries resulting in reduced overall conductivity
Solution Approach 1:
The patent changes the synthesis approach from solid state reaction to solution-based combustion synthesis, altering the physical and chemical parameters of the process. This enables dopant-free cubic LLZO formation by changing how the material is synthesized, avoiding impurity formation while maintaining phase stability
Solution Approach 2:
The patent removes extrinsic dopants from the synthesis process entirely. By using combustion synthesis with controlled oxidation, the cubic phase can be stabilized without adding foreign elements that would create impurity phases at grain boundaries, thus extracting the harmful dopant component while maintaining the desired cubic structure
2Stability of the object's composition
If high temperatures are used in solid state reactions to stabilize the cubic phase, then the cubic LLZO can be obtained, but lithium volatilization increases and energy consumption rises
Solution Approach 1:
The patent replaces the traditional solid state mechanical reaction process with a solution-based combustion synthesis process. This substitution allows the reaction to proceed at lower temperatures through chemical combustion mechanisms rather than requiring prolonged high-temperature thermal treatment, reducing energy consumption while achieving the same cubic phase stabilization
Solution Approach 2:
The patent changes the temperature parameter from high temperature (solid state reaction) to lower temperature (combustion synthesis). The combustion process provides localized high energy that enables phase transformation at lower overall temperatures, reducing lithium volatilization and energy loss
3Stability of the object's composition
If repeated heat treatments and ball milling are used in solid state reactions, then the cubic phase can be formed, but the process complexity and time increase
Solution Approach 1:
The patent merges multiple separate steps (mixing, heating, cooling, repeated treatments) into a single combustion synthesis step. The solution-based approach allows all reactants to be pre-mixed at the molecular level, and the combustion process simultaneously achieves decomposition, reaction, and phase formation in one operation, eliminating the need for repeated heat treatments and ball milling
Solution Approach 2:
The patent performs preliminary mixing of all reactants in solution form before the combustion reaction. This pre-mixing at the molecular level ensures homogeneous distribution of elements, eliminating the need for subsequent ball milling and repeated heat treatments to achieve uniform cubic phase formation
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 achieves high conductivity and stability of the cubic phase in LLZO, reducing lithium volatilization and energy consumption, enabling simpler and less costly device fabrication with enhanced densification and sintering properties.
Implementation Method 1
the solid is heated in the presence of oxygen to pyrolyze the organic compound to yield a product including nanosized cubic LLZO
Implementation Method 2
Heating the solid typically includes forming a carbonaceous foam including the organic compound or a degradation product thereof
Implementation Method 3
the onset temperature of sintering is substantially lower for nanosized ceramic particles due to the relatively higher surface energy of nanoparticles compared to bulk particles
Data Source
AI summary
Nanosized cubic lithium lanthanum zirconate is synthesized by forming a solution including an organic compound and compounds of lithium, lanthanum, and zirconium; drying the solution to yield a solid; and heating the solid in the presence of oxygen to pyrolyze the organic compound to yield a product comprising nanosized cubic lithium lanthanum zirconate.